Patent Application
20120156475
1. Technical Field
The present disclosure relates to magnesium alloy articles and a method for making the same.
2. Description of the Related Art
Magnesium alloy articles generally includes a magnesium alloy base and a coating. The coating can be formed on the magnesium alloy base by physical vapor deposition (PVD). However, the yielded coating by PVD often produces needle-like holes in the exterior coating surface, badly influencing erosion resistance and abrasion resistance.
Therefore, there is room for improvement within the art.
Many aspects of the present 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.
A method for making the magnesium alloy article 10 includes following steps.
A base 11 is provided as being a magnesium alloy containing magnesium and aluminum. The base 11 may have some grease and tiny protrusions on the surface from punching or casting. It is necessary to clean the grease and remove the tiny protrusions from the base 11.
The base 11 is cleaned by a cleaning solution to clean grease on the surface of the base 11. The cleaning solution can be a mixture solution that contains sodium carbonate (Na2CO3), 12H2O sodium phosphate (12H2O.Na3PO4), octylphenol polyoxyethylene and H2O, the Na2CO3, the Na3PO4 and the octylphenol polyoxyethylene having the weight concentration in a range of 25 g/l-30 g/l, 20 g/l-25 g/l, and 1 g/l-3 g/l, respectively. During cleaning, the base 11 is placed into the cleaning solution, the cleaning solution is at the temperature of about 60° C. to about 80° C. for about 30 seconds to about 60 seconds.
The base 11 can be further rinsed in water after the cleaning to remove any remaining cleaning solution on the surface of the base 11.
The base 11 is etched by a conventional etching solution after being washed in water to remove the tiny protrusions of the base 11. The etching solution can be prepared from sodium hydroxide (NaOH), sodium phosphate (Na3PO4), sodium carbonate (Na2CO3), sodium fluoride (NaF) and H2O. The NaOH, the Na3PO4, the Na2CO3, and the NaF have the weight concentration in a range of 40 g/l-70 g/l, 10 g/l-20 g/l, 25 g/l-30 g/l and 40 g/l-50 g/l, respectively. During etching, the base 11 is placed into the etching solution, the etching solution at a temperature of 40° C.-50° C., for about 3 s-5 s. The tiny protrusions substantially contact and the chemical reacts with the etching solution, thus, the mini-protrusions can be eliminated completely, the surface of the base 11 is substantially flattened.
The base 11 is activated in an activating solution after the etching to strengthen the bonding of intermediate layer 12 and the base 11. The activating solution can be prepared from nitric acid (HNO3), floric acid (HF), and H2O. HNO3 has a weight percentage of 1-10% of the entire solution, and HF has a weight percentage of 1-8% of the entire solution. The weight ratio between the HNO3 and the HF can be 3:1. The base 11 is immersed into the activating solution at a room temperature for about 3 seconds to about 20 s.
The base 11 is processed by a conversion solution after activation to form the intermediate layer 12 on the surface of the base 11. The conversion solution can be prepared by ammonium di-hydrogen phosphate, potassium permanganate (KMnO4), an additive, and H2O. The additive includes an inorganic component of sulphide and an organic component of ammonia. The sulphide and the ammonia respectively have a weight percentage of 10-20% in the entire additive. The ammonium di-hydrogen phosphate has a weight concentration in a range of 60 g/l-100 g/l, the KMnO4 has a weight concentration in a range of 1 g/l-40 g/l, and the additive has a weight concentration in a range of 1 g/l-6 g/l. The base 11 is placed into the conversion solution, the solution at a temperature of 30° C. for about 20 minutes. Thus, the surface of the base 11 has the intermediate layer 12 evenly formed thereon. The intermediate layer 12 has a thickness of 0.2 μm-5 μm, and the intermediate layer 12 is a mixture of components with Mg, Al, O, P, Mn having the atomic number ratio that Mg:Al:O:P:Mn=(1-5):(1-5):(2-10):(1-10):(3-10). The intermediate layer 12 is formed by chemical reactions among the elements Mn, P, O with the Mg, Al contained in the base 11. After processing by the conversion solution, the base 11 is taken out from conversion solution and dried.
The base 11 is processed by PVD after forming of the intermediate layer 12 on the base 11 for forming the coating layer 13 on the intermediate layer 12. Referring to
A coating layer 13 is deposited on the substrate 11. The vacuum level inside the sputtering coating chamber 20 is set to about 8.0×10−3 Pa. The temperature in the sputtering coating chamber 20 is set between about 100° C. (Celsius degree) and about 300° C. A bias voltage applied to the substrate 11 may be between about −150 volts and about −300 volts. Argon, Nitrogen and Oxygen are fed into the sputtering coating chamber 20 from the gas inlets 24, with Argon at a flux between about 1 Standard Cubic Centimeters per Second (sccs) and about 300 sccs, with Nitrogen at a flux between about 1 sccs and about 50 sccs, with Nitrogen and Oxygen at a flux between about 1 sccs and about 50 sccs. The speed of the rotating bracket is set about 0.5 revolutions per minute (rpm). The first targets 22 in the sputtering coating chamber 20 are evaporated at a power between about 8 kW and about 16 kW. After about 60 minutes, a first layer 131 is formed the intermediate layer 12 and mainly includes MgxOyNz. Then, the first targets 22 are turned off, the second targets 23 are turned on. The second targets 22 are loaded with a power 8˜16 Kilowatt (KW), and the rotating speed of the bracket 21 can be 0.5r/min. By sputtering about 60 minutes, a second layer 132 is formed on the first layer 131 and mainly includes CrxOyNz. The second layer 132 bonding with the first layer 131 forms the coating layer 13 having a thickness of 2 μm-5 μm. The first layer 131 firmly attach to the intermediate layer 12 and the second layer 132, the second layer 131 is colored. Therefore, the magnesium alloy article 10 is manufactured.
Relative to the present magnesium alloy article 10, due to the intermediate layer 12, the coating layer 13 firmly bonds with the base 11. Additionally, the coating layer 13 has a sound hardness, and the magnesium alloy article 10 has sound abrasion resistance and corrosion resistance.
It is to be understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of assemblies and functions of various embodiments, 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 invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010592384.2 | Dec 2010 | CN | national |
