共沉淀法合成ZrO2-ZrW2O8复合材料的工艺研究

以硝酸氧锆[ZrO(NO₃)₂·5H₂O]和钨酸铵(H₄₀N₁₀O₄₁W₁₂·xH₂O)为原料,采用共沉淀法合成了低热膨胀的ZrO₂-ZrW₂O₈复合陶瓷, 着重研究了不同热处理条件对前驱体转变为ZrO₂-ZrW₂O₈复合陶瓷的影响, 并探讨了前驱体生成及其转变的反应历程. 通过X射线衍射仪(XRD)、热重-差示扫描量热(TG-DSC)、扫描电子显微镜(SEM)、热膨胀仪等分析手段对样品的晶体结构、物相转变、断面微观形貌和热膨胀性能进行表征. 结果表明: 采用共沉淀法制备的前驱体在1150℃热处理2h可以合成高纯度、混合均匀的ZrO₂-ZrW₂O₈复合陶瓷; 随烧结时间的延长, ZrW₂O₈衍射峰半高宽逐渐减小, 晶粒在不断长大; ZrO₂-50wt%ZrW₂O₈复合陶瓷在30～600℃内的平均热膨胀系数为-3.2295×10^-6K^-1.

Study on the Technology of ZrO2-ZrW2O8 Composites Prepared by Co-precipitation Method

A low-thermal-expansion ceramic composite of ZrO₂-ZrW₂O₈ was synthesized by co-precipitation route using analytically pure zirconium nitrate [ZrO(NO₃)₂·5H₂O] and ammonium tungstate(H₄₀N₁₀O₄₁W₁₂·xH₂O) as starting materials. Effects of heat-treatment on the transformation from the precursor to ZrO₂-ZrW₂O₈ composite were investigated, and the chemical reaction process of the precursor was explored. The crystal structure, phase transition, cross-section morphology and thermal expansion coefficient of the samples were investigated by X-ray diffraction(XRD), thermogravimetric and differential scanning calorimetry(TG-DSC), scanning electron microscope(SEM) and dilatometry respectively. The results show that the homogeneous ZrO₂-ZrW₂O₈ composites are synthesized after sintering at 1150℃ for 2h. With the increase of sintering time, the full width at half maximum (FWHM) of the ZrW₂O₈ diffraction peaks decreases, and the grain grows up gradually. ZrO₂-50wt%ZrW₂O₈ composite has an average thermal expansion coefficient of -3.2295×10^-6K^-1 from 30℃ to 600℃.