Electrodeposition of Ni from low-temperature sulfamate electrolytes

Abstract

The structure and properties of Ni deposited from sulfamate electrolytes is reported. Particulate filtering of the electrolyte has significant consequences with respect to the microstructure and resulting mechanical properties. Effects were most pronounced at low current densities, and gradually disappeared as current density increased. At low current density (3 mA cm2), deposits plated from a filtered electrolyte were fine-grained and exhibited 〈011〉 texture orientation, characteristic of "inhibited" growth. The strengths of these deposits ranged from 700 MPa to 1 GPa; increasing with increasing deposition temperature from 28 to 50°C. Low-current-density deposits from unfiltered electrolyte exhibited a temperature dependent instability in grain morphology and texture. At low temperatures (≤32°C) deposits were coarse grained and predominantly 〈001〉, while at 50°C, deposits were fine grained and 〈011〉. At intermediate temperatures, the deposits grew initially in the uninhibited, coarse grain 〈001〉 mode but then transitioned to the fine grain, 〈011〉 inhibited growth mode. At high current density (15 mA cm2), the structure and properties of electrodeposits were unaffected by particle filtering. Irrespective of deposition temperature or filtering condition, deposits had the grain morphology and crystallography characteristics of uninhibited growth - namely, coarse, columnar grains with preferred 〈001〉 texture. The measured strength of these deposits were 350- 400 MPa. © 2006 The Electrochemical Society. All rights reserved.