Tungsten, as a metal element, the color of tungsten is steel gray or silver-white, with high hardness, high melting point and room temperature from air erosion. The main purpose is to manufacture filament and high-speed cutting alloy steel, super-hard molds, but also for optical instruments, chemical apparatus, and tungsten.
Tungsten is rare and with high melting point metal, belonging to the family of VIB of the periodic table of the sixth cycle (second cycle). Tungsten is a silver-white metal which has the similar appearance with steel. Tungsten is of high melting point, low vapor pressure and the evaporation rate is also quite small. The chemical properties of tungsten are very stable at room temperature without reaction with air and water, any concentration of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid tungsten does not work unless under the condition of heat, when the temperature rose to 80℃-100℃, the above-mentioned acid addition to hydrofluoric acid, other acids of tungsten weak role. Room temperature, the tungsten can be quickly dissolved in the mixed acid of hydrofluoric acid and concentrated nitric acid, but does not work in the alkali solution.