热喷涂层的残余应力多尺度演化机理及涂层损伤行为研究

According to the requirement of reliable service and life prediction of thermal spraying remanufactured parts, the aim of the present project is to analysis the residual stress evolution mechanism and coating damage behavior due to the interaction of residual stress and coating multi-scale structure. The following issues will be focused in the present project: (1) A unified numerical model,which includes with spraying parameters, spray flume and coating, is delveloped and experimentally verified. This research can be used to describe the source of residual stress of thermal sprayed coating. (2) According to the interaction of coating microstructures and residual stress, relaxation behavior of residual stress of coating in micro-scale is analysed with finite element method. The influence of relaxation of residual stress on coating microstructures can be clarified. (3) Based on contact fatigue experiment and acoustic emission online monitoring technique, evolution mechanism residual stress with coating multi scale structures, on working condition, can be experimentally analyzed. In this interdisciplinary program, the mechanical and material analyses were included. Residual stress is as the object of theoretical and experimental research in this project, and the technique criterion about coating failure modes can be proposed.Finally, the project provide some important insights on coating life cycle assessment.

面向热喷涂再制造零件的可靠运行及寿命预测的需求，针对热喷涂层残余应力与涂层多尺度结构相互作用下的演化机理及涂层损伤行为开展研究。主要包括：（1）通过数值分析方法建立喷涂参数、焰流及涂层的联合分析模型，并进行实验验证，以对涂层残余应力的产生机理进行科学分析；（2）通过涂层内部微观结构与涂层残余应力的交互关系，采取有限元方法分析残余应力在涂层微观尺度上的释放机制，以揭示服役过程中残余应力的释放对涂层微观结构的影响规律；（3）基于接触疲劳试验和声发射信号监测技术，实验分析服役过程中残余应力在涂层多尺度结构上的变化机理。本项目体现了力学与材料等多学科领域的交叉，以残余应力为理论和实验的研究对象，在涂层失效机制的技术判据上有所突破，将为涂层的寿命评估工作提供科学依据。

本项目针对超音速等离子涂层残余应力在涂层整个制备过程、服役过程的变化机制为突破口，以分析循环接触载荷作用下残余应力在涂层失效过程的作用机制为目标，结合数值分析技术，重点了解决如下基础问题：1）涂层制备过程残余应力的产生机理，并通过数值分析方法为主，实验验证为辅助的方法，并考察了试验验证方法的有效性；2）分析涂层残余应力释放机制及其与涂层微观结构的相互关系，采用实验观测和数值分析相结合的方法分别研究涂层的蠕变、裂纹微观尺度上的涂层残余应力释放机制；3）利用滚动接触疲劳试验考察循环载荷作用下涂层内部残余应力的变化，重点研究涂层缺陷从微观尺度到宏观尺度的变化过程中涂层残余应力的变化机制，特别是失效前后涂层残余应力的变化，并分析了残余应力在涂层滚动接触疲劳载荷条件下的作用机制。