镍含量对激光熔覆镍钛合金涂层组织与性能的影响  

Influence of Ni Content on Microstructure and Properties of NiTi Alloy Coatings Fabricated by Laser Cladding

作　　者：丰玉强 杜泽旭 胡正飞[1] Feng Yuqiang;Du Zexu;Hu Zhengfei(Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials,School of Materials Science and Engineering,Tongji University,Tongji University,Shanghai 201804,China)

机构地区：[1]同济大学材料科学与工程学院上海市金属功能材料开发应用重点实验室,上海201804

出　　处：《中国激光》2022年第8期232-243,共12页Chinese Journal of Lasers

基　　金：国家自然科学基金(51971163)。

摘　　要：镍钛合金55NiTi粉末与纯Ni粉末混合,通过激光熔覆的方法,在316L不锈钢基体上制备了熔覆涂层,借助X射线衍射仪、扫描电子显微镜及能谱仪对涂层组织结构进行了分析,并对比了混合粉末制备的涂层与55NiTi合金粉末涂层的耐磨及耐腐蚀性能。结果表明,Ni的添加使55NiTi涂层的组织更加致密,晶粒尺寸更小,表面硬度可达830HV,提高了约7%,摩擦磨损实验中的失重减少了约10%,摩擦系数也更小。使用电化学工作站研究了涂层的耐腐蚀性能,Ni的添加使涂层的自腐蚀电流和腐蚀速度降低了50%以上,耐腐蚀性能得到了显著的提高。Objective The NiTi alloy,also called 55NiTi or equiatomic NiTi,is well known due to its unique super-elastic property and shape memory effects(SME)and widely used in aerospace,navigation,military,biomedicine,and other fields.In recent years,the 60NiTi alloy,as a Ni-rich version of 55NiTi,has drawn a lot of attention due to its excellent corrosion resistance and better mechanical properties than those of 55NiTi.However,the poor workability and high cost of this new NiTi alloy limit its further applications.In this paper,the powder raw material instead of the bulk NiTi alloy is used in consideration of the cost,and laser cladding is applied to fabricate the NiTi alloy coatings on the given substrate to enhance their surface properties.Highlight is to use cheap and commercial mixed powder consisting of 55NiTi alloy powder and single Ni powder to replace expensive and customized 60NiTi alloy powder.The effect of Ni addition on the microstructures and properties of 55NiTi alloy coatings is studied.Methods The 55NiTi alloy powder and single Ni powder are mixed together to get the blend powder(called 55NiTi+5Ni)with the mass fraction ratio between Ni and Ti of 60%∶40%.The mixed raw powders are used to prepare the NiTi coatings on the AISI 316Lsubstrate via laser cladding.The microstructures and phase compositions of these coatings are investigated using the scanning electron microscope(SEM)with the configured energy-dispersive spectrometer(EDS)and X-ray diffractometer(XRD).The hardness and wear resistance of these coatings are studied with a microhardness tester and a friction and wear tester,respectively.In addition,a Gamry electrochemical workstation is applied to measure the potentiodynamic polarization(PD)and electrochemical impedance spectroscopy(EIS)of these coatings.Results and Discussions The 55NiTi+5Ni coatings are successfully fabricated on the substrate.The laser cladding tracks on the substrate are smooth without burrs and there are no pores and cracks found in the cross-sectional figure.The boundary line

关 键 词：激光技术 镍钛合金 微观组织 耐磨性能 耐腐蚀性能 

分 类 号：TN249[电子电信—物理电子学] TG146.15[一般工业技术—材料科学与工程] TG146.23[金属学及工艺—金属材料]