Tungsten foil is a kind of thin tungsten sheet with thinner thickness of 0.05mm to 0.3mm and more narrow width of 50mm to 400mm. With more than 99.95% purity, it owns excellent thermal, mechanical, chemical and electrical properties, and is widely used in many fields.
Regarding its physical and chemical properties, it is a silver-gray metal sheet with metallic luster, with a melting point of about 3410 °C, a boiling point of about 5660 °C, a relative density of 19.35g/cm3, and characteristics of low vapor pressure, small evaporation rate, low plastic-brittle transition temperature, low resistivity, good chemical stability, creep resistance, heat resistance and toughness.
Under normal temperature and pressure, it will not react with air, water, concentrated hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid and aqua regia, but will dissolve in the mixed acid of hydrofluoric acid and concentrated nitric acid. In addition, under heating conditions, it will weakly react with mineral acids (excluding hydrofluoric acid) such as concentrated hydrochloric acid, sulfuric acid, and nitric acid.
From the perspective of production method, tungsten metal foil is first purified by recrystallization method of ammonium paratungstate, and heated in a porcelain crucible. After the ammonia volatilizes, tungsten oxide can be obtained, and then the tungsten oxide is reduced with hydrogen to prepare tungsten powder, and then the tungsten powder is processed, etc. The tungsten slab is prepared by static pressing and sintering at high temperature. Finally, the tungsten slab is rolled by a rolling mill, and then the foil is cut and formed by a shearing machine.
In terms of usage, the foil can be used to manufacture electric light source parts, electric vacuum devices, medical shielding parts, current collectors for aluminum ion batteries, heating elements and heat shields for electric vacuum furnaces/high temperature furnaces. In addition, it can also be stamped into a tungsten boat, which can be applied to vacuum-coated utensils.
Meanwhile, in addition to molybdenum foils, tantalum foils, nickel foils and titanium foils that can be used as current collectors for batteries, tungsten foils can also be used. Studies have shown that tungsten foil has stable electrochemical performance in the voltage window range of 0-2.5v.
