| 摘要 |
PURPOSE:To easily produce the high-purity silicon carbide powder from inexpensive silicon carbide by crushing the silicon carbide, recrystallizing the crushed material by heating and removing the remaining impurities by pickling. CONSTITUTION:The inexpensive silicon carbide contg. impurities is precrushed into the powder having <=100mu average grain diameter, and the powder is heated at 1500-2200 deg.C in a nonoxidizing atmosphere. Consequently, the powder is recrystallized, and the metallic impurities such as iron, Ca and Cr other than Si are moved to the surface from between the crystals in the powder. The heat-treated powder is cleaned with an inorg. acid such as hydrochloric acid, nitric acid, hydrofluoric acid and a mixture of hydrochloric acid and nitric acid to remove the impurities such as iron, Ca and Cr other than Si. By this method, the high-purity silicon carbide powder is easily and inexpensively obtained, and the powder is effectively utilized as the material for a liner tube in a diffusion furnace for producing semiconductors. |
