Patent Publication Number: US-10759147-B2

Title: Laminated glass article and method for forming the same

Description:
This application is a divisional of U.S. patent application Ser. No. 15/309,055 filed on May 7, 2015 which claims the benefit of priority under 35 U.S.C. § 371 of International Application No. PCT/US2015/029671 filed May 7, 2015, which claims the benefit of priority to U.S. Application No. 61/989,704 filed May 7, 2014 the content of each of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     This disclosure relates to glass articles, and more particularly to laminated glass articles comprising a plurality of glass layers and methods for forming the same. 
     2. Technical Background 
     A glass article can be molded to form a shaped glass article having a non-planar or 3-dimensional shape. Typically, a glass article is heated to its softening point and then deformed to conform to the surface of a solid mold. 
     SUMMARY 
     Disclosed herein are laminated glass articles and methods for forming the same. 
     Disclosed herein is a glass article comprising a glass core layer and a glass cladding layer adjacent to the core layer. An average coefficient of thermal expansion (CTE) of the core layer is greater than an average CTE of the cladding layer. An effective 10 9.9  P temperature of the glass article is at most about 750° C. 
     Also disclosed herein is a method comprising contacting a glass sheet with a forming surface to form a shaped glass article. The glass sheet comprises a glass core layer and a glass cladding layer adjacent to the core layer. An average coefficient of thermal expansion (CTE) of the core layer is greater than an average CTE of the cladding layer. An effective 10 9.9  P temperature of the glass sheet is at most about 750° C. 
     Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of one exemplary embodiment of a glass article. 
         FIG. 2  is a cross-sectional view of one exemplary embodiment of an overflow distributor that can be used to form a glass article. 
         FIG. 3  is a schematic view of one exemplary embodiment of an automobile. 
         FIG. 4  is a graphical illustration of the predicted strength profiles of one exemplary embodiment of a glass article and an exemplary tempered glass sheet presented as retained strength. 
         FIG. 5  is a graphical illustration of the predicted strength profiles of one exemplary embodiment of a glass article and an exemplary tempered glass sheet presented as failure load. 
         FIG. 6  is a graphical illustration of the predicted strength profiles of one exemplary embodiment of a glass article and an exemplary ion exchanged glass sheet presented as failure load. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the exemplary embodiments. 
     As used herein, the term “average coefficient of thermal expansion” refers to the average coefficient of thermal expansion of a given material or layer between 0° C. and 300° C. As used herein, the term “coefficient of thermal expansion” refers to the average coefficient of thermal expansion unless otherwise indicated. 
     As used herein, the term “strength profile” refers to the strength of a glass article determined after introduction of flaws into an outer surface of the glass article as a function of flaw size. In some embodiments, the strength of the glass article is presented as failure load, which is a measure of the rigidity of the glass article up to catastrophic failure. In other embodiments, the strength of the glass article is presented as retained strength, which is based on the failure load normalized by the thickness of the glass article. The flaw size comprises the depth of the flaw measured from the outer surface of the glass, which can be determined using fractography analysis. 
     As used herein, the term “10 9.9  P temperature” of a glass composition, a glass layer, or a glass article refers to the temperature at which the glass composition, glass layer, or glass article has a viscosity of about 10 9.9  Poise (P). 
     In various embodiments, a glass article comprises at least a first layer and a second layer. For example, the first layer comprises a core layer, and the second layer comprises one or more cladding layers adjacent to the core layer. The first layer and/or the second layer are glass layers comprising a glass, a glass-ceramic, or a combination thereof. In some embodiments, the first layer and/or the second layer are transparent glass layers. The glass article can comprise a glass sheet or a shaped glass article comprising a suitable 3-dimensional (3D) shape. In some embodiments, a glass sheet can be formed into a shaped glass article. An average coefficient of thermal expansion (CTE) of the first layer is greater than an average CTE of the second layer. Such a CTE mismatch can aid in strengthening the glass article. An effective 10 9.9  Poise (P) temperature of the glass article is at most about 750° C. Such a relatively low effective 10 9.9  P temperature can enable forming of glass articles having various 3D shapes. 
       FIG. 1  is a cross-sectional view of one exemplary embodiment of a glass article  100 . In some embodiments, glass article  100  comprises a laminated sheet comprising a plurality of glass layers. The laminated sheet can be substantially planar as shown in  FIG. 1  or non-planar. In other embodiments, the glass article comprises a shaped glass article. For example, the laminated sheet contacted with a forming surface of a mold to form the shaped glass article. Glass article  100  comprises a core layer  102  disposed between a first cladding layer  104  and a second cladding layer  106 . In some embodiments, first cladding layer  104  and second cladding layer  106  are exterior layers as shown in  FIG. 1 . In other embodiments, the first cladding layer and/or the second cladding layer are intermediate layers disposed between the core layer and an exterior layer. 
     Core layer  102  comprises a first major surface and a second major surface opposite the first major surface. In some embodiments, first cladding layer  104  is fused to the first major surface of core layer  102 . Additionally, or alternatively, second cladding layer  106  is fused to the second major surface of core layer  102 . In such embodiments, the interfaces between first cladding layer  104  and core layer  102  and/or between second cladding layer  106  and core layer  102  are free of any bonding material such as, for example, a polymer interlayer, an adhesive, a coating layer, or any non-glass material added or configured to adhere the respective cladding layers to the core layer. Thus, first cladding layer  104  and/or second cladding layer  106  are fused directly to core layer  102  or are directly adjacent to core layer  102 . In some embodiments, the glass article comprises one or more intermediate layers disposed between the core layer and the first cladding layer and/or between the core layer and the second cladding layer. For example, the intermediate layers comprise intermediate glass layers and/or diffusion layers formed at the interface of the core layer and the cladding layer. The diffusion layer can comprise a blended region comprising components of each layer adjacent to the diffusion layer. In some embodiments, glass sheet  100  comprises a glass-glass laminate (e.g., an in situ fused multilayer glass-glass laminate) in which the interfaces between directly adjacent glass layers are glass-glass interfaces. 
     In some embodiments, core layer  102  comprises a first glass composition, and first and/or second cladding layers  104  and  106  comprise a second glass composition that is different than the first glass composition. For example, in the embodiment shown in  FIG. 1 , core layer  102  comprises the first glass composition, and each of first cladding layer  104  and second cladding layer  106  comprises the second glass composition. In other embodiments, the first cladding layer comprises the second glass composition, and the second cladding layer comprises a third glass composition that is different than the first glass composition and/or the second glass composition. 
     The glass article can be formed using a suitable process such as, for example, a fusion draw, down draw, slot draw, up draw, or float process. In some embodiments, the glass article is formed using a fusion draw process.  FIG. 2  is a cross-sectional view of one exemplary embodiment of an overflow distributor  200  that can be used to form a glass article such as, for example, glass article  100 . Overflow distributor  200  can be configured as described in U.S. Pat. No. 4,214,886, which is incorporated herein by reference in its entirety. For example, overflow distributor  200  comprises a lower overflow distributor  220  and an upper overflow distributor  240  positioned above the lower overflow distributor. Lower overflow distributor  220  comprises a trough  222 . A first glass composition  224  is melted and fed into trough  222  in a viscous state. First glass composition  224  forms core layer  102  of glass article  100  as further described below. Upper overflow distributor  240  comprises a trough  242 . A second glass composition  244  is melted and fed into trough  242  in a viscous state. Second glass composition  244  forms first and second cladding layers  104  and  106  of glass article  100  as further described below. 
     First glass composition  224  overflows trough  222  and flows down opposing outer forming surfaces  226  and  228  of lower overflow distributor  220 . Outer forming surfaces  226  and  228  converge at a draw line  230 . The separate streams of first glass composition  224  flowing down respective outer forming surfaces  226  and  228  of lower overflow distributor  220  converge at draw line  230  where they are fused together to form core layer  102  of glass article  100 . 
     Second glass composition  244  overflows trough  242  and flows down opposing outer forming surfaces  246  and  248  of upper overflow distributor  240 . Second glass composition  244  is deflected outward by upper overflow distributor  240  such that the second glass composition flows around lower overflow distributor  220  and contacts first glass composition  224  flowing over outer forming surfaces  226  and  228  of the lower overflow distributor. The separate streams of second glass composition  244  are fused to the respective separate streams of first glass composition  224  flowing down respective outer forming surfaces  226  and  228  of lower overflow distributor  220 . Upon convergence of the streams of first glass composition  224  at draw line  230 , second glass composition  244  forms first and second cladding layers  104  and  106  of glass article  100 . 
     In some embodiments, first glass composition  224  of core layer  102  in the viscous state is contacted with second glass composition  244  of first and second cladding layers  104  and  106  in the viscous state to form the laminated sheet. In some of such embodiments, the laminated sheet is part of a glass ribbon traveling away from draw line  230  of lower overflow distributor  220  as shown in  FIG. 2 . The glass ribbon can be drawn away from lower overflow distributor  220  by a suitable means including, for example, gravity and/or pulling rollers. The glass ribbon cools as it travels away from lower overflow distributor  220 . The glass ribbon is severed to separate the laminated sheet therefrom. Thus, the laminated sheet is cut from the glass ribbon. The glass ribbon can be severed using a suitable technique such as, for example, scoring, bending, thermally shocking, and/or laser cutting. In some embodiments, glass article  100  comprises the laminated sheet as shown in  FIG. 1 . In other embodiments, the laminated sheet can be processed further (e.g., by cutting or molding) to form glass article  100 . 
     Although glass article  100  shown in  FIG. 1  comprises three layers, other embodiments are included in this disclosure. In other embodiments, a glass article can have a determined number of layers, such as two, four, or more layers. For example, a glass article comprising two layers can be formed using two overflow distributors positioned so that the two layers are joined while traveling away from the respective draw lines of the overflow distributors or using a single overflow distributor with a divided trough so that two glass compositions flow over opposing outer forming surfaces of the overflow distributor and converge at the draw line of the overflow distributor. A glass article comprising four or more layers can be formed using additional overflow distributors and/or using overflow distributors with divided troughs. Thus, a glass article having a determined number of layers can be formed by modifying the overflow distributor accordingly. 
     In some embodiments, glass article  100  comprises a thickness of at least about 0.05 mm, at least about 0.1 mm, at least about 0.2 mm, or at least about 0.3 mm. Additionally, or alternatively, glass article  100  comprises a thickness of at most about 3 mm, at most about 2 mm, at most about 1.5 mm, at most about 1 mm, at most about 0.7 mm, or at most about 0.5 mm. For example, glass article comprises a thickness of from about 0.2 mm to about 3 mm, from about 1 mm to about 3 mm, or from about 1.5 mm to about 2.5 mm. In some embodiments, a ratio of a thickness of core layer  102  to a thickness of glass article  100  is at least about 0.7, at least about 0.8, at least about 0.85, at least about 0.9, or at least about 0.95. In some embodiments, a thickness of the second layer (e.g., each of first cladding layer  104  and second cladding layer  106 ) is from about 0.01 mm to about 0.3 mm. 
     In some embodiments, glass article  100  is configured as a strengthened glass article. For example, in some embodiments, the second glass composition of first and/or second cladding layers  104  and  106  comprises a different average coefficient of thermal expansion (CTE) than the first glass composition of core layer  102 . For example, first and second cladding layers  104  and  106  are formed from a glass composition having a lower average CTE than core layer  102 . The CTE mismatch (i.e., the difference between the average CTE of first and second cladding layers  104  and  106  and the average CTE of core layer  102 ) results in formation of compressive stress in the cladding layers and tensile stress in the core layer upon cooling of glass article  100 . In various embodiments, each of the first and second cladding layers, independently, can have a higher average CTE, a lower average CTE, or substantially the same average CTE as the core layer. 
     In some embodiments, the average CTE of core layer  102  and the average CTE of first and/or second cladding layers  104  and  106  differ by at least about 5×10 −7 ° C. −1 , at least about 15×10 −7 ° C. −1 , at least about 25×10 −7 ° C. −1 , or at least about 30×10 −7 ° C. −1 . Additionally, or alternatively, the average CTE of core layer  102  and the average CTE of first and/or second cladding layers  104  and  106  differ by at most about 100×10 −7 ° C. −1 , at most about 75×10 −7 ° C. −1 , at most about 50×10 −7 ° C. −1 , at most about 40×10 −7 ° C. −1 , at most about 30×10 −7 ° C. −1 , at most about 20×10 −7 ° C. −1 , or at most about 10×10 −7 ° C. −1 . In some embodiments, the second glass composition of first and/or second cladding layers  104  and  106  comprises an average CTE of at most about 66×10 −7 ° C. −1 , at most about 55×10 −7 ° C. −1 , at most about 50×10 −7 ° C. −1 , at most about 40×10 −7 ° C. −1 , or at most about 35×10 −7 ° C. −1 . Additionally, or alternatively, the second glass composition of first and/or second cladding layers  104  and  106  comprises an average CTE of at least about 25×10 −7 ° C. −1 , or at least about 30×10 −7 ° C. −1 . Additionally, or alternatively, the first glass composition of core layer  102  comprises an average CTE of at least about 40×10 −7 ° C. −1 , at least about 50×10 −7 ° C. −1 , at least about 55×10 −7 ° C. −1 , at least about 65×10 −7 ° C. −1 , at least about 70×10 −7 ° C. −1 , at least about 80×10 −7 ° C. −1 , or at least about 90×10 −7 ° C. −1 . Additionally, or alternatively, the first glass composition of core layer  102  comprises an average CTE of at most about 110×10 −7 ° C. −1 , at most about 100×10 −7 ° C. −1 , at most about 90×10 −7 ° C. −1 , at most about 75×10 −7 ° C. −1 , or at most about 70×10 −7 ° C. −1 . 
     In various embodiments, the relative thicknesses of the glass layers can be selected to achieve a glass article having desired strength properties. For example, in some embodiments, the first glass composition of core layer  102  and the second glass composition of first and/or second cladding layers  104  and  106  are selected to achieve a desired CTE mismatch, and the relative thicknesses of the glass layers are selected, in combination with the desired CTE mismatch, to achieve a desired compressive stress in the cladding layers and tensile stress in the core layer. Without wishing to be bound by any theory, it is believed that the strength profile of the glass article can be determined predominantly by the relative thicknesses of the glass layers and the compressive stress in the cladding layers, and that the breakage pattern of the glass article can be determined predominantly by the relative thicknesses of the glass layers and the tensile stress in the core layer. Thus, the glass compositions and relative thicknesses of the glass layers can be selected to achieve a glass article having a desired strength profile and/or breakage pattern. The glass article can have the desired strength profile and/or breakage pattern in an as-formed condition without additional processing (e.g., thermal tempering or ion-exchange treatment). For example, the as-formed glass sheet or shaped glass article can have an improved strength profile as compared to thermally tempered or ion-exchanged glass articles as described herein. 
     In some embodiments, the compressive stress of the cladding layers is at most about 800 MPa, at most about 500 MPa, at most about 350 MPa, or at most about 150 MPa. Additionally, or alternatively, the compressive stress of the cladding layers is at least about 10 MPa, at least about 20 MPa, at least about 30 MPa, at least about 50 MPa, or at least about 250 MPa. Additionally, or alternatively, the tensile stress of the core layer is at most about 150 MPa, or at most about 100 MPa. Additionally, or alternatively, the tensile stress of the core layer is at least about 5 MPa, at least about 10 MPa, at least about 25 MPa, or at least about 50 MPa. 
     In some embodiments, glass article  100  is configured as a durable glass article. For example, glass article  100  is resistant to degradation in response to exposure to a reagent. In some embodiments, the second glass composition of the first and/or second cladding layers  104  and  106  comprises a durable glass composition that is resistant to degradation in response to exposure to the reagent. In some embodiments, the glass article comprises a core enveloped within a cladding. For example, core layer  102  is enveloped within a cladding comprising first cladding layer  104  and second cladding layer  106  as shown in  FIG. 1 . In some of such embodiments, the first glass composition of core layer  102  comprises a non-durable glass composition that is non-resistant to degradation in response to exposure to the reagent. The durable cladding can aid in protecting the core from exposure to the reagent. In other embodiments, the first glass composition comprises a durable glass composition that is resistant to degradation in response to exposure to the reagent. Thus, because the core is enveloped within the cladding, the first glass composition of the core of the durable glass article can comprise a durable or non-durable glass composition. 
     In various embodiments, the reagent comprises, an acid, a base, or a combination thereof. In some embodiments, the reagent comprises an acid such as, for example, a mineral acid (e.g., HCl, HNO 3 , H 2 SO 4 , H 3 PO 4 , H 3 BO 3 , HBr, HClO 4 , or HF), a carboxylic acid (e.g., CH 3 COOH), or a combination thereof. For example, in some embodiments, the reagent comprises HCl (e.g., 5 vol % aqueous HCl solution). Additionally, or alternatively, the reagent comprises HNO 3  (e.g., 1 M aqueous HNO 3  solution). Additionally, or alternatively, the reagent comprises H 2 SO 4  (e.g., 0.02 N aqueous H 2 SO 4  solution). In some embodiments, the reagent comprises a base such as, for example, LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH) 2 , Sr(OH) 2 , Ba(OH) 2 , or a combination thereof. In some embodiments, the reagent comprises a soap (e.g., potassium oleate), kerosene, an alcohol (e.g., undiluted denatured alcohol such as Formula SD No. 30, methyl alcohol, ethyl alcohol, and/or isopropanol), gasoline, an ether (e.g., a glycol ether such as glycol monomethyl ether), ammonia (e.g., ammonium hydroxide), water, or combinations thereof. 
     The chemical durability of a glass composition can be represented by a degradation rate of the glass composition in response to exposure to a reagent at a particular temperature for a particular period of time. The degradation rate can be expressed, for example, as mass of the sample lost per surface area of the sample. In some embodiments, a degradation rate of the second glass composition of first and/or second cladding layers  104  and  106  in response to exposure to a 5 vol % aqueous HCl solution at 95° C. for 6 h is at most about 0.018 mg/cm 2 , at most about 0.009 mg/cm 2 , or at most about 0.005 mg/cm 2 . Additionally, or alternatively, a degradation rate of the second glass composition of first and/or second cladding layers  104  and  106  in response to exposure to a 1 M aqueous HNO 3  solution at 95° C. for 24 h is at most about 0.08 mg/cm 2 , at most about 0.06 mg/cm 2 , or at most about 0.03 mg/cm 2 . Additionally, or alternatively, a degradation rate of the second glass composition of first and/or second cladding layers  104  and  106  in response to exposure to a 0.02 N aqueous H 2 SO 4  solution at 95° C. for 24 h is at most about 0.04 mg/cm 2 , at most about 0.02 mg/cm 2 , or at most about 0.005 mg/cm 2 . In other embodiments, chemical durability of a glass composition is determined as described in ANSI Z26.1, Test 19; RECE R43, Test A3/6; ISO 695; ISO 720; DIN 12116; each of which is incorporated by reference herein in its entirety; or a similar standard. 
     In some embodiments, glass article  100  is configured as a formable glass article. For example, glass article  100  is contacted with a forming surface of a forming unit to form a shaped glass article. Such a process can be referred to as a reforming process or a molding process. In some embodiments, glass article  100  comprises a substantially planar glass sheet, and the shaped glass article comprises a non-planar 3D shape. In other embodiments, the glass article comprises a non-planar 3D shape, and the shaped glass article comprises a different non-planar 3D shape. The forming unit can comprise a suitable mold including, for example, a vacuum mold, a pressure mold, a sagging mold, or a press mold. Glass article  100  is heated to a forming temperature that is sufficiently high that, in response to contacting the glass article at the forming temperature with the forming surface, the glass article is deformed. In some embodiments, glass article  100  is deformed to conform to the contour of the forming surface. Thus, the resulting formed glass article comprises a 3D shape that is complementary to the shape of the forming surface. In other embodiments, glass article  100  is deformed to sag into a void of the forming surface (e.g., a central void of a ring-shaped mold). Thus, the resulting formed glass article comprises a curved 3D shape sloping inward from the forming surface. The viscosity of glass article  100  at the forming temperature is low enough to allow viscous deformation to form the shaped glass article with the desired 3D shape (e.g., to achieve a sufficiently small bend radius). Thus, a relatively low viscosity at the forming temperature can aid in achieving a shaped glass article with the desired 3D shape. In some embodiments, the forming surface is coated with a coating material to reduce glass surface damage and/or mold degradation. 
     An effective 10 9.9  P temperature T 9.9P,eff  of glass article  100  can be indicative of the formability of the glass article. Effective 10 9.9  P temperature T 9.9,Peff  of glass article  100  comprises a thickness weighted average 10 9.9  P temperature of the glass article. For example, in some embodiments, core layer  102  comprises a thickness t core , and each of first cladding layer  104  and second cladding layer  106  comprises a thickness t clad . The first glass composition comprises a 10 9.9  P temperature T 9.9P,core , and the second glass composition comprises a 10 9.9  P temperature T 9.9P,clad . Thus, the effective 10 9.9  P temperature of glass article  100  is represented by equation 1. 
     
       
         
           
             
               
                 
                   
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     In some embodiments, effective 10 9.9  P temperature T 9.9P,eff  of glass article  100  is at most about 750° C., at most about 725° C., at most about 700° C., or at most about 675° C. Such a relatively low effective 10 9.9  P temperature T 9.9P,eff  of glass article  100  can enable forming of the glass article into a shaped glass article having a desired 3D shape. For example, glass article  100  can be formed into a 3D shape at a forming temperature similar to the temperatures generally used for 3D forming of soda lime glass. 
     In various embodiments, a glass article can be used in applications in which strength, chemical durability, and/or formability are beneficial. For example, chemical durability can be beneficial for applications in which the glass will be used outdoors (e.g., automotive glass or architectural glass) or for other applications in which the glass article is likely to come into contact with potentially corrosive reagents such as acids or bases (e.g., laboratory benchtops). Strength and formability can be beneficial in these same applications to avoid breakage of the glass article and to enable the glass article to take on a variety of 3D shapes. 
     Conventional shaped glass articles generally are formed from soda lime glass. Thus, many forming industries (e.g., automotive glass or architectural glass forming industries) have equipment designed to form or mold soda lime glass. In some embodiments, a glass article (e.g., a laminated glass sheet) can be formed at temperatures similar to the temperatures used to form soda lime glass. Thus, the glass article can be formed on the same equipment conventionally used to form soda lime glass. The glass article can have chemical durability similar to that of soda lime glass and strength greater than that of soda lime glass at a lower thickness. Thus, the glass article can be used as a replacement for a similar soda lime glass article while providing increased strength and reduced weight (e.g., as a result of the reduced thickness). 
     In some embodiments, an automotive glazing comprises glass article  100 .  FIG. 3  is a schematic view of one exemplary embodiment of an automobile  300 . Automobile  300  can comprise an automotive glazing including, for example, a windshield, a sidelite (e.g., a door glass or a quarter window), a sun roof, a moon roof, a rear backlite, a lighting cover (e.g., a headlamp or taillamp cover), a mirror (e.g., a side mirror or a rearview mirror), an instrument panel or gauge cover, an interior or exterior panel (e.g., for a pillar or other applique), or another suitable glass or window. In the embodiment shown in  FIG. 3 , the automotive glazing comprises a windshield  302 , door glass  304 , a sun roof  306 , and a rear backlite  308 , any or all of which can comprise glass article  100 . 
     In some embodiments, rear backlite  308  comprises glass article  100 . Rear backlite  308  comprises a non-planar curved shape. For example, rear backlite  308  is curved to wrap around a rear portion of the passenger compartment of automobile  300 . In some embodiments, rear backlite  308  comprises a pattern  310  printed on a surface thereof (e.g., an inside surface and/or an outside surface). For example, pattern  310  comprises a plurality of lines or curves, a grid, or another suitable pattern. In some embodiments, pattern  310  comprises a conductive pattern. For example, pattern  310  comprises a conductive ink or enamel that is applied to the surface of rear backlite  308  and then set (e.g., by curing or firing). Thus, pattern  310  can serve as a defroster or an antenna integrated into rear backlite  308 . 
     In some embodiments, glass article  100  comprises a glass sheet. The glass sheet is contacted with a forming surface to form a shaped glass article. In some embodiments, the glass sheet is strengthened as described herein (e.g., by CTE mismatch). Additionally, or alternatively, the glass sheet is formable as described herein (e.g., by comprising a low effective 10 9.9  P temperature T 9.9P,eff ). In some embodiments, pattern  310  is printed on the glass sheet prior to contacting the glass sheet with the forming surface. For example, pattern  310  is printed on the glass sheet while the glass sheet is substantially planar, which can enable use of a variety of printing processes. In some embodiments, the printing process is selected from the group consisting of screen printing, flexographic printing, gravure printing, photo pattern printing, pad printing, and combinations thereof. The formability of the glass sheet enables forming of the glass sheet with the pattern printed thereon at a relatively low temperature (e.g., at or near effective 10 9.9  P temperature T 9.9P,eff ) to form the shaped glass article. Thus, the glass sheet is formable into the shaped glass article without damaging the pattern printed on the glass sheet. In some embodiments, the glass sheet is fired after the printing step and prior to or concurrent with the contacting step. 
     In some embodiments, other components of automobile  300  including, for example, light covers (e.g., for headlights, taillights, turn signals, or fog lights), mirrors (e.g., rearview mirror or sideview mirrors), or instrument covers can comprise glass article  100 . 
     In some embodiments, a display (e.g., an LED or LCD display) comprises glass article  100 . For example, the display comprises a cover glass comprising glass article  100 . In some embodiments, the cover glass comprises an integrated cover glass and color filter. In some embodiments, the cover glass comprises an integrated touch cover glass. 
     In some embodiments, an architectural panel comprises glass article  100 . 
     The first glass composition of core layer  102  and the second glass composition of first and/or second cladding layers  104  and  106  can comprise suitable glass compositions capable of forming a glass article with desired properties as described herein. Exemplary glass compositions and selected properties of the exemplary glass compositions are shown in Tables 1 and 2, respectively. The amounts of the various components are given in Table 1 as mol % on an oxide basis. The chemical durability data reported as “5% HCl, 95° C., 6 h (mg/cm 2 )” was determined using the following procedure. A glass sample with a width of about 2.5 cm, a length of about 2.5 cm, and a thickness of about 0.05 cm to about 0.08 cm was soaked in Opticlear at 40° C. and rinsed with IPA. The glass sample was wiped with cheese cloth while rinsing with deionized water and then dried at 140° C. for at least 30 minutes. 200 mL of an aqueous 5% HCl solution was added to a preleached 250 ml FEP bottle and preheated for about 1-2 hours in an oven set at 95° C. The glass sample was leaned upright against the side wall of the bottle and allowed to soak for 6 hours at 95° C. About 15 mL of the resulting solution was poured into a centrifuge tube and reserved for ICP. The remainder of the solution was disposed of and the glass sample, still remaining in the bottle, was immediately quenched in deionized water. After quenching, the glass sample was retrieved from the bottle, rinsed in deionized water, and dried at 140° C. for at least 30 minutes. The weight loss of the glass sample was measured and the chemical durability was determined as weight loss per unit surface area. The chemical durability data reported as “1 M HNO 3 , 95° C., 24 h (mg/cm 2 )” was determined using the same procedure except that a 1 M HNO 3  solution was substituted for the HCl solution and the glass sample was allowed to soak in the acid solution for 24 hours as opposed to 6 hours. The chemical durability data reported as “0.2 N H 2 SO 4 , 95° C., 24 h (mg/cm 2 )” was determined using the same procedure except that a 0.2 N H 2 SO 4  solution was substituted for the HCl solution and the glass sample was allowed to soak in the acid solution for 24 hours as opposed to 6 hours. 
     In various embodiments, a glass article comprises a first layer (e.g., a core layer) comprising one of the exemplary glass compositions and a second layer (e.g., one or more cladding layers) comprising another of the exemplary glass compositions. The glass compositions of the first layer and the second layer are selected such that the glass article comprises strength, chemical durability, and/or formability properties as described herein. For example, the glass compositions of the first layer and the second layer are selected such that the glass article comprises a desired CTE mismatch. Additionally, or alternatively, the glass composition of the second layer is selected such that the glass article comprises a desired chemical durability. Additionally, or alternatively, the glass compositions of the first layer and the second layer are selected such that the glass article comprises a desired effective 10 9.9  P temperature, or another desired effective viscosity temperature. 
     In some embodiments, the first glass composition comprises a glass network former selected from the group consisting of SiO 2 , Al 2 O 3 , B 2 O 3 , P 2 O 5 , and combinations thereof. For example, the first glass composition comprises at least about 45 mol % SiO 2 , at least about 50 mol % SiO 2 , at least about 60 mol % SiO 2 , at least about 70 mol % SiO 2 , or at least about 75 mol % SiO 2 . Additionally, or alternatively, the first glass composition comprises at most about 80 mol % SiO 2 , at most about 75 mol % SiO 2 , at most about 60 mol % SiO 2 , or at most about 50 mol % SiO 2 . Additionally, or alternatively, the first glass composition comprises at least about 5 mol % Al 2 O 3 , at least about 9 mol % Al 2 O 3 , at least about 15 mol % Al 2 O 3 , or at least about 20 mol % Al 2 O 3 . Additionally, or alternatively, the first glass composition comprises at most about 25 mol % Al 2 O 3 , at most about 20 mol % Al 2 O 3 , at most about 15 mol % Al 2 O 3 , or at most about 10 mol % Al 2 O 3 . Additionally, or alternatively, the first glass composition comprises at least about 1 mol % B 2 O 3 , at least about 4 mol % B 2 O 3 , or at least about 7 mol % B 2 O 3 . Additionally, or alternatively, the first glass composition comprises at most about 10 mol % B 2 O 3 , at most about 8 mol % B 2 O 3 , or at most about 5 mol % B 2 O 3 . Additionally, or alternatively, the first glass composition comprises at least about 2 mol % P 2 O 5 . Additionally, or alternatively, the first glass composition comprises at most about 5 mol % P 2 O 5 . 
     In some embodiments, the first glass composition comprises an alkali metal oxide selected from the group consisting of Li 2 O, Na 2 O, K 2 O, and combinations thereof. For example, the first glass composition comprises at least about 5 mol % Na 2 O, at least about 9 mol % Na 2 O, or at least about 12 mol % Na 2 O. Additionally, or alternatively, the first glass composition comprises at most about 20 mol % Na 2 O, at most about 16 mol % Na 2 O, or at most about 13 mol % Na 2 O. Additionally, or alternatively, the first glass composition comprises at least about 0.01 mol % K 2 O, at least about 1 mol % K 2 O, at least about 2 mol % K 2 O, or at least about 3 mol % K 2 O. Additionally, or alternatively, the first glass composition comprises at most about 5 mol % K 2 O, at most about 4 mol % K 2 O, at most about 3 mol % K 2 O, or at most about 1 mol % K 2 O. 
     In some embodiments, the first glass composition comprises an alkaline earth oxide selected from the group consisting of MgO, CaO, SrO, BaO, and combinations thereof. 
     In some embodiments, the first glass composition comprises one or more additional components including, for example SnO 2 , Sb 2 O 3 , As 2 O 3 , Ce 2 O 3 , Cl (e.g., derived from KCl or NaCl), ZrO 2 , or Fe 2 O 3 . 
     In some embodiments, the second glass composition comprises a glass network former selected from the group consisting of SiO 2 , Al 2 O 3 , B 2 O 3 , and combinations thereof. For example, the second glass composition comprises at least about 65 mol % SiO 2 , at least about 68 mol % SiO 2 , at least about 70 mol % SiO 2 , or at least about 75 mol % SiO 2 . Additionally, or alternatively, the second glass composition comprises at most about 80 mol % SiO 2 , at most about 77 mol % SiO 2 , at most about 75 mol % SiO 2 , or at most about 70 mol % SiO 2 . Additionally, or alternatively, the second glass composition comprises at least about 1 mol % Al 2 O 3 , at least about 5 mol % Al 2 O 3 , or at least about 9 mol % Al 2 O 3 . Additionally, or alternatively, the second glass composition comprises at most about 15 mol % Al 2 O 3 , at most about 11 mol % Al 2 O 3 , at most about 5 mol % Al 2 O 3 , or at most about 3 mol % Al 2 O 3 . Additionally, or alternatively, the second glass composition comprises at least about 1 mol % B 2 O 3 , at least about 5 mol % B 2 O 3 , or at least about 9 mol % B 2 O 3 . Additionally, or alternatively, the second glass composition comprises at most about 20 mol % B 2 O 3 , at most about 16 mol % B 2 O 3 , or at most about 10 mol % B 2 O 3 . 
     In some embodiments, the second glass composition comprises an alkali metal oxide selected from the group consisting of Li 2 O, Na 2 O, K 2 O, and combinations thereof. For example, the second glass composition comprises at least about 1 mol % Na 2 O, or at least about 2 mol % Na 2 O. Additionally, or alternatively, the second glass composition comprises at most about 15 mol % Na 2 O, at most about 11 mol % Na 2 O, or at most about 5 mol % Na 2 O. Additionally, or alternatively, the second glass composition comprises from about 0.1 mol % to about 6 mol % K 2 O, or from about 0.1 mol % to about 1 mol % K 2 O. In some embodiments, the second glass composition is substantially free of alkali metal. For example, the second glass composition comprises at most about 0.01 mol % alkali metal oxide. In other embodiments, the second glass composition comprises from about 2 mol % to about 15 mol % alkali metal oxide. 
     In some embodiments, the second glass composition comprises an alkaline earth oxide selected from the group consisting of MgO, CaO, SrO, BaO, and combinations thereof. For example, the second glass composition comprises at least about 0.1 mol % MgO, at least about 1 mol % MgO, at least about 3 mol % MgO, at least about 5 mol % MgO, or at least about 10 mol % MgO. Additionally, or alternatively, the second glass composition comprises at most about 15 mol % MgO, at most about 10 mol % MgO, at most about 5 mol % MgO, or at most about 1 mol % MgO. Additionally, or alternatively, the second glass composition comprises at least about 0.1 mol % CaO, at least about 1 mol % CaO, at least about 3 mol % CaO, at least about 5 mol % CaO, or at least about 7 mol % CaO. Additionally, or alternatively, the second glass composition comprises at most about 10 mol % CaO, at most about 7 mol % CaO, at most about 5 mol % CaO, at most about 3 mol % CaO, or at most about 1 mol % CaO. In some embodiments, the second glass composition comprises from about 1 mol % to about 25 mol % alkaline earth oxide. 
     In some embodiments, the second glass composition comprises one or more additional components including, for example SnO 2 , Sb 2 O 3 , As 2 O 3 , Ce 2 O 3 , Cl (e.g., derived from KCl or NaCl), ZrO 2 , or Fe 2 O 3 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Exemplary Glass Compositions 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
               
               
                 SiO 2   
                 76.33 
                 72.12 
                 54.03 
                 45.61 
                 60.53 
                 52.83 
                 73.7 
               
               
                 Al 2 O 3   
                 7.17 
                 9.15 
                 15.92 
                 21.37 
                 12.35 
                 17.01 
                 6.83 
               
               
                 B 2 O 3   
                 4.05 
                 4.16 
                 8.13 
                 7.07 
                 1.99 
                 5.2 
               
               
                 P 2 O 5   
                   
                   
                 3.18 
                 4.92 
                 0.0244 
                 2.517 
               
               
                 Na 2 O 
                 12.18 
                 9.88 
                 14.7 
                 15.73 
                 13.94 
                 14.839 
                 12.01 
               
               
                 K 2 O 
                 0.01 
                 2.53 
                 3.62 
                 0.006 
                 3.67 
                 1.752 
                 2.74 
               
               
                 MgO 
                 0.01 
                 0.03 
                 0.0033 
                 0.0055 
                 0.6046 
                 0.31 
                 4.52 
               
               
                 CaO 
                 0.04 
                 0.02 
                 0.018 
                 0.0246 
                 0.0221 
                 0.03 
               
               
                 BaO 
                   
                   
                   
                 0.0013 
                 0.0041 
               
               
                 ZnO 
                   
                 1.9 
                 0.002 
                 4.64 
                 6.14 
                 5.403 
               
               
                 SnO 2   
                 0.2 
                 0.2 
                 0.0367 
                 0.3208 
                 0.1453 
                 0.308 
                 0.19 
               
               
                 ZrO 2   
                   
                   
                 0.0544 
                 0.0334 
                 0.0267 
                 0.026 
               
               
                 CeO 2   
                   
                   
                 0.2179 
               
               
                 MnO 2   
                   
                   
                 0.0003 
               
               
                 TiO 2   
                   
                   
                 0.0085 
                   
                 0.0035 
               
               
                 Fe 2 O 3   
                   
                   
                 0.0089 
                 0.0081 
                 0.009 
                 0.008 
               
               
                 Sb 2 O 3   
                   
                   
                 0.002 
                 0.0782 
                 0.0666 
                 0.072 
               
               
                   
               
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
               
               
                   
               
               
                 SiO 2   
                 78.67 
                 77.9 
                 77.4 
                 77 
                 76.6 
                 77 
                 77 
               
               
                 Al 2 O 3   
                 1.95 
                 3.42 
                 7 
                 7 
                 7 
                 7 
                 7 
               
               
                 B 2 O 3   
                 14.19 
                 9.82 
               
               
                 P 2 O 5   
               
               
                 Na 2 O 
                 3.64 
                 7.01 
                 10 
                 10.2 
                 10.4 
                 5.3 
                 10.4 
               
               
                 K 2 O 
                 0.01 
                   
                 0.1 
                 0.3 
                 0.5 
                 5.2 
                 0.1 
               
               
                 MgO 
                 0.02 
                 0.09 
                 4.8 
                 4.8 
                 4.8 
                 4.8 
                 2.8 
               
               
                 CaO 
                 0.85 
                 1.64 
                 0.5 
                 0.5 
                 0.5 
                 0.5 
                 2.5 
               
               
                 BaO 
                 0.58 
               
               
                 ZnO 
               
               
                 SnO 2   
                 0.07 
                   
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
               
               
                 ZrO 2   
               
               
                 CeO 2   
               
               
                 MnO 2   
               
               
                 TiO 2   
               
               
                 Fe 2 O 3   
               
               
                 Sb 2 O 3   
               
               
                   
               
               
                   
                 15 
                 16 
                 17 
                 18 
                 19 
                 20 
                 21 
               
               
                   
               
               
                 SiO 2   
                 77 
                 77 
                 77 
                 77 
                 76.5 
                 76.5 
                 75 
               
               
                 Al 2 O 3   
                 6.5 
                 6.5 
                 6.5 
                 6.5 
                 6.5 
                 6.5 
                 8 
               
               
                 B 2 O 3   
               
               
                 P 2 O 5   
               
               
                 Na 2 O 
                 10.7 
                 11 
                 10.4 
                 9.8 
                 8 
                 7 
                 6 
               
               
                 K 2 O 
                 0.1 
                 0.1 
                 0.1 
                 0.1 
                 0.1 
                 0.1 
                 0.1 
               
               
                 MgO 
                 2.5 
                 2.7 
                 3 
                 3.3 
                 4.5 
                 5 
                 5.5 
               
               
                 CaO 
                 3 
                 2.5 
                 2.8 
                 3.1 
                 4.2 
                 4.7 
                 5.2 
               
               
                 BaO 
               
               
                 ZnO 
               
               
                 SnO 2   
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
               
               
                 ZrO 2   
               
               
                 CeO 2   
               
               
                 MnO 2   
               
               
                 TiO 2   
               
               
                 Fe 2 O 3   
               
               
                 Sb 2 O 3   
               
               
                   
               
               
                   
                 22 
                 23 
                 24 
                 25 
                 26 
                 27 
                 28 
               
               
                   
               
               
                 SiO 2   
                 70 
                 72 
                 68 
                 70 
                 72 
                 68 
                 70 
               
               
                 Al 2 O 3   
                 11 
                 9 
                 11 
                 9 
                 7 
                 9 
                 9 
               
               
                 B 2 O 3   
               
               
                 P 2 O 5   
               
               
                 Na 2 O 
                 5 
                 5 
                 5 
                 5 
                 5 
                 5 
                 3 
               
               
                 K 2 O 
               
               
                 MgO 
                 7 
                 7 
                 7 
                 7 
                 7 
                 13 
                 13 
               
               
                 CaO 
                 7 
                 7 
                 9 
                 9 
                 9 
                 5 
                 5 
               
               
                 BaO 
               
               
                 ZnO 
               
               
                 SnO 2   
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
               
               
                 ZrO 2   
               
               
                 CeO 2   
               
               
                 MnO 2   
               
               
                 TiO 2   
               
               
                 Fe 2 O 3   
               
               
                 Sb 2 O 3   
               
               
                   
               
               
                   
                 29 
                 30 
                 31 
                 32 
                 33 
                 34 
                 35 
               
               
                   
               
               
                 SiO 2   
                 72 
                 68 
                 70 
                 72 
                 68 
                 68 
                 70 
               
               
                 Al 2 O 3   
                 7 
                 9 
                 7 
                 11 
                 7 
                 9 
                 7 
               
               
                 B 2 O 3   
               
               
                 P 2 O 5   
               
               
                 Na 2 O 
                 3 
                 3 
                 3 
                 5 
                 3 
                 1 
                 1 
               
               
                 K 2 O 
               
               
                 MgO 
                 13 
                 13 
                 13 
                 7 
                 13 
                 13 
                 13 
               
               
                 CaO 
                 5 
                 7 
                 7 
                 5 
                 9 
                 9 
                 9 
               
               
                 BaO 
               
               
                 ZnO 
               
               
                 SnO 2   
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
               
               
                 ZrO 2   
               
               
                 CeO 2   
               
               
                 MnO 2   
               
               
                 TiO 2   
               
               
                 Fe 2 O 3   
               
               
                 Sb 2 O 3   
               
               
                   
               
               
                   
                 36 
                 37 
                 38 
                 39 
                 40 
                 41 
                 42 
               
               
                   
               
               
                 SiO 2   
                 72 
                 70 
                 72 
                 68 
                 72 
                 70 
                 72 
               
               
                 Al 2 O 3   
                 11 
                 11 
                 9 
                 11 
                 11 
                 11 
                 9 
               
               
                 B 2 O 3   
               
               
                 P 2 O 5   
               
               
                 Na 2 O 
                 3 
                 3 
                 3 
                 3 
                 1 
                 1 
                 1 
               
               
                 K 2 O 
               
               
                 MgO 
                 7 
                 7 
                 7 
                 13 
                 7 
                 13 
                 13 
               
               
                 CaO 
                 7 
                 9 
                 9 
                 5 
                 9 
                 5 
                 5 
               
               
                 BaO 
               
               
                 ZnO 
               
               
                 SnO 2   
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
                 0.2 
               
               
                 ZrO 2   
               
               
                 CeO 2   
               
               
                 MnO 2   
               
               
                 TiO 2   
               
               
                 Fe 2 O 3   
               
               
                 Sb 2 O 3   
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 43 
                 44 
                 45 
               
               
                   
                   
               
               
                   
                 SiO 2   
                 68 
                 70 
                 72 
               
               
                   
                 Al 2 O 3   
                 11 
                 9 
                 7 
               
               
                   
                 B 2 O 3   
               
               
                   
                 P 2 O 5   
               
               
                   
                 Na 2 O 
                 1 
                 1 
                 1 
               
               
                   
                 K 2 O 
               
               
                   
                 MgO 
                 13 
                 13 
                 13 
               
               
                   
                 CaO 
                 7 
                 7 
                 7 
               
               
                   
                 BaO 
               
               
                   
                 ZnO 
               
               
                   
                 SnO 2   
                 0.2 
                 0.2 
                 0.2 
               
               
                   
                 ZrO 2   
               
               
                   
                 CeO 2   
               
               
                   
                 MnO 2   
               
               
                   
                 TiO 2   
               
               
                   
                 Fe 2 O 3   
               
               
                   
                 Sb 2 O 3   
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Properties of Exemplary Glass Compositions 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
               
               
                 Softening 
                 808.7 
                 838 
                 713.1 
                 763.8 
                 757.6 
                 764.4 
                 832 
               
               
                 Point (° C.) 
               
               
                 CTE 
                 66.7 
                 74.3 
                 93.1 
                 88.7 
                 89.8 
                 91.3 
                 84.3 
               
               
                 (×10 −7 ° C. −1 ) 
               
               
                 10 9.9  P 
                 658 
                 668 
                   
                   
                   
                   
                 687 
               
               
                 Temp (° C.) 
               
               
                 Liquidus 
                 2662 
                 7003 
                 &gt;1000 
                 7090 
                   
                 2150 
               
               
                 Viscosity 
               
               
                 (kP) 
               
               
                 Liquidus 
                 885 
                 900 
                   
                   
                   
                   
                 &lt;740 
               
               
                 Temp (° C.) 
               
               
                 35 kP 
                 1117 
                 1201.4 
                 967 
                 1054 
                 1051 
                 1053 
                 1152 
               
               
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 5% HCl, 
                 0.0004 
                 0.0074 
                   
                   
                   
                   
                   
               
               
                 95° C., 6 h 
               
               
                 (mg/cm 2 ) 
               
               
                 1M HNO 3 , 
                 0.01 
                 0.0395 
                   
                   
                   
                   
                 0.0089 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 0.2N 
                 0 
                 0.0174 
                   
                   
                   
                   
                 0.0015 
               
               
                 H 2 SO 4 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 NIX 
               
               
                 ISO720 
               
               
                 DIN12116 
               
               
                 ISO695 
               
               
                   
               
               
                   
                 8 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
               
               
                   
               
               
                 Softening 
                 800.9 
                 785 
                 964 
                 951 
                 939 
                 989 
                 914 
               
               
                 Point (° C.) 
               
               
                 CTE 
                 34.7 
               
               
                 (×10 −7 ° C. −1 ) 
               
               
                 10 9.9  P 
                 644 
               
               
                 Temp (° C.) 
               
               
                 Liquidus 
                 6111 
               
               
                 Viscosity 
               
               
                 (kP) 
               
               
                 Liquidus 
                 950 
               
               
                 Temp (° C.) 
               
               
                 35 kP 
                 1124 
               
               
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 5% HCl, 
                 0.0003 
                   
                   
                   
                   
                   
                   
               
               
                 95° C., 6 h 
               
               
                 (mg/cm 2 ) 
               
               
                 1M HNO 3 , 
                 0.023 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 0.2N 
                 0.005 
               
               
                 H 2 SO 4 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 NIX 
                   
                 31.9 
                 46.2 
                 46.2 
                 42.1 
                 42.1 
                 48.3 
               
               
                 ISO720 
               
               
                 DIN12116 
                   
                   
                 −0.39 
                 −0.37 
                 −0.39 
                 −0.47 
                 −0.35 
               
               
                 ISO695 
                   
                   
                 −64 
                 −42 
                 −50 
                 −67 
                 −62 
               
               
                   
               
               
                   
                 15 
                 16 
                 17 
                 18 
                 19 
                 20 
                 21 
               
               
                   
               
               
                 Softening 
                 881 
                 878 
                 897 
                 908 
                 941 
                 950 
                 975 
               
               
                 Point (° C.) 
               
               
                 CTE 
               
               
                 (×10 −7 ° C. −1 ) 
               
               
                 10 9.9  P 
               
               
                 Temp (° C.) 
               
               
                 Liquidus 
               
               
                 Viscosity 
               
               
                 (kP) 
               
               
                 Liquidus 
               
               
                 Temp (° C.) 
               
               
                 35 kP 
               
               
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 5% HCl, 
                   
                   
                   
                   
                   
                   
                   
               
               
                 95° C., 6 h 
               
               
                 (mg/cm 2 ) 
               
               
                 1M HNO 3 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 0.2N 
               
               
                 H 2 SO 4 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 NIX 
                 47.3 
                 57.5 
                 47.3 
                 49.3 
                 39 
                 33.9 
                 32.9 
               
               
                 ISO720 
               
               
                 DIN12116 
                 −0.48 
                 −0.28 
                 −0.43 
                 −0.35 
                 −0.4 
                 −0.55 
                 −0.48 
               
               
                 ISO695 
                 .53 
                   
                 −63 
                 −63 
                 −44 
                   
                 −66 
               
               
                   
               
               
                   
                 22 
                 23 
                 24 
                 25 
                 26 
                 27 
                 28 
               
               
                   
               
               
                 Softening 
                 969 
                 963 
                 944 
                 941 
                 935 
                 936 
                 971 
               
               
                 Point (° C.) 
               
               
                 CTE 
                 48.1 
                 48.5 
                 50.6 
                 51.3 
                 52.2 
                 48.4 
                 41.8 
               
               
                 (×10 −7 ° C. −1 ) 
               
               
                 10 9.9  P 
               
               
                 Temp (° C.) 
               
               
                 Liquidus 
               
               
                 Viscosity 
               
               
                 (kP) 
               
               
                 Liquidus 
               
               
                 Temp (° C.) 
               
               
                 35 kP 
               
               
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 5% HCl, 
                   
                   
                   
                   
                   
                   
                   
               
               
                 95° C., 6 h 
               
               
                 (mg/cm 2 ) 
               
               
                 1M HNO 3 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 0.2N 
               
               
                 H 2 SO 4 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 NIX 
                 38.7 
                 43.1 
                 46 
                 48.5 
                 56.8 
                 63.4 
                 35.4 
               
               
                 ISO720 
               
               
                 DIN12116 
               
               
                 ISO695 
               
               
                   
               
               
                   
                 29 
                 30 
                 31 
                 32 
                 33 
                 34 
                 35 
               
               
                   
               
               
                 Softening 
                 971 
                 948 
                 952 
                 993 
                 924 
                 967 
                 967 
               
               
                 Point (° C.) 
               
               
                 CTE 
                 42.8 
                 45.4 
                 44.7 
                 44.7 
                 65.7 
                 41.2 
                 40.9 
               
               
                 (×10 −7 ° C. −1 ) 
               
               
                 10 9.9  P 
               
               
                 Temp (° C.) 
               
               
                 Liquidus 
               
               
                 Viscosity 
               
               
                 (kP) 
               
               
                 Liquidus 
               
               
                 Temp (° C.) 
               
               
                 35 kP 
               
               
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 5% HCl, 
                   
                   
                   
                   
                   
                   
                   
               
               
                 95° C., 6 h 
               
               
                 (mg/cm 2 ) 
               
               
                 1M HNO 3 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 0.2N 
               
               
                 H 2 SO 4 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 NIX 
                 38.2 
                 47.1 
                 45.6 
                 28.9 
                 58.3 
                 39.2 
                 40.9 
               
               
                 ISO720 
               
               
                 DIN12116 
               
               
                 ISO695 
               
               
                   
               
               
                   
                 36 
                 37 
                 38 
                 39 
                 40 
                 41 
                 42 
               
               
                   
               
               
                 Softening 
                 1005 
                 981 
                 980 
                 970 
                 1021 
                 1001 
                 1009 
               
               
                 Point (° C.) 
               
               
                 CTE 
                 39.7 
                 43.2 
                 43.7 
                 41.2 
                 36.7 
                 35.4 
                 34.9 
               
               
                 (×10 −7 ° C. −1 ) 
               
               
                 10 9.9  P 
               
               
                 Temp (° C.) 
               
               
                 Liquidus 
               
               
                 Viscosity 
               
               
                 (kP) 
               
               
                 Liquidus 
               
               
                 Temp (° C.) 
               
               
                 35 kP 
               
               
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 5% HCl, 
                   
                   
                   
                   
                   
                   
                   
               
               
                 95° C., 6 h 
               
               
                 (mg/cm 2 ) 
               
               
                 1M HNO 3 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 0.2N 
               
               
                 H 2 SO 4 , 
               
               
                 95° C., 24 h 
               
               
                 (mg/cm 2 ) 
               
               
                 NIX 
                 25.8 
                 34.4 
                 33.1 
                 41.2 
                 23.5 
                 24.7 
                 27.3 
               
               
                 ISO720 
               
               
                 DIN12116 
               
               
                 ISO695 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 43 
                 44 
                 45 
               
               
                   
                   
               
               
                   
                 Softening 
                 988 
                 987 
                 991 
               
               
                   
                 Point (° C.) 
               
               
                   
                 CTE 
                 38.1 
                 38.4 
                 38.4 
               
               
                   
                 (×10 −7 ° C. −1 ) 
               
               
                   
                 10 9.9  P 
               
               
                   
                 Temp (° C.) 
               
               
                   
                 Liquidus 
               
               
                   
                 Viscosity 
               
               
                   
                 (kP) 
               
               
                   
                 Liquidus 
               
               
                   
                 Temp (° C.) 
               
               
                   
                 35 kP 
               
               
                   
                 Temp (° C.) 
               
            
           
           
               
            
               
                 Chemical Durability 
               
            
           
           
               
               
               
               
               
            
               
                   
                 5% HCl, 
                   
                   
                   
               
               
                   
                 95° C., 6 h 
               
               
                   
                 (mg/cm 2 ) 
               
               
                   
                 1M HNO 3 , 
               
               
                   
                 95° C., 24 h 
               
               
                   
                 (mg/cm 2 ) 
               
               
                   
                 0.2N 
               
               
                   
                 H 2 SO 4 , 
               
               
                   
                 95° C., 24 h 
               
               
                   
                 (mg/cm 2 ) 
               
               
                   
                 NIX ISO720 
                 34.2 
                 34.8 
                 38.7 
               
               
                   
                 DIN12116 
               
               
                   
                 ISO695 
               
               
                   
                   
               
            
           
         
       
     
     The glass articles described herein can be used for a variety of applications including, for example, for cover glass or glass backplane applications in consumer or commercial electronic devices including, for example, LCD and LED displays, computer monitors, and automated teller machines (ATMs); for touch screen or touch sensor applications, for portable electronic devices including, for example, mobile telephones, personal media players, and tablet computers; for integrated circuit applications including, for example, semiconductor wafers; for photovoltaic applications; for architectural glass applications; for automotive or vehicular glass applications; or for commercial or household appliance applications. 
     EXAMPLES 
     Various embodiments will be further clarified by the following examples. 
     Example 1 
     A glass sheet having the general configuration shown in  FIG. 1  is formed. The glass sheet has a thickness of 2 mm. Each of the first cladding layer and the second cladding layer has a thickness of 200 μm and a compressive stress of 300 MPa. The core layer has a thickness of 1.6 mm and a tensile stress of 75 MPa. 
     Example 2 
     A glass sheet having the general configuration shown in  FIG. 1  is formed. The glass sheet has a thickness of 0.7 mm. Each of the first cladding layer and the second cladding layer has a thickness of 200 μm and a compressive stress of 100 MPa. The core layer has a thickness of 300 μm. 
     Example 3 
     A glass sheet having the general configuration shown in  FIG. 1  is formed. The core layer is formed from exemplary glass composition  1 . Each of the first cladding layer and the second cladding layer is formed from exemplary glass composition  8 . 
     Example 4 
     A glass sheet having the general configuration shown in  FIG. 1  is formed. The core layer is formed from exemplary glass composition  2 . Each of the first cladding layer and the second cladding layer is formed from exemplary glass composition  8 . 
     Example 5 
     A glass sheet having the general configuration shown in  FIG. 1  is formed. The core layer is formed from exemplary glass composition  7 . Each of the first cladding layer and the second cladding layer is formed from exemplary glass composition  8 . The glass sheet has a thickness of 1.5 mm. Each of the first cladding layer and the second cladding layer has a thickness of 188 μm and a compressive stress of 137 MPa. The core layer has a thickness of 1.124 mm and a tensile stress of 46 MPa. 
     Comparative Example 1 
     A monolithic soda lime glass sheet is formed. The glass sheet has a thickness of 3 mm. The glass sheet is thermally tempered, resulting in a compressive stress of 100 MPa. 
     Comparative Example 2 
     A monolithic ion exchangeable glass sheet is formed. The glass sheet has a thickness of 0.7 mm. The glass sheet is subjected to an ion exchange process, resulting in a compressive stress of 730 MPa and a depth of layer of 40 μm. 
       FIG. 4  is a graphical illustration of the predicted strength profiles of the glass sheets of Example 1 and Comparative Example 1 presented as retained strength, and  FIG. 5  is a graphical illustration of the predicted strength profiles of the glass sheets of Example 1 and Comparative Example 1 presented as failure load. The strength values in failure load are predicted based on a model of ring-on-ring loading using a 1 in diameter support ring and a 0.5 in diameter loading ring on a 2 in square glass sheet. The contact radius of the ring is 1.6 mm, and the head speed is 1.2 mm/min. 
     As illustrated by  FIGS. 4-5 , the laminated glass sheet of Example 1 has improved strength profiles compared to the tempered glass sheet of Comparative Example 1, even though the laminated glass sheet is much less thick than the tempered glass sheet. The improved strength profile is evidenced by the higher retained strength and failure load values of the laminated glass sheet at increasing flaw sizes, indicating that the laminated glass sheet is able to withstand damage that may be inflicted during handling or use. Thus, the laminated glass sheet can be used as an in-kind replacement for the tempered glass sheet (e.g., for automotive glazing or other applications in which thermally tempered glass is currently used). 
     The laminated glass sheet has a reduced weight compared to the tempered glass sheet because of the reduced thickness of the laminated glass sheet compared to the tempered glass sheet. For example, the laminated glass sheet of Example 1 has a weight of from about 0.46 g/cm 2  to about 0.52 g/cm 2 . In contrast, the tempered glass sheet of Comparative Example 1 has a weight of from about 0.69 g/cm 2  to about 0.78 g/cm 2 . Thus, replacing the tempered glass sheet with the laminated glass sheet can reduce the weight of the glass by from about 24% to about 41%. In other embodiments, the weight can be reduced by nearly 100% (e.g., by using a 1.8 mm thick laminated glass sheet). In an automotive glazing application, such reduced weight can aid in reducing total vehicle weight, which can improve fuel efficiency, reduce CO 2  emissions, and improve vehicle handling. 
       FIG. 6  is a graphical illustration of the predicted strength profiles of the glass sheets of Example 2 and Comparative Example 2 presented as failure load. The strength values are predicted based on the same ring-on-ring loading model described with reference to  FIGS. 4-5 . As illustrated by  FIG. 6 , the laminated glass sheet of Example 2 has improved strength profiles compared to the ion exchanged glass sheet of Comparative Example 2, even though the laminated glass sheet has a significantly lower compressive stress than the ion exchanged glass sheet. The improved strength profile is evidenced by the relatively stable failure load value of the laminated glass sheet at increasing flaw sizes, indicating that the laminated glass sheet is able to withstand damage that may be inflicted during handling or use. 
     It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.