Tungsten carbide

Tungsten Carbide is a compound of tungsten and carbon. Black hexagonal, with a metallic luster, hardness close to diamond, electricity, good heat conductor. Tungsten is insoluble in water, hydrochloric acid and sulfuric acid, nitric acid soluble - a mixed acid of hydrofluoric acid. Pure tungsten carbide is fragile, if the incorporation of a small amount of titanium, cobalt and other metals, can be reduced brittleness. Tungsten steel cutting tools used, often by adding titanium carbide, tantalum or mixtures thereof, in order to improve the anti-knock capacity. Stable chemical properties of tungsten carbide, cemented carbide is widely used in the production of the material.

Processing characteristics of tungsten

In metals, tungsten metal has the highest melting point, high temperature strength, creep resistance and thermal conductivity, good electrical conductivity and electron emission properties of Tungsten melting point,heavy, hard and brittle, difficult process, but as long as there is a reasonable process, tungsten can be made by powder metallurgy billet, extrusion, forging, rolling, spinning and drawing, and other processing timber. As the plastic processing tungsten improvement in the level of their organization, tensile strength and ductility - brittle transition temperature is greatly improved.

The features of high density tungsten alloy

Tungsten heavy alloy for counter balance with a series of excellent characteristics, than the major: general proportion of high 16.5-18.75g / cm3 ,, strength: tensile strength of 700-1000Mpa, absorb radiation and strong: its capacity 30-40% higher than lead thermal conductivity coefficient: 5-fold die steel; thermal expansion coefficient: Only iron or 1 / 2-1 / 3, good conductive properties of steel; Tungsten alloys has good weldability and formability. Given the high proportion alloy has the above excellent features, it is widely used in the aerospace, aviation, military, oil drilling, electrical instrumentation, medical and other industries.

Tungsten heavy alloy properties

Tungsten alloy Counterweight is a class of 80-98% distributed in the matrix Ni-Fe-W solid solution of two-phase composite. A combination of Tungsten high-density, high strength and good ductility matrix phase, therefore, it has a good plasticity, good-ray absorption capacity, good corrosion resistance and high temperature oxidation resistance, good machining properties, good electrical conductivity, thermal conductivity and low thermal expansion coefficient, good weldability and surface electroplating, and a series of excellent physical, chemical and mechanical properties.

Tungsten heavy alloy

Tungsten heavy alloy (referred WHA) products are usually made WNiFe or WNiCu or WNiCuFe manufactured by powder metallurgy production process. Depending on the product use and working environment requirements, High density Tungsten alloy products are usually distributed tungsten content of 79% W ~ 97% W, a density in the range of 15.00g / cm ~ 18.50g / cm. While adding some rare elements (Co, Mo, Cr, etc.) in order to improve the performance of the product portion, such as: hardness, ultimate tensile strength, yield strength, elongation and the like.

Defined of tungsten alloy

Tungsten alloy is tungsten-based alloys by adding other elements. In metals, the highest, high temperature strength and creep resistance and thermal conductivity, electrical conductivity and electron emission properties of tungsten melting point are good, than the major, in addition to a large number of alloys used in the manufacture of carbide and as additives, tungsten and Tungsten alloys are widely used electronic, electric light industry, but also aerospace, casting, weaponry and other sectors for the production of rocket nozzles, casting molds,penetrator, contacts, heating element and a heat shield and so on.

What should be noted tungsten material

Tungsten alloy metals in the interstitial impurities, microstructure and alloying elements, as well as plastic processing and surface condition of the tungsten material plastic - brittle transition temperature has a significant impact. In addition to rhenium tungsten material can significantly reduce plastic - brittle transition temperature, the other alloying elements on the lower ductility - brittle transition temperatures with little success. Poor oxidation resistance of tungsten oxide and molybdenum similar characteristics, will take place at more than 1000 ℃ tungsten trioxide volatile, have a "disastrous" oxidation. Must be protected in a vacuum or under an inert atmosphere, if used in high temperature oxidizing atmosphere, you must add a protective coating high temperature Tungsten alloys material.

Improve ways to enhance tungsten materials

Tungsten alloy materials use of high temperature materials, simple method to increase the use of solid-solution strengthening effect is not high temperature strength of tungsten. However, on the basis of solid-solution strengthening further dispersion (or precipitation) hardening, can greatly improve the high temperature strength to ThO2 and precipitation particle dispersion strengthening effect HfC best. In about 1900 ℃ W-Hf-C series and W-ThO2 alloys have high temperature strength and creep strength. In the recrystallization temperature of Tungsten alloys used below, take temperature hardening methods to produce strain hardening is an effective way of strengthening. Such as fine tungsten wire with high tensile strength, total processing deformation rate of 99.999%, a fine tungsten wire having a diameter of 0.015 mm, tensile strength at room temperature up to 438 kg / mm.

Research and development of tungsten products

Tungsten was first used to produce incandescent filament, not pendulous tungsten filament and cathode materials are excellent extensive use. In order to make Tungsten alloy materials is used as high-temperature components used in the aerospace industry. Tungsten smelting and processing forming technology also carried out the research, the use of consumable arc and electron beam melting tungsten ingot obtained and made by extrusion and plastic processing certain products; but the melting of the ingot coarse grains, plastic poor , processing difficulties, finished product rate, thus melting - plastic processing failed to become a major means of production. In addition to chemical vapor deposition (CVD method) and plasma spraying can produce very few products, powder metallurgy is still the primary means of manufacturing tungsten metals products.

Tungsten and molybdenum alloy

Consisting of tungsten and molybdenum alloys. Commonly used tungsten and molybdenum alloy of tungsten content of 30% to 50% (by mass). Preparation method of tungsten and molybdenum and molybdenum metals alloy having the same material is, after sintering powder metallurgy processing and smelting and processing of two ways, can be prepared from rods, plates, wires or other profiles. Tungsten and molybdenum alloy containing tungsten 30% (by mass) has excellent resistance to the corrosive effect of liquid zinc, zinc industry for the manufacture of a stirrer, a pipe and container linings and other components. Tungsten and molybdenum alloy due to high temperature strength, performance and tungsten similar but smaller than the proportion of Tungsten alloy materials, so can be used under high temperature conditions corresponding rockets, missiles in the high temperature components, tube filament, parts and other high-temperature materials.