Bright and hard electrodeposits of nickel from nickel acetate-formamide bath

Abstract

The electrodeposition of nickel from nickel acetate dissolved in pure formamide was carried out and the effect of pH, current density, temperature, and boric acid concentration was studied. The temperature range of 40-50° C wasfound to be the best operating parameter at which usually bright and hard deposits having high cathode current efficiencies were obtained. A concentration of 0·1M boric acid in conjunction with 0’2M ammonium acetate resulted in deposits having exceptionally high levels of hardness. Variation of pH by hydrochloric acid led to bright, fine grained hard deposits, while changing pH by acetic acid possessing bulkier acetate ions resulted in soft and thin electrodeposits. Scanning electron microscopy revealed refinement in grain size with increasing temperature. A definite change in microstructure occurred when nickel electroplates were annealed to 400-600°C for 1h and cooled slowly under atmospheric pressure. © 1988 The Institute of Metals.