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第一代热障涂层(TBCs)由氧化钇部分稳定的氧化锆(YSZ)陶瓷隔热层和金属粘结层组成,该涂层长期使用温度低于1 200℃。随着先进航空发动机向着高推重比发展,迫切要求发展新一代超高温、高隔热热障涂层材料。LaTi2Al9O19(LTA)在1 500℃长期保持相稳定,是一种非常有前景的超高温热障涂层候选材料。本文采用大气等离子喷涂(APS)制备了LTA涂层,研究了喷涂工艺对涂层微观组织结构和热物理性能的影响。结果表明沉积态涂层中含少量的非晶态,在860℃和1 130℃出现晶化峰。等离子喷涂过程中La2O3挥发量较多,导致沉积态涂层中La元素与原始粉末相比含量偏低,而其他组分的化学成分随喷涂功率变化不大。LTA涂层的热扩散系数在1 400℃下为0.3～0.4mm2.s-1,热导率为1.1～1.6W.m-1.K-1。1 050℃经过20小时热处理后,得到晶化的涂层在晶化温度范围内的热扩散系数和热导率值均增大。随着喷涂功率减小,涂层孔隙率增加,热导率减小。
The first generation of Thermal Barrier Coatings (TBCs) consists of a partially stabilized zirconia (YSZ) ceramic thermal barrier and a metallic bonding layer that has a long-term service temperature below 1200C. With the development of advanced aeroengines toward high thrust-to-weight ratio, it is urgent to develop a new generation of ultra-high temperature and high thermal barrier thermal barrier coating materials. LaTi2Al9O19 (LTA) has long-term phase stability at 1 500 ℃ and is a very promising candidate for ultra-high temperature thermal barrier coatings. In this paper, LTA coating was prepared by atmospheric plasma spraying (APS), and the effect of spraying process on the microstructure and thermophysical properties of the coating was studied. The results show that the as-deposited coatings contain a small amount of amorphous state, with crystallization peaks at 860 ℃ and 1 130 ℃. La2O3 volatilized more during plasma spraying, resulting in a lower content of La in the as-deposited coating than the original powder, while the chemical composition of other components did not change much with the spraying power. The thermal diffusivity of the LTA coating is 0.3-0.4 mm2.s-1 at 1400C and the thermal conductivity is 1.1-1.6Wm-1.K-1.1 After 050C heat treatment for 20 hours, the crystallized The thermal diffusivity and thermal conductivity of the coatings both increase in the crystallization temperature range. As the spray power decreases, the porosity of the coating increases and the thermal conductivity decreases.