Lanthanum zirconate

Thermal barrier coating both insulation and anti-oxidation function, is the most advanced high-temperature alloy surface protective coating technology, widely used in aviation, aerospace, automotive and large-scale thermal power and other industries. In particular, with the development of gas turbine / aircraft engine towards high temperature and high efficiency, the performance requirements of ceramic layer materials are getting higher and higher. The traditional Y2O3 stable ZrO2 (YSZ) material has been difficult to meet the high performance requirements. At higher temperatures, thermal barrier coating materials have become the focus of research at home and abroad. Lanthanum zirconate (La2Zr2O7, LZ) is considered to be a very promising new type of high temperature thermal barrier coating material because of its high melting point, stable phase structure and low thermal conductivity. In this paper, La2Zr2O7-based powders were prepared by different methods, and a novel lanthanum-lanthanum-based thermal barrier coating was prepared by atmospheric plasma spraying (APS). The thermal expansion coefficient, thermal shock resistance, thermal conductivity and bonding strength of the coating were systematically studied. The main contents and conclusions are as follows:

(1) La2Zr2O7 powder was prepared by coprecipitation spray granulation technique, but the segregation was found. The La2Zr2O7 powder with pyrochlore structure was prepared by the method of molten salt for the first time. The effects of reaction time, reaction temperature and salt content on the phase and particle size of the product were studied. By changing the experimental conditions, the output of the appropriate amplification. After the spray granulation, the powder flow and bulk density can meet the requirements of plasma spraying.

(2) The coating of two kinds of powders was prepared by plasma spraying. By comparing the properties of the two coatings, it was found that the nano-ceramic thermal barrier coating had higher thermal expansion coefficient compared with the traditional micron-scale thermal barrier coating, Higher bonding strength, better thermal shock resistance, lower thermal diffusivity and better thermal insulation.

(3) Dy and Gd ion doped La2Zr2O7 powders were prepared by molten salt method. The effects of Dy and Gd ion doping on the properties of La2Zr2O7 coating were studied. The results show that Dy and Gd doping can improve the bonding strength, thermal shock, thermal expansion coefficient and thermal conductivity of La2Zr2O7 coating.

(4) The effect of Ta ion on the properties of La2Zr2O7 coating at position B was investigated. With the increase of Ta content, the bulk density of the prepared powder increases gradually. When the content of Ta is increased with the increase of Ta content, the thermal expansion coefficient of La2TaxZr2-xO7 coating is increased as a whole, and the bonding strength And the thermal shock resistance of the coating decreases obviously with the increase of Ta content. When the x = 0-3, the thermal conductivity of the coating can be reduced obviously.