Patent Publication Number: US-2012040136-A1

Title: Ceramic coating, article coated with coating, and method for manufacturing article

Description:
BACKGROUND 
     1. Technical Field 
     The exemplary disclosure generally relates to ceramic coatings, and particularly relates to articles coated with the ceramic coatings and method for manufacturing the articles. 
     2. Description of Related Art 
     Electroplating is used to form coatings on the housings of electronic devices. However, electroplating cannot directly coat patterns on a substrate without any other additional processing. Furthermore, electroplating can be environmentally unfriendly. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 ceramic coating, article coated with coating, and method for manufacturing 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. 
         FIG. 1  is a top view of an exemplary article coated with a ceramic coating. 
         FIG. 2  is a cross-sectional view of an exemplary article in  FIG. 1 . 
         FIG. 3  is a schematic view of an evaporation machine for manufacturing the article in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an exemplary ceramic coating  13  is composed of alumina or zirconia. The ceramic coating  13  defines a plurality of recesses  133  on a surface  130 . These recesses  133  give the coating  13  a leather-like appearance. The recesses  133  may intersect with each other. The ceramic coating  13  is formed by a physical vapor deposition (PVD) process, such as ion beam assisted evaporation. Also, the ceramic coating  13  is nonconductive so as to not block electromagnetic waves. The thickness of the ceramic coating  13  is about 10 nm-200 nm. 
     Referring to  FIG. 2 , an exemplary article  10  includes a substrate  11  and the ceramic coating  13  is deposited on the substrate  11 . The substrate  11  may be made of plastic materials, such as polycarbonate (PC), polyethylene (PE), polymethyl methacrylate (PMMA), or acrylonitrile-butadiene-styrene (ABS). The substrate  11  also may be made of metal, ceramic, or glass. In this exemplary embodiment, the ceramic coating  13  is composed of alumina. The article  10  may be a housing of an electronic device. It is to be understood that the article  10  may further include a transparent protective layer  15  formed on the ceramic coating  13  for protecting the ceramic coating  13 . The protective layer  15  may comprise a single layer or multiple layers of transparent paint. The paint may be thermal-curable or photo-curable paint. The thickness of the protective layer  15  is about 10 μm-50 μm. The protective layer  15  may contain colorant therein, presenting desired color for the article  10 . 
     Referring to  FIGS. 2 and 3 , an exemplary method for manufacturing the article  10  may include at least the following steps. 
     The substrate  11  is provided. 
     The substrate  11  may be pretreated by ultrasonic cleaning, to remove impurities such as grease or dirt from the substrate  11 . 
     The ceramic coating  13  is formed on the substrate  11  by ion beam assisted evaporation. An exemplary ion beam assisted evaporation process for forming the ceramic coating  13  may be performed by the following steps. 
     Before depositing the ceramic coating  13 , the substrate  11  is cleaned by plasma cleaning. The substrate  11  is held by a rotating bracket  43  in a vacuum chamber  41  of an evaporation machine  40  as shown in  FIG. 3 . The machine  40  includes a plasma source  42  coupled with a power source  44 . Plasma is generated by utilizing the power source  44  to dissociate ions from a processing gas, such as argon, thereby forming a supply of ions that can accelerate toward the substrate  11 . The vacuum chamber  41  maintains an internal pressure of about 5.0×10 −3  Pa-5.0×10 −2  Pa. The temperature in the vacuum chamber  41  is maintained at about 50° C.-70° C. The potential of the power source  44  may be controlled in a range of about 110 volts (V)-130V with a current density in a range of about 2.5 A-3.5 A to form an ion beam. The ion beam bombards the substrate  11  for about 50 second (sec)-90 sec, further removing any impurities thereon. Thus, bonding between the substrate  11  and the ceramic coating  13  will be enhanced. In this exemplary embodiment, the potential of the power source  44  is about 120V with a current density of about 3 A. The duration of plasma cleaning is about 60 sec. 
     Once the plasma cleaning is finished, oxygen is supplied into the vacuum chamber  41  to compensate for the oxygen atoms lost during the deposition. The oxygen creates a working atmospheric pressure of about 1.5×10 −3  Pa-9.5×10 −3  Pa in the vacuum chamber  41 . The temperature in the vacuum chamber  41  is maintained at about 50° C.-70° C. Evaporation source  45  of crystal alumina or zirconia is evaporated at a rate of about 2.0 angstroms per second (Å/s)-4.5 Å/s to deposit the ceramic coating  13  by electron beam evaporation. The ion beam bombards the substrate  11  during the ceramic coating  13  deposition. The ion beam is generated by controlling the potential of the power source  44  in a range of 140V-160V with a current density in a range of 4.5 A-5.5 A. The ceramic coating  13  having the recesses  133 , which presents a leather-like appearance, is formed in this step. In this exemplary embodiment, the potential of the power source  44  is about 150V with a current density of about 4 A, and the target is crystal alumina. 
     During the deposition of the ceramic coating  13 , the ion beam bombards the ceramic coating  13 , thereby portions of the ceramic coating  13  may be removed to form the recesses  133 . The presence of the ion beam during the deposition of the ceramic coating  13  also enhances the packing density of the ceramic coating  13 . 
     After the deposition of the ceramic coating  13  is finished, the substrate  11  with the ceramic coating  13  is retained in the vacuum chamber  41  and continuously bombarded by the ion beam for about 3 min-10 min. In this step, the potential of the power source  44  is controlled in a range of 140V-160V with a current density in a range of about 3.5 A-4.5 A. In this exemplary embodiment, the potential of the power source  44  is about 150 volts with a current density of about 4 A. The presence of the ion beam after the deposition of the ceramic coating  13  enhances the bonding of the ceramic coating  13  and the substrate  11  and etches the recesses  133 . 
     Owing to the present process, an article  10  having a leather-like appearance is obtained. 
     Additionally, the method for manufacturing the article may further include forming the transparent protective layer  15  on the ceramic coating  13 , which can be achieved by spray painting. 
     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.