GB942867A - Improvements in or relating to the electrodeposition of nickel - Google Patents

Abstract

Nickel plating baths are improved by adding a coumarin compound of formula <FORM:0942867/C3/1> where n is 1 or 2, X represents a hydrogen, chlorine, or bromine atom, the NH-group being attached to the adjacent benzene ring in the 5, 6, 7 or 8 position, and when n is 1, Y represents a hydrogen atom, a phenyl group, or a monovalent aliphatic group containing 1 to 4 carbon atoms, and when n is 2, Y represents a phenylene group, a divalent aliphatic group containing 1 to 4 carbon atoms or a covalent bond. These compounds which are of high m.pt. can be used alone or with (a) sulphonic acids, sulphonimides, and sulphonamides, e.g. dibenzene sulphonamide, (b) chloral hydrate, bromal hydrate, or formaldehyde, (c) anti-foaming agents e.g. sodium 2-ethyl hexyl sulphate. A small amount of fluoboric acid may be added to suppress the precipitation of iron. The nickel salt used in the plating bath can be sulphate, chloride, fluoborate, sulphamate, or in the form of a Watts bath. In the examples, baths containing nickel sulphate or chloride have added thereto 6-acetamino coumarin, 6-acetamino 3-bromo coumarin, and oxalyl 6.61-diamino dicoumarin, together with formaldehyde, 2-butane 1.4-disulphonic acid, allyl sulphonic acid, or allyl quinaldinium bromide. The plating may be effected with air agitation.