Initial Sintering of Alumina and Hematite

Experimental measurements of the rate of shrinkage of pressed Al₂O₃ compacts, the neck growth between single-crystal Al₂O₃ spheres and plates, and the effect of particle size on neck growth between single-crystal Al₂O₃ spheres and plates are mutually consistent with the bulk diffusion sintering model. Tbe temperature dependence of the rate of shrinkage and neck growth in Al₂O₃ is characterized by an activation energy of 165 kcal. per mole. Apparent diffusion coefficients and temperature dependence calculated from the shrinkage of pressed compacts of Fe₂O₃ agree with measured diffusion coefficients for the diffusion of Fe in Fe₂O₃.