Tribochemical induced wear and ultra-low friction of superhard ta-C coatings
Tribochemical induced wear and ultra-low friction of superhard ta-C coatings
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DOI：
10.1016/j.wear.2017.08.015
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发表时间：
2017-12
期刊：
影响因子：
5
通讯作者：
S. Makowski;F. Schaller;V. Weihnacht;Gregor Englberger;M. Becker
中科院分区：
文献类型：
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作者：
S. Makowski;F. Schaller;V. Weihnacht;Gregor Englberger;M. Becker
通过广泛的参数研究，使用采用发动机油、甘油和单油酸甘油酯 (GMO) 润滑的振荡平球测试装置，在边界润滑状态下研究了非晶碳涂层 (a-C)、四面体非晶碳涂层 (ta-C) 和单晶金刚石的摩擦和磨损性能。甘油和 GMO 证实了超低摩擦 (μ< 0.04)。同时，仅针对 GMO 发现超硬 ta-C 涂层的磨损非常高。对润滑剂化学、表面杂质、测试温度、配合体材料以及碳涂层的 sp3 分数和结晶度进行了系统研究，表明低磨损磨损和高化学磨损之间存在显着差异。根据测量数据，考虑了化学性质和磨损促进因素，表明涂层中非晶态 sp3-碳与润滑剂中不饱和碳键的有害相互作用。建立了 GMO 低摩擦和接触压力的关系，导致接触压力低于 600 MPa 时摩擦最低。测试装置的球板几何形状的任一部件的高磨损导致接触面积的变化，从而强烈影响摩擦计模型测试的摩擦行为。
Employing a broad parameter study, friction and wear properties of amorphous carbon coatings (a-C), tetrahedral amorphous carbon coatings (ta-C) and single crystalline diamond were investigated in boundary lubrication regime, using an oscillating ball-on-flat test setup with engine oil, glycerol, and glycerol monooleate (GMO) lubrication. Ultra-low friction (µ< 0.04) was confirmed with glycerol and GMO. At the same time, very high wear of the superhard ta-C coating was found for GMO solely.A systematic study of lubricant chemistry, surface impurities, testing temperature, counter body material, and the carbon coating regarding sp3-fraction and crystallinity was conducted, indicating a strong difference between low abrasion wear and high chemical wear.Based on the measured data, the chemical nature and wear promoting factors are considered, suggesting detrimental interaction of amorphous sp3-carbon in the coating and unsaturated carbon bonds in the lubricant.Furthermore, a relation for low friction of GMO and contact pressure was established, leading to lowest friction for contact pressure below 600 MPa. High wear on either component of the ball-on-plate-geometry of the test setup led to a change of the contact area, thus strongly influencing frictional behavior of the tribometer model test.