EFFECT OF ADDITIVES ON THE PROPERTIES OF Al_2O_3-GRAPHITE MATERIAL HEAT-TREATED IN NITROGEN ATMOSPHERE

摘要

Al_2O_3-graphite material was heat-treated in nitrogen atmosphere. The effect of different additives on phase composition, microstructure, and properties of Al_2O_3-graphite was investigated carefully. Compared with Al_2O_3-graphite with addition of silicon or aluminum, which was heat-treated in carbon bed, it was found that Al_2O_3-graphite material with the same composition but heat-treated in nitrogen atmosphere possessed relatively good properties. Moreover, the addition of silicon or aluminum could improve the bending strength both at room temperature and at 1400□, oxidation resistance, and thermal expansion coefficient. In addition, the thermal expansion coefficient of Al_2O_3-graphite with aluminum addition was lower than that of the one with silicon addition. Furthermore, the addition of proper amount of aluminum could result in high hot MOR, relatively good thermal shock resistance. The reason was also analyzed based on the phase composition and microstructure.