A Fundamental Study on Environmentally Benign Wet-Type Forming Process of Ceramics by Ultrasonic Attenuation Spectroscopy

利用超声衰减光谱技术对陶瓷的环保型湿成形工艺进行了基础研究。衰减光谱法可以表征高浓度浆料的粒径分布。该技术可以直接测量高浓度浆料中分散体的PSD，而不需要考虑在测量前稀释对PSD可能产生的变化。本文研究了分散剂添加量不同对氧化铝和钛酸钡浆料宏观和微观性能的影响。结果表明，当分散剂全部吸附在氧化铝表面时，Al_2O_3颗粒的zeta电位不是控制氧化铝浆液粘度的因素，而粒径分布宽度(表示为Iog（d_<84>/d_<50>）和大颗粒分数（LPF）影响氧化铝浆液的粘度。当浆料中存在非吸附分散剂时，PSD和Iog（d_<84>/d_<50>）与粘度行为无关。结果表明，声衰减谱法可以为浆料粘度等宏观性质与微观性质之间的关联开辟道路。钛酸钡的结果也表现出与氧化铝浆料相同的趋势。总结这些结果，我们得出结论，应该根据颗粒的原位微观性质，如粒径分布和颗粒表面羟基的数量和性质，建立一个指导方针。

A fundamental study on environmentally benign wet-type forming process of ceramics was investigated by ultrasonic attenuation spectroscopy. An attenuation spectroscopy can characterize the particle size distribution (PSD) of highly concentrated slurries. This technique can directly measure the PSD of dispersions in highly concentrated slurries without considering the possible change of the PSD by diluting prior to measurement. The present study investigated a correlation between macroscopic and microscopic properties of alumina and barium titanate slurries when the added amount of dispersant was changed.It is found that the zeta potential of the Al_2O_3 particles is not a factor of controlling the viscosity of alumina slurry, but particle size distribution width , represented as Iog(d_<84>/d_<50>), and large particle fractopn (LPF) affect the viscosity of alumina slurry when all the amount of dispersant was adsorbed on to the alumina surface. When non-adsorbing dispersant was present in the slurry, the PSD and Iog(d_<84>/d_<50>) cannot be related with the behavior of viscosity. The obtained results demonstrated that the acoustic attenuation spectroscopy can open the way for correlating between macroscopic property such as viscosity and microscopic properties of slurry. The results on the barium titanate also shows the same tendency of that of alumina slurry. Summarizing these results, we concluded that a guide line should be established based on the results of in situ microscopic properties, such as particle size distribution and the number and nature of the hydroxyl groups on the particle surface.