热障涂层用La2O3、Y2O3共掺杂ZrO2陶瓷粉末的制备及其相稳定性

采用反向化学共沉淀法制备了热障涂层用La₂O₃-Y₂O₃-ZrO₂（LaYSZ）原始复合粉末, 将原始粉末团聚造粒和热处理后得到适于等离子喷涂的团聚粉末. 采用电感耦合等离子体原子发射光谱（ICP-AES）、扫描电子显微镜（SEM）、霍尔流速计、X射线衍射（XRD）等方法分别对LaYSZ的化学组成、微观形貌、流动性和松装密度、高温相稳定性进行了研究. 结果表明: LaYSZ团聚粉末室温呈四方ZrO₂结构, 在1150℃热处理2h后为致密的球形或近球形颗粒, 粉末流动性较好, 适于等离子喷涂. LaYSZ团聚粉末在1300℃热处理100h后仍保持单一的四方ZrO₂晶型, 而8YSZ中有12mol%的四方相转变为单斜相; LaYSZ在1400℃热处理100h后, 单斜相含量为2mol%, 而8YSZ中单斜相含量达到47mol%, 表明La₂O₃、 Y₂O₃共掺杂稳定ZrO₂较单一Y₂O₃ 稳定ZrO₂具有更好的高温相稳定性.

Preparation and Phase Stability of La_2O_3, Y_2O_3 Co-doped ZrO_2 Ceramic Powder Application for Thermal Barrier Coating

La_2O_3-Y_2O_3-ZrO_2 (LaYSZ) green composite ceramic powder was prepared by converse chemical coprecipitation method. The powder was conglomerated and heat-treated to be suitable for plasma spraying. The chemical compositions, microstructures, flowability and apparent density, phase stability at high temperatures were analyzed by means of inductively coupled plasma-atomic emission spectrometre (ICP-AES), scanning electron microscope (SEM), hall flowmeter, X-ray diffraction, respectively. The results show that the green composite powder presents tetragonal ZrO_2 phase structure at room temperature. After heat-treated at 1150℃ for 2h, the conglomerated powder with spherical shape and dense surface exhibits good flowability, which can be used for plasma spraying. After heat-treated at 1300℃ for 100h, LaYSZ still keeps single tetragonal ZrO_2 structure, while 12mol% tetragonal phase of 8YSZ transforms to monoclinic phase. After heat-treatment at 1400℃ for 100h, the amount of monoclinic phase in LaYSZ is of 2mol%, and that in the 8YSZ is of 47mol%. It shows that La_2O_3, Y_2O_3 co-doped ZrO_2 exhibits better phase stability than single Y_2O_3-doped ZrO_2.