Effect of Mechanochemical Activation on the Powder Dispersity of an Aluminum–Magnesium Spinel and Obtaining Dense Nanoceramics

Resumo

Crystalline hydrate of Al(NO₃)₃ · Mg(NO₃)₂ · nH₂O salts is obtained by the method of the joint crystallization of the solutions of nitric acid salts of aluminum and magnesium that are taken in the required ratio for the synthesis of an (MgAl₂O₄) aluminum–magnesium spinel, which was subjected to thermal decomposition at a temperature of 500°C to form a MgAl₂O₄ compound. The effect of the mechanochemical activation (MA) on the dispersity of the MgAl₂O₄ powder is studied. The optimal regimes of activation and sintering of the synthesized MgAl₂O₄ powder for forming dense single-phase ceramics are selected. Mechanical activation makes it possible to obtain ceramics with an open porosity of ~2% and a grain size of 60 to 65 nm at 1400°C, which is lower than the temperature of the solid-phase synthesis of the aluminum–magnesium spinel (1700–1750°C). The physicochemical properties of the sintered ceramic samples of MgAl₂O₄ are determined.