多孔二氧化锆基隔热材料的制备及性能

Preparation and Properties of Porous Zirconia Based Thermal Insulation Materials

为制备高气孔率的隔热材料,采用水基凝胶注模法制备了多孔二氧化锆基陶瓷材料。研究了干燥方式、添加氧化铝粉体、固相含量、烧结温度等因素对多孔陶瓷气孔率、密度、微观形貌等的影响,对比了低温干燥、溶液置换干燥和真空冷冻干燥三种干燥方式对低固相含量凝胶注模湿坯干燥的影响。通过实时监测坯体在高温下的烧结影像及尺寸变化,研究了二氧化锆基陶瓷的烧结收缩行为,揭示了添加氧化铝粉体对二氧化锆基陶瓷烧结收缩的抑制作用机理。结果表明真空冷冻干燥是最佳干燥工艺。添加体积分数为32%氧化铝粉体的样品的烧结收缩相比未添加氧化铝粉体的样品减少近60%。通过对固相含量、烧结温度的调配,并结合适宜的干燥工艺及添加氧化铝等手段对坯体收缩进行控制,最终获得了气孔率达到74.44%,压缩强度为3.19 MPa的多孔二氧化锆基陶瓷材料。

In order to obtain thermal insulation materials with high porosity,porous zirconia based ceramic was prepared by water-based gel-casting method.The influences of drying method,addition of alumina powder,solid content and sintering temperature on porosity,density and microstructure of porous ceramic were studied.The effects of three drying methods such as conventional drying at low temperature,liquid desiccant drying and vacuum freeze drying on the drying of low solid content gel-casting wet green were compared.The sintering shrinkage behavior of zirconia based ceramic was studied by real-time monitoring the sintering image and size change of the green body at high temperature,and the inhibition effect of adding alumina powder on the sintering shrinkage of zirconia was revealed.The results show that vacuum freeze drying is the optimum method.The sintering contraction of the sample with 32%volume fraction alumina powder decreases by nearly 60%compared to the sample without alumina powder.The porous zirconia based ceramic with porosity of 74.44%and compressive strength of 3.19 MPa is obtained by adjusting the solid content,sintering temperature,proper drying process and adding alumina.