Processing and study of different properties of
alumina product prepared by Slip Casting

Abstract

In present work, alumina articles with different dopant percentage were prepared to study their various mechanical and high temperature properties. Before casting, alumina with different particles size gradation were obtained or prepared by planetary milling by varying the time of milling. The primary dopant used here is Nano-magnesia prepared by the precipitation method. An Ammonium Polymethacrylate solution was used as dispersant which has reduced likeliness to foam and produces slurries of abysmally low viscosities. The stability of the slip which clearly depends on the percentage of dispersant added, which was determined by the Zeta Potential data. Gypsum moulds were used for the casting process in which the both solid casting and drain casting was carried out to prepare bodies of different shapes and size. The casting was done as per the conventional methods and fired at 1650oC for 4 hours. Thereafter different properties such as Apparent Porosity, Bulk Density, Linear Shrinkage, Permanent Linear Change upon Reheating and Cold Modulus of Rupture were studied.Surface area of the milled sample scaled to 4.8m2/gram. Density of up to 90% theoretical density and porosity with up to <1% porosity was achieved through this process. The CMOR values that were obtained had a highest value of about 181.9MPa. The PLCR values, in percentage, were found to lie within 0.3% whose acceptance limit is below 0.5%.