Electroless Nickel Plating with Different Pre-Treatments on Silicon Carbide Particles

摘要

The quality of interface between the reinforcing phase and the metallic matrix plays a very important role during the production of Al/SiC composites by means of powder metallurgy. A transient layer, a plating shall be developed on the reinforcing particles in order to form a better mechanical contact between the ceramic particles and the metallic matrix. Owing to the inert surface of silicon-carbide, the metallic layer can be formed by a chemical reduction only in case if a surface-activation is carried out. Different types of pre-treating materials were tested in order to do this procedure. A partial activation can be obtained after the pre-treatment by using Na-hypophosphite and lactic acid and therefore the desired plating is not continuous. A compact layer of silica formed at the surface of the ceramic particles in the course of surface oxidation by which a compact plating can be developed in case of a stable chemical Ni-bath. The development of continuous plating is promoted by the formation of metallic palladium nuclei in the course of using the two-step activation by palladium-chloride. The developed pre-treating layers were investigated by XPS and XRD and the plating was investigated by SEM.