tungsten powder

Tungsten powder

chemical composition(%)

It is a gray-black metal (BCC crystal) with metallic luster. The melting point is 3400°C. Boiling point 5555

℃. The hardness of tungsten is the hardest among metals. The hardness of the sintered tungsten rod is 200-250, and the hardness of the tungsten rod passed through the electric hammer is 350-400. Mixed acid soluble in nitric acid and hydrofluoric acid. Fusion with a mixture of sodium hydroxide and sodium carbonate. Slightly soluble in nitric acid, sulfuric acid, aqua regia; insoluble in water, hydrofluoric acid, potassium hydroxide. Tungsten comes in two varieties, a and b. Form A is a stable bcc structure at standard temperature and atmospheric pressure. Type B tungsten can only occur in the presence of oxygen. It is stable below 630°C, and turns into tungsten a above 630°C, and this process is irreversible.

Performance and Standards

In addition to the impurity content of tungsten powder, the oxygen content should be controlled within a certain range. The average particle size of tungsten powder is 2-10μm. Tungsten powder is polygonal. In addition, the specific surface area, bulk density and shaking density of tungsten powder also vary within a certain range. The performance of tungsten powder directly affects the production of tungsten materials and the quality of tungsten powder metallurgy products, especially the influence of purity and particle size. Tungsten powder is classified according to its purity, particle size and different uses.

The earliest produced tungsten powder was divided into three grades according to chemical purity; Japan formulated the industry standard of "tungsten powder and tungsten carbide powder" (JISH2116-1979); Britain, France and the former Soviet Union have unified national standards for tungsten powder. In 1982, the tungsten powder produced in my country formulated the "Technical Conditions for Hydrogen Reduction of Tungsten Powder" (GB3458-82). Trial-manufacture tungsten powder for special purposes and military use according to user requirements.

usage

Tungsten is mostly used in the production of cemented carbide and ferrotungsten. Tungsten, chromium, molybdenum and cobalt form heat-resistant and wear-resistant alloys used in the manufacture of cutting tools, metal surface hardening materials, gas turbine blades and combustion tubes, etc. Tungsten and tantalum, niobium, molybdenum and other refractory alloys. Tungsten copper and tungsten silver alloys are used as electrical contact materials. High-density tungsten-nickel-copper alloy is used as radiation shielding. Tungsten wires, rods, plates, etc. are used to make parts of light bulbs and tubes and electrodes for arc welding. Tungsten powder can be sintered into filters of various porosities. FW-1 is used as raw material for large slabs and W-Re couples. Fw-2 is used for contact alloys and shielding materials with high specific gravity. Fwp-1 is used for plasma spraying materials.

Tungsten powder is the main raw material for processing powder metallurgy tungsten products and tungsten alloys. Pure tungsten powder can be made into wire, rod, tube, plate and other processing materials and products of certain shapes. Tungsten powder can be mixed with other metal powders 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 the preparation of tungsten carbide powder, and then the preparation of cemented carbide tools, such as turning tools, milling cutters, drills and molds.

grade

According to particle size, tungsten powder can be divided into 14 grades