热障涂层用La2O3、Y2O3共掺杂ZrO2陶瓷粉末的制备及其相稳定性

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

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 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 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.