压痕法确定热障涂层蠕变参数

Determination of Creep Parameters of the Thermal Barrier Coatings Using an Impression Creep Test

摘要:

对单相半无限大材料和涂层/基体材料系统分别进行平头压痕蠕变试验的有限元模拟。对于每一种材料系统，分别考虑不同尺寸的压头，研究压头尺寸对涂层/基体材料系统压痕蠕变应力指数的影响规律。通过对有限元计算结果的分析，提出一个考虑压头尺寸的权重函数来量化涂层和基体对涂层/基体系统压痕蠕变指数的影响程度。基于此权重函数，提出一个确定涂层蠕变指数的分析法。最后根据压头尺寸对涂层/基体系统压痕蠕变指数的影响规律，提出确定涂层蠕变指数的外推法

Abstract:

An extensive accurate finite element (FE) analysis of the impression creep test was performed for two material systems, i.e. a single phase half infinite system and a coating/substrate system. For each case, the FE analysis was carried out for different classes of punch sizes aimed to develop methods to separate creep properties of a coating from a coating/substrate system. The study emphasis was placed on understanding how the punch size influenced the impression creep exponent of a certain coating/substrate system. A weight expression was proposed to quantify the coating’s and the substrate’s contributions to the impression creep exponent of the coating/substrate system. The results of finite element analysis show that the value of the weight expression exhibits a good power-law dependence on the radius of the punch for a certain coating/substrate system. The weight function proposed allows developing an analytic approach to separate coating’s creep exponent from a coating/substrate system. Then a numerical approach including procedures of fitting the curve of n vs R/Tc and extrapolating to R=0 was put forward to determine the coating’s creep exponent. Both of the results obtained by the two methods agree reasonably well with the input FE model