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

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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.