掺杂氧化物对ZrO_2相结构稳定性及烧结性能的影响

Effect of doping oxides on the structure stability and sintering properties of ZrO_2 phase

采用共沉淀-凝胶方法,通过低温煅烧和中温烧结,分别制备了Y2O3、Al2O3掺杂的ZrO2粉体和陶瓷;利用X射线衍射分析、扫描电镜和透射电镜等手段,对掺杂不同氧化物ZrO2相结构的稳定性及烧结性能进行了研究.结果表明:在ZrO2中掺杂摩尔分数5%的Y2O3或者Al2O3,870℃焙烧15min的粉体前者为立方相,后者为四方相;它们的粉体成型后经1400℃烧结4h,前者在室温下仍能保持立方相,后者却得到的是单斜相;在焙烧粉末中,Al3+固溶到ZrO2的晶格中,对ZrO2四方相晶格起到稳定作用,而在其陶瓷中,Al3+从ZrO2的晶格中扩散到晶界,对ZrO2不起稳定作用,只起促进烧结和细化晶粒的作用.

ZrO2 powders and ceramics doped with Y2O3 and Al2O3 respectively were prepared by a copreeipitation-gel method using low temperature calcining and medium temperature sintering. The structure stability and sintering properties of ZrO2 phase doped with the different oxides were studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that calcined at 870℃ for 15 min, ZrO2 powders doped with Y2O3 of 5% in molar fraction have a cubic phase, but those doped with Al2O3 of 5% in molar fraction have a tetragonal phase. After sintering the formed powders at 1 400 ℃ for 4 h, the former remains the cubic phase at room temperature, but the latter has a monoclinic phase. In the calcining powders, Al3＋ dissolves into the lattice of ZrO2 and stabilizes the ZrO2 tetragonal lattice; whereas in their ceramic, Al3＋ diffuses from the ZrO2 lattice to the grain boundaries, so it can not afford a stabilizing effect on the ZrO2 , only plays a role in promoting the sintering and thinning grain.