www.fotamcarbide.com provide 99.95% Pure Tungsten Products Tungsten Crucibles W Crucible for Sapphire Growing Because of the high melting point(3410â??) of tungsten, tungsten crucible is widely used in the industrial furnaces such as sapphire single crystal growth furnace, quartz glass melting furnace, rare earth smelting furnace and other industrial furnaces of which the working temperature is over 2000â??. Especially for sapphire single crystal growth furnace, tungsten crucible with features of high purity, high density, no crack, precise size, smoothy internal and external wall is the key note to seed success rate, crystal quality control, off crystal stick pan and service life in sapphire crystal growth process. During sapphire production, Al2O3 - the compound that is to become the future single crystal - is melted in tungsten crucibles. It is in the Kyropoulos process that our crucibles show their strengths to best effect. They arerepeatedly heated to more than 2 000 �°C (3632 �°F) and then cooled down again. This process, which would cause fissures and distortions in other materials, is not a problem for our products.