超音速火焰喷涂Fe基合金涂层的抗汽蚀性能

Cavitation erosion resistance of Fe-based alloy coating by HVOF thermal spraying

采用超音速火焰(HVOF)喷涂在1Cr18N i9Ti不锈钢基体上制备了200μm厚的Fe基(含Cr、N i等)合金涂层。采用金相显微镜、扫描电镜、显微硬度计、磁致伸缩汽蚀仪对涂层的组织、硬度和抗汽蚀性能进行了研究。结果表明,Fe基合金涂层组织均匀致密,孔隙率低,具有层状结构,涂层的平均硬度为993 HV0.1,是基体硬度的5.8倍;Fe基涂层抗汽蚀性能明显优于1Cr18N i9Ti不锈钢,1Cr18N i9Ti不锈钢汽蚀沿晶界和孪晶界破坏,而Fe基合金涂层汽蚀沿表面微小孔隙破坏,破坏由孔隙边缘向外扩展,损伤程度由汽蚀试样表面中心向外递减,最终不同损伤程度的汽蚀坑分布于表面。

Fe-based（including Cr,Ni,etc.） alloy coating was prepared by HVOF thermal spraying method on 1Cr18Ni9Ti stainless steel with thickness of 200 μm,and the microstructure,microhardness,cavitation erosion resistance of the Fe-based alloy coating were investigated by optical microscopy（OM）,scanning electron microscopy（SEM）,microhardness tester and magnetostrictive cavitation device.The results show that the coating has uniform density,low porosity,high hardness and lamellar structure.The average hardness of the Fe-based alloy coating is 993 HV0.1,which is 5.8 times of the steel substrate.The cavitation erosion resistance of the Fe-based coating is higher than that of 1Cr18Ni9Ti stainless steel.The mass loss of 1Cr18Ni9Ti steel initiated at the grain boundary and twin boundary,while cavitation erosion damage of the Fe-based alloy coating began at the edge of small pores and extended toward outside and reduced gradually from the center to the outside of the sample,eventually the surface of the sample was filled with different depth of pits.