低温低压等离子弧辅助离子渗316L不锈钢的耐磨耐蚀性能

Wear and Corrosion Resistance of Plasma Arc-assisted Ion Permeable 316L Stainless Steel at Low Temperature and Low Pressure

目的提高316L不锈钢的硬度、耐磨性。方法在400℃、2 Pa下,利用空心阴极直流弧辅助,进行了316L奥氏体不锈钢离子渗氮(PN)、离子氮碳共渗(PNC)及离子氮碳共渗加离子渗氮复合(PNC+PN)处理。针对处理后的样品,用莱卡显微镜、扫描电镜(SEM)、X射线衍射仪(XRD)、维氏硬度仪、3D形貌仪、球盘式摩擦磨损仪及电化学工作站等对组织、形貌、物相、机械性能及耐蚀性能进行表征。采用显微硬度计、微纳米综合力学系统测试分析处理后样品的力学性能。结果在空心阴极直流弧辅助下,三种工艺可获得超过3 mm/h的渗层生长速度。同316L不锈钢基体相比,PNC+PN复合处理样品的表面硬度提高3倍以上,在3.5%Na Cl中性电解质中的耐蚀电流密度降低约50%。结论 PNC处理和PNC+PN复合处理可获得更大的渗层厚度和更高的表面硬度,渗层中C、N含量越高,渗层组成相的晶格参数越大,渗层中产生的滑移带密度越大。低温低压等离子弧辅助离子渗不仅能有效提高316L不锈钢的表面硬度,还能提高不锈钢的耐蚀能力。

The work aims to improve hardness and wear resistance of 316 L stainless steel. Assisted by hollow cathode DC arc, 316 L austenitic stainless steel was plasma nitrided（PN）, plasma nitrocarburized（PNC） and plasma nitrocarburized ＋ plasma nitrided（PNC＋PN） at 400 and 2 Pa. Microstructure, morphology, phase, mechanical property and corrosion resistance of thetreated samples were characterized with Lycra microscope, scanning electron microscope（SEM）, X-ray diffractometer（XRD）, Vickers hardness tester, 3D morphology meter, pin-on-disk wear instrument and electrochemical workstation. Physical properties of the treated samples were analyzed with microharness tester HV-1000 and CSM micro-nanoindentor. Assisted by the hollow cathode DC arc, growth rate of diffusion layer could exceed 3 mm/h by adopting the three processes. Compared with the 316 L stainless steel substrate, surface hardness of PNC＋PN treated sample increased by more than 3 times, corrosion current density decreased by nearly 50% in 3.5%Na Cl neutral electrolyte. PNC treatment and PNC＋PN composite treatment can obtain higher diffusion layer thickness and surface hardness. The higher the content of C and N in the layer is, the higher lattice parameter of the phase constituting the layer is, the greater the slip band density in the layer is. Low temperature and low pressure plasma arc-assisted ion diffusion can not only improve surface hardness of 316 L stainless steel effectively, but also enhance its corrosion resistance.