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滚动接触疲劳法表征结合强度的剪切应力幅是一个对界面因素敏感,而对非界面因素不敏感的力学参量,能真实反映膜基结合状态,是较为合理的动态结合强度评价方法。但由于应力计算的模型采用弹性力学方法,对膜基结合强度较高而厚度很小的薄膜,往往加大载荷也较难使膜基界面发生分离。本文采用小直径、高弹性模量Al_2O_3球的滚动接触疲劳方式,对高结合强度的硬质薄膜进行评价,并采用有限元方法计算弹塑性变形条件下的应力分布,切应力幅的计算结果具有合理性。改进后的滚动接触疲劳法允许基体发生弹塑性变形,界面切应力大幅度提高,能够在相对较少周次下造成薄膜剥落,失效部位发生于界面,因而更适合于评价结合强度较高的硬质薄膜。
Rolling contact fatigue method to characterize the shear strength of bonding strength is a sensitive parameter to the interface, while the non-interfacial factor is not sensitive to the mechanical parameters, can truly reflect the film-based bonding state, is a more reasonable dynamic bonding strength evaluation method. However, since the stress calculation model uses the elastic mechanics method, it is difficult to increase the load to separate the film-based interface to the film with high film-based bonding strength and small thickness. In this paper, rolling contact fatigue of Al 2 O 3 spheres with small diameter and high modulus of elasticity was used to evaluate the hard film with high bonding strength. The stress distribution under elastic-plastic deformation was calculated by finite element method. The calculated results of shear stress amplitude rationality. The improved rolling contact fatigue method allows the substrate to undergo elastic-plastic deformation, greatly improve the interfacial shear stress, cause the film to peel off in a relatively few cycles, and the failure site occurs at the interface, so it is more suitable for evaluating the strength of the hard Thin film.