Phase formation upon heat treatment of chemically deposited mixtures for alumo-and chrome-magnesium spinels

A comparative study of the processes of phase formation of aluminum and chromo-magnesium spinels obtained from chemically precipitated mixtures has been carried out. It is shown that a significant difference in the formation of these spinels during heat treatment is due to the interaction of MgO and Al ₂ O ₃ during deposition, leading to the formation of crystalline hydrate Mg ₅ Al ₄ O ₁₁ & times; 15Н ₂ O. The formation of chromium-magnesium spinel is much slower and requires higher temperatures. It has been found that the fine chemical synthesis of MgOx; Al ₂ O ₃ and MgOx; Cr ₂ O ₃ contributes to a decrease in the temperature of completion of their formation by 400 - 500 and 150 - 200 ° C, respectively, in comparison with traditional solid-phase synthesis. Il. 2, bibliography: 16 titles.