Tungsten is a kind of the most difficult melting and volatile metal.Its melting point reaches 3380 degress. Its further processing products like tungsten wire, tungsten rod, tungsten electrode, twisted tungsten wire, tungsten heaters, tungsten crucible, tungsten boat,tungsten sheet, tungsten plate,etc. is widely used in lighting industry, vacuum industry, rare earth metal smelting industry, and sapphire crystal growing furnace, etc.