Abstract:
A coated article, includes a substrate, an anti-corrosion layer deposited on the substrate, the anti-corrosion layer being composed of ZrW 2 O 8  and AlON. The disclosure also describes a method to make the coated article.

Description:
BACKGROUND  
       [0001]    1. Technical Field 
         [0002]    The exemplary disclosure generally relates to coated articles and a method for manufacturing the coated articles. 
         [0003]    2. Description of Related Art 
         [0004]    With the development of wireless communication and information processing technology, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. Aluminum alloy and magnesium alloy have good heat dissipation and can effectively shield electromagnetic interference, and thus have been widely used for coated articles of the portable electronic devices. However, aluminum alloy and magnesium alloys have low corrosion resistance. 
         [0005]    Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Many aspects of the embodiments 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 exemplary coated article and method for manufacturing the coated article. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment. 
           [0007]      FIG. 1  is a cross-section view of an exemplary embodiment of coated article. 
           [0008]      FIG. 2  is a schematic view of a magnetron sputtering coating machine for manufacturing the coated article of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0009]      FIG. 1  shows an exemplary embodiment of a coated article  10  including a substrate  11  and an anti-corrosion layer  13  deposited on the substrate  11 . 
         [0010]    The substrate  11  can be made of metallic material, such as aluminum, aluminum alloy, magnesium or magnesium alloy. 
         [0011]    The anti-corrosion layer  13  substantially comprising ZrW 2 O 8  and AlON, wherein the mass percentage of ZrW 2 O 8  is about 15-35%, the remainder substantially AlON. The anti-corrosion layer  13  is deposited by magnetron sputtering. The anti-corrosion layer  13  has a thickness between about 0.5 micrometers (μm) and about 1.1 μm. 
         [0012]    A method for manufacturing the coated article  10  may include at least the following steps: 
         [0013]    Providing a substrate  11  that may be made of aluminum, aluminum alloy, magnesium or magnesium alloy. 
         [0014]    Pretreating the substrate  11  by washing with a solution (e.g., Alcohol or Acetone) in an ultrasonic cleaner to remove impurities and contaminations, such as grease, or dirt, the substrate  11  is then dried. The substrate  11  is then cleaned by argon plasma cleaning. 
         [0015]    Providing a vacuum sputtering coating machine  20 . Referring to  FIG. 2 , the vacuum sputtering coating machine  20  includes a sputtering coating chamber  21  and a vacuum pump  30  connected to the sputtering coating chamber  21 . The vacuum pump  30  is used to evacuate the sputtering coating chamber  21 . The vacuum sputtering coating machine  20  further includes two aluminum-based targets  23 , a rotating bracket  25 , and a plurality of gas inlets  27 . The rotating bracket  25  rotates the substrate  11  in the sputtering coating chamber  21  relative to the aluminum-based targets  23 . The aluminum-based targets  23  face each other, and are respectively located on opposite sides of the rotating bracket  25 . 
         [0016]    The aluminum-based targets  23  substantially comprising ZrW 2 O 8  and aluminum, wherein the mass percentage of ZrW 2 O 8  is about 20-40%, the remainder substantially aluminum. A method for manufacturing the aluminum-based targets  23  comprising the following steps: providing powders of ZrW 2 O 8  and aluminum, wherein the mass percentage of the ZrW 2 O 8  powder is about 20-40%, the remainder is aluminum powder; blending the ZrW 2 O 8  and aluminum powders to produce a blended powder; compacting the blended powder by cold isostatic pressing (CIP); consolidating the compacted powder by vacuum sintering at a temperature of about 800 to about 880° C. for about 2 to about 5 hours. The method for manufacturing the aluminum-based target  23  further comprising: polishing the aluminum-based target  23  to smoothen the surfaces of the aluminum-based target  23 . 
         [0017]    Cleaning the aluminum-based targets  23  by argon (Ar) plasma. The substrate  11  is retained on a rotating bracket  25  in a sputtering coating chamber  21 . The vacuum level inside the sputtering coating chamber  21  is set to about 3.0*10 −5  Pa. Argon gas is fed into the sputtering coating chamber  21  at a flux rate about 500 Standard Cubic Centimeters per Minute (sccm) from the gas inlets  27 . A bias voltage applied to the substrate  11  may be between about −50 volts (V) and about −150 volts. The argon particles strike against and clean the surface of aluminum-based targets  23 . 
         [0018]    An anti-corrosion layer  13  is deposited on the substrate  11 . The temperature in the sputtering coating chamber  21  is set between about 100° C. (Celsius degree) and about 120° C. Argon gas is fed into the sputtering coating chamber  21  at a flux between about 100 Standard Cubic Centimeters per Minute (sccm) and about 300 sccm from the gas inlets  27 . Nitrogen is fed into the sputtering coating chamber  20  at a flux between about 10 sccm and 20 sccm and oxygen is fed into the sputtering coating chamber  20  at a flux between about 10 sccm and 20 sccm from the gas inlets  27 . The aluminum-based targets  23  in the sputtering coating chamber  21  are evaporated at a power between about 6 kW and about 8 kW. A bias voltage applied to the substrate  11  may be between about −50 volts and about −150 volts, for between about 30 minutes and about 120 minutes, to deposit the anti-corrosion layer  13  on the substrate  11 . The anti-corrosion layer  13  has a thickness between about 0.5 μm and about 1.1 μm. Once cooled down, the coated article  10  can be removed. 
         [0019]    With the decrease of the temperature of the substrate  11  after depositing the anti-corrosion layer  13 , ZrW 2 O 8  is capable of expanding to fill gaps between the AlON particles due to their (i.e., the ZrW 2 O 8 ) negative thermal expansion coefficient. Which makes the anti-corrosion layer  13  achieve a more compact structure relative to an AlON layer, thus can improve the corrosion resistance of the coated article  10 . 
         [0020]    It is to be understood that the method for manufacturing the coated article  10  may further includes depositing a bonding layer between the substrate  11  and the anti-corrosion layer  13  to improve bonding force between the substrate  11  and the anti-corrosion layer  13  so the anti-corrosion layer  13  can be firmly deposited on the substrate  30 . 
       EXAMPLES 
       [0021]    Experimental examples of the present disclosure are described as follows. 
       Example 1 
       [0022]    A sample of aluminum alloy substrate was pretreated and then was placed into the sputtering coating chamber  21  of the vacuum sputtering coating machine  20 . The temperature in the sputtering coating chamber  21  was set about 100° C. Argon was fed into the sputtering coating chamber  21  at a flux about 250 sccm from the gas inlets  27 . Nitrogen was fed into the sputtering coating chamber  20  at a flux about 15 sccm and oxygen is fed into the sputtering coating chamber  20  at a flux between about 15 sccm from the gas inlets  27 . The aluminum-based targets  23  in the sputtering coating chamber  21  were evaporated at a power about 6 kW. A bias voltage applied to the substrate  11  was between about −100 volts for about 60 minutes, to deposit an anti-corrosion layer on the aluminum alloy substrate. 
         [0023]    The aluminum-based targets  23  were manufactured as follows. Providing powders of ZrW 2 O 8  and aluminum wherein the mass percentage of the ZrW 2 O 8  powder was about 50%, the remainder is aluminum powder; and the powders of ZrW 2 O 8  and aluminum was blended to produce a blended powder. The blended powder was compacted by Cold Isostatic Pressing (CIP). Next, The compacted powder was then consolidated by vacuum sintering at a temperature of 810° C. for about 3.5 hours. 
       Example 2 
       [0024]    Unlike the example 1, in the example 2, The substrate was made of magnesium alloy. The aluminum-based targets  23  were evaporated at a power between about 7 kW. The time of depositing the anti-corrosion layer  13  was about 75 minutes. The mass percentage of the ZrW 2 O 8  powder was about 30% in the blended powders of ZrW 2 O 8  and aluminum. The temperature of consolidating the compacted powder was about 880° C. Except the above difference, the remaining experiment conditions of example 2 were same as example 1. A substrate of magnesium alloy coated with an anti-corrosion layer was obtained according to example 2. 
       Comparison Example 
       [0025]    Unlike the example 1, in the comparison example, the flux of the nitrogen was between about 80 sccm and the flux of the oxygen was between about 20 sccm. The aluminum-based targets were replaced by aluminum targets, and the aluminum targets in the sputtering coating chamber  21  are evaporated at a power about 8 kW. A bias voltage applied to the substrate was about −200 volts for about 40 minutes. Except the above difference, the remaining experiment conditions of comparison example were same with example 1. A substrate of aluminum alloy coated with an AlON layer was obtained according to comparison example. 
       The Salt Spray Test Results  
       [0026]    The samples coated with the anti-corrosion layer and the sample coated with AlON layer were tested by salt spray test (35° C., 5% NaCl). The sample coated with AlON layer was subjected to the 72 hour salt spray test. But, the samples coated with the anti-corrosion layer were subjected to the 120 hour salt spray test. Thus, it is clear that The samples coated with the anti-corrosion layer have better corrosion resistance than the sample coated with AlON layer. 
         [0027]    It is to be understood, however, that even through numerous characteristics and advantages of the exemplary disclosure have been set forth in the foregoing description, together with details of the system and function of the 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 disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.