Nondestructive testing method for residual stress in thermal barrier coating

Abstract

The invention discloses a nondestructive testing method for residual stress at different depths in a thermal barrier coating, and the method is used for carrying out nondestructive detection on the residual stress at different depths in the thermal barrier coating of an aero-engine by adopting an X-ray diffraction instrument. The method comprises the following steps of firstly, placing and fixinga thermal barrier coating test piece on a sample table, enabling a normal direction of a sample to be consistent with a normal direction of an incident ray, setting the scanning range, adjusting the power of a ceramic X-ray tube, the frequency of the X-ray, the reproducibility of an angular instrument, the controllable minimum step, the maximum counting rate of a PIXcel3D super-energy detector, the sample table direction correction and other factors, emitting the X-ray with the specific frequency, and determining the residual stress at different depths in the thermal barrier coating on the basis of a relation between the displacement of an X-ray diffraction peak and the macroscopic stress. According to the nondestructive testing method for the residual stress in the thermal barrier coatinghas high measurement precision and efficiency and good reproducibility, and is widely applied to nondestructive detection of the residual stress of the thermal barrier coating of the aero-engine.

Description

technical field [0001] The invention relates to a nondestructive testing method for residual stress of thermal barrier coatings, in particular to nondestructive testing of residual stress in thermal barrier coatings used on aero-engines. Background technique [0002] Thermal barrier coating is an important protective coating on aero-engine blades, which is composed of a chromium-containing ceramic layer, a metal bonding layer, and a metal bottom layer. In the process of use, due to the accumulation of thermal stress or residual stress to a certain extent, thermal growth oxidation, cracks and even peeling will occur at the interface of the thermal barrier coating, which brings great hidden dangers to the safety of use. Therefore, it is of great significance to detect the internal stress of thermal barrier coatings in real time. The detection of residual stress in thermal barrier coatings is a very complex problem, mainly because the coating is thin, hard and brittle, which i...

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Problems solved by technology

[0003] Chinese patent CN105486437A discloses a Raman spectroscopy method to detect the stress state at the silicon wafer interface. This method is suitable for detecting the residual stress at the shallow surface of the silicon wafer material, but cannot detect the residual stress at the deeper part of the coating.

The method for detecting residual force disclosed in Chinese patent CN201610128220 needs to use the drilling method to destroy the sample, which cannot meet the requirements of non-destructive testing of thermal barrier coatings

Chinese patent CN108181032A needs to set standard parts without any residual stress relief treatment, and the measured result is the surface residual stress ratio, and the accurate stress value of a certain interface of the thermal barrier coating cannot be measured

Therefore, the above-mentioned existing technologies can only be used in occasions where the quality requirements are not high, and cannot accurately detect the residual force at different depths of the thermal barrier coating.

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