Fine Al-rich spinel MgO·1.5Al2O3 powder was synthesized by hydrolysis of mixed alkoxides. High sinterability of powder allowed to obtain relative density higher than 95% at temperature as low as 1300 °C by pressureless sintering in air. Samples sintered at temperature of 1100-1500 °C had quite heterogeneous microstructure owing to precipitation of large corundum particles (<1400 °C) and discontinuous grain growth of spinel matrix (>1400 °C). However, homogeneous microstructure with fine grains could be obtained by a two step sintering process in which spinel grain growth at high temperature was inhibited by corundum particles momentarily retained above solvus temperature. Precipitation behavior during sintering was compared with that during annealing, and the precipitation mechanism was discussed.
Microstructure development during sintering in polycrystalline MgO.1.5Al2O3 spinel
PROVERBIO, Edoardo;
1993-01-01
Abstract
Fine Al-rich spinel MgO·1.5Al2O3 powder was synthesized by hydrolysis of mixed alkoxides. High sinterability of powder allowed to obtain relative density higher than 95% at temperature as low as 1300 °C by pressureless sintering in air. Samples sintered at temperature of 1100-1500 °C had quite heterogeneous microstructure owing to precipitation of large corundum particles (<1400 °C) and discontinuous grain growth of spinel matrix (>1400 °C). However, homogeneous microstructure with fine grains could be obtained by a two step sintering process in which spinel grain growth at high temperature was inhibited by corundum particles momentarily retained above solvus temperature. Precipitation behavior during sintering was compared with that during annealing, and the precipitation mechanism was discussed.Pubblicazioni consigliate
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