水基流延成型制备Li_(1+x-y)Nb_(1-x-3y)Ti_(x+4y)O_3微波介质陶瓷膜片的研究(英文)

Preparation of Li_(1+x-y)Nb_(1-x-3y)Ti_(x+4y)O_3 Microwave Ceramic Green Sheets by Aqueous Tape Casting

以Li1+x-yNb1-x-3yTix+4yO3微波介质陶瓷为原料,聚乙烯醇水溶液为粘结剂,乙二醇为增塑剂,聚羧酸铵盐为分散剂,通过水基流延成型工艺制备出了微观结构均匀的陶瓷素坯膜。通过对陶瓷粉体Zeta电位的考察研究了在水溶液中的粉体表面的带电情况。对陶瓷浆料的流变性进行了研究,考察了分散剂对浆料粘度的影响。最后对成型后陶瓷膜片的微观结构进行了观察。结果表明,添加分散剂后,Li1+x-yNb1-x-3yTix+4yO3陶瓷粉体在水溶液中的等电点由pH3移动到pH2.4,并且粉体的Zeta电位有大幅度的提高。Li1+x-yNb1-x-3yTix+4yO3微波介质陶瓷水基流延成型浆料为典型的假塑性流体,并且不存在触变性,满足流延成型工艺的要求。当分散剂的添加量为0.2wt%时,浆料的粘度最低。扫描电镜观察表明,水基流延成型后陶瓷素坯膜的微观结构均匀。

The aqueous tape casting process was systematically developed and investigated for the tape casting of Li1＋x-yNb1-x-3yZix＋4yO3 microwave ceramics. The well-dispersed aqueous ceramic slurries were prepared, with water-soluble PVA as binder, ethylene alcohol as plasticizer, and ammonium salt of polycarboxylate as dispersant. The results show that the amount of the dispersant required to achieve a minimum of viscosity was equal to 0.2wt%. The isoelectric point of the ceramic particles moved slight toward more acid region after the dispersant absorbed on the particles, while the zeta potential increased significantly. The rheological test indicates that the ceramic slurry exhibited a typical shear-thinning behavior and scarcely no time dependent behavior. In addition, SEM micrographs show that the microstructure of the green ceramic sheets is homogeneous.