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.
La2O3-Y2O3-ZrO2 (LaYSZ) green composite ceramic powder was prepared by converse chemical coprecipitation method. The powder was conglomerated and heattreated 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 ZrO2 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 ZrO2 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 La2O3, Y2O3 co-doped ZrO2 exhibits better phase stability than single Y2O3-doped ZrO2.
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