The electroless nickel plating of porous sintered iron-base parts

Abstract

1. The electroless nickel plating of sintered parts should not be performed in alkaline solutions. The best results were obtained by nickel plating in acid solutions (pH 5–5.2). 2. For obtaining nickel deposits 20–25μ thick, capable of resisting 3% NaCl solution for 7 h or longer, nickel plating should be performed in two stages. 3. In order to prevent the corrosion of the internal surface, the pores must be impregnated with GKZh-94 liquid before plating, and polymerization must be carried out. 4. For raising the corrosion resistance of the nickel deposit, the latter should also be impregnated with a weak solution of GKZh-94 and then subjected to polymerization. 5. If the nickel plating solution is to operate in a stable manner and be capable of correction, sodium citrate (15 g/liter) and glycocoll (30 g/liter) must be added to it. 6. The nickel plating solution is replaced by a fresh one after 5–6 operating cycles, when its phosphite content has reached 50–60 g/liter.