热障涂层激光表面处理技术研究现状和发展趋势OA

With the continuous development of aero-engines and gas turbines towards higher thermal efficiency,their internal operating temperatures and pressures keep increasing,imposing more stringent requirements on high-temperature protective materials.Thermal barrier coatings(TBCs),owing to their unique multi-layered structure and excellent high-temperature performance,have become critical materials for ensuring the reliable operation of hot-end components,garnering extensive attention and application.However,under the harsh service environment involving thermal-mechanical-chemical multi-field coupling,inherent defects within the coating,such as pores and microcracks,easily become channels for the infiltration of hot corrosion media,triggering CMAS corrosion(mainly composed of CaO,MgO,Al2O3,SiO2)and molten salt corrosion(e.g.,V2O5,Na2SO4).These corrosion processes often lead to phase transformations and the formation of new compounds in the coating,generating stresses that cause coating spallation and failure.To address this challenge,laser surface treatment technique has emerged.Through precise processing and modification of the coating surface,it effectively refines grains,enhances density,and improves microstructural homogeneity,thereby significantly improving the hot corrosion resistance and service life of TBCs.Therefore,it has become an important technical approach for optimizing coating performance. The work aims to outline the commonly used materials,structures,and preparation processes for TBCs,highlighting their advantages and limitations and then provide a comprehensive review on the effects of different laser surface treatment techniques on the surface quality,high-temperature corrosion resistance,thermal shock resistance,and mechanical properties of TBCs.Based on the process characteristics and application objectives of laser surface treatment for TBCs,the techniques are categorized into three types,including laser glazing,laser remelting,and laser etching.Laser glazing utilizes high-energy laser irradiation on the coating surface to achieve ultra-rapid melting and solidification of the surface micro-region,forming a thin,dense microcrystalline or amorphous layer(with a thickness ranging from several micrometers to tens of micrometers).Technically,it is a special form of laser remelting,making it more suitable for scenarios with stringent surface performance requirements.In contrast,traditional laser remelting involves greater processing depth,larger melt pool volumes,and thicker remelted layers,which is prone to significant thermal stress and the formation of high-density cracks.Laser etching,on the other hand,uses laser selective ablation to create specific microstructures on the coating surface,thereby altering the physical properties of the coating. To better illustrate the effect of laser glazing in enhancing the hot corrosion resistance of TBCs,its benefits are analyzed from three aspects such as improvement in coating surface quality and formation of a densified surface layer structure.The corresponding failure mechanisms are also summarized.Additionally,the issue of network cracks induced by thermal stress during laser surface treatment is discussed.While these cracks can enhance the strain tolerance of the coating,they may also serve as channels for hot corrosion media to penetrate the coating interior at high temperatures.Four improvement strategies are identified,including glazing with high-energy,short-wavelength lasers,structural modification of the glazed or remelted layer,doping with self-healing materials and crack filling. Finally,the current limitations of laser surface treatment for TBCs are pointed out.For instance,existing research primarily focuses on traditional YSZ ceramic layers,while studies on laser surface treatment of new materials such as rare-earth-doped zirconia/high-entropy ceramics are still insufficient and controlling the temperature field and residual stresses during laser processing remains a major challenge.Based on this,future development trends are prospected,including novel multi-component ceramic TBCs,composite treatment of TBCs with new laser sources and multiple laser processes,and the establishment of integrated laser surface treatment platforms.