Effect of Stiff Coatings on EHL Film Thickness in Point Contacts
Effect of Stiff Coatings on EHL Film Thickness in Point Contacts
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DOI：
10.1115/1.2908908
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发表时间：
2008-07
影响因子：
2.5
通讯作者：
Yuchuan Liu;Q. Wang;D. Zhu
中科院分区：
文献类型：
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作者：
Yuchuan Liu;Q. Wang;D. Zhu
涂层广泛用于增强界面性能和提高部件寿命，以及用于防腐蚀和表面装饰。越来越多的机械部件，特别是那些在恶劣条件下工作的部件，都涂有硬（硬）薄涂层。然而，涂层对润滑特性的影响，如膜厚和摩擦，还没有得到很好的理解，设计涂层的最佳摩擦学性能是一个巨大的挑战。基于作者新近建立的点接触等温弹流润滑模型，研究了涂层材料性能和涂层厚度对润滑膜厚度的影响。结果表明，在很宽的工作条件下，最小膜厚变化的趋势作为涂层厚度和弹性模量的函数。数值结果的曲线拟合表明，最小膜厚的最大增加量Imax和相应的最佳无量纲涂层厚度H2 max可以用以下形式表示：Imax = 0.769M0.0238R0.0297L0.1376exp（-0.0243ln2L）和H2max = 0.049M0.4557R-0.1722L0.7611exp（-0.0504In2M-0.0921ln2L）。这些公式可用于估算涂层对弹流润滑油膜厚度的影响。
Coatings are widely used for interface performance enhancement and component life improvement, as well as for corrosion prevention and surface decoration. More and more mechanical components, especially those working under severe conditions, are coated with stiff (hard) thin coatings. However, the effects of coatings on lubrication characteristics, such as film thickness and friction, have not been well understood, and designing coating for optimal tribological performance is a grand challenge. In this paper, the influences of coating material properties and coating thickness on lubricant film thickness are investigated based on a point-contact isothermal elastohydrodynamic lubrication (EHL) model developed recently by the authors. The results present the trend of minimum film thickness variation as a function of coating thickness and elastic modulus under a wide range of working conditions. Curve fitting of numerical results indicates that the maximum increase in minimum film thickness, I max , and the corresponding optimal dimensionless coating thickness, H 2max , can be expressed in the following forms: I max =0.769M 0.0238 R 0.0297 L 0.1376 exp(-0.0243ln 2 L) and H 2max =0.049M 0.4557 R -0.1722 2 L 0.7611 exp(-0.0504 In2 M-0.0921 ln 2 L). These formulas can be used to estimate the effect of coatings on film thickness for EHL applications.