Electroless Ni-P-SiC Composite Coatings with Superfine Particles

Superfine silicon carbide particles reinforced nickel-phosphorus (Ni-P) matrix composite coatings were prepared by electroless deposition.The morphology and structure as well as the phase transformation of the composite coatings were studied by SEM,XRD,TEM and DSC.It is shown that SiC particles co-deposited homogeneously,and the structure of Ni-P-SiC composite coatings as deposited was amorphous.After certain heat treatment,the matrix of composite coatings crystallized into nickel crystal and nickel phosphide.At higher temperature,nickel reacted with SiC and generated nickel silicides accompanied by free carbon.Final products of Ni-P-SiC coating after completely heat treatment were consisted of Ni,Ni3P,Ni3Si and carbon.The finer the SiC particles in composite coating,the lower the temperature for the reaction to take place.