Measuring method for residual stress in coating

Abstract

The invention discloses a method for measuring the residual stress inside the coating, which comprises the following steps: determining the parameters of temperature difference, a coating to be measured and a substrate; calculating the distance delta between a bending moment axial line and the coating, the curvature K of the bending moment axial line and the substrate interface, and the strain component epsilon i of plane direction caused by each layer of the plane stress of the coating; calculating the straining of each layer of the coating according to that epsilon i is equal to epsilon i+K(z+epsilon); and calculating the residual stress sigma i inside each layer of the coating according to that sigma i is equal to Ei'epsilon i. The method not only can accurately measure the residual stress value inside common multilayer coating, but also can accurately measure the residual stress value inside each layer of the functional gradient coating, and provide effective theoretical basis for the optimal design of materials before manufacturing the coating.

Description

technical field [0001] The invention relates to a method for measuring residual stress, in particular to a method for measuring internal residual stress of a coating. Background technique [0002] Due to the thermal expansion coefficient mismatch between the coating and the substrate, the coating and the substrate will deform as the temperature changes, and residual stress will be generated inside the coating, and these residual stresses will seriously affect some of the main properties of the coating. Such as peeling resistance, fatigue life, bonding strength, etc. Therefore, in order to improve the service life and mechanical integrity of the coating, it is of great engineering significance to predict the residual stress value and stress state inside the coating. [0003] At present, the known methods for obtaining the residual stress of a single-layer coating include: using the deformation coordination conditions of the coating and the substrate to obtain a theoretical s...

AI Technical Summary

Problems solved by technology

However, due to the limitation of deformation coordination conditions, the difficulty of obtaining the closed solution of residual stress of multi-layer coatings increases with the increase of coating layers

In this case, two methods are generally used to obtain the internal residual stress value of many coatings: 1. Simplify the solution conditions, such as assuming that the elastic modulus of each layer inside the coating is equal, but these simplifications will give the final residual stress of the coating The calculation of the value brings some error

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