Influence of heat treatment on properties of Ni-P-SiO_2 composite coatings

The experiments of electroless Ni-P-SiO2 composite plating were carried out,and then heat treatments for the obtained composite coatings were performed under different heating temperatures and holding time.After heat treatment,the metallographic structure,hardness and porosity of the composite coatings were examined by using XJP-6A type microscope,HVS1000 type micro-hardmeter and the paste filter paper method,respectively.The results show that by heating to 400 ℃ and holding for 90 min,the structures of Ni-P-SiO2 composite coatings have a more homogeneous density.Besides having a higher hardness,the binding force between composite coatings and the matrix is well,and the porosity are almost zero.