抄録
The surface film, produced by cathodic treatment of steel sheets in a dilute chromic acid solution containing small amounts of sulfuric acid and a fluoride, consisted of an upper layer of hydrated chromium oxide and a lower layer of metallic chromium. Low carbon steel sheets of various surface states specially prepared were subjected to cathodic treatment in the dilute chromic acid solution, and then, coated with clear epoxy-phenolic lacquer. The examinations of surface roughness, reflectivity, and lightness were made on the steel substrates, cathodic-treated sheets, and lacquered sheets. The results of examinations were as follows. The surface roughness of cathodic-treated sheets was almost the same as that of original steel substrates. The reflectivity of cathodic-treated sheets largely depended upon that of original steel substrates and the former value was lower than the latter value. The reflectivity of the lacquered steels merely depended upon that of original sheet substrates. The lightness of the cathodic-treated sheets depended upon that of original steel substrates; that is, the former linearly increased with the increase of the latter. The lightness of the lacquered sheets also depended upon that of original steel substrates, and the relation between the both was expressed by a linear function.
