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The Solubility Limit of CaO in α-Alumina at 1600°C


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The solubility limit of Ca in 99.99% pure α-Al2O3 (alumina) was measured using a wavelength dispersive spectrometer mounted on a scanning electron microscope. Al2O3 samples were equilibrated at a concentration which ensured saturation of the Al2O3 grains with Ca, and were quenched in water from 1600°C. The results were compared with those from samples which were furnace cooled from 1600°C. For the quenched samples, the Ca solubility limit was found to be 51 ± 1 ppm, which is significantly larger than the solubility limit for samples which were furnace cooled (26 ± 1 ppm).