Electrodeposition of nanocrystalline cobalt from sulfate baths containing butynediol ethoxylate

Cobalt electrodeposit is a potential ideal matrix for precision diamond tools. In this work, cobalt electrodeposition was conducted in sulfate baths and the effects of butynediol ethoxylate (BEO) on the surface morphology, crystal structure, surface roughness and microhardness of cobalt deposits were investigated. Experimental results revealed that BEO had a strong inhibitory effect on the cobalt deposition process due to its high adsorption ability on cobalt; the addition of BEO favored the formation of smooth deposits of hexagonal close packed structure with [0002] preferred orientation, whose morphology was characterized by tiny granular structures, but it had trivial effects on their microhardness and average crystallite size. The changes in the properties of cobalt deposits could be related to the adsorption of BEO on (0002) plane of cobalt crystals, since the adsorption energy of BEO on this plane is much lower than that on other planes according to the results of molecular dynamics simulation.