As a surface thermal protection coating, thermal barrier coating has excellent high temperature resistance, corrosion resistance and low thermal conductivity. It is widely used in aerospace, shipbuilding, automobile and other industrial fields. Plasma spraying is a commonly used process for preparing thermal barrier coatings. In this paper, the development of plasma sprayed thermal barrier coatings at home and abroad is reviewed from the perspective of patents, and the material composition, structure and preparation process are emphatically analyzed. 1 Introduction Thermal barrier coating (TBC) is a surface thermal protection technology that combines ceramic and metal substrates in the form of coating by taking advantage of the superior high temperature resistance, corrosion resistance and low thermal conductivity of ceramic materials. Thermal barrier coating is applicable to gas turbine, engine and other hot end components, which can significantly improve their working temperature, prolong the service life of hot end components and improve work efficiency. Thermal barrier coating is usually composed of ceramic oxide surface layer and metal bonding bottom layer with good thermal insulation performance. At present, the commonly used thermal barrier coating preparation technology mainly includes plasma spraying and electron beam physical vapor deposition. Among them, the plasma spraying coating has a layered structure, the thermal insulation performance of the coating is better than that of the electron beam physical vapor deposition coating, and the coating cost is low, so it is widely used. In this paper, the domestic and foreign patent documents related to the preparation of thermal barrier coatings by plasma spraying are searched and sorted out, and the development of this technology is classified, summarized and analyzed. 2 Development of plasma sprayed thermal barrier coating materials As a metal high-temperature protection material, thermal barrier coating material is required to have superior high temperature resistance, corrosion resistance and low thermal conductivity. Therefore, these materials are mostly based on ZrO2, Al2O3, TiO2, etc., with high melting point and high stability. Develop new materials through doping, solid solution, composite and structural design. 2.1 Material composition of thermal barrier coating ZrO2 has high melting point, strong oxidation resistance and is suitable for high temperature environment. Therefore, ZrO2 based material is a widely used thermal barrier coating material. (1) ZrO2 based coating material ZrO2 stabilized by Y2O3 is a widely used thermal barrier coating material. Its research began in the 1980s. In 1981, the National Aeronautics and Space Administration of the United States applied for plasma spraying for * * times to prepare metal bonding layer, and Y2O3 stabilized ZrO2. Barrier coating patent [1]. Pure ZrO2 will change from monoclinic phase to tetragonal phase from room temperature to high temperature. There is 3% to 5% volume shrinkage in this process. This volume change causes ZrO2 to break easily under thermal cycling conditions. Y2O3-stabilized ZrO2 (YSZ) is obtained by adding 6-8wt% Y2O3. It can maintain metastable tetragonal phase when cooling from high temperature to room temperature, and will not crack due to volume change. However, the traditional YSZ has its own defects, for example, the working temperature is limited by ZrO2 and Y2O3 materials. Therefore, various improvements have been made to the traditional ZrO2 based thermal barrier coating at home and abroad. ① Dope other stabilizers. Using scandium oxide as stabilizer can resist the erosion of sulfur and vanadium [2]; The porosity of gadolinium oxide stabilized zirconia coating is 5-20%, and the thermal conductivity is low, which can increase the coating life and reduce the cost [3]. ② Use coated YSZ powder. Heterogeneous coated YSZ powder was prepared by heterogeneous precipitation method. The coating is lanthanum oxide, cerium oxide or europium oxide. After heat treatment, the grain of the coating grows slowly, has good sintering resistance, low temperature conductivity, and good thermal insulation performance [4]; YSZ-based composite thermal barrier coating material is prepared by plasma spraying method by coating YSZ material with core-shell calcium silicate composite powder. The internal structure is relatively dense, and the distribution of pores and microcracks is relatively dense. For uniforms [5]. ③ Add CMAS corrosion resistant ingredients. Use a thermal barrier coating with a ceramic top layer composed of Li2O-YSZ. Thermal barrier coating can alleviate coating failure caused by different thermal expansion coefficients of CMAS and YSZ [6]. ④ SiO2 doped ZrO2 material. Using SiO2 silica sol as raw material can not only play the role of additive, but also play the role of bonding, which can improve the bonding strength and thermal shock life of the coating [7]. (2) Other ceramic layer materials The traditional Y2O3-stabilized ZrO2 has high thermal expansion coefficient, low thermal conductivity and good thermal shock resistance, but the long-term use temperature of YSZ cannot exceed 1200 ℃, because YSZ will produce significant phase transformation and accelerate sintering. The coating falls off and fails. Therefore, researchers are actively studying various new thermal barrier coating material systems. Zircon material. This material is mainly made of rare earth Doping or two-phase composite form to improve the stability and bonding strength of the coating. ① Rare earth doped zirconate, A2 (ZrxCe1-x) 2O7 (A is a rare earth element), this ceramic material has high thermal expansion coefficient and phase stability [8]; La2Zr2-xCexO7 has low thermal conductivity, large linear thermal expansion coefficient and good high temperature stability [9]. ② The two-phase composite material Zr1-x-yHfxREyO2-y/2 is compounded with the negative thermal expansion material Zr1-yREyW2-zMozO8-y/2 to achieve a good match between the coating and the substrate [10]. Aluminate material. Such materials usually need to be doped with single or multiple rare earth elements to improve thermal stability. For example, the rare earth aluminate thermal barrier coating composed of rare earth aluminate garnet structure compound R3A15O12 or rare earth aluminate perovskite compound XAlO3 (where R and X are rare earth elements) has very low oxygen permeability, which can improve the resistance of the oxidation coating [11]. Multi-element rare earth doped thermal barrier coating, LnyLn'zLn "1-y-zMexAl12-xO19+ δ (Ln, Ln ', Ln "are rare earth elements, Me is metal elements Mn, Mg, etc.), its advantages of high temperature phase stability [12].