Production of Zirconia Microspheres Using a Newly Developed Semi-Continuous System of Agglomeration in Liquid.

Abstract

The production of zirconia microspheres in a newly developed semi-continuous system of agglomeration in liquid was investigated. Semi-continuous agglomeration experiments were carried out using zirconia powder containing 2.6 mol% of Y2O3 (surface area=6.76m2/g, mean particle diameter=0.45μm), a paraffin type organic liquid as suspending media and four levels of bridging liquid additions, i. e. 0.095, 0.105, 0.115 and 0.125ml/g. Several runs were performed for each bridging liquid dosage. A decrease in the amount of bridging liquid prolongs agglomeration time and decreases the diameter of agglomerates. The sintered agglomerates produced by using different dosages of bridging liquid have sphericity, i. e. the ratio of the maximum length and breath diameter, ‹1.14, density› 5.93g/cm3, mean diameter of 282-701μm and narrow size distribution. The agglomeration time and properties of agglomerates obtained from several runs of the semi-continuous agglomerator exhibited good reproducibility. However, the semi-continuous agglomerator can be sensitive to even minor changes in bridging liquid dosage which affect the agglomeration time and the properties of agglomerates. Consequently, there is a great need to develop a reliable instrumentation method for on-line monitoring of the agglomeration process. Cognizant to this need, the possibility of using power consumption, temperature, pressure, laser attenuation and noise relative energy for on-line monitoring was investigated. It was concluded that on-line monitoring of the agglomerate growth during the process of agglomeration in liquid was possible by measuring the laser attenuation and noise relative energy.