Characterization of nanocrystalline and amorphous cobalt-phosphorous electrodeposits

Amorphous and nanocrystalline Co-P coatings were successfully prepared by DC electrodeposition. The effect of annealing on the morphology, texture, grain size and hardness of coatings was studied. The results showed that the grain size and texture of nanocrystalline coating remained unchanged after annealing while its microhardness increased from 650 to about 900 VHN owning to the precipitation of intermediate phases. On the other hand a nanocrystalline structure was obtained after annealing of amorphous coatings. This structure exhibited a hardness value of 1180 VHN which is significantly greater than that obtained for as-deposited amorphous coatings, i.e. 720 VHN. This can be related to the difference in phosphorus content of two coatings and therefore different amounts of Co-P precipitates formed during the annealing. (c) 2008 Elsevier B.V. All rights reserved.