Ceramics-Silikáty 16, (4) 267 - 272 (1972)

The rate of dissolution was measured and the diffusion coefficient computed for dissolution of ruby monocrystal and of three different types of polycrystalline materials translucent and opaque corundum, and Oxal 995 material) at 1400 and 1500 °C respectively. Within this temperature interval the rate of dissolution ranges from 2.08 to 3.47 x 10^-1 cm/s, the diffusion coefficient from 1.92 to 3.88 x 10^-8 cm²/s. The mutual replaceability of the materials is restricted by the temperature limits involved in the formation of a swelling layer of the polycrystalline material at the area of contact with the liquid phase. The value of this limit (1429 °C for Oxal, 1500 °C for opaque corundum) depends on the type of polycrystalline material, its porosity and impurities in the basic corundum matter.