抄録
Hardness and Wear Resistance
With the object of studying hard anodizing process at room temperature, hardness and were resistance of anodic oxidation coatings of aluminum from mixed bath of sulfuric-oxalic-citric acids were examined. The results of experiments were as follows.
(1) Good uniform coatings were not obtained from the electrolyte of sulfuric acid lower than 40g/l in concentration, but uniform coatings were obtained when sulfuric acid was mixed with oxalic acid.
(2) Hardness increased on addition of citric acid to sulfuric-oxalic acid bath. Particularly, the increase was greater when the coatings were thicker.
(3) Both hardness and wear resistance of the coatings from the above mixed bath were higher than those from other baths at room temperature, and it was found that the mixed bath was very effective for hard anodizing at room temperature.
(4) Hardness at the cross-section of thick coatings increased toward the inner part of layer; however, it slightly decreased near the boundary layer of substrate metal.
