Physico-mechanical properties of nickel electrodeposited from nickel acetate–amide baths

Abstract

Electrodeposition of nickel from nickel acetate dissolved separately in formamide (FA), N-methylformamide (NMF), and N,N-dimethylformamide (DMF) was carried out. The effects of current density, temperature, boric acid addition, and basis metal were studied. To obtain satisfactory deposits, higher current densities were required using the NMF bath, while FA and DMF baths gave good results at lower current densities. For all types of bath the optimum temperature range for the production of hard deposits was 50–60°C. A higher concentration of boric acid was required to enhance the buffering action for the FA bath, less for the NMF bath, and least for the DMF bath. The DMF and NMF baths also resulted in nickel deposits of high hardness. Scanning electron microscopy revealed a definite change in microstructure when the copper basis metal was replaced by brass which produced fine grains and thereafter by a copper-deposited copper substrate which produced large grains. Reduced cracking was found in the electrodeposited nickel and refinement in grain size occurred when the amide hydrogen of formamide was respectively replaced by one or two methyl groups.MST/1011