Tungsten powders are used as consumables in industries such as 3D printing of tungsten and tungsten alloys, porous materials, and highly dense powder coating. This paper focuses on the preparation, applications, and prospects of tungsten powders.
Preparation of Spherical Tungsten Powder
With the rapid development of 3D printing technology, porous materials, highly dense powder coating, and injection molding, the demand for high-quality spherical tungsten powders is increasing.
High-quality spherical tungsten powder is not only good flowability, good sphericity, high apparent density and vibrational density, and low oxygen content.
The high price of high-quality spherical tungsten powders on the market has hindered the further development of 3D printing technology for tungsten products with complex structures. The advent of plasma spheroidisation of tungsten powders has alleviated this phenomenon.
Plasma, with its high temperature, high enthalpy, and high chemical reactivity, meets the demand for a heat source for tungsten powder spheroidisation in the tungsten powder spheroidisation process. Plasma spheroidisation technology involves the spraying of irregularly shaped particles by a carrier gas through a charging gun into a plasma arc. Under the action of heat transfer mechanisms such as radiation, convection, and conduction, the powder is rapidly heated to whole or partial melting, and the molten particles rapidly solidify and shrink under surface tension to form a dense spherical powder. The advantages of plasma spheroidised tungsten powder are the high concentration of energy, the large temperature gradient, the ability to precisely control the energy input by controlling the process parameters, and the thermal energy utilization of up to 75%. After plasma spheroidisation, the fluidity of the tungsten is improved and the apparent density and vibrational density of the tungsten powder are increased.
The Application of Tungsten Powder
Compared to powder metallurgy, 3D printed tungsten parts not only have a wider variety of shapes but also higher overall properties such as shielding and high-temperature resistance, which makes them more versatile. 3D printed tungsten has the following main applications.
1) Manufacture of medical collimators. Compared to lead metal, tungsten alloy is more suitable for the production of collimators, not only because the alloy is environmentally friendly and non-toxic, but also because it has a strong ability to protect against radiation rays. Collimators are the component parts of the radiation head of medical accelerators, mainly used in oncological radiotherapy.
2) Manufacture of nozzles. Compared to ordinary brass or steel nozzles, tungsten alloy nozzles have better thermomechanical properties, mainly in terms of good heat resistance, good thermal conductivity, rigidity, high-temperature strength, and less susceptibility to extreme tempering.
3) Manufacture of components for x-ray scanning equipment. The high density gives tungsten alloys extremely good radiation protection, while the higher melting point and lower coefficient of volume expansion also give them a greater range of applications for use in high-temperature environments.
4) Manufacture of screws. With its high specific gravity, low-temperature resistance, and corrosion resistance, tungsten screws are widely used in counterweight parts for golf heads, parts for revival trainsets, and aerospace equipment.
5) Manufacture of heat insulation screens. It is suitable for application in vacuum resistance furnaces because of its good heat insulation effect, good corrosion resistance, strong ability to absorb radiation lines, excellent high-temperature resistance, and strong oxidation resistance.
(6) Manufacture of tungsten anti-scattering grids. 3D printed tungsten anti-scattering grids are suitable for use in CT scanners, an important weapon in the fight against new coronaviruses, due to their high-temperature resistance, wear-resistance and strong radiation resistance.
In addition to the tungsten parts mentioned above, 3D printing technology can also be used to produce products such as tungsten pins, contacts, die-casting molds, and heat generators.
The Prospects of Spherical Tungsten Powder in 3D Printing
As the most important consumable for 3D printed tungsten products, spherical tungsten powder has It has replaced conventional tungsten powder with its unique advantages. The preparation of spherical powder by halogenation and tungsten powder reoxidation reduction methods has various drawbacks such as low spheronization rate, low yield, and waste liquid disposal. The microwave single cavity method of spheroidizing tungsten powder has a low spheroidization rate, a low yield, and the need to dispose of the waste solution. The microwave single cavity method of spheroidizing tungsten powder has an insufficient heat source, and the performance of the tungsten powder produced is unstable and the consistency is poor.
At present, the spherical tungsten powder prepared in China still suffers from a wide particle size distribution, low yield, poor uniformity, and a high degree of stability. The research and development of spherical tungsten powder are still in the development stage. The research and development of spherical tungsten powder is still in the development stage, and the preparation process, technology, and procedure still need to be further studied.
The research and development of spherical tungsten powder are still in the development stage, and the preparation process, technology, and procedure still need to be further studied. The plasma spheroidization technology is characterized by high energy consumption, gas consumption high energy consumption, gas consumption, large investment in equipment, high operating costs, immature technology development, and other problems. However, the high energy of the plasma and the controllable reaction atmosphere allows for the preparation of other The plasma spheroidisation technique has problems of energy consumption, equipment investment, high operating costs, and mature technology development. The spherical tungsten powder produced by the plasma has a high sphericality. The prepared spherical tungsten powder has good sphericity, uniform particle size distribution, high densities and good fluidity. The whole preparation process is fast and continuous. Therefore, plasma spheroidization will be an alternative for the preparation of spherical tungsten powder. Therefore, plasma spheroidization is an alternative for the preparation of spherical tungsten powder. In combination with numerical simulations, the process parameters can be optimized quickly by combining numerical simulations. With the continuous improvement of plasma spheroidisation technology, the reduction of production costs, and the rapid optimization of the process parameters, plasma spheroidisation can be used to produce tungsten powder.
With the continuous improvement of plasma spheronization technology, the reduction of production cost, and the increase of powder yield, plasma spheronization technology will play an important role in the production of tungsten powder. The plasma spheroidisation technology will have a bright future in the industrial production of tungsten powder periodization.