为了探索无铅压电陶瓷凝胶注模技术, 对0.94Na0.5Bi0.5TiO3-0.06BaTiO3陶瓷的水基凝胶注模成型方法以及对材料结构和性能的影响进行了研究. 研究结果表明: 在陶瓷浆料悬浮液中加入0.5wt%聚甲基丙烯酸铵(PMAA-NH4)分散剂, 调节pH值为9.2, 可以得到高固相含量(50vol%)、低粘度(<1Pa·s)的稳定陶瓷浆料悬浮液. 并用浓度为10wt%的过硫酸铵溶液对生坯进行了8~10h的浸泡预处理, 使后续干燥过程容易进行, 易于得到无缺陷的陶瓷坯体. SEM形貌分析表明, 经凝胶注模工艺制备的陶瓷, 其晶粒均匀, 结构致密, 压电性能优良, 其d33=132pC/N, εr=1319, tgδ=0.019.
In order to develop an efficient gelcasting technique used for lead free piezoceramics, aqueous gelcasting was applied to prepare 0.94Na0.5Bi0.5TiO3-0.06BaTiO3(BNBT6) ceramic and its effects on the ceramic microstructure and piezoelectric performance were intensively investigated as well. PMAA-NH4 was used as the dispersant in the process. When the suspension contained 0.5wt% PMAA-NH4 and pH value was adjusted at around 9.2, the BNBT6 suspension was stable with low viscosity (<1Pa·s) and high solid loading (50vol%). The dipping pretreatment was also conducted for pre-drying gelled parts. In the process, the gelled parts were immersed in 10wt% ammonium persulphate solution for 8--10h. After the dipping pretreatment, desiccation and dehydration of the gelled parts without defects became easily controlled. SEM micrographs show that the BNBT6 ceramic prepared by the gelcasting route exhibits homogeneous microstructure and high density. The optimal piezoelectric and dielectric properties are obtained, namely d33=132pC/N; εr=1319; tgδ=0.019.
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