The electroless deposition of nickel on SiC particles for aluminum matrix composites

Nickel coatings have been deposited by an electroless method on SiC powder particles. Three different SiC powder grades, in terms of average particle size, were chosen, i.e. 8, 14 and 70 μm. The coating process was performed in few steps consisting of the SiC powder cleaning by acetone, its sensitization by HCl aqueous solution containing Sn2+, followed by its activation by HCl aqueous solution containing Pd2+, and finally—hydrometallurgical nickel deposition using aqueous solution containing Ni2+, as a nickel carrier. The influence of the deposition conditions on the coating layer properties was studied. The thickness, morphology and microstructure of the layers were controlled by the growth conditions. SEM and digital image analyzing techniques were used for those purposes. Since the Ni-coated SiC powders were produced as reinforcement for Al matrix composites, their compatibility as compared with the uncoated SiC powders was also controlled by metallography.