Abstract: The rheological behavior of colloidal barium titanate suspension with PAA-NH4 as a dispersant to aid the powder dispersion was investigated. The nanosized barium titanate powder was synthesized by a continuous high-gravity reactive precipitation process, and then annealed at 900℃ for 2 h. By measuring the Zeta potential and the particle size distribution of BaTiO3 in an aqueous medium the optimum conditions for preparing suspension with low viscosity and high stability can be obtained. An isoelectric point at pH=2.8 is found. The Zeta potential decreases upon addition of PAA-NH4. Using the particle size distribution tests, it is found that the stabilization of suspensions is attained at pH greater than or equal to 10 and concentrations greater than or equal to 12 mg/g (dispersant/powder). FT-IR spectroscopy shows that polyelectrolytes are bound to the BaTiO3 surface via the carboxylic acid groups with physical and chemical adsorption. By rheological measurements, pseudoplastic behavior and thixotropy are observed in the suspensions. The maximum solid content attained during this work is 45%(j). The green density of BaTiO3 tape is up to 55.4% of the theoretical density after tape casting of the suspension.

Key words: nanosized BaTiO3, PAA-NH4, dispersion, aqueous suspension

摘要： 通过测定超重力法制备的纳米钛酸钡悬浮体的Zeta电位和团粒尺寸分布，确定了纳米BaTiO3在水中稳定分散的基本条件，制备了不同体积分数的悬浮体并研究了其流变学特性. 该纳米BaTiO3在水中的等电点约为pH 2.8，加入分散剂PAA-NH4后，颗粒零电点向更低pH值移动；当分散剂用量为干粉量的1.2%(w)时，悬浮体中平均团粒尺寸最小，分散效果最佳. FT-IR分析证明颗粒表面上PAA-NH4的吸附为物理化学吸附. 制备了体积分数高达45%的纳米BaTiO3悬浮体，其流变特性表现为剪切变薄行为，流延成型的BaTiO3陶瓷生坯片具有较高的相对密度(55.4%).

关键词: 纳米BaTiO3, PAA-NH4, 分散, 水基悬浮体