The Study Of Microstructure And Performance Of Ni-WC-RE Composite Coating By Vacuum Fusion Sintering

It is an effective method to improve the properties of metal surface layer coated by vacuum fusion sintering, such as increase the wear-resistance and corrosion-resistance properties of the metal surface. Therefore, it is important to investigate coating processes and its properties. The microstructure, mechanical property, wear-resistance and corrosion-resistance of vacuum fusion sintering Ni-base alloy WC composite coatings were investigated with different contents of CeO₂ and different heat treatment processes.The macrostructure, microstructure of the coatings was observed by digital camera, optics microscope and scanning electron microscope (SEM). The chemical composition of phase was measured by energy-dispersive apparatus. The experimental results are as follows: The best macrostructure appears in the coating with 1.0% CeO₂. There is diffusive layer between the substrate and the Ni-base alloy WC coating. The diffusive layers were slightly wider and the hard particles smaller.Due to the HRC hardness and microhardness of the coatings were measured, under the same heat treatment condition, the addition of CeO₂ increased the hardness of the coatings. The coating with 1.0% CeO₂ had the highest hardness. The hardness of the coatings decreased after heat-treatment. The distribution of the cross-section microhardness of the coating is that the hardness in the middle is higher than those of the sides. The addition of CeO₂ made the hardness curve wider. The heat treatment hardly had influence on the coatings, except of widening the hardness curve. Therefore, wear-resistance to the coatings were increased.In the wearing tests, the wearing volume of high-speed steel is more than 2.5 times than that of Ni-base alloy coatings, with water as the lubrication, the wearing volume of quenching and tempering 45^# steel more than 5 times than that of and Ni-base alloy coatings. CeO₂ increased wear-resistance of Ni-base alloy coatings. Addition of the best result came from the coating with 1.0% CeO₂.The strength of Ni-base alloy coatings increased as the increase of CeO₂...