等离子喷涂ZrC基涂层逐道逐层沉积残余应力模拟与实验验证

Residual Stresses of Plasma Sprayed ZrC-based Coatings during Path-by-path and Layer-by-layer Deposition:Simulation and Experimental Verification

采用商用ANSYS14.5软件,依据复合梁增层力学模型,采用逐道逐层累积模型模拟了C/C复合材料表面等离子喷涂ZrC基涂层沉积残余应力的特征,分析了SiC过渡层、第二相(SiC,MoSi2)和涂层厚度对ZrC基涂层残余应力的影响,并进行了实验验证。结果表明,SiC过渡层有效缓解了涂层与基体的热失配应力。涂层体系的应力随着涂层厚度的增加逐渐减小,符合应力松弛和叠加规律。在涂层内部的径向应力以拉应力为主,基体中主要为压应力,且在界面边缘存在压应力集中的极限区域,易使涂层产生裂纹并沿界面扩展。该模拟采用逐道逐层累积的方法更逼近实际喷涂过程,能更准确预测涂层的残余应力。

Commercial ANSYS14.5 software was used to simulate the residual stress characteristics in the deposition process of plasma sprayed ZrC-based coatings on the surface of C/C composite substrates.The simulation combined the mechanical model of composite beam adding laminate layer,and the finite element model of accumulation of path-by-path and layer-by-layer.Effects of SiC transition layer,second phase (SiC,MoSi2) and coating thickness on residual stresses of the ZrC-based coatings were analyzed and validated by experiments.All results show that the SiC transition layer effectively relieve thermal mismatch stress between the coating and the substrate.Stress of the coating decreases gradually with the increase of coating thickness,which conforms to the stress relaxation and superposition law.There exist tensile stress in the coating,and compressive stress in the substrate.Moreover,compressive stress concentration is found at the interface edge,which is easly induced cracks formation and propagation along the interface.Therefor,our simulation method in present study could simulate actual spray process and predict residual stress of the coatings accurately.