氧化锆基双陶瓷层热障涂层表层材料研究进展

双陶瓷层热障涂层是热障涂层技术的发展方向之一。等离子喷涂和电子束-物理气相沉积技术是目前最常用的双层涂层制备技术，但存在的固有缺点影响涂层性能的发挥。可实现非视线沉积的等离子-物理气相沉积技术效率高，能对涂层微观结构进行精准调控，发展潜力巨大。稀土氧化物掺杂ZrO2、A2B2O7型烧绿石和萤石结构化合物、钇铝石榴石、独居石结构的稀土磷酸盐、氧化铝等材料被作为表层陶瓷，分别与传统的6%~8%Y2O3部分稳定的ZrO2（(6~8)YSZ）层组合构成双陶瓷层，可有效降低涂层的热导率，极大地改善抗熔盐热腐蚀性能，提高耐热温度等。如YSZ/CeO2和TiO2共稳定的ZrO2双层涂层可大幅提高隔热性能，La2(Zr0.7Ce0.3)2O7能有效提高整个涂层的使用寿命，钇铝石榴石能阻隔氧渗入YSZ层并防止粘结层金属的氧化，GdPO4能与Na2SO4+V2O5熔盐反应形成稠密反应层并抑制熔盐的进一步渗入，纳米Al2O3可形成致密结构，并提高涂层的抗热腐蚀能力和抗高温氧化能力。但是，绝大部分材料的热膨胀系数较低、断裂韧性较差，限制了涂层整体性能的发挥。结合纳米技术和等离子-物理气相沉积等新的制备技术，改性修饰稀土锆酸盐等表层材料的热物理性能，引入稀土钽酸盐等热导率低、韧性强、阻氧性好的材料，被认为能提高双层涂层的隔热性能和使用寿命。

Research Progress on Top Coating Materials of Thermal Barrier Coatings with Double-ceramic-layer Based on Zirconia

Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) are one of development directions of novel TBCs. Plasma spraying technology and electron beam-physical vapor deposition technology are the commonly used technologies to prepare DCL TBCs, but the inherent defects of the two technologies restrict the performances of DCL TBCs. With high efficiency and the ability of nonline-of-sight depositing, PS-PVD technology can accurately adjust and control the microstructure of TBCs, thus having great application potentials. DCL coatings could be prepared by ZrO2 doped by rare earth oxide, A2B2O7-type pyrochlore and fluorite, yttrium aluminium garnet, rare earth phosphates of monazite structure, and aluminium oxide as top coating and zirconia stabilized by 6wt.%~8wt.% Y2O3 as bottom coating, thus reducing the thermal conductivity effectively, improving the resistance to molten salt hot corrosion largely, increasing the thermal resistance, etc. For example, YSZ/CeO2 and TiO2 co-stabilized ZrO2 DCL TBCs could improve thermal barrier effect substantially, La2(Zr0.7Ce0.3)2O7 could effectively increase the service life of TBCs, yttrium aluminium garnet could obstruct oxygen infiltration and prevent oxidation of metals in bond coating, GdPO4 could react with Na2SO4+V2O5 and form dense reation layer to inhibit permeation of molten salts and nano-structured Al2O3 could form compact structure to enhance hot corrosion resistance and high temperature oxidation resistance. However, the performances were still restricted by lower coefficient of thermal expansion and poor fracture toughness. For this, some proposals to improve thermal barrier performaces and service life of DCL TBCs, such as combining with nanotechnology and PS-PVD technology, modifying thermophysical properties of such new materials as rare earth zirconate by doping, inducing new materials (e.g. tantalate) with low thermal conductivity, strong fracture toughness, and good resistance to oxygen transmission, were put forward.