铸铁表面感应熔覆铁基涂层组织及耐磨性能

Microstructure and wear resistance of Fe-based coating prepared by induction cladding on cast iron surface

采用添加银钎焊熔剂和增加保温阶段的工艺方法,在HT300表面成功制备了感应熔覆铁基涂层,并研究了涂层的微观组织形貌、物相组成、显微硬度变化和耐磨性。结果表明:银钎焊熔剂可以降低铁基合金粉末的熔点;保温阶段可以提高涂层组织的均匀性和致密性;涂层主要由α-(Fe,Cr)、Fe3C和(Cr,Fe)7C3相组成;涂层横截面的显微硬度呈现梯度变化的趋势,涂层的平均显微硬度约为764.8 HV0.1,高于基体硬度,但低于镍基涂层;涂层的摩擦系数较大,但磨损量低于镍基涂层和HT300基体;涂层的磨损机理以磨料磨损和氧化磨损为主,牢固附着在涂层表面的氧化物可以有效降低其磨损量。

Fe-based coating was successfully prepared on the surface of HT300 by ultrasonic frequency induction cladding technlolgy with silver brazing flux agent and increasing holding time. The microstructure, phase composition, microhardness and wear resistance of the coating were studied. The results show that the silver brazing flux can reduce the melting point of the Fe-based alloy powder, the microstructure uniformity and compactness of the coating can be improved in the holding stage;the coating is mainly composed of α-(Fe,Cr), Fe3C and(Cr,Fe) 7C3 phases. The microhardness of the cross section of the coating shows a gradient change trend, and the average microhardness of the coating is about 764.8 HV0.1, higher than that of the substrate, but lower than that of the nickel-based coating. The friction coefficient of the Fe-based alloy coating is comparatively high, but the wear mass loss of the Fe-based alloy coating is lower than that of Ni-based alloy coating and HT300 substrate. The wear mechanism of the coating is mainly abrasive wear and oxidation wear, and the oxide firmly attached to the surface of the coating can effectively reduce the wear mass loss of the coating.