Sintering Behavior and Pore Structure Development of Kaolin-Alumina Ceramics

Abstract

Sintering behavior and pore structure of 60 mass% kaolin-40 mass% Al₂O₃ ceramics have been studied. Linear shrinkage of the heated sample occurs during the dehydration and transformation of kaolin, sintering process and mullite formation. The sintered sample shows a normal pore size distribution in which the average pore diameter increases from 0.6 to 1.5 μm with the sintering temperature increasing from 1373 to 1873 K for 1 h. Apparent density is about 2.97∼3.07 g cm^-3 and reveals an opposite trend to open porosity. Open porosity decreases from 48.5 to 37.2% when the sintering temperature increases from 1373 to 1673 K; but it increases to 39.6% as sintered at 1773 K. Both of the linear shrinkage and open porosity reveal a decrease trend as sintered at 1473 K for duration from 1 to 7 h; however, they show an increase tendency as sintered at 1723 K.