内燃机用Ti600钛合金表面激光熔覆NiCr/TiAl涂层组织及摩擦磨损性能  

Surface Modification of Ti600 Ti-Alloy with Laser Cladded NiCr/TiAl Coating

作　　者：程彩霞 李炎粉 刘师多[2] Cheng Caixia;Li Yanfen;Liu Shiduo(School of Automotive Engineering,Yellow River Traffic University,Jiaozuo 454950,China;College of Vehicle Engineering,Henan University of Science and,Technology,Zhengzhou 450000,China)

机构地区：[1]黄河交通学院汽车工程学院,焦作454950 [2]河南科技大学车辆工程学院,郑州450000

出　　处：《真空科学与技术学报》2020年第12期1166-1170,共5页Chinese Journal of Vacuum Science and Technology

基　　金：国家自然科学基金资助项目(51605416)。

摘　　要：为了提高内燃机用Ti600钛合金的综合性能,对其表面进行激光熔覆处理制得NiCr/TiAl涂层,同时测试了该涂层的各成分与组织结构,之后对其处于环境中的耐磨性进行了模拟测试。研究结果表明:涂层中形成了许多等轴晶,枝状组织以及许多细小的组织,引起晶粒明显细化。形成了块状的晶体组织与部分球形晶粒,还生成了一些纳米尺寸的晶粒。涂层的平均截面显微硬度为832 HV,与界面相距50μm的部位发生了硬度快速减小,在界面处的基体达到了比Ti600基体更高硬度。激光熔覆涂层具备比基体更低的磨损率,常温时涂层达到了最大摩擦系数和磨损率;处于真空环境中最低。常温中进行磨损区域生成了许多磨屑并产生了明显犁沟结构。在高温、低温与真空环境中测试得到了相近的磨损表面组织形态,都形成了磨屑、犁沟与粘着剥落坑。The surfaces of Ti600 Ti-alloy,an advanced internal combustion engine material,were modified with the NiCr/TiAl coatings synthesized by laser cladding of the mixture of TiAl and NiCr powders with a mass ratio of 3.5∶1.0.The microstructures and tribological behavior of the coatings were characterized with X-ray diffraction,scanning/transmission electron microscopy and conventional mechanical probes.The results show that the NiCr/TiAl coatings significantly improved the tribological behavior.To be specific,the NiCr/TiAl coatings,comprising high density of equiaxed grains,dendritic grains and fine-clusters,considerably decreased the wear-rate,reduced the friction coefficient and increased the hardness to 3 times higher than that of the substrate and with an average of 832 HV.Moreover,the top-down hardness depth profile showed a"spike-plateau-valley"curve.The abrasive wear was found to be responsible for the wear mechanism of the NiCr/TiAl coatings.

关 键 词：钛合金 NiCr/TiAl涂层 激光熔覆 微观组织 摩擦性能 

分 类 号：TG174.4[金属学及工艺—金属表面处理]