METHOD FOR RECEIVING RAW MATERIAL OF ALUMINA FOR LEUCOSAPPHIRE MONOCRYSTAL GROWTH

摘要

The method for receiving raw material for leucosapphire monocrystal growth includes melting of alumina mixture with 0.4-0.6 wt. % of carbon in the form of fine graphitic power, receiving a melting operation product in the skull and its following breakage. The received broken aluminous material is filled up previously before growth into the melting pot with a fuse put inside, the melting pot is disposed into the furnace chamber with graphite refractory facing and heating elements placed underneath. The atmosphere is vacuum-pumped to the pressure of 0.1-0.2 mm hg, the material is heated to premelting temperature for 20-24 hours. Then the argon is put on to the pressure 800-850 mm hg increasing the heating temperature to 2100-2200 DEGREE C for 1-2 hours, liquid melt is aged for 2-3 hours and after cooling the melting pot with raw cake is taken out. The method provides the decreasing of the impurities content in the received raw material.