What is Tungsten Powder?

What is tungsten powder?
Tungsten powder refers to the metal tungsten in powder form, which is the raw material for preparing tungsten processing materials, tungsten alloys and tungsten products.
 
Tungsten is a metallic gray black metal (BCC crystal). Melting point 3400 ℃. Boiling point 5555 ℃. The hardness of tungsten is the hardest in metal. The hardness of sintered tungsten bar is 200-250, and that of rotary hammer is 350-400. Tungsten is soluble in a mixture of nitric acid and hydrofluoric acid. Melting with a mixture of sodium hydroxide and sodium carbonate. Slightly soluble in nitric acid, sulfuric acid and aqua regia; insoluble in water, hydrofluoric acid and potassium hydroxide. There are two variants of tungsten, a and B. At standard temperature and atmospheric pressure, type A is a stable bcc structure. Type B tungsten can only appear in the presence of oxygen. It is stable below 630 ℃ and converted to tungsten a above 630 ℃, and this process is irreversible.
 
Grade and standard of tungsten powder
In addition to the requirement of impurity content, the oxygen content of tungsten powder should be controlled within a certain range. In general, the particle size of tungsten powder in common use is 2-10 μ m, which is polygonal. In addition, the specific surface, bulk density and rolling density of tungsten powder also change in a certain range. The properties of tungsten powder have a direct impact on the production of tungsten materials and the quality of tungsten powder metallurgy products, especially on the purity and particle size.
 
The earliest production of tungsten powder is classified into three grades according to chemical purity; Japan has formulated the industrial standard of tungsten powder and tungsten carbide powder (jish2116-1979); Britain, France, the former Soviet Union and other countries have unified national standards for tungsten powder. The technical conditions for hydrogen reduction of tungsten powder (gb3458-82) was formulated in 1982. The standard specifies the performance and classification brand of tungsten powder, as well as the inspection method, acceptance rules, packaging, transportation, storage and other items. For tungsten powder for special use and military industry, the manufacturer can trial produce according to the user's requirements.
 
Tungsten powder uses
Tungsten powder is the main raw material for processing P / M tungsten products and tungsten alloys. Pure tungsten powder can be made into tungsten wire, rod, tube, plate and other processing materials and certain shape products. Tungsten powder can be mixed with other metal powder to make various tungsten alloys, such as tungsten molybdenum alloy, tungsten rhenium alloy, tungsten copper alloy and high density tungsten alloy. Another important application of tungsten powder is to make tungsten carbide powder, and then to prepare cemented carbide tools, such as turning tools, milling cutters, drills and dies.