Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Patent
1986-04-30
1988-09-13
Niebling, John F.
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
204 383, 204 387, 204 584, 20419231, 427405, 427409, 4274195, 4284111, 428414, 4284231, 4284258, 428447, 428469, 428524, C23C 2800, C23C 1402
Patent
active
047709464
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a surface-treated magnesium (Mg) or Mg alloy suitable, for example, for aerospace machines and instruments, electric precision machines and instruments, and automobile parts which are to be improved in corrosion resistance, surface conductivity, abrasion resistance, and heat shock resistance, and to a surface treatment process therefor.
BACKGROUND ART
Light alloys including aluminum (Al) are widely used as the metallic materials employed for aerospace machines and instruments, electric precision machines and instruments, and automobile parts from the view points of reduction of weight, reduction of consumed energy, and upgrading of performance. For example, as can be seen in a casing of an artificial satellite transponder housing, surface conductivity is necessary in a housing including electric and electronic parts and/or circuits for securing stable grounding and improving the electromagnetic interference resistance. In the case of an Al alloy heretofore employed in such a housing, formation of a thick corrosion-resistant insulating film is not needed, since the alloy is excellent in corrosion resistance.
Recently, there has developed a tendency to use an Mg alloy having a 30% or more lighter specific weight than that of the Al alloy instead of the Al alloy in the above-mentioned machines and instruments. Mg is the most chemically active among practical metals. Thus, formation of a rustproof film on the surface of Mg or the Mg alloy is necessary in practical utilization thereof. As to the method of preventing the Mg alloy from corrosion, many studies, including one disclosed in Spencer, L. F. "Chemical Coatings for Magnesium Alloys" (Metal Finishing; Sept., 1970, 63-66 and the same journal; Oct., 1970, 52-57), have been made. Nevertheless, the technique of preventing the Mg alloy from corrosion is not established as yet. Even if a rustproof film is formed on the surface of magnesium by a chemical conversion treatment, an anodizing treatment, wet plating, dry plating, coating, or the like as usual, the rustproof film has micro pinholes present therein, and, hence, cannot prevent the diffusion of the magnesium into the surface film to cause deterioration of the corrosion resistance. Furthermore, when a conductive metallic film of gold (Au), silver (Ag), or the like is disposed on the corrosionproof oxidized film to impart a surface conductivity to Mg or an Mg alloy, cells are formed between the Mg or Mg alloy and conductive metallic film under a wet environment to allow corrosion of Mg or the Mg alloy to progress.
As described above, no effective method of preventing Mg or an Mg alloy from corrosion is established as yet, much less Mg or an Mg alloy satisfactory in both corrosion resistance and surface conductivity is materialized. There has been no method of surface treatment of Mg or an Mg alloy satisfactory for meeting the purpose.
DISCLOSURE OF INVENTION
As described above, the conventional method of surface treatment of Mg or an Mg alloy does not provide not only sufficient corrosion resistance and surface conductivity but also sufficient heat shock resistance and abrasion resistance.
The object of the present invention is to obviate the defects of the conventional method of surface treatment of Mg or an Mg alloy, particularly to provide a surface-treated Mg or Mg alloy excellent in not only corrosion resistance and surface conductivity but also heat shock resistance and abrasion resistance, and a surface treatment process therefor.
For attaining the object, the surface-treated Mg or an Mg alloy according to the present invention is characterized by comprising an oxidized film formed on Mg or an Mg alloy, a thermosetting resin film provided on the oxidized film, and a conductive film provided on the thermosetting resin film.
Here, the thermosetting resin film may be a resin layer consisting of a plurality of different thermosetting resin layers. The conductive film may be a film consisting of a plurality of different metallic layers. The thermose
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patent: 4348463 (1982-09-01), Ohno et al.
patent: 4643951 (1987-02-01), Keem et al.
H. K. DeLong, Practical Finishes for Magnesium, Metal Progress, Jun. 1970, pp. 105-108.
Brian Chapman, Glow Discharge Processes, John Wiley & Sons, N.Y., 1980, pp. 253-255.
Lester F. Spencer, Chemical Coatings for Magnesium Alloys, Metal Finishing, Sep. 1970, pp. 63-66; Oct. 1970, pp. 52-57.
PCT/JP85/00571/International Search Report No. 0198092.
Arita Kishio
Koide Yoshitaka
Masuda Jun'ichi
Matsudaira Yuzo
Mino Masato
Leader William
Niebling John F.
Nippon Telegraph and Telephone Corporation
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