Preparation of aluminum oxy-nitride (AlON) through investigating the rheological behavior and gel-casting parameters of alumina/aluminum nitride

Abstract

In this research, the mixture of alumina powders and nanoparticle of aluminum nitride was used with the alumina stoichiometric ratio in order to characterize the gel casting parameters. The milling method and three-dimensional mixer were used for agglomeration and slurry, respectively. The surface of the powders was modified by phosphoric acid to prevent the hydrolysis of aluminum nitride in water. The results of analysis such as the pH test, FT-IR, XRD and FE-SEM reveal that the effect of phosphoric acid was activated after 17 h. The characterization of rheological properties was performed by the optimization of slurry parameters with a rotary viscometer. Dolapic CE-64 was used as a dispersant to disperse slurry. Acrylamide and methacrylamide, methylene bisacrylamide, ammonium sulfate and tetraethyl ethylene di-amine were used as the monomer, transverse coupler, initiators, and catalysts, respectively. In order to determine the optimal density of samples and achieve the aluminum oxy-nitride phase (AlON), the sintering of the samples was carried out by the sintering method without pressure. The highest relative density of the crude body (55%) and sintered body (96%) was obtained for a sample containing 75% by weight of solids and 5% by weight of monomer with a ratio of 3:1. The differential thermal analysis of the crude body shows that the existing monomers were removed from the body at a temperature of 250–450 °C. The porosity test showed that the appropriate time for the de-agglomeration of the slurry is 5 h.