抄録
Ni-Co alloy deposits were obtained by electroless plating from an acetate bath using dimethyl-amine borane at a rate of about 7μm/h at 60°C. Thallous nitrate was employed as a stabilizer of the bath. Under these conditions, both thallium and boron were co-deposited into Ni-Co alloys. It was, however, confirmed that boron content in the alloy deposit decreased significantly with an increase of thallous nitrate in the bath. Internal stress, electrical resistance and hardness of the alloy deposits were discussed on the basis of the composition of Ni-Co alloys. The internal stress of the Ni-Co alloy deposits seemed to decrease with a decrease in boron content of the alloys. The specific resistance of the Ni-Co alloy deposits as-plated was found to be 60-80μΩcm. However, it decreased to about 20μΩcm upon heat treatment at 400-600°C in vacuum. The hardness of the alloy deposits heat-treated at 400°C depended on boron content in the alloys; the higher boron content gave rise to the higher hardness of the alloy deposits up to that of hard chromium coatings.
