2012年5月10日星期四

Tungsten is considered to be of low toxicity


Harmful effects:
Tungsten is considered to be of low toxicity.

Characteristics:
Tungsten is a very hard, dense, silvery-white, lustrous metal that tarnishes in air, forming a protective oxide coating. In powder form tungsten is gray in color.

The metal has the highest melting point of all metals, and at temperatures over 1650 oC also has the highest tensile strength. Pure tungsten is ductile, and tungsten wires, even of a very small diameter, have a very high tensile strength.

Tungsten is highly resistant to corrosion. It forms tungstic acid (H2WO4), or wolframic acid from the hydrated oxide (WO3) and its salts are called tungstates, or wolframates.

Tungsten is one of the five major refractory metals (metals with very high resistance to heat and wear). The other refactory metals are molybdenum, tantalum, rhenium and niobium.
Uses of Tungsten

Tungsten and its alloys are widely used for filaments in older style (not energy saving) electric bulbs and electronic tubes. It is used for making heavy metal alloys because of its hardness. Tungsten is used for high-temperature applications such as welding.

High speed steel (which can cut material at higher speeds than carbon steel), contains up to 18% tungsten.

Tungsten carbide (WC or W2C) is extremely hard and is used to make drills. It is also used for jewelry because of its hardness and wear resistance.

没有评论:

发表评论