预氮化对复合CrTiAlN薄膜组织和摩擦性能的影响

Impact of Nitridationon Wear Behavior of CrTiAlN Composite Coatings

采用物理气相沉积技术和离子氮化技术,在模具钢表面形成氮化层和氮化层/多元复合CrTiAlN硬质薄膜。采用扫描电子显微镜、X射线衍射仪、能谱仪研究了氮化处理对多元复合CrTiAlN硬质薄膜组织结构的影响;通过硬度仪和摩擦磨损测试仪等手段研究了氮化处理对多元复合CrTiAlN硬质薄膜的磨损性能的影响。研究结果表明,薄膜表面光滑平整,呈柱状晶生长,无明显缺陷。渗氮处理能够提高CrTiAlN薄膜耐磨损性能和与基体的结合强度。随着载荷从5到30 N的增加,薄膜的磨损率逐渐增加,而摩擦系数却有下降趋势。薄膜的摩擦系数随着磨粒粒径的变大先增大后减小;磨粒粒径分别为10、20μm时,未经渗氮和经渗氮后的薄膜摩擦系数达到最大值,分别为0.42和0.36。同时随着磨粒粒径的增加,摩擦系数曲线振动幅度也逐渐增大。

The CrTiAlN compositecoatings were synthesizedby physical vapor deposition（ PVD） on the ion nitridedsubstrate of die steel. The effect of the nitridation on the microstructures and tribological properties of the hard coatings were investigated withscanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,andconventional mechanical probes. The preliminary results show that the nitridation significantly improved the tribological behavior of the compact and smooth CrTiAlN coatings,dominated with columnar grains. To be specific,the nitidation strongly increased the wear-resistance and interfacial adhesion,but decreased the highest friction coefficient from 0. 42（ without nitridation） to 0. 36,possibly because of nitridation induced surface hardening. Possible mechanisms responsible for improvement of the tribological properties were also tentatively discussed.