Tungsten metal

Tungsten metal wire is a kind of filament material made of tungsten metal, with extremely high melting point, high resistance, and can be stable at high temperature to emit light and heat, which is widely used in lighting, electronics, high temperature equipment and other fields.

Characteristics

High melting point: The melting point of tungsten metal is as high as about 3410℃, which is the higher melting point of all pure metals, which makes tungsten metal wire can still remain solid and not easy to melt under high temperature environment, and it is suitable for high-temperature working scenarios, such as high-temperature lighting equipments such as incandescent filament and the heating materials of some high-temperature furnaces.

Hardness: The high hardness of tungsten metal wire makes it have better resistance to deformation, but at the same time, it also leads to its brittleness, which makes it easy to break when it is subjected to shock or vibration.

High density: The density of tungsten metal is approximately 19.35 g/cm3. This relatively high density gives tungsten wire a high mass for the same volume, which needs to be taken into account in some applications where material weight is important.

Low Coefficient of Thermal Expansion: The relatively small coefficient of thermal expansion of tungsten metal wires results in relatively small dimensional changes during temperature changes, which helps to maintain the stability of tungsten metal wires during operation and reduces structural changes or damages caused by thermal expansion and contraction.

Higher resistivity: the resistivity of tungsten metal wire is 5.3×10-⁸Ω・m, and the higher resistivity enables tungsten metal wire to generate more heat when passing current, thus realising the function of luminous emission or heat generation, etc., and thus it is widely used in electric light source and electronic devices.

Higher electron escape work: The electron escape work of tungsten metal wire is relatively high, which means that the electrons on the surface of tungsten metal wire need higher energy to escape, and in some electronic devices, such as the thermionic of the electron tube, a higher voltage is needed to make the tungsten metal wire emit electrons.

High tensile strength: tungsten metal wire has high tensile strength, generally speaking, the tensile strength is 40-110 g/mg・200 mm (i.e. 40-110 g for every 200 mm length of tungsten wire), which makes tungsten metal wire able to withstand a certain tensile force without breaking, and it is suitable for occasions that need to withstand a certain mechanical stress.

Straightness: The straightness of tungsten metal wire is an important index, which is usually adjusted by mechanical or heat treatment during the production process to ensure that the tungsten wire can maintain a good straightness in the process of use.

Corrosion resistance: tungsten metal has good resistance to acid and alkali at room temperature, but it is easy to be oxidised in humid air, so the fine tungsten wires can not be stored in humid environment for too long.

Thermal radiation properties: tungsten wire absorbs almost 100% of the electromagnetic waves that are shot into the surface, and its thermal radiation is close to the blackbody radiation whose spectrum is only related to the temperature, which makes the tungsten wire able to emit thermal radiation efficiently after being heated, and it is an ideal material for heat generation and luminescence.

Applications

Electronic industry field:

Electron tube thermons: In electron tubes, tungsten wires can be used as thermons. The function of the thermon is to be heated by electric current to provide the necessary heat and electron emission conditions for the working of the electron tube. For example, in some old-fashioned radios, televisions and other electronic equipment, the electron tube is an important part, and the tungsten wire thermistor is one of the key components for the normal operation of the electron tube.

Lead material: Because tungsten wire has good conductivity and high strength, it can be used as lead material in some electronic components, connecting the various parts of electronic components to ensure the transmission of current and the normal work of the circuit.

Mechanical processing field:

High-speed cutting of alloy steel: tungsten wire can be made into fine wire or fibre for high-speed cutting of alloy steel and other hard materials. During the cutting process, the hardness and high temperature resistance of tungsten wire can effectively cut and process hard materials, improving processing efficiency and quality.

Mould processing: In mould manufacturing, tungsten wires can be used as electrodes for electric discharge machining (EDM). Through the high temperatures and pressures generated by the discharge, tungsten wire electrodes can accurately machine the desired shapes and sizes on the mould material.

Aerospace & Military:

High-temperature components: In the aerospace field, some high-temperature components require the use of high-temperature-resistant materials. Due to its high melting point and good high-temperature performance, tungsten wire can be used to manufacture high-temperature components such as combustion chambers and turbine blades of engines, which can maintain stable performance under extreme high-temperature environments.

Missile and rocket components: In the military field, tungsten wires can be used to manufacture certain key components of missiles and rockets, such as sensors and fuzes in the guidance system, etc. These components need to work in harsh environments such as high temperature, high pressure and strong vibration, and tungsten wires are able to meet these requirements.

Chemical industry field:

Catalyst carrier: tungsten wires can be used as catalyst carriers for catalysing some chemical reactions. The high surface area and good thermal stability of tungsten wires enable them to effectively carry catalysts, improve the activity and stability of catalysts, and promote chemical reactions.

Corrosion-resistant parts: In some chemical industrial production processes, corrosion-resistant materials are needed to manufacture equipment and parts. Tungsten wire has good acid and alkali resistance, and to a certain extent, it can resist the corrosion of chemical substances, so it can be used to manufacture some corrosion-resistant parts, such as chemical pipelines and valves.

Medical field:

X-ray tube filament: In an X-ray tube, tungsten wire is used as a filament to produce X-rays. When the electric current passes through the tungsten filament, the tungsten filament heats up and emits electrons, which hit the anode target to produce X-rays, which have important applications in medical diagnosis and treatment, such as X-rays, CT scans and so on.

Medical Device Components: Due to its biocompatibility, tungsten wire is also used in some medical devices, such as components used in the manufacture of certain minimally invasive surgical instruments, such as tweezers, scissors, and so on.