Thermal Expansion of Al2O3, BeO, MgO, B4C, SiC, and TiC Above 1000oC.

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Thermal-expansion data on Al2O3, BeO, MgO, B4C, SiC, and TiC were obtained to the temperatures where permanent deformation begins, due to sintering or other causes. The thermal expansion for these materials was found to be approximately linear over the measured temperature range. But as a linear extrapolation to room temperature was not possible, the coefficient of thermal expansion is not a constant over this temperature range. The results are compared with the latest published data for each material. The average coefficients of linear thermal expansion are given as follows: All BeO specimens which were heated to above 2050°C. had a very large expansion. Visual examination of the cooled specimens revealed that they had bent and cracked, the physical dimensions had enlarged, and the color had changed to a bright milky white. A brief discussion of the probable reasons for these changes is given. In the attempt to extend the expansion measurements, the melting point of BeO was obtained. A specimen of hot-pressed BeO melted at 2450°± 30°C., whereas a slip-cast BeO specimen melted at 2470°± 20° C.