等离子喷涂Sc_2O_3-Y_2O_3-ZrO_2热障涂层组织结构和性能研究

Microstructure and Properties of Plasma Sprayed Sc_2O_3-Y_2O_3-ZrO_2 TBCs

采用化学共沉淀-煅烧法制备了7.1mol%Sc2O3 ～ 1.5mol%Y2O3-ZrO2（ScYSZ）设计成分复合陶瓷原粉,将该原粉经团聚造粒和高温烧结处理,使粉末流动性及松装密度满足等离子喷涂工艺要求.经大气等离子喷涂制备了超高温热障涂层.采用场发射扫描电子显微镜、X- 射线衍射对粉末组织结构、形貌进行了测试,并进行了涂层组织结构、高温相稳定性、隔热性能、热冲击性能及抗氧化性能进行了测试分析.结果表明所制备的ScYSZ团聚粉末在1200℃烧结处理2h 后,粉末呈球形、流动性好,满足等离子喷涂工艺要求.ScYSZ 粉末及其涂层室温均呈单一四方结构,1500℃热处理300h 后,ScYSZ 涂层无单斜相出现,具有非常优秀的高温相稳定性.在900℃～ 1500℃温度测量范围内,等离子喷涂ScYSZ 涂层的热导率为0.93 ～ 1.19W/m·K,明显低于目前广泛应用的等离子喷涂Y2O3-ZrO2 涂层的热导率（1.2 ～ 1.5W/m·K）.Sc2O3 的加入在提高了热障涂层的高温相稳定性的同时,也显著提高了涂层的隔热性能及抗热冲击性能,Sc2O3-Y2O3-ZrO2 很有希望成为1500℃使用的超高温热障涂层材料.

Scandia, yttria-stabilized zirconia(7.1mol%Sc_2O_3~ 1.5mol%Y_2O_3-ZrO_2, abbreviated as ScYSZ) powder for plasma spraying ultra-high temperature TBCs was synthesized by chemical co-precipitation and calcination processes. The ceramic powder was agglomerated and sintered at 1200℃ for 2 hours. The microstructure, morphology and phase stability of the powder and the plasma sprayed ScYSZ coatings were analyzed by means of scanning electron microscope and X-ray diffraction. The thermal conductivity, thermal shock resistance and oxidization resistance of plasma sprayed ScYSZ coatings were investigated. The agglomerated and sintered ScYSZ powder exhibited good flowability and suitable apparent density to be suitable for plasma spraying process. The ScYSZ ceramic powder and coating exhibits excellent stability to retain single non-transformable tetragonal zirconia even after high temperature(1500℃) exposure for 300 hours and does not undergo a tetragonalto-monoclinic phase transition upon cooling. Furthermore, the plasma sprayed ScYSZ coating also exhibits lower thermal conductivity(900 ℃ ~ 1500 ℃, 0.93 ~ 1.19W/m·K) than yttria stabilized zirconia coating(1.2 ~ 1.5W/m K) currently used in gas turbine engine industry. Sc_2O_3 can improve phase stability, reduce thermal conductivity and raise thermal shock resistance for TBCs comparing with those of the Y_2O_3-ZrO_2 coatings used in present-day gas turbines. ScYSZ can be explored as a novel prospective candidate material for ultra-high temperature thermal barrier coating application for 1500℃.