2021年4月25日星期日

Ammonium Paratungstate

Ammonium Paratungstate(APT) is an important raw material product in tungsten smelting process, the appearance is white crystalline.

It is mainly used for the reduction of tungsten oxide or ammonium metatungstate, and also used as catalysts or additives in chemical industry.


The tungsten concentrate is screened and pressed, ammonium tungstate solution was prepared by ion exchange or extraction process, after the crystallization process, ammonium paratungstate was obtained.

In the process of smelting, ammonium paratungstate solution (Na2WO4) was obtained from tungsten concentrate by ion exchange or extraction, in order to truly use ammonium paratungstate, an important process is needed: crystallization process.

The crystallization process of ammonium paratungstate is one of the important processes in the tungsten smelting process, the crystallization methods of APT in industry mainly include evaporation crystallization method, neutralization crystallization method and freezing crystallization method. Evaporation crystallization is the most widely used method in China. The process and equipment are simple and easy to be large-scale. At the same time, it has the function of purification of tungsten, and the efficiency is the best.

Ammonium paratungstate is one of the main products of tungsten export in China. However, the added value of raw materials such as ammonium paratungstate is low, it has low profit, therefore, the export amount of ammonium paratungstate is also decreasing year by year in China.

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Nanometer Tungsten Sulfide Will Treat Cancer Cells In The Future

Photothermal therapy utilizes with high light heat conversion efficiency, inject it into the human body, target recognition technique is used to aggregate near the tumor tissue.

The method of converting light energy into heat energy to kill cancer cells under the irradiation of external light source is a kind of cancer treatment method with great expectation by human beings.

In the process of photothermal therapy, the selection of photothermal agents is a key link. These therapeutic agents can effectively convert laser energy into heat energy, thus enhancing the heating efficiency of laser. In order to achieve effective and selective photothermal therapy, photothermal agents must meet several conditions: It can absorb and transform laser energy effectively; A solvent that can be dissolved in a biologically friendly solvent, ensure that the treatment agent enters the tumor tissue smoothly; The surface of particles is easy to be functionalized, which is conducive to the cooperation with other methods such as targeted therapy; Low toxicity of the material itself.


Graphene has excellent biocompatibility, stability, low cytotoxicity and other advantages, the band gap of graphene is zero, the fluorescence intensity of quantum dots is weak, the quantum yield is low, and it is not a perfect photothermal agent. When graphene is abandoned, transition metal two dimensional sulfides have attracted much interest, nano tungsten sulfide (molybdenum) is a sandwich structure consisting of hexagonal metal atoms sandwiched between two layers of sulfur elements, the band gap of the two-dimensional structure is 2.0eV (1.9eV), it has better light conversion and absorption capacity, tungsten itself is an excellent X- ray absorbing material, it has a wide range of applications in the field of hospital testing imaging equipment, therefore, in the process of photothermal therapy, tungsten sulfide can be used for contrast imaging, and can be used for the treatment of operation, can achieve dynamic tracking, diagnosis and treatment integration.

Uniform size tungsten disulfide nanosheets were obtained by intercalation of lithium ions, the surface modification of poly (ethylene glycol) polymer makes it have better water solubility and biocompatibility, tungsten sulfide nanomaterials have good optical absorption properties in the near infrared region. The sulfur nanoparticles were injected into the mice through the caudal vein, and the tumor was enriched by the high permeability and retention effect (EPR effect) of the tumor. Because tungsten can absorb X- rays, it is the first time to achieve very good tumor CT imaging in animal models. At the same time, based on the near-infrared absorption property of tungsten sulfide nanomaterials, it can be used for photoacoustic imaging of tumors. Under the near-infrared laser irradiation, all the tumors were completely killed and reached the goal of complete cure.

Research shows that nano tungsten sulfide treatment agent in the future will likely be large-scale clinical application in cancer therapy, as a tool for human tumor sniper, which is mainly due to nano material not only has good absorption of tungsten sulfide and light conversion properties, but also has low toxicity, and can be modified through molecular and simple cells compatible.

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Tungsten Disulfide Lubricant

The industrial production department has put forward more and more strict requirements on the performance of lubricating oil (grease).

Ordinary equipment is often replaced by low-performance lubricants (grease) instead of high-performance products, causing equipment damage or lubricating oil (grease) consumption, therefore, it is of great significance to accelerate the research and development of high temperature lubricating oil (grease) to meet the needs of the domestic market.

Tungsten sulfide is a compound of tungsten and sulfur, and it is a new kind of solid lubricant with excellent performance, not only suitable for general lubrication conditions, but also for high temperature, high pressure, high vacuum, high load, radiation and corrosive medium working environment, the magnetic properties of WS2 clusters are not only lubricated but also adsorbed on the metal surface during lubrication. A layer of nano protective lubricating membrane is formed on the metal surface.

Tungsten sulfide has a very small coefficient of friction (about 0.03), it can be used as additive in metal powder to improve the adhesion of metal powder under high speed friction condition and to obtain stable friction coefficient. Nanometer WS2 has excellent oxidation resistance, can be used as additive in lubricating oil (grease), it can effectively improve the lubricating oil (grease) properties of extreme pressure and anti-wear performance, it is not only good lubricating performance, and long service life.

The purity of tungsten sulfide is still very expensive, especially nano tungsten sulfide. In China, in addition to aerospace, tungsten sulfide has been widely applied in various industrial machinery operation in high temperature, the most mainstream collocation is that use tungsten sulfide ultrafine powder as additives in lithium complex greases, both can control costs, and to effect.

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Reactive Magnetron Sputtering Method Preparing Nanometer Tungsten Sulfide Membrane

Tungsten sulfide is an excellent solid lubricant material, it has high application value in the field of super solid lubrication, especially its role in the aerospace industry.

Tungsten sulfide membrane have layered structure, it has lower hardness and better stability under high temperature, it is suitable to be used as a solid lubricant for friction parts in special environment. There are three main methods for preparing tungsten disulfide membrane which include RF sputtering method, reactive magnetron sputtering method, chemical deposition method.


Reactive magnetron sputtering method is used to bombard pure tungsten targets with high energy noble gas and hydrogen sulfide mixed gas ions, the sputtered atoms react with the sulfur ions released from hydrogen sulfide gas to form a thin membrane on the substrate, reactive magnetron sputtering is also one of the most commonly used methods to obtain WS2 thin membranes.

Preparation of WS2 thin membranes on quartz substrates by reactive magnetron sputtering. A tungsten target with a purity of 99.95% was used, the substrate is 10 cm away from the target, the background vacuum is 4 x 10-4 Pa, fill in argon, the working pressure is 1 ~ 6Pa, sputtering power is 100W, the WS2 membrane with base orientation can be obtained by this method.

The operaion of reactive magnetron sputtering is that when the low-energy ions collide with the target surface, the atoms can not be sputtered directly from the solid surface, instead, the momentum is transferred to the colliding atoms, causing chain induced collisions of atoms on lattice lattices, the collision will follow all directions of the crystal lattice, at the same time, collisions are most effective in the direction of the closest arrangement of atoms, as a result, the atoms on the surface of the crystal get more and more energy from the nearest atom, if this energy is greater than the binding energy of the atom, the atoms will be sputtered out, the compound particles are formed by reacting with the active gas ions added to the inert working gas to form a compound film which is different from the target composition.

The target materials used in reactive magnetron sputtering, such as single element targets or multi-element targets and reactive gases, can obtain high purity, therefore, it is beneficial to prepare high purity compound membrane.

Reactive magnetron sputtering is suitable for the preparation of large area homogeneous membrane and can achieve the industrial production of coating million square meters per year.

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2021年4月7日星期三

Preparation Method of High Crystallinity Tungsten Carbide Powder

Tungsten carbide-based cemented carbide is widely used in cemented carbide, and high-quality tungsten carbide powder is the basis for preparing high-performance cemented carbide. What is the preparation method of high crystallinity tungsten carbide powder?

A preparation method of tungsten carbide powder with high carbonization crystal integrity and fast carbonization rate includes the following steps:

1) After mixing tungsten powder and carbon black, press the compact into a compact by a press; 2) Carburize the compact in step (1), after the carbonization is completed, ball milling and sieving can obtain high crystallinity tungsten carbide powder.

Precautions for this preparation method:

1. In step (1), the F.S.S.S. particle size of the tungsten powder is 3-40μm, and the particle size of the tungsten powder is too fine and it is not easy to form during pressing. The pressing pressure of the press is 1.0-2.0mpa. The mixing is ball mill mixing, and the mixing time is 1~6h.

2. In step (2), the carbonization temperature is 1500-2500°C. As a preference, when the tungsten powder's F.S.S.S. particle size in step (1) is 3-13μm, the carbonization temperature is 1500-2000°C. When the particle size is greater than 13μm, the carbonization temperature is generally 2000-2500°C.

3. In step (2), the carbonization should be carried out in a vacuum, inert gas or hydrogen atmosphere. The carbonization time is 1 to 6 hours, preferably 2 to 4 hours. The ball milling time is 0.5 to 4 hours. The sieving is twice sieving, the first sieving, the sieve mesh is 100-264 mesh, the second sieving, the sieve mesh is 60-180, the second sieving sieve aperture is larger than the first time.

The principle of the preparation method: in the process of producing tungsten carbide powder, the main function of using a press to press the mixture of tungsten powder and carbon black into a compact includes the following aspects: (1) The compacting effect makes the carbon black particles and the tungsten powder particles close together, and shortens the carbonization reaction distance. (2) Thermal insulation, make full use of the exothermic heat of the carbonization reaction to increase the speed of the carbonization reaction. (3) Forming function, the massive tungsten carbide does not need to be pre-crushed, directly enters the next ball milling process. (4) Isolation. There is no surface penetration of tungsten powder and carbon black compacts and sintering vessels during the carbonization process, which eliminates the surface dirty phenomenon in the traditional carbonization process and improves the quality of tungsten carbide.

Compared with the tungsten oxide reduction-carbonization method widely used in the mass production of tungsten carbide at home and abroad, the method introduced in this article can prepare high-quality tungsten carbide powder and is relatively simple to implement. It only needs to put a press in traditional tungsten carbide production lines.

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Six Preparation Methods of Spherical Tungsten Powder

Spherical tungsten powder is used as a raw material in industries such as tungsten and tungsten alloy 3D printing, porous materials, and high-density powder spraying, and its preparation methods have attracted attention. So, what are the 6 preparation methods for spherical tungsten powder?

The main domestic methods for preparing spherical tungsten powder are as follows:

1.Using the technology of secondary oxidation and reduction of tungsten powder, quasi-spherical tungsten powder can be obtained, and the manufacturing cost is low, but the spheroidization is not sufficient.

2. Using the granulation and sintering method to produce spherical powder for thermal spraying, spherical tungsten powder with a particle size of 40-750μm can be obtained. The density of the tungsten powder is not high, and the particle diameter is relatively large, and the powder is relatively coarse.

3. Use tungsten hexafluoride as raw material to prepare fine-particle (3~5μm) spherical tungsten powder. This method involves a strong corrosive gas and the production conditions are relatively harsh. In today's society, there is a high environmental protection requirement. There is still a certain distance from large-scale production.

4. The tungsten rod uses the rotating electrode DC arc plasma method to prepare spherical tungsten powder. This method can only used for preparing coarser particles (150-1700μm), but cannot prepare fine spherical tungsten powder, and the equipment cost is very expensive.

The main methods for preparing spherical tungsten powder abroad are as follows:

1. Obtain large particle size (40~650um) spherical tungsten powder from tungsten hexafluoride by vapor deposition. Because the process involves strong corrosive hydrofluoric acid, the production conditions are harsh and the environmental protection requirements are high, so It is difficult to gain widespread popularity in practical applications.

2. Spheroidizing and air-cooling Cr, Ta, Mo, W, MgO and other powders with an inductively coupled plasma torch can obtain spherical tungsten powder, but this preparation method requires a large cooling chamber, which must be using high-purity argon gas, the cost is very high, and the spheroidization rate of the powder after one treatment can only reach 85%. If you want to obtain all spherical powders, you need to perform multiple sorting and re-spheroidization processes. This obviously greatly increases production costs.

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Tungsten Oxide Boosts the Achievement of Carbon Neutral

 Carbon neutral refers to the use of afforestation, energy saving and emission reduction to offset the carbon dioxide emissions generated by itself and achieve "zero emissions" of carbon dioxide. Carbon neutral is a solution proposed in response to global warming.

Climate warming is the most concerned climate issue of humans all over the world today, and the core of climate warming is the increase in greenhouse gas carbon dioxide emissions caused by the increase in human activities.

In response to this issue, from the 2009 United Nations Climate Change Conference in Copenhagen to the 2015 United Nations Climate Change Conference in Paris, all emphasis was placed on reducing carbon emissions.

Up to now, the European Union, China, Japan, South Korea, etc. have all proposed carbon neutrality goals. The US President-elect Biden also proposed in his speech that the United States should return to the Paris Agreement. The basic requirement is the time when the United States should propose carbon neutral schedule. In other words, within the next year, all major economies in the world will participate in the process of achieving carbon neutrality.

Two important speeches this year in China both mentioned the need to control carbon emissions, and the Economic Work Conference also list carbon peaking and carbon neutral as one of the eight key tasks for next year. The 14th Five-Year Plan will become the key stage for China's carbon peak and carbon neutral. China promotes of carbon neutral also has the meaning of ensuring energy security, promoting economic transformation and promoting global development.

Two paths for tungsten oxide to help achieving the goal of carbon neutral:

First, carbon reduction at the power generation end: including photovoltaic, wind power, hydropower, nuclear power, and UHV links. As the main raw material of photovoltaic silver, tungsten oxide has excellent electrical conductivity.

Second, carbon reduction on the consumer side: including promoting the consumption of new energy vehicles, the development of energy storage, the use of degradable plastics, and green buildings. Because of its larger specific surface area and higher theoretical capacity, tungsten oxide has gradually become an ideal choice for replacing cobalt as a cathode material for lithium batteries.

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Ammonium Metatungstate Thermal Insulating Agricultural Membrane

Due to the intensification of the global greenhouse effect, extreme climate changes have been caused, resulting in a significant reduction in the area of arable land and making crops difficult to grow. Greenhouse cultivation can reduce the disasters caused by the climate to agricultural production, and maintain the stable production of crops, and solve the famine problems that may be faced in the future. 

It is a gradual trend in crop planting methods. Due to the increasingly serious problem of oil shortage and global warming, the promotion of energy conservation and reduction of carbon dioxide emissions have become the goals of various governments. Among them, the promotion of energy-saving green buildings is a key project, so energy-saving greenhouses that can reduce energy use have also become a new development trend.

The greenhouse shell shoulders the important functions of sheltering wind, rain, light regulation, heat insulation or heat preservation. The light-transmitting covering material is the main structural component that affects the exchange of light, heat and air inside and outside the greenhouse. The temperature in the greenhouse rises to very high in summer, which is not conducive to plant growth and personnel work. Artificial cooling measures also waste energy and increase cultivation costs. Although the high-performance greenhouse light-transmitting covering material has the opportunity to isolate the heat radiation part of the sun, and maintain high light transmission, solve the problem of indoor overheating. However, the currently commercially available greenhouse light-transmitting covering materials are insufficiently insulated, and there is still much room for improvement.

The wavelength of solar thermal energy reaching the surface of the earth is mainly at 280~3000nm. Among them, 280~380nm is ultraviolet light, 380~780nm is visible light, and 780~3000nm is infrared light. For plants, light in the 400-700nm wavelength range is required for photosynthesis, especially the strongest absorption band of chlorophyll is in the blue-violet light 400-480nm and red-orange light region 600-680nm, which has a great impact on plant growth. The response of plants to the length of day and night is the photoperiod. Red light and far-red light have a significant impact on the photoperiod effect. The red light of 600~700nm will inhibit the elongation of the stem and the divergence of the plant, and sometimes cause the leaves to be small and thick, and affect the flowering of the plant. The far-red light of 700~780nm will promote the elongation of stems and affect the flowering of plants. Ultraviolet light 280~380nm generally has an adverse effect on plants, but UVB at 280~315nm has minimal impact on morphology and physiological processes. The major impact is UVA at 315~380nm, which will affect the photoperiod effect and prevent stem extension. Long, plants are easy to burn, stimulate the germination of fungal spores, pathogens and viruses are also easy to invade, but it can make the flowers or fruits of plants brighter.

Optical performance requirements for greenhouse films

1. High light transmittance and stable

2. High light scattering

3. High infrared light barrier

4. Proper UV light barrier properties

The thermal insulation dispersion prepared by ammonium metatungstate and acrylic glue are used to make a nano organic-inorganic hybrid coating, and then this coating is coated on the surface of the polyester film to form a high-performance thermal insulating agricultural membrane. This transparent nanoparticle coating film can provide high see-through rate while blocking infrared rays, thus achieving high light transmission and high heat insulation effects. The optical properties of the thermal insulation film are related to the dispersibility of the thermal insulation powder in the resin. Generally speaking, the overall light transmittance of the heat insulation film can be maintained at 60~80%, and the infrared light blocking rate can reach 78~98%. Compared with the optical performance of the top-level thermal insulation films on the market, the optical performance of each other is not much different. Therefore, the use of nano-coating methods can produce products comparable to the top-level commercially available thermal insulation film, which has the advantages of simple manufacturing process and low cost. Therefore, greenhouse films will have great market demand in the future to maintain stable production of crops.

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Inorganic Fullerene / Tungsten Disulfide Composite Lubricant

Fullerene is the third allotrope of elemental carbon was found by a carbon, any elements in spherical, oval shaped structure of the material...