クロムめっき膜の残留ひずみに及ぼすニッケル基板と水素共析反応の影響

抄録

The effects of two kinds of nickel substrate on the average strain in a substrate that has been self-deformed by hydrogen absorbed during hydrogen evolution in a sulfuric acid solution, and on the average strain in a chromium film plated from a conventional chromium plating bath were investigated by an electric resistance wire type strain gauge setup on the reverse side of the substrate. One substrate was a nickel sheet with a preferred (220) orientation as received and the other was a nickel film with a preferred (200) orientation deposited on a copper sheet from a Watts bath. It was found that: (1) In the cathodic electrolysis of the sulfuric acid solution, the overpotential for hydrogen evolution on the commercially available nickel sheet was always smaller than that on the nickel film deposited from the Watts bath, and the compressive strain deformation of the substrate by absorption of hydrogen was larger in the commercially available nickel sheet than in the substrate with the deposited nickel film. (2) For the commercially available nickel sheet, the time variation in the strain deformation of the substrate in cathodic electrolysis of sulfuric acid solution was quite similar to that of the substrate in chromium plating. (3) For the nickel film substrate as deposited, the time variation in the strain deformation of the substrate in cathodic electrolysis of sulfuric acid solution was different from that of the substrate in chromium plating. As a substrate for chromium plating, the nickel film deposited from the Watts bath was superior in current efficiency to the commercially available nickel sheet.