| 摘要 |
PURPOSE:To make the surface of an Al or Al alloy member finely uneven in a stable manner by etching the member with an aqueous NaOH soln. contg. Zn and by immersing the member in an aqueous soln. contg. Cl. CONSTITUTION:An Al or Al alloy member is etched by immersion in an etching bath at 30-60 deg.C for 2-20min. An aqueous NaOH soln. contg. 5-1,000ppm Zn and having 50-100g/l concn. of NaOH is used as the etching bath. The member is washed and immersed in 10-20% sulfuric acid to remove smut. It is then immersed in an aqueous soln. contg. >=100ppm Cl ions such as sulfuric acid, hydrochloric acid or nitric acid to make the surface of the member finely and densely uneven. An Al or Al alloy member whose surface has a milk white or gray color tone or a satin appearance by the irregular reflection of light due to the unevenness is obtd. |
