激光重熔处理对超音速火焰喷涂NiCr-Cr3C2涂层组织及性能的影响

Effect of laser re-melting treatment on microstructure and properties of high velocity oxy-fuel sprayed NiCr-Cr3C2 coating

采用激光重熔方法对超音速火焰喷涂Ni Cr-Cr3C2涂层进行后处理。通过SEM、XRD、显微硬度计、电化学以及摩擦磨损试验等手段对涂层的显微组织形貌、物相结构、力学性能以及耐蚀、耐磨性能进行表征。结果表明：激光重熔处理后,涂层孔隙率下降,组织均匀性、显微硬度提高,大量高密度亚微米级（10~300 nm）二次Cr3C2由过饱和Ni Cr合金相中析出,增强了合金相硬度及韧性,并使涂层断裂韧性、耐磨损性能以及耐腐蚀性能同步提高。

The laser re-melting（LR）process was applied on high velocity oxy-fuel（HVOF）sprayed Ni Cr-Cr3C2coating to improve its properties.The effect of LR treatment on the microstructure,microhardness,fracture toughness,corrosion and wear resistance of HVOF coating was studied by using SEM,XRD,microhardness and electrochemical measurement,as well as abrasion test.The results show that the porosity of coating decreases,while the uniformity of microstructure and the microhardness improve after LR treatment,plenty of fine secondary carbides with the size of about 10-300 nm precipitate from the supersaturated as-sprayed Ni Cr binder matrix,which leads to enhanced alloy phase hardness and toughness,and that the fracture toughness,wear resistance and corrosion resistance of the coating are simultaneously improved.