Preparation of composite powders by pressure reduction with hydrogen

Preparation of nickel-coated composite powders is presented by pressure reduction with hydrogen of aqueous Ni(II) from acetate feed solutions containing various base powders (graphite, tungsten carbide, and aluminium). Particularly, the effect of major process variables (pressure of hydrogen, temperature, concentration of Ni(II), concentration of acetates) on both the course of reduction and on the quality of resultant composite powders were investigated. Optimum conditions were established for preparation of nickel-coated graphite, tungsten carbide, and aluminium composite powders. Moreover, the effect of the presence of Bi(III), Sb(III), and As(V) in the feed Ni(II) acetate solutions on the course of pressure reduction and on the quality of nickel coating was examined and determined. The best quality nickel-coated composites were obtained from feed solutions containing Bi(III) at concentrations less than 1.0 g/l.