热喷涂涂层残余应力的测试与分析

Measuring and Analysis of Residual Stress in Thermal Sprayed Coatings

利用改进的Ａｌｍｅｎ 试验方法对多种热喷涂涂层的残余应力进行了测试与分析。首次提出了热喷涂涂层应变滞后于温度或外加应力这种现象的物理模型，并提出了因热喷涂涂层本身的多孔特性而引起的“气塞”作用是造成这一现象的主要原因。试验证明了热喷涂涂层的残余应力与涂层的厚度是线性关系，并且无论涂层的残余应力是压应力还是拉应力，它们都随涂层厚度的增加而增大。本文还证实了热喷涂工艺方法对涂层残余应力有着重大的影响，其主要原因是热喷涂涂层的残余应力与喷涂颗粒的温度和飞行速度有着密切的关系。

With the modified Almen test, the measuring and analysis of residual stress in several thermal sprayed coatings had been accomplished in this paper. The physical model to explain the phenomenon of the hysteresis between the strain in a thermal sprayed coating and the temperature or the applied stress had been proposed first. Furthermore, the analysis and testing results had identified that the 'Gas Fix' action introduced in the paper first as a result of the porous characteristic of a thermal sprayed coating is the major reason that results in the hysteresis phenomenon. The test results also confirmed that the relationship between the residual stress in a coating and the coating thickness is linear, and anyhow the residual stress in the coating is either a tensile stress or a compressive stress, it increases with the increase of the coating thickness. Meanwhile, the test results in the paper proved that the technique of depositing a coating has a significant influence on the residual stress level in the coating, because of the close relationships between the residual stress in a coating and the depositing particle temperature and flying velocity.