Abstract
AbstractThe discontinuous dissolution of oxide particles has been investigated in the Al2O3 -Fe2O3 system by changing oxygen partial pressure (PO2) and temperature. In PO2 change experiment, 95Al2O3-5Fe2O3 (in wt%) powder compacts were sintered at 1500°C in PO2=0.001 atm and then annealed at 1500°C in air. In temperature change experiment, 85Al2O3-15Fe2O3 (in wt%) powder compacts were sintered at 1600°C in air and then annealed at 1450°C in air. During annealing the sintered specimens, which contained corundum grains and iron aluminate spinel particles, the grain boundaries migrated concomitantly with the dissolution of spinel particles. A discontinuous dissolution of spinel precipitates thus occurred, when the grain boundary migration of alumina in a two phase mixture of corundum and spinel was induced by PO2 or temperature change. The present result would be a distinct observation of the discontinuous dissolution of precipitates in ceramic systems.
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