Patent Publication Number: US-2016236445-A1

Title: Composite Layer, Metal Layer and Anodized Layer

Description:
BACKGROUND 
     Composite materials are materials made from two or more constituent materials with different physical properties. When combined, the constituent materials produce a material with characteristics different from the individual components. For example, a light metal infiltrated carbon fiber composite, such as a carbon fiber metal matrix composite (MMC), may have carbon fibers embedded in a light metal matrix, such as aluminum, magnesium, or titanium. The resultant composite may have high strength and low density. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain examples are described in the following detailed description and in reference to the drawings, in which: 
         FIG. 1  illustrates an example composite material including a composite layer, a metal layer, and an anodized layer. 
         FIG. 2  illustrates an example composite material having two second metal layer and two anodized layers; 
         FIG. 3  illustrates an example method of manufacturing a composite material; 
         FIG. 4A  illustrates an example electronic device having a housing comprising a composite material; and 
         FIG. 4B  illustrates a magnified portion of the housing of  FIG. 4A , illustrating the composite material, 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EXAMPLES 
     Users of consumer electronics, such as smartphones, laptops, and tablets, may desire electronics housings having certain qualities. For example, users may desire a housing that is scratch resistant, has a metallic feel, or that may be available in various colors. Anodized light metals, such as aluminum, magnesium, titanium, or their alloys, may provide such qualities. Anodizing is an electrolytic passivation process that forms an anodized metal layer on the surface of a metal by increasing the natural oxide layer of the metal. The resultant anodized layer may be harder than the underlying metal, providing a wear resistant coating that retains a metallic feel. Additionally, the anodized layer may be dyed various colors. 
     However, directly anodizing a light metal infiltrated carbon fiber composite material may provide an inferior anodized coating. In some cases, it may be difficult to achieve a consistent anodized layer thickness directly on a light metal infiltrated carbon fiber material. For example, the composite material may lack an anodized layer on exposed areas of carbon fiber, resulting in an irregular anodized layer structure. This may cause unsatisfactory texture and introduce color variation between different articles manufactured under the same processes. 
     Implementations of the disclosed technology may provide a composite material having an anodized coating on an infiltrated light metal carbon fiber composite substrate. The anodized coating may provide a high performance metallic finish with improved wear resistance and color uniformity. Such composite materials may be used in electronics, such as portable electronic products like notebook and tablet computers, and smartphones. 
       FIG. 1  illustrates an example composite material  100  including a composite layer  101 , a metal layer  102 , and an anodized layer  103 . For example, the composite material  100  may be used in the construction of articles such as housing for electronics devices, such as laptops, tablets, smartphones, and peripherals. 
     The example composite material  100  includes a composite layer  101 . In some implementations, the composite layer  101  may include a fiber material and a first metal infiltrating the fiber material. For example, the composite layer  101  may be a light metal infiltrated fiber material. The composite layer  101  may determine the bulk properties of the material  100 , such as stiffness, plasticity, strength, and density. The composite layer  101  may have a variety of thicknesses depending on its application. For example, when used in the manufacture of a laptop housing, the composite layer  101  may have a thickness on the order of a few millimeters. For example, the composite layer  101  may have a thickness between 0.5-12 mm. 
     In some implementations, the first metal of composite layer  101  may be a light metal. In some cases, the light metal may comprise aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, or titanium alloys. For example, the light metal may comprise magnesium alloyed with lithium and zinc (LZ), such as LZ91, or magnesium alloyed with aluminum and zinc (AZ), such as AZ31 or AZ91. As another example, the light metal may comprise pure aluminum, or aluminum alloyed with magnesium, such as a 5000 or 6000 series aluminum alloy. 
     In some implementations, the fiber material of composite layer  101  may comprise continuous or discontinuous fibers. For example, the fiber material may be a continuous, woven cloth. As another example, the fiber material may be in a discontinuous, unidirectional web. In various implementations, the fiber material of composite layer  101  may include carbon nanotubes, carbon fibers, glass fibers, ceramic fibers, silicon carbide fibers, aramid fibers, or metal fibers. Additionally, in some implementations, the fibers of composite layer  101  may be coated or uncoated. For example, the fiber material may be coated or uncoated carbon fibers, such as polyacrylonitrile-derived carbon fibers (PAN carbon fibers). In one implementation, the composite layer  101  may be an L2 alloy infiltrated woven PAN carbon fiber composite. 
     The composite material  100  may comprise a metal layer  102  on the composite layer  101 . In some implementations, the metal layer  102  may comprise a second metal. In various implementations, the second metal of metal layer  102  may be the same as or different from the first metal of composite layer  101 . In some cases, the second metal may be any metal capable of being anodized. For example, the metal layer  102  may include a light metal such as aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, or titanium alloy. In some implementations, the metal layer  102  may be composed of aluminum or an aluminum alloy, such as a 5000 or 6000 series aluminum alloy. In other implementations, the metal layer  102  may be composed of magnesium or a magnesium alloy, such as LZ91, AZ31 or A291.In some implementations, the metal layer  102  may provide a metallic feel to the composite material  100  and may serve as a substrate for an anodized layer  103 . In some cases, the metal layer  102  may have a thickness of greater than 50 μmm. 
     The example composite material  100  may comprise an anodized layer  103  on the metal layer  102 . For example, the anodized layer  103  may be a layer composed of oxides of the second metal of metal layer  102 . The anodized layer  103  may provide a harder surface than the metal layer  102  or the composite layer  101 . Accordingly, a composite material  100  having an anodized layer  103  may be more scratch resistant than a composite material lacking such an anodized layer  103 . Additionally, the anodized layer  103  may include a dye or colorant. In various implementations, the anodized layer  103  may have varying thickness depending on application. In some instances, the anodized layer  103  may be between 6 to 150 μm thick. The thickness may depend on the anodizing process and desired final characteristics. For example, a thin, transparent anodized layer  103  may produce iridescence effects, while a thicker anodized layer  103  may be used to retain dyes. In a particular implementation, the anodized layer  103  may be produced using a sulfuric acid anodizing process and have a thickness between 10 and 50 μm. 
       FIG. 2  illustrates an example composite material  200  having a second metal layer  204  and a second anodized layer  205 . For example, composite material  200  may be used in applications where both surfaces of the material  200  will be visible. In this example, the composite material  200  has a first metal layer  202  on a composite layer  201 . The composite material  200  further has a second metal layer  204  on a side of the composite layer  201  opposite the first layer  202 . In this example, the composite material  200  may have a first anodized layer  203  on the first metal layer  202  and a second anodized layer  205  on the second metal layer  204 . 
     In some implementations, the composite layer  201  has a composition similar to the composite layer  101  of  FIG. 1 . The composite layer  201  may include a fiber material and a first metal infiltrating the fiber material. For example, the composite layer  201  may be a light metal infiltrated fiber material. The composite layer  201  may determine the bulk properties of the material  200 , such as stiffness, plasticity, strength, and density. The composite layer  201  may have a variety of thicknesses depending on its application. For example, when used in the manufacture of a laptop housing, the composite layer  201  may have a thickness on the order of a few millimeters. For example, the composite layer  201  may have a thickness between 0.5-12 mm. 
     In some implementations, the first metal of composite layer  201  may be a light metal. For example, the light metal may comprise aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, or titanium alloys. For example, the light metal may comprise magnesium alloyed with lithium and zinc (LZ). such as LZ91, or magnesium alloyed with aluminum and zinc (AZ), such as AZ31 or AZ91. As another example, the light metal may comprise pure aluminum, or aluminum alloyed with magnesium, such as a 5000 or 6000 series aluminum alloy. 
     In some implementations, the fiber material of composite layer  201  may comprise continuous or discontinuous fibers. In various implementations, the fiber material of composite layer  201  may comprise carbon nanotubes, carbon fibers, glass fibers, ceramic fibers, silicon carbide fibers, aramid fibers, or metal fibers. Additionally, in some implementations, the fiber material of composite layer  201  may comprise coated or uncoated fibers. For example, the fiber material may comprise coated or uncoated carbon fibers, such as polyacrylonitrile-derived carbon fiber (PAN carbon fibers). In some implementations, the fiber material may be woven or unwoven. For example, the fiber material may be woven PAN carbon fiber. In some examples, the fiber material may be unwoven, unidirectional fibers. For example, the fiber material may be unidirectional PAN carbon fiber. In one implementation, the composite layer  201  may be an LZ alloy infiltrated woven PAN carbon fiber composite. 
     In some implementations, the first metal layer  202  and second metal layer  204  may have a composition similar to the metal layer  102  of  FIG. 1 . For example, the first metal layer  202  and second metal layer  204  may comprise second and third metals capable of being anodized. For example, the first metal layer  202  and second metal layer  204  may include light metals such as aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, or titanium alloy. In some implementations, the first metal layer  202  and the second metal layer  204  are composed of aluminum or aluminum alloys, such as a 5000 or 6000 series aluminum alloy. In other implementations, the first metal layer  202  and the second metal layer  204  are composed of magnesium or magnesium alloys, such as LZ91, AZ31 or AZ91. In some implementations, the first metal layer  202  and the second metal layer  204  may provide a metallic feel to both surfaces of the composite material  200  and may serve as substrates for the first anodized layer  203  and the second anodized layer  205 , respectively. 
     In some implementations, the first metal layer  202  may have a different composition than the second metal layer  204 . For example, the first metal layer  202  may be composed of aluminum or an aluminum alloy while the second metal layer  204  may be composed of magnesium or a magnesium alloy. In other implementations, the first metal layer  202  and the second metal may have the same composition. Additionally, in some implementations, the first metal layer  202  may have a different thickness than the second metal layer  204 . In other implementations, the first metal layer  202  and the second metal layer  204  have the same thickness. In some cases, the first metal layer  202  and the second metal layer  204  have thicknesses less than 2 mm. 
     The example composite material  200  may further include a first anodized layer  203  on the first metal layer  202  and a second anodized layer  205  on the second metal layer  204 . In some implementations, the first anodized layer  203  may be a layer composed of oxides of the metal of the first metal layer  202 . Similarly, the second anodized layer  205  may be a layer composed of oxides of the metal of the second metal layer  204 . Additionally, the first anodized layer  203  and the second anodized layer  205  may include dyes or other colorants. In various implementations, the first anodized layer  203  and the second anodized layer  205  may have different thicknesses or may have the same thicknesses. Additionally, depending on the composition of the first metal layer  202  and the second metal layer  204 , the first anodized layer  203  and the second anodized layer  205  may have different compositions or the same composition. Similarly, if dyed, the first anodized layer  203  and the second anodized layer  205  may be dyed different colors, or only one anodized layer  203 ,  205  may be dyed. 
       FIG. 3  illustrates an example method of manufacturing a composite material. For example, the illustrated method may be used to manufacture a composite material such as the composite material  100  described with respect to  FIG. 1  or the composite material  200  described with respect to  FIG. 2 . 
     The example method may include block  301 . Block  301  may include obtaining a composite layer comprising a fiber material and a first metal infiltrating the fiber material. For example, the composite layer may be similar to composite layer  101  of  FIG. 1  or composite layer  201  of  FIG. 2 . In some implementations, the composite layer may be obtained in a pre-fabricated form. In other implementations, obtaining the composite layer may include forming the composite layer. For example, the composite layer may be formed by bonding a metal with a fiber material. In some cases, bonding the metal with the fiber material may include solid state methods such as powder blending and consolidation or foil diffusion bonding. In other cases, bonding the metal with the fiber material may include liquid state methods such as electroformlng, stir or squeeze casting, spray deposition, or reactive processing. In still further cases, bonding the metal with the fiber material may include physical vapor deposition methods, such as sputtering. 
     In some instances, the metal of the composite layer may include aluminum, an aluminum alloy, magnesium, a magnesium alloy, titanium, or a titanium alloy. Additionally, the fiber material may be continuous or discontinuous. For example, the fiber material may be in a continuous, woven form. In some implementations, the fiber material may be woven or unwoven. As another example, the fiber material may be in a discontinuous, unidirectional form. In various implementations, the fiber material may comprise carbon nanotubes, carbon fibers, glass fibers, ceramic fibers, silicon carbide fibers, aramid fibers, or metal fibers. Additionally, in some implementations, the fiber material may comprise coated or uncoated fibers. For example, the fiber material may comprise coated or uncoated carbon fibers, such as polyacrylonitrile-derived carbon fiber (PAN carbon fibers). 
     The example method may also include block  302 . Block  302  may include applying a metal layer to the composite layer. For example, the metal layer may be as described with respect to metal layer  102  of  FIG. 1  or metal layers  202 ,  204  of  FIG. 2 . In some implementations, applying the metal layer may include applying a metal foil to the composite layer and bonding the metal foil to the composite layer. For example, the metal foil may be bonded to the composite layer using diffusion bonding under heat and pressure. In other examples, the metal foil may be bonded to the composite layer through soldering, brazing, adhesive bonding, or other bonding techniques. In other implementations, applying the metal layer may include depositing the metal layer on the composite layer. For example, the metal layer may be deposited on the composite layer using a vapor deposition technique, such as physical vapor deposition. 
     In some implementations, block  302  may include applying a second metal layer to the composite layer on a side of the composite layer opposite the first metal layer. For example, the second metal layer may be as described with respect to metal layer  204  of  FIG. 2 . In some implementations, the second metal layer may be applied in the same manner as the first metal layer. For example, the second metal layer may be applied as a metal foil and bonded to the composite layer. In other implementations, the second metal layer may be applied in a different manner that the first metal layer. For example, the first metal layer may be applied as a metal foil bonded to the composite layer while the second layer may be applied through vapor deposition. 
     The example method may also include block  303 . Block  303  may include anodizing the metal layer applied to the composite layer. For example, this may form an anodized layer as described with respect to anodized layer  103  of  FIG. 1  or anodized layer  203  of  FIG. 2 . In some implementations, the metal layer is anodized by playing the bonded composite layer and metal layer into a chemical bath and passing an electric current through the bath, causing the surface of the metal layer to oxidize. In a particular implementation, the chemical bath may include sulfuric acid, chromic acid, caustic Soda, sodium nitrate, sodium nitrite, trisodium phosphate, orthophosporic acid, nitric acid, acetic acid glacial, silicic acid, boric acid, phosphoric acid, molybdic acid, vanadic acid, permanganic add, stannic acid and tungstic acid, nickel, and urea. 
     In some cases, by anodizing the metal layer after it is applied to the composite layer, the anodized layer is formed only on the external surface of the metal layer. Accordingly, an anodized layer may not be present at the interface between the metal layer and the composite layer. 
     In implementations where block  302  includes applying a second metal layer, block  303  may include anodizing the second metal layer applied to the composite layer. In some implementations, block  303  may include anodizing the second metal layer simultaneously with the first metal layer. For example, the first and second metal layers may be submerged into the same chemical acid bath during a single anodization process. In other implementations, block  303  may include anodizing the second metal layer separately from the first metal layer. In further embodiments, the second metal layer may not be anodized. For example, the second metal layer may be applied after the first metal layer is applied and anodized. 
     In some implementations, the example method may include block  304 . Block  304  may include performing various post processing steps. For example, block  304  may include dying the anodized layer. If two layers are present, block  304  may include dying the first and second anodized layers, or only one of the anodized layers. As another example, block  304  may include sealing the anodized layer or layers. The sealing may reduce or eliminate pores in the anodized layer or layers. For example, sealing may include immersion in hot deionized water or steam, or impregnation with a sealant such as polytetrafluoroethylene (PTFE), nickel acetate, cobalt acetate, sodium dichromate, or potassium dichromate. 
       FIG. 4A  illustrates an example electronic device  400  having a housing  402  comprising a composite material.  FIG. 4B  illustrates a magnified portion  403  of the housing  402 , illustrating the composite material. The example device  400  may include a display  401  and a housing  402 . In further examples, the device  400  may include further components, such as buttons, keyboards, speakers, cameras, ports or additional screens. For example, the electronic device  400  may be a smartphone, media player, tablet computer, laptop or notebook computer, or other portable device. 
     In this example, the housing  402  may comprise a metal-fiber composite layer  404 . In some implementations, the metal-fiber composite layer  404  may be as described with respect to composite layer  101  of  FIG. 1  or composite layer  201  of  FIG. 2 . For example, the metal-fiber composite layer  404  may have a metal matrix with an embedded fiber material. In some implementations, the metal matrix may comprise an aluminum, aluminum alloy, magnesium, magnesium, magnesium alloy, titanium, or titanium alloy matrix. In some implementations, the fiber material may comprise continuous or discontinuous carbon nanotubes, carbon fibers, glass fibers, ceramic fibers, silicon carbide fibers, aramid fibers, or metal fibers. Additionally, the fiber material may be in a woven or unidirectional form. 
     The housing  402  may further comprise a metal layer  405  bonded to the metal-fiber composite layer  404 . In some implementations, the metal layer  405  may be as described with respect to metal layer  102  of  FIG. 1 . Additionally, in further implementations, the housing  402  may comprise a second metal layer bonded to the metal-fiber composite layer  404  on the opposite side of the metal fiber composite layer  404 . In such implementations, the first metal layer  405  and the second metal layer may be as described with respect to metal layers  202  and  204  of  FIG. 2 . For example, the metal layer  405  or layers may comprise a layer  405  or layers of aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, or titanium alloy. In particular implementations, the metal layer  405  may comprise a layer of aluminum or aluminum alloy. 
     The housing  402  may further comprise an anodized layer  406  formed on the metal layer  405 . In some implementations, the anodized layer  406  may be as described with respect to anodized layer  103  of  FIG. 1 . Additionally, if a second metal layer is present, a second anodized layer may be formed on the second metal layer. In such an implementation, the first and second anodized layers may be as described with respect to anodized layers  203  and  205  of  FIG. 2 . 
     In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some or all of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.