Effects of deflocculants, Binders and mold types on optical property of alumina ceramic prepared by slip casting

Abstract

Fabrication of alumina green body with high density and low impurity is one of the most important processes to produce transparent alumina ceramic. Using of submicron particles as raw materials and appropriated sintering processes will give rise to such transparent alumina specimens. Once green body of alumina with low porosity and low impurities could be prepared, good optical properties would be obtained. With advantages of slip casting technique, it provides not only homogeneous specimen but also lower operating cost compared with other technique. From experimental results, alumina green body with density higher than 60% can be prepared from alumina suspension with solid content of 75% and deflocculant concentration of 0.05%. In addition, adding binder of 0.05% could increase physical strength of the prepared green body without negative effect on density of the specimens. However, disadvantage of this technique is contamination of gypsum mold, which could be eliminated by using acid treatment before sintering. It is found that acid treatment was not only efficiently eliminated gypsum contamination, but also provided specimens with high density at lower sintering temperature. The prepared specimen exhibited the uniformity grain size after sintering, which is beneficial to optical property of the specimens.