TA2钛合金真空脉冲气体氮化层的性能

Performance of Gas-Nitriding Surface Layer on TA2 Alloy by Vacuum Pulse Method

为了进一步提高钛合金表面改性层的质量,采用真空脉冲气体氮化法在不同温度下对工业纯钛TA2进行氮化处理。利用金相显微镜、扫描电镜、X射线衍射仪、硬度仪、摩擦磨损试验及极化曲线分析了氮化层的组织结构、耐磨性能、耐腐蚀性能和表面硬度梯度等,研究了氮化温度对氮化层性能的影响。结果表明:TA2钛合金经过不同温度氮化处理后,其表面主要形成Ti N_(0.3)相;氮化层厚度和表面硬度都随温度的升高而增加,当温度升高到900℃时,氮化层厚度达60μm,表面硬度达750 HV,耐磨性及耐蚀性较基材大幅提高,磨损速率由基材的0.277 8 mg/(h·cm^2)减小至0.000 4 mg/(h·cm^2),腐蚀速率降低了2个数量级;800~900℃温度范围内,氮化温度对氮化层的耐腐蚀性能影响不大,但是温度的升高使得表面组织变得粗大,同时脆性有所增加。

In order to improve the quality of surface layer on titanium alloy,TA2 was treated by low pressure vacuum pulsed gas-nitriding method,and the surface phase evolution was characterized through XRD and SEM.Results showed that a novel phase of TiN_(0.3) emerged on the surface of TA2.Besides,the thickness and surface microhardness of the new surface layer were increased with the elevating nitriding temperature.When the temperature reached 900℃,the thickness of the new nitride layer was around 60 μm and the hardness achieved 750 HV.Also,the wear resistance and corrosion resistance were improved much more than those of the untreated samples.The wear rate was decreased to 0.000 4 mg/(h · cm^2) from0.277 8 mg/(h · cm^2) of the untreated sample and the corrosion rate was decreased by two orders of magnitude.At 800 ~ 900℃,the nitriding temperature did not influence the corrosion resistance of the nitride layers much,however,the increase of temperature enlarged the surface structure and increased the brittleness in a certain degree.