Formation of aluminum or aluminum alloy surface film

Abstract

Abstract PURPOSE:To form a surface film having superior corrosion resistance and superior adhesive strength to a paint film and having a desired color, by electrolytically etching an Al material in an aqueous soln. contg. hydrochloric acid or the like and by immersing it in an acidic soln. to carry out desmutting and chemical etching. CONSTITUTION:Al or an Al alloy is electrolytically etched in an aqueous soln. contg. hydrochloric acid or nitric acid using DC, AC or pulse current. The etched Al is immersed in an acidic soln. such as an aqueous soln. of hydrochloric acid, sulfuric acid, nitric acid or hydrofluoric acid to carry out chemical etching after removing smut. Thus, a chemically converted fine-grained film having superior adhesive strength to paint, high corrosion and weather resistances is obtd. The film has a desired color tone from gray to off-white in accordance with the extent of etching. After carrying out chemical etching while leaving pores produced by said electrolytic etching, a transparent paint film may be formed to manufacture a member having a superior decorative effect.

Inventors

• 👤 Tetsuji Iwama
• 👤 岩間　哲治
• 👤 Koji Mitamura
• 👤 三田村　康二
• 👤 Isao Takeuchi
• 👤 竹内　庸

Bibliographic Details