Super-low Friction Mechanisms of Carbon Nitride Coatings with Adsorbed Nitrogen Gas

本课题组研究发现，非晶氮化碳（CNx）等薄的润滑硬质涂层具有超低摩擦性能（摩擦系数为0.01量级），特别是与氮气吸附气体结合时，其摩擦性能更佳，本课题旨在分析氮化碳涂层与氮气吸附气体结合的超低摩擦机理。主要得到以下结果：1.通过吹氮气使CNx涂层与CNx涂层球之间的滑动产生约0.01-0.02的稳定摩擦系数。在此条件下，球的磨损率很低，为1.13 × 10 ~ 3 <-8>mm ~ 3/Nm。2.获得稳定低摩擦系数的最佳吹氮量为2.10 cc/mm ~ 2 s。（a）摩擦机制显示约0.1和（B）摩擦机制在0.01 ~ 0.1之间。4.在本研究中产生的低摩擦系数0.1时的所有磨痕上，拉曼光谱显示出一定的结构变化，表明sp^2微区的尺寸和/或数量增加，其可以被认为是非常小的石墨结构。5.离子辐照使CNx/CNx复合材料的摩擦系数从0.01提高到0.1，特别是在N_2气吹下。因此，可以认为磨损表面的带电影响了氮气对CNx涂层的低摩擦机理。

Our research group had found that thin lubricious hard coatings such as amorphous carbon nitride (CNx) coating gave super-low friction (0.01 order of friction coefficient) in particular when combined with adsorbed gases of nitrogen.The purpose of this research was to analyze super-low friction mechanisms of carbon nitride coatings with adsorbed nitrogen gas. In addition, necessary coating condition and operating condition for giving such super low friction was clarified.The following results were mainly obtained.1.Sliding between CNx coating against CNx coated ball generates stable friction coefficient of about 0.01-0.02 by blowing of nitrogen gas. In such condition, wear rate of ball shows very low value of 1.13x10^<-8>mm^3/Nm.2.Optimum value of blowing nitrogen gas to generate stable and low friction coefficient is around 2.10cc/mm^2s.3.Low friction mechanism of the CNx coating by nitrogen gas is explained by two models ;(a)friction mechanism to shows about 0.1 and (b)friction mechanism to show between 0.01 and 0.1.4.On all wear scars when low friction coefficient of 0.1 is generated in this research, Raman spectra show certain structural changes, indicating the increase in the size and/or number of the sp^2 microdomain that can be considered as a very small graphitic structure. Therefore, it is considered that low friction in this system is generated by the graphitic structure, which has low shearing strength.5.Friction coefficient of CNx/CNx in particular under N_2 blow increases from 0.01 up to 0.1 by ion irradiation. Thus, it is considered that electrification on the wear surface affect on low friction mechanism of the CNx coating by nitrogen gas.