MICROSTRUCTURE AND PROPERTIES OF Ni/Al₂O₃ COMPOSITE INFILTRATED LAYER ON COPPER SURFACE

Ni/Al2O3 surface composite layers were prepared by vacuum infiltration casting process with different contents of Al2O3 particles in order to enhance the wear resistance and oxidation resistance of copper surface at high temperatures.The thickniss of infiltration layer was up to 1～2 mm.The microstructure,elemental distribution,hardness and adhere intensity of the infiltrated layer were studied by means of scanning electron microscopy (SEM),X-ray diffrection (XRD),electron probe microanalysis (EPMA).The infiltrated layer included surface composite layer and transition layer.The distribution of Al2O3 particles was uniform.The interface between the base metal and the penetrated layer contained no holes and the structure was compact.There was no micro-cracks between the Al2O3 particles and at the interface of the surface composite layer and the substrate.The infiltrated layer was composed of Ni-based solid solution,Al2O3,Ni31Si12 and Ni3B,which could enhance the hardness,intensity and wear insistence of the copper surface.