The Study Of Microstructure And Performance Of La₂ O₃+CeO₂-Ni-WC Composite Coating By Vacuum Fusion Sintering

This paper made the Rare-earth Ni-based alloy WC composite coating on 45# steel substrate by vacuum fusion sintering technique. The surface patternmicrostructure and each phase's chemical component of the Rare-earth Ni-based alloy WC composite coating were observed and analyzed by Scanning Electron Microscopy(SEM), Optical Microscope(OM) and Energy-Dispersive Spectrometer(EDS). And the hardness and the high temperature oxidation performance of composite coating were researched and analyzed by Rockwell hardometer,microhardness instrument,MTS810 and box-type resistance batch. Theresults showed that::(1)When the content of La2O3+CeO2 came up to 0.6% , the interact-melt associability between coating and matrix was the best,and the defects such as porosity,crack and so on was the least.(2) When the content of La2O3+CeO2 came up to 0.6%,the coatings'structure was smaller and more homogeneous,the fusion was the best,the coatings'hardnessand was the highest. When the content of La2O3+CeO2 came up to 0.6%,the coatings'tensile strength was the highest. The fracture is mixed with gliding frature and brittle fracture. The size of WC grain is become more refined and well distributed, when put into 0.6% La2O3+CeO2,the surface hardness, microhardness and the tensile strength value are improved efficiently. The surface hardness is up to HRC56.7, the microhardness is up to 906HV0.05, and the tensile strength is up to 380.12MPa.(3) According to GB/T13303-91 criterion,45# steel with coating was oxygenated at 800℃for 100h. According to Wanger oxidation experience formula,using the scatter date simulation computing method had gained oxidation kinetics equations,oxidation kinetics curve is drawn by Origin software. The grain size of the coatings with 0.8% ,the coatings'heat temperature oxidation property was the best.