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采用化学共沉淀法合成前驱体,经1150℃烧结3.5 h得到近零膨胀26 wt%ZrW2O8/ZrO2复合陶瓷,并利用X射线衍射仪、扫描电镜和热膨胀仪研究了原料中加入Al(NO3)3.9H2O对26 wt%ZrW2O8/ZrO2复合陶瓷的相组成、致密度和热膨胀性能的影响。研究结果表明,少量添加Al(NO3)3.9H2O可有效提高复合材料致密度,所得复合陶瓷的组分仍为立方结构的α-ZrW2O8和单斜的m-ZrO2,其中添加2.21 wt%Al(NO3)3.9H2O的复合材料的致密度达到理论密度的98.67%,且对复合陶瓷的热膨胀性能影响不大。其促进致密化机制为晶界处低熔点液相物质Al2(WO4)3提高了复合材料的烧结性能,消除气孔促进致密化。
The precursors were synthesized by chemical coprecipitation method and sintered at 1150 ℃ for 3.5 h to obtain nearly zero-expansion 26 wt% ZrW2O8 / ZrO2 composite ceramics. The effects of the addition of Al (NO3) 3.9 on the composites were investigated by XRD, SEM and thermal dilatometer Effect of H2O on Phase Composition, Density and Thermal Expansion of 26wt% ZrW2O8 / ZrO2. The results show that the addition of a small amount of Al (NO3) 3.9H2O can effectively increase the density of the composites. The composition of the obtained composite ceramics is still cubic α-ZrW2O8 and monoclinic m-ZrO2, in which 2.21 wt% Al (NO3 ) 3.9H2O composites reached a theoretical density of 98.67% of the density, and thermal expansion of composite ceramics has little effect. The mechanism of densification is that Al2 (WO4) 3, a low-melting point liquid phase material at the grain boundary, improves the sintering properties of the composite material and eliminates the pores to promote densification.