激光熔覆碳化物增强镍基涂层组织与性能的热处理调控  

Heat treatment tailoring of microstructure and properties of laser cladding carbide reinforced nickel based coatings

作　　者：董逸君 王勇刚[1,2] 李东亚 朱珊珊[1] 许淑红 王瑶 DONG Yijun;WANG Yonggang;LI Dongya;ZHU Shanshan;XU Shuhong;WANG Yao(Applied Technology College of Soochow University,Suzhou,215325,China;School of Mechanical and Electrical Engineering,Soochow University,Suzhou,215137,China;School of Mechanical Engineering,Taiyuan University of Science and Technology,Taiyuan,030024,China)

机构地区：[1]苏州大学,应用技术学院,苏州215325 [2]苏州大学,机电工程学院,苏州215137 [3]太原科技大学,机械工程学院,太原030024

出　　处：《焊接学报》2024年第10期59-68,共10页Transactions of The China Welding Institution

基　　金：江苏省高等学校自然科学研究面上项目(633);苏州市科协青年科技人才托举工程资助(苏科协[2024]49号)。

摘　　要：基于激光熔覆技术成形了Ni35-WC-MoS_(2)-CeO_(2)自润滑耐磨涂层,研究了热处理对涂层的物相组成、显微组织、显微硬度、残余应力以及摩擦磨损性能的影响,揭示了涂层的磨损机理.结果表明,激光熔覆层质量良好,没有出现明显气孔和裂纹,涂层与基体呈致密的冶金结合.物相组成主要包括γ-(Fe,Ni),Cr_(7)C_(3),M_(7)C_(3)以及MoS_(2)和CrS两种润滑相等,显微组织主要为柱状晶和等轴晶,在基体中包含了块状硬质相和球形润滑相,平均显微硬度为904 HV,表面残余拉应力为304.6 MPa.涂层的摩擦系数和磨损率分别为0.51和3.64×10^(-4)mm^(3)/(N·m),磨损机理为磨粒磨损和疲劳磨损;经300℃和600℃热处理之后,涂层中没有发生相变,但固溶体和碳化物发生分解,同时晶粒组织长大并呈现出分解现象,导致显微硬度和残余拉应力幅值均降低,磨损率进一步降低,摩擦过程更稳定,磨损机理转变为粘着磨损和磨粒磨损.因此,对激光熔覆Ni35-WCMoS_(2)-CeO_(2)自润滑涂层进行热处理,使显微组织更加均匀并释放残余热应力,碳化物硬质相不易于从涂层中被剥离,使涂层保持较高的硬度和韧性,有助于提高摩擦磨损性能.A Ni35-WC-MoS_(2)-CeO_(2) self-lubricating anti-wear coating was prepared by laser cladding,and the effects of heat treatment on the phase composition,microstructure,microhardness,residual stress,and wear properties of the coating were analyzed,the wear mechanisms of the coating were revealed.The results showed that the laser cladding coating was of good quality without obvious pores and cracks.The coating had a dense metallurgical bond with the substrate.The phase compositions wereγ-(Fe,Ni),Cr_(7)C_(3),M_(7)C_(3),MoS_(2) and CrS lubrication phase,etc.The microstructure was mainly columnar and equiaxial crystals,and the bulk hard phase and spherical lubrication phase were contained in the matrix,and the average microhardness was 904 HV,and the residual tensile stress on the surface was 304.6 MPa.The friction coefficient and wear rate of the laser cladding coating were0.51 and 3.64×10^(4) mm^(3)/(N·m),and the wear mechanisms were abrasive wear and fatigue wear,respectively.After heat treatment at 300℃and 600℃,no phase transformation occurred in the coating,but the solid solution and carbide decomposition occurred,and the grains grew and showed the phenomenon of decomposition,which led to a decrease in the microhardness and the magnitude of residual tensile stress.After the heat treatment,the wear rate was reduced,and the friction process was more stable.The wear mechanisms were changed to adhesive wear and abrasive wear.Therefore,the heat treatment of the laser cladded self-lubricating coating could make the micro structure more uniform and release the residual thermal stresse.The hard phase of carbides was not easily peeled off from the coating,so that the coatings maintained high hardness and toughness,could help to improve the friction and wear performance.

关 键 词：激光熔覆 自润滑涂层 显微组织 残余应力 磨损性能 

分 类 号：TG441.8[金属学及工艺—焊接]