Views: 8 Author: Site Editor Publish Time: 2022-09-20 Origin: Site
Like tungsten plate, tungsten rod and tungsten wire, tungsten foil is also a typical tungsten product. It is a thin sheet of metal tungsten (W). The purity is generally greater than 99.9% and the thickness is 0.05~0.3mm. The width is 100~400mm, and the length is 400~1500mm. The surface state includes alkali pickling surface, annealing state and polished surface. With its excellent thermal, mechanical, chemical and electrical properties, it is widely used in many fields.
In terms of physical and chemical properties, tungsten foil is a silver-gray metal flake 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, low vapor pressure, small evaporation rate, and low plasticity. 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 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 tungsten foil is cut and formed by a shearing machine.
In terms of usage, tungsten 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, the tungsten foil can also be stamped into a tungsten boat, which can be applied to vacuum-coated utensils.