Abstract:
A method for manufacturing a mold core includes the following steps: providing a body having a forming surface; forming an iridium dioxide layer preform on the forming surface to obtain a mold core preform; and reducing iridium dioxide of a surface of the iridium dioxide layer preform into iridium, so that the iridium dioxide layer preform is converted to an iridium dioxide layer and an iridium layer formed on the iridium dioxide layer to obtain the mold core.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure generally relates to mold cores and methods for manufacturing a mold core, and particularly to a mold core for making a glass sheet and a method for manufacturing the mold core. 
         [0003]    2. Description of Related Art 
         [0004]    Mold cores used for making glass sheets need to have good detachability, mechanical strength and chemical stability, so a protection film is required to be formed on a surface of a body of the mold core. The body of the mold core is usually made of stainless steel, tungsten carbide (WC), or silicon carbide (SiC). The protection film is usually made of noble metal, such as platinum-iridium (Pt-Ir) alloy, iridium (Ir) alloy, or ruthenium (Ru) alloy. The protection film is deposited on the surface of the body usually by physical vapor deposition (PVD) method. However, a sputtering target of the noble metal used in the PVD method is expensive, so a cost for manufacturing the mold core is high. 
         [0005]    Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or like elements of an embodiment. 
           [0007]      FIG. 1  shows a cross-sectional view of a mold core of one embodiment. 
           [0008]      FIG. 2  is a flowchart showing a method for manufacturing the mode core of  FIG. 1 . 
           [0009]      FIG. 3  shows a cross-sectional view of a preform of the mold core of  FIG. 1 . 
           [0010]      FIG. 4  shows an XPS spectrum of Ir 4f in a surface of a mold core of a first example. 
           [0011]      FIG. 5  shows an XPS spectrum of Ir 4f in a surface of a mold core of a second example. 
           [0012]      FIG. 6  shows an XPS spectrum of Ir 4f in a surface of a mold core of a third example. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring to  FIG. 1 , an embodiment of a mold core  100  used for making a glass sheet (not shown) is illustrated. The mold core  100  includes a body  10 , a tungsten carbide (WC) layer  20 , a titanium (Ti) layer  30 , an iridium dioxide (IrO 2 ) layer  40 , and an iridium (Ir) layer  50 . The body  10  includes a forming surface  11 . The WC layer  20  is formed on the forming surface  11 . The Ti layer  30  is formed on the WC layer  20 . The IrO 2  layer  40  is formed on the Ti layer  30 . The Ir layer  50  is formed on the IrO 2  layer  40 . 
         [0014]    In the illustrated embodiment, the body  10  is made of stainless steel. The WC layer  20 , the Ti layer  30 , and the IrO 2  layer  40  can be made by PVD methods or plasma enhanced chemical vapor deposition (PECVD) methods. The Ir layer  50  is formed by reducing an IrO 2  layer preform, and a part of the IrO 2  layer preform forms the IrO 2  layer  40 . A thicknesses of the WC layer  20  is in a range from about 100 nanometers (nm) to about 500 nm. A thickness of the Ti layer  30  is in a range from about 100 nm to about 500 nm. A thickness of the IrO 2  layer  40  is in a range from about 100 nm to about 500 nm. A thickness of the Ir layer  50  is in a range from about 100 nm to about 500 nm. 
         [0015]    In an alternative embodiment, the body  10  can be made of high temperature ceramic materials, such as WC or SiC, or high temperature graphite materials. Thicknesses of the above mentioned layers can be changed to suit the glass sheet being formed or other manufacturing conditions. If a binding force between the IrO 2  layer  40  and the body  10  can reach a usage need, the WC layer  20  and the Ti layer  30  can be omitted, and the IrO 2  layer  40  can be formed directly on the forming surface  11 . 
         [0016]    Also referring to  FIG. 2 , an embodiment of a method for manufacturing the mold core of the embodiment is illustrated as follows. 
         [0017]    In step S 101 , a body  10  is provided. The body  10  includes a forming surface  11 . The body  10  can be made of high temperature ceramic materials, such as 
         [0018]    WC or SiC, or high temperature graphite materials. In an illustrated embodiment, the body  10  is made of stainless steel, so the body  10  has high mechanism strength and a long lifespan. 
         [0019]    In step S 102 , a WC layer  20  is deposited on the forming surface  11 . The WC layer  20  can be deposited by PVD methods or PECVD methods. In the illustrated embodiment, the WC layer  20  is deposited by a PVD method. A thickness of the WC layer  20  is in a range from about 100 nm to about 500 nm. In other embodiments, the thickness of the WC layer  20  can be changed as manufacturing methods or materials of the glass sheet being formed. 
         [0020]    In step S 103 , a Ti layer  30  is deposited on the WC layer  20 . The Ti layer  30  can be deposited by PVD methods or PECVD methods. In the illustrated embodiment, the Ti layer  30  is deposited by a PVD method. A thickness of the Ti layer  30  is in a range from about 100 nm to about 500 nm. In other embodiments, the thickness of the Ti layer  30  can be changed with the manufacturing methods or the materials of the glass sheet being formed. 
         [0021]    In step S 104 , referring also to  FIG. 3 , an IrO 2  layer preform  41  is deposited on the Ti layer  30  to get a body preform  101 . The IrO 2  layer preform  41  can be deposited by PVD methods or PECVD methods. In the illustrated embodiment, the IrO 2  layer preform  41  is deposited by a PVD method. A thickness of the IrO 2  layer preform  41  is in a range from about 500 nm to about 1000 nm. In other embodiments, the thickness of the IrO 2  layer preform  41  can be changed with the manufacturing methods or the materials of the glass sheet being formed. 
         [0022]    In step S 105 , IrO 2  of a surface of the IrO 2  layer preform  41  is reduced, so that the IrO2 layer preform  41  is converted into the IrO 2  layer  40  and the Ir layer  50  deposited on the IrO 2  layer  40 . In the illustrated embodiment, the IrO 2  layer preform  41  is reduced by a thermal decomposition method. In the embodiment, the IrO 2  layer preform  41  is heated to a temperature equal to or higher than about 500 degrees Celsius for about 30 minutes (min) to about 120 min, keeping a pressure equal to or lower than about 1.33×10 −4  Pascal (Pa). IrO 2  of the surface of the IrO 2  layer preform  41  is decomposed into Ir and Oxygen (O 2 ), so that the IrO 2  layer  40  and the Ir layer  50  are obtained. A thickness of the IrO 2  layer  40  is in a range from about 100 nm to about 500 nm. A thickness of the Ir layer  50  is in a range from about 100 nm to about 500 nm. In other embodiments, other methods can be employed to reduce the IrO 2  layer preform  41 , such as a method of reacting IrO 2  of the surface of the IrO 2  layer preform  41  with a reducing gas. The reducing gas can be hydrogen (H 2 ) or ethyne (C 2 H 2 ). 
         [0023]    During the manufacturing process of the mold core  100  of the embodiment, the IrO 2  layer preform  41  is formed in advance. And then the Ir layer  50  is formed by reducing IrO 2  of the surface of the IrO2 layer preform  41 , so an Ir sputtering target with a high cost, which is needed when forming the Ir layer  50  directly, can be omitted. Thus, a manufacturing cost of the mold core is low. Furthermore, a binding force between the IrO 2  layer  40  and the Ir layer  50  is high, so that the usage life of the mold core  100  is prolonged. In addition, crystal lattices of the WC layer  20 , the Ti layer  30 , the body  10 , and the IrO 2  layer  40  are similar, the WC layer  20  and the Ti layer  30  are formed between the body  10  and the IrO 2  layer  40 , so binding forces between the above mentioned layers and the body  10  is improved, which further prolongs the lifespan of the mold core  100 . 
         [0024]    In other embodiments, if a binding force between the IrO 2  layer  40  and the body  10  can reach a usage need, the WC layer  20  and the Ti layer  30  can be omitted, and the IrO 2  layer  40  can be formed directly on the forming surface  11 . 
         [0025]    An example 1 of the method for manufacturing the mold core of the embodiment is as follows. 
         [0026]    In a first step, a body made of stainless steel is provided. The body includes a forming surface. 
         [0027]    In a second step, a WC layer is deposited on the forming surface by a vacuum sputtering process. Parameters of the vacuum sputtering process of the example  1  are as follows. A sputtering target is tungsten (W) target; a reacting gas is C 2 H 2 , and a flow velocity of C 2 H 2  is about 60 standard-state cubic centimeter per minute (sccm); a radio frequency power is about 200 watts; a pressure is equal to or lower than about 1.33 Pa, and a sputtering time is about 400 seconds. A thickness of the WC layer is about 100 nm. 
         [0028]    In a third step, a Ti layer is deposited on the WC layer by a vacuum sputtering process. Parameters of the vacuum sputtering process of the example 1 are as follows. 
         [0029]    A sputtering target is Ti target; a protection gas is argon (Ar), and a flow velocity of Ar is about 30 sccm; a radio frequency power is about 200 watts; a pressure is equal to or lower than about 1.33 Pa, and a sputtering time is about 150 seconds. A thickness of the Ti layer is about 200 nm. 
         [0030]    In a fourth step S 104 , an IrO 2  layer preform is deposited on the Ti layer to get a body preform by a vacuum sputtering process. Parameters of the vacuum sputtering process of the example 1 are as follows. A sputtering target is IrO 2  target; a plurality of reacting gases are Ar and O 2 , a flow velocity of Ar is about 20 sccm, and a flow velocity of O 2  is about 80 sccm; a direct current power is about 200 watts; a pressure is equal to or lower than about 0.9 Pa; a temperature is about 200 degrees Celsius; and a sputtering time is about 300 seconds. A thickness of the IrO 2  layer preform is about 600 nm. 
         [0031]    In a fifth step, IrO 2  of a surface of the IrO2 layer preform is reduced. The body preform is heated to about 550 degrees Celsius for about 60 minutes, keeping a pressure equal to or lower than about 1.33×10 −4  Pa and a nitrogen flow with a flow velocity of 100 sccm. IrO 2  of a surface of the IrO2 layer preform is decomposed into Ir and O 2 , an Ir layer is formed on an IrO 2  layer, so that the mold core is obtained. A thickness of the IrO 2  layer is about 150 nm. A thickness of the Ir layer is about 450 nm. 
         [0032]    As shown in  FIG. 4 , the successful reduction of IrO 2  of the surface of the IrO2 layer preform is demonstrated by the XPS experiments. The signals at peak A 1  and peak C 1  of 4f 7/2  and 4f 5/2  (about 60.5 eV and about 63.5 eV) exhibit essentially identical binding energies for the Ir 4f orbit in accord with Ir 0 . The signals at peak B 1  and peak D 1  of Ir 4f 7/2  and Ir 4f 5/2  (about 61.7 eV and about 64.7 eV) exhibit essentially identical binding energies for the Ir 4f orbit in accord with Ir 4+ . 
         [0033]    An example 2 of the method for manufacturing the mold core of the embodiment is similar to the example 1 of the method for manufacturing the mold core of the embodiment. However, for the example 2, in a fifth step, the preform is heated to about 550 degrees Celsius for about 90 minutes to reduce IrO 2  of the surface of the IrO2 layer preform. A thickness of the IrO 2  layer is about 100 nm. A thickness of the Ir layer is about 500 nm. As shown in  FIG. 5 , the signals at peak A 2  and peak C 2  of 4f 7/2  and 4f 5/2  (about 60.5 eV and about 63.5 eV) exhibit essentially identical binding energies for the Ir 4f orbit in accord with Ir 0 . Signals exhibiting identical binding energies for the Ir 4f orbit in accord with Ir 4+  are not distinct, which suggests a content of the IrO 2  is relatively low in the surface of the mold core. 
         [0034]    An example 3 of the method for manufacturing the mold core of the embodiment is similar to the example 1 of the method for manufacturing the mold core of the embodiment. However, for the example 3, in a fifth step, the preform is heated to about 600 degrees Celsius for about 60 minutes to reduce IrO 2  of the surface of the IrO2 layer preform. A thickness of the IrO 2  layer is about 150 nm. A thickness of the Ir layer is about 450 nm. As shown in  FIG. 6 , the signals at peak A 3  and peak C 3  of 4f 7/2  and 4f 5/2  exhibit essentially identical binding energies for the Ir 4f orbit in accord with Ir 0 . The signals at peak B 3  and peak D 3  of Ir 4f 7/2  and Ir 4f 5/2  exhibit essentially identical binding energies for the Ir 4f orbit in accord with Ir 4+ . 
         [0035]    It is to be understood, however, that even through numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.