关键词: 航空发动机与燃气轮机, 热端部件热障涂层, 表面裂纹, 剪滞模型, 预热温度, 应变能

Abstract: Aircraft engine and gas engine are the major strategic equipments related to the national energy security, defense security and industrial competitiveness, and thermal barrier coating system (TBCs) on hot components is one of the key technologies related to its safety and life. In recent years, with the development of advanced aircraft engine and gas turbine technologies, the work temperature of hot components such as combustion chamber and blades is increasing, putting forward higher and higher requirements for the thermal insulation and service life of TBCs, which can’t be satisfied by the tradition air plasma sprayed (APS) coatings. It is a new TBCs technology with great economy and feasibility by introduction periodic surface cracks with certain density into ceramic coating to improve both the thermal insulation and service life of TBCs. However, the formation mechanism of surface cracks in ceramic layer is still unrevealed. In this work, a shear-lag model considering thermal stresses in multilayer structure is developed, and the analytical solutions of the stress and displacement fields in ceramic layer before the formation of surface cracks are derived. The evolution of average stress, average strain energy density and total strain energy in plasma sprayed ceramic layer with coating thickness under different preheating temperatures are obtained. The results illustrate the effect of preheating temperature on the formation of surface cracks in TBCs, which providing theoretical guidance for the controllable preparation of advanced TBCs.

Key words: Aircraft engine and gas turbine, Thermal barrier coating system for hot components, Surface cracks, Shear-lag model, Preheating temperature, Strain energy