COATED ARTICLE AND METHOD FOR MANUFACTURING SAME

Abstract

A coated article includes a substrate including a porous surface and an anodic oxidation film. The porous surface defines a plurality of nanopores. The anodic oxidation film is formed on the substrate covering the porous surface by anodic oxidation process. The anodic oxidation film has a plurality of bonding protrusions, and each bonding protrusion is retained in one of the nanopores to improve a binding force between the substrate and the anodic oxidation film.

Description

BACKGROUND

1. Technical Field

The disclosure generally relates to coated articles and method for manufacturing the coated articles.

2. Description of Related Art

For improving corrosion resistance of metal, such as aluminum or aluminum alloy, physical vapor deposition (PVD) can be used to deposit a coating on a surface of the metal. However, coatings deposited by PVD typically contain micropores that can allow penetration of contaminants, such as air and moisture, which can corrode the metal.

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 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.

FIG. 1 illustrates a cross-sectional view of a substrate of an embodiment of a coated article, in which a plurality of nanopores are defined in the substrate.

FIG. 2 illustrates a cross-sectional view of an embodiment of a coated article.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a coated article 100 includes a substrate 10, an anodic oxidation film 20 deposited on the substrate 10 and a color layer 30 deposited on the anodic oxidation film 20. The coated article 100 may be a housing of an electronic device.

The substrate 10 may be made of aluminum or aluminum alloy. The substrate 10 includes a porous surface 12 that defines a plurality of nanopores 122 made by electrochemical etching. Each nanopore 122 has a pore opening size between 8 nanometers (nm) and 20 nm in circumference. In this exemplary embodiment, each nanopore 122 has a pore opening size between 10 nm and 15 nm.

The anodic oxidation film 20 is formed on the substrate 10 covering the porous surface 12 by anodic oxidation process. The anodic oxidation film 20 has a plurality of bonding protrusions 22, and each bonding protrusion 22 enters into one of the nanopores 122 so the anodic oxidation film 20 is firmly attached to the substrate 10 by the combination of the bonding protrusions 22 and the nanopores 122. The anodic oxidation film 20 has a thickness between about 5 micrometers and about 20 micrometers.

The color layer 30 is formed on the anodic oxidation film 20 opposite to the substrate 10 by vacuum deposition. The color layer 30 has a thickness between about 0.5 micrometers and about 2 micrometers. The color layer 30 may be a titanium nitride (TiN) layer, a titanium nitric-oxide (TiNO) layer, a titanium carbon-nitride (TiCN) layer, a chromium nitride (CrN) layer or a chromium carbon-nitride (CrCN) layer.

A method for manufacturing the coated article 100 may include at least the following steps.

Providing a substrate 10. The substrate 10 may be made of aluminum or aluminum alloy.

Pre-treating the substrate 10 by washing the substrate with a solution (e.g., deionized water or acetone) in an ultrasonic cleaner, to remove impurities, such as grease or dirt. The substrate 10 is dried. The substrate 10 is then treated by alkali treatment in the following way: dipping the substrate 10 in a solution including about 30-50 g/L of NaOH and about 1-2 g/L of sodium gluconate at a temperature of about 40 Celsius degree (° C.)-60° C. for a time of about 1 minute-5 minutes.

The substrate 10 is electrochemically etched to form a porous surface 12 with a plurality of nanopores 122. During electrochemical etching, the substrate 10 acts as an anode, a platinum plate acts as cathode, using about 20 g/L-30 g/L of hydrochloric acid or about 250 g/L-350 g/L of sulphuric acid as electrolyte. A constant power having a current density between about 6 A/d m² and about 10 A/d m² is applied between the anode and the cathode for about 5 minutes to about 10 minutes to form the porous surface 12.

The substrate 10 is treated by anodic oxidation process, to form an anodic oxidation film 20 on the porous surface 12. Sulphuric acid having about 180 g/L-220 g/L is used as electrolyte. The electrolyte has a temperature between about 19° C. and 21° C. A constant power having a current density between about 1 A/m² and about 1.5 A/m² is applied to the electrolyte for about 20 minutes to about 40 minutes to form the anodic oxidation film 20. During depositing the anodic oxidation film 20, portions of the anodic oxidation film 20 enter into the nanopores 122 to form a plurality of bonding protrusions 22. Additionally, each bonding protrusion 22 is retained in one of the nanopores 122 to improve a binding force between the substrate 10 and the anodic oxidation film 20.

The substrate 10 is dipped in an about 5 g/L-10 g/L of nickel acetate solution at a temperature between 90° C. and 100° C. for a time of 10 minutes to 15 minutes, to seal the anodic oxidation film 20. Therefore, corrosion resistance of the anodic oxidation film 20 is improved.

A color layer 30 is deposited on the anodic oxidation film 20 by vacuum deposition, such as vacuum sputtering or vacuum evaporation.

In above exemplary, the substrate 10 defines a plurality of the nanopores 122, the anodic oxidation film 20 includes a plurality of the bonding protrusions 22. Each bonding protrusion 22 is retained in one of the nanopores 122 so a binding force between the substrate 10 and the anodic oxidation film 20 can be improved. Additionally, the anodic oxidation film 20 can prevent the coated article from electrochemically etching.

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.

Claims

1. A coated article, comprising:

a substrate including a porous surface, the porous surface defining a plurality of nanopores; and

an anodic oxidation film formed on the substrate covering the porous surface by anodic oxidation process;

wherein the anodic oxidation film has a plurality of bonding protrusions, and each bonding protrusion is retained in a nanopore to improve a binding force between the substrate and the anodic oxidation film.

2. The coated article as claimed in claim 1, wherein the substrate is made of aluminum or aluminum alloy.

3. The coated article as claimed in claim 1, wherein the nanopores are formed by electrochemical etching.

4. The coated article as claimed in claim 1, wherein each nanopore has a pore opening size between 8 nm and 20 nm in circumference.

5. The coated article as claimed in claim 1, wherein each nanopore has a pore opening size between 10 nm and 15 nm in circumference.

6. The coated article as claimed in claim 1, wherein the anodic oxidation film has a thickness between about 5 micrometers and about 20 micrometers.

7. The coated article as claimed in claim 1, further comprising a color layer formed on the anodic oxidation film opposite to the substrate.

8. The coated article as claimed in claim 7, wherein the color layer has a thickness between about 0.5 micrometers and about 2 micrometers.

9. The coated article as claimed in claim 7, wherein the color layer is one selecting from a group consisting of a titanium nitride layer, a titanium nitric-oxide layer, a titanium carbon-nitride layer, a chromium nitride layer and a chromium carbon-nitride layer.

10. A method for manufacturing a coated article, the method comprising:

providing a substrate, the substrate including a porous surface, the porous surface defining a plurality of nanopores;

forming an anodic oxidation film on the substrate covering the porous surface by anodic oxidation process;

during forming the anodic oxidation film, portions of the anodic oxidation film enter into the nanopores to form a plurality of bonding protrusions, and each bonding protrusion is retained in one of the nanopores to improve a binding force between the substrate and the anodic oxidation film.

11. The method of claim 10, wherein the substrate is made of aluminum or aluminum alloy.

12. The method of claim 10, wherein before the anodic oxidation film is deposited on the substrate, the substrate is treated by alkali treatment.

13. The method of claim 12, wherein during the substrate is treated by alkali treatment, the substrate is dipped in a solution including 30-50 g/L of NaOH and 1-2 g/L of sodium gluconate at a temperature of 40-60° C. for a time of 1-5 minutes.

14. The method of claim 10, wherein the nanopores are defined by electrochemical etching.

15. The method of claim 14, wherein during electrochemical etching, the substrate acts as an anode, a platinum plate acts as cathode, using 20-30 g/L of hydrochloric acid or 250-350 g/L of sulphuric acid as electrolyte, a constant power applied between the anode and the cathode have a current density between about 6 A/d m2 and about 10 A/d m2 for about 5 minutes to about 10 minutes to define the nanopores.

16. The method of claim 10, wherein during anodic oxidation, using 180-220 g/L of sulphuric acid as electrolyte, the electrolyte has a temperature between 19° C. and 21° C., a constant power applied to the electrolyte has a current density between about 1 A/m2 and about 1.5 A/m2 for about 20 minutes to about 40 minutes to form the anodic oxidation film.

17. The method of claim 10, wherein after depositing the anodic oxidation film, the substrate is dipped in a 5-10 g/L of nickel acetate solution at a temperature between 90° C. and 100° C. for a time of 10 minutes to 15 minutes, to improve corrosion resistance of the anodic oxidation film.

18. The method of claim 10, further comprising a step of depositing a color layer on the anodic oxidation film by vacuum deposition.