Because of high melting point of tungsten 3410 degrees, high boiling point, high strength, good wear resistance and corrosion resistance, large heat conduction rate, low coefficient of thermal expansion and good quenching, so the tungsten crucible is widely used in sapphire single crystal growth furnace, rare earth smelting furnaces and other industrial furnace core container, in fact, the working temperature environment is generally above 2000 degrees. Especially for sapphire single crystal growth furnace, the tungsten crucible with high purity, high density, no crack, precise size, smooth inside and outside wall played a key role to seed success rate, crystal quality control, off crystal adhesive of sapphire crystal growth process.

The crucible is a kind of vessel or melting pot that is made of refractory materials such as clay, graphite, kaolin, quartz or difficult to melt the metal iron, etc. The crucible is a bowl shaped container with a deep bottom of the ceramic. When the solid is heated by fire, it is necessary to use the crucible. Because it can withstand high temperatures compared with the glass. When the crucible is used, the crucible cover is usually placed on the crucible to prevent heated object from jumping out, and the air can freely and easily carry out the possible oxidation reaction. Because of its bottom of crucible is very small, it generally need to stand in the mud triangle to directly heat by fire. After being heated of tungsten crucible, it shall not be placed on the cold metal surface immediately to avoid cracking due to sharp cooling.