基于显微照片的增层模型涂层温度场模拟

Temperature Field Simulation by Layer Deposition Model Based on Micrograph

熔射成形中涂层的使用性能与其残余热应力密切相关,而残余热应力则是由于沉积过程中温度场分布不均匀导致的,因此,研究涂层温度场是分析其残余热应力的基础。针对现有涂层沉积温度场模拟普遍采用的增层模型不能考虑涂层孔隙的缺陷,提出一种基于显微照片的含孔隙涂层生长增层模型,并使用该模型对其温度场进行模拟。计算结果表明,孔隙不仅对沉积过程中的涂层温度场具有重要影响,而且对基体温度场也有影响。涂层中靠近孔隙的位置其温度下降比远离孔隙位置更慢,且沉积初期这种差异更明显。含孔隙涂层温度场的模拟为含孔隙涂层残余热应力的研究及涂层起翘、开裂和剥落等失效机理的分析提供了基础。

The service performance of coatings manufactured by plasma spray forming is closely related with their thermal residual stresses, and the thermal residual stresses are caused by the nonuniformity of temperature field during the coating deposition process. Therefore, the research on coating temperature field is the basis of residual stress analysis. Aiming at the problem that the layer deposition models generally adopted for the simulation of coating deposition temperature field cannot take the coating pore s into consideration, a layer deposition model based on micrograph is proposed, in which the effects of pores are considered, is presented. The computation results show that not only the temperature field of the coatings but also that of the substrate are influenced by the pores. In the coatings, the temperature of the position near the pores decreases faster than that of the position far from the pores, and the difference is more significant at the beginning of deposition. The temperature field study with the consideration of pore effects provides the basis for the analysis of thermal residual stresses and the solution of coating failures such as warping, cracking and spaUing.