PRODUCTION OF METALLIC COBALT POWDER

摘要

A process for the production of powdered metallic cobalt including ultra fine metallic cobalt by reduction of cobaltous ammonium sulphate solutions. A soluble silver salt, preferably silver sulphate or silver nitrate, is added in an amount to provide a soluble silver to cobalt weight ratio in the range of 1 g to 10 g silver: 1 kg cobalt, an organic dispersant such as bone glue or polyacrylic acid, or mixture thereof, is added in an amount of 0.01 to 2.5 % of the weight of the cobalt, an ammonia to cobalt mole ratio in the range of about 1.5:1 to 3.0:1, preferably about 2.0:1 is established, and the solution is heated to a temperature in the range of 150 to 250 DEG C, preferably about 180 DEG C, with agitation under a hydrogen pressure of 3000 to 4000 kPa for an induction period and a reduction period sufficient to reduce cobaltous sulphate to cobalt metal powder. The ultra fine cobalt powder is submicron in size, is nodular, and has a surface area in excess of 2.0 M<2>/g. The particle size and surface area are essential to allow for lower sintering temperatures to achieve the required sintered product density.