The Effects of Some Aromatic Sulphonic Acids on the Stress, Structure, and Composition of Electrodeposited Nickel

Abstract

A systematic study has been made of the efiects of certain aromatic sulphonic acids added to a Watts nickel bath. Benzene derivatives contribute sulphur but no carbon to the deposits which are characterized by (100) orientations. Deposits obtained from baths containing naphthalene derivatives are usually characterized by a random structure or a (110) orientation and contain sulphur but no carbon unless nitrogen is present in the addition agent molecule when all three elements are present in the deposits. Solutions containing naphthylamine mono-sulphonic acids transfer the entire brightener molecule to the deposit. Benzene derivatives and naphthalene sulphonic acids reduced the stress normally present in Watts nickel. Naphthol sulphonic acids and naphthyl- amine sulphonic acids lead to an inverse form of the usual stress/thickness relationship. The greater the separation of substituent groups in the latter compounds, the more pronounced is the initial rise in stress and the higher the final stress level. The results are discussed in terms of possible interaction of chemisorped electron donor groups on the growing nickel surface.