双电源低温渗氮工艺在316不锈钢上的应用

Application of low temperature nitriding process with double power supplies on 316 stainless steel

通过正交试验研究了交流脉冲电压、直流脉冲偏压和温度对316不锈钢表面硬度和渗层厚度的影响,获得了双电源低温渗氮最佳工艺参数。通过光学显微镜(OM)、X射线衍射仪(XRD)、显微硬度计、电化学工作站以及摩擦磨损试验机等研究了最佳工艺下渗氮试样的性能。结果表明,影响渗氮试样性能因素的顺序为:交流脉冲电压>温度>直流脉冲偏压。最佳工艺参数为交流脉冲电压360 V,直流脉冲偏压270 V,温度380℃。对最佳工艺制备的试样与单电源进行对比:渗层厚度为43.4μm,是单电源的8.5倍;表面硬度为1350 HV0.025,是单电源的3.1倍;自腐蚀电位由-256 mV(vs SCE,下同)提高到-180 mV;自腐蚀电流密度从13.90μA/cm^(2)降低到0.45μA/cm^(2);摩擦因数从0.55降低到0.42。双电源渗氮速率的提高是由于高能离子轰击引起的表面结构缺陷和渗氮气体的高度离解。

Effects of AC pulse voltage,DC pulse bias voltage and temperature on surface hardness and nitrided layer thickness of 316 stainless steel were studied by orthogonal test,and the optimal process parameters of double power supplies for low temperature nitriding were obtained.The properties of the nitrided specimens treated by optimal process were evaluated by means of optical microscope(OM),X-ray diffraction(XRD),microhardness tester,electrochemical workstation and friction and wear tester.The results show that the order of factors affecting properties of the nitrided specimens is:AC pulse voltage>temperature>DC pulse bias voltage.The optimum process parameters are AC pulse voltage of 360 V,DC pulse bias voltage of 270 V,and temperature of 380℃.Compared with single power supply,the thickness of nitrided layer treated by double power supplies is 43.4μm,which is 8.5 times of single power supply;the surface hardness is 1350 HV0.025,which is 3.1 times of single power supply;the self-corrosion potential increases from-256 mV(vs SCE)to-180 mV(vs SCE),and the self-corrosion current density decreases from 13.90μA/cm^(2) to 0.45μA/cm^(2);the friction coefficient is reduced from 0.55 to 0.42.The increase of nitriding rate of double power supplies is due to the surface structure defects caused by high energy ion bombardment and the high dissociation of nitriding gas.