离子束增强沉积CrN膜层及其微动摩擦学性能研究

以不同氮离子辅助轰击能量制备CrN膜层．利用纳米压入仪及显微硬度计分别测试单晶Si片上膜层的硬度及断裂韧度K1C．使用XRD、XPS及EPMA分析离子轰击能量对镀层组织结构的影响。结果表明，采用能量较低的氮离子轰击得到的涂层，由于金属Cr的存在，涂层硬度虽有所降低，但断裂韧度K1C数值较高。选择较低的4keV辅助轰击能量，在M2高速钢基体上沉积CrN涂层，膜层在空气介质中表现出优异的耐磨减摩特性.但在水介质条件下，由于膜层接触区域的去钝化，再钝化使腐蚀和磨损相互加速，导致CrN膜层摩擦系数，尤其是磨损量明显高于基材。

Study on Fretting Wear Behaviour of CrN Coatings by IBED

CrN coatings were prepared on M2 high-speed steel and Si chips by an ion beam enhanced deposition(IBED)technique with varying nitrogen ion bombarding energy.The CrN coatings on Si chips were used to characterize micro-mechanical and structural properties, such as microhardness,fracture toughness(K_ 1C),microstructure and composition,with nano-indentation,microhardness test,X-ray diffraction spectrometry,X-ray photoelectron spectroscopy and electron probe microanalysis techniques.The CrN coatings on M2 steel were employed to measure their tribological properties in ambient air of 50% relative humidity(RH) and de-mineralized water with a fretting wear tester.The results show that microhardness of the CrN coatings increases with increasing bombarding energy from 4 to 12 keV.Coversely,K_ 1C value of the coatings decreases with increasing the bombarding energy.These results can be attributed to the increase of nitrogen content in the coatings with increasing the nitrogen ion bombardment energy.Whereas the Cr/N ratio is greater than one at 4 keV,the ratio is smaller than one at 8 keV and 12 keV.Fretting wear tests indicate that the CrN coatings can significantly lower the firction coefficient,and improve the wear resistance of the coated M2 steel in ambient air of 50% RH.However,the CrN coatings do not perform so well in water as in ambient air.The inherent pinholes in the coatings may cause the mutual enhancement of corrosion-wear during the fretting wear tests,thus contributing to the underperformance of the CrN coated steel in aqueous electrolytes.