基于晶体微观有限元方法的多相复合涂层高温摩擦应力场模拟

Simulation of High Temperature Friction Stress Field of Multiphase Composite Coating Based on Crystal Microscopic Finite Element Method

对高温摩擦磨损工况下多相复合涂层的热-力耦合应力场的模拟研究尚不充分。基于Voronoi多边形建立NiCr-Cr_(3)C_(2)-CaF_(2)/BaF_(2)多相复合涂层的晶体微观有限元模型,模拟复合涂层中各相的占比、分布形态和热-力学参数,求解得到热-力耦合工况下的von Mises应力和第一主应力分布。结果表明:在高温摩擦工况下,多相复合涂层的应力显著高于均匀涂层,尤其是在硬质相尖端附近易产生局部高应力区域,改善相的形态将锐角钝化能够有效缓解局部高应力现象;热-力耦合应力场与黏结相和硬质相的弹性模量密切相关,通过调节各相模量能够有效调控复合涂层的Mises应力和拉应力值。基于微观有限元方法的热-力耦合应力场模拟可为高温摩擦磨损工况下多相复合涂层的优化设计提供理论依据。

Thermal sprayed NiCr-Cr_(3)C_(2)-CaF_(2) / BaF_(2) composite coatings can be used as high-temperature wear-resistant material for aeroengine brush seal runway. High temperature friction and wear produces a coupling stress field formed by the superposition of thermal stress and friction stress. At the same time, the morphology and properties of each phase in the composite coating will have a significant impact on the coupling stress field. The thermal-mechanical coupling stress field simulation study of multiphase composite coatings under high temperature friction and wear conditions is still insufficient. The coupling stress distribution is simulated by finite element method to predict the potential failure mode of the coating and provide a basis for the design of brush sealing coating. Based on Voronoi polygon, the crystal micro finite element model of NiCr-Cr_(3)C_(2)-CaF_(2)/BaF_(2) multiphase composite coating is established. The proportion, distribution morphology and thermal-mechanical parameters of each phase in the composite coating is simulated, and the von Mises stress and the first principal stress distribution under thermal-mechanical coupled conditions is obtained. The results show that the stress of the composite coating is significantly higher than that of the uniform coating, especially at the tip of the hard phase. Improving the morphology of the phase and passivating the acute angle can effectively alleviate the local intense stress. At the same time, the thermal-mechanical coupling stress field is closely related to the elastic modulus of bonded phase and hard phase.Mises stress and tensile stress of composite coating can be effectively controlled by adjusting the modulus of each phase. The thermal-mechanical coupling stress field simulation based on the microscopic finite element method provides a theoretical basis for the optimal design of multiphase composite coatings under high temperature friction and wear conditions.