Nondestructive testing method of residual stress of thermally grown oxide layers in thermal barrier coatings

Abstract

The invention provides a nondestructive testing method of residual stress of thermally grown oxide layers in thermal barrier coatings. The method comprises the following steps: a laser beam with a specific wavelength enters to the surface of a thermally grown oxide layer to be tested, and a fluorescence spectrum of a trace element Cr3+ in the thermally grown oxide layer of the thermal barrier coating is excited; a characteristic peak of the fluorescence spectrum of excited Cr3+ and a characteristic peak of a fluorescence spectrum of Cr3+ excited in a stress-free state are compared, and distribution of internal stress in the thermally grown oxide layer is calculated according to offset of the characteristic peak. The method can solve the technical problem that traditional stress detection methods are difficult to realize stress measurement of TGO (thermally grown oxide) layers; changes of internal stress of TGO layers before and after examinations in various conditions (such as thermal shock, constant temperature oxidation, heat cycle or high temperature plume flow thermal shock, etc.) of a coating sample can be detected without destroy of the sample itself, and experiment foundation is provided for researching service behaviors and failure mechanisms of coatings; feasibility of nondestructive test of TGO internal stress in the coating of a practical workpiece before and after service is provided.

Description

technical field [0001] The present invention relates to a non-destructive detection method for the residual stress of a thermally grown oxide layer in a thermal barrier coating, and more particularly, to a thermal barrier coating prepared by a plasma spraying-physical vapor deposition (PS-PVD) process Method for non-destructive testing of residual stress in thermally grown oxide (TGO) layers. Background technique [0002] Thermal barrier coatings (TBCs) are one of the three key technologies of engine blade technology. To promote the development of advanced engines, it is particularly important to obtain thermal barrier coatings with excellent high-temperature service performance, high reliability, and long life. At present, the common preparation technology of thermal barrier coating mainly adopts plasma spraying (PS) and electron beam-physical vapor deposition (EB-PVD). Plasma sprayed thermal barrier coating is composed of molten and semi-molten droplets deposited, spread ...

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Problems solved by technology

[0008] In order to overcome the deficiencies of the above-mentioned existing stress detection technology, the technical problem to be solved by the present invention is to provide a non-destructive detection method for the residual stress of the thermally grown oxide layer in the thermal barrier coating, which can successfully solve the stress detection of other coatings. The means cannot measure the lack of stress distribution in the TGO layer without destroying the tested sample

[0010] According to the present invention, ① can pass Cr 3+ The distribution of internal stress in the TGO layer is obtained by fluorescence compression spectroscopy, which solves the technical problem that the traditional stress detection method is difficult to measure the stress of the TGO layer; The change of internal stress of the TGO layer before and after the assessment under various working conditions (such as thermal shock, constant temperature oxidation, thermal cycle or high temperature flame thermal shock, etc.) provides an experimental basis for the research on the service behavior and failure mechanism of the coating; ③ for the actual The non-destructive testing of TGO internal stress in the coating before and after the service of the workpiece provides the feasibility

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