2021年6月30日星期三

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 existence.

In the field of lubricants, tungsten disulfide is a typical layered structure, easy to slip away, it is widely used in the field of lubricants, but tungsten disulfide due to its crystal edge of the unsaturated suspension bond with chemical activity, easy in the friction process oxidized, the tribological properties of graphene are greatly reduced, especially in humid atmosphere. Graphene has good chemical stability, so it is applied in practice, people tend to be tungsten disulfide and graphene compound made of lubricants, but some scholars use inorganic fullerene C60 instead of graphene, and get better results.


The inorganic fullerene structure eliminates the dangling bonds on the edge and has higher chemical inertness. The hollow cage structure can provide higher elasticity and increase the resilience in the load range, in order to reduce the dissipation related to wear, some scholars have used uniaxial shock wave to test the dynamic compressive properties of two tungsten sulfide / inorganic fullerene structures, it is found that the inorganic fullerene structure has excellent compressive wave absorbing ability, and its maximum compressive pressure is high, which is now found in the most tough molecular cage structure, its compressive properties are better than those of other carbon cage like structures, even under lower pressure, it will collapse or transform into other diamond structures. Its compressive properties are better than those of other carbon cage like structures, even under lower pressure, it will collapse or transform into other diamond structures. Therefore, when the inorganic fullerene structure is used as a solid lubricant, it can withstand more graded load conditions, performance is not inferior to graphene / tungsten disulfide composite lubricant, and the environmental strain is stronger than the former.

The study found that the lubricating oil by adding a small amount of inorganic fullerene / two tungsten sulfide composite lubricant can greatly improve its tribological properties, adding a small amount of inorganic fullerene / two tungsten sulfide composite lubricant can significantly prolong the service life of the engine in automobile lubricating oil, reduce fuel consumption of motor vehicles.

Taking spacecraft as an example, the tribological properties of materials in the transition from atmosphere to high vacuum, from low temperature to high temperature and from humid atmosphere to dry atmosphere are extremely demanding, at this point, liquid lubricants are difficult to meet the needs of use. Only inorganic fullerene / two tungsten sulfide can achieve excellent antifriction and wear resistance. In order to reduce the energy consumption of the transmission system, prolong the service life of components and improve the reliability of the system, it provides a new effective way to solve the tribological problems of materials under extreme conditions.

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Nano Tungsten Disulfide / Graphene Composite Catalyst

The fuel cell has easily obtained raw materials, high energy density, long service life, cleaning and other advantages, as a new energy efficient conversion system.

It has the potential to become one of the micro electronic components of the alternative energy. Electrocatalysis is a key element in fuel cells. Electrocatalysts must have the following characteristics: high electrocatalytic activity, large specific surface area, good electrical conductivity, good stability and proper support.


Graphene, as a typical two-dimensional material, has large specific surface area, good flexibility, and very high electron conduction rate. With the discovery of graphene and characterization of transition metal chalcogenides, same as the typical layered structure of compounds such as WS2 exfoliatedinto research on lubricant, lithium battery, photoelectric catalysis, super capacitors and other aspects of the single or few layer structure has also made good progress. In the past, some scholars have tried to use nano-tungsten carbide / graphene composite electrocatalytic methanol fuel cell, and achieved good results. Recently, some scholars have tried to combine graphene with nano-tungsten disulfide with monolayer structure, composition of nano tungsten disulfide / graphene composite catalyst. What about the effect?

Layered six dimensional WS2/RGO composites were synthesized by in-situ hydrothermal synthesis on the surface of graphene oxide using tungsten chloride as tungsten source and thioacetamide as sulfur source. The results show that after high-temperature heat treatment, WS2 forms a few layer structure and uniformly adheres to graphene to form a stable two-dimensional composite. Compared with pure WS2 and RGO, the catalytic oxygen reduction activity of the composites was greatly improved because of the synergistic effect between WS2 and RGO, and the defects and active sites of RGO were increased during in situ synthesis, in the process of oxygen reduction, it is beneficial to the dissociation of O2 molecule and the activation energy of the system, which is more conducive to the process of oxygen reduction in the four electron pathway.

With more in-depth research on monolayer 2D materials, scientists have found that the nanotite tungsten disulfide / graphene composite catalyst has a corrected starting potential and a limiting current density. It has excellent cycle stability and methanol tolerant performance than pt. Moreover, the process of hydrothermal synthesis of this composite is simple, and the cost of the composite material is lower than that of platinum, and it has good electrocatalytic performance. Therefore, nano-tungsten disulfide / graphene composite catalyst in the field of fuel cells also has the great potential out of the laboratory.

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Tungsten Disulfide / Lithium Grease Composite Performance Evaluation

As a new type of solid lubricating material, tungsten disulfide has excellent lubricity and environmental strain ability. It is a high-end precision industrial lubricating material.

Tungsten disulfide is suitable for lubrication in various harsh conditions such as high temperature, heavy load, high pressure, high vacuum, high speed, high radiation, strong corrosion and ultra-low temperature. It has important application value in the fields of aviation, spaceflight and defense industry.

Lithium grease is made from natural fatty acid (stearic acid or 12- hydroxy stearic acid lithium soap), made of mineral oil or synthetic thickener of lubricating oil, the added antioxidants, anti rust agent and extreme pressure agent, has become a multi effect long-life grease, can replace calcium base grease and sodium base grease, bearing lubrication for aircraft, automobiles, tanks, machine tools and various mechanical equipment. Undoubtedly, lithium-based grease (oil) is the ideal carrier of tungsten disulfide, the addition of high-temperature lithium-based grease lubricating grease (oil) to achieve a substantial increase in lubrication performance. 


According to GB/T 3142 method, the MQ-800 four ball friction testing machine was used to test the bearing capacity of grease, the ball is made of GCr15, the diameter of 12.7000 mm. In the experiment, it was found that tungsten sulfide has the advantage.

1.The bearing capacity, WS2 additives can improve the bearing capacity of the grease, grease containing 2% WS2 additive mass fraction 112.8% more than the base grease in the maximum card-free bite loading (PB), the sintering load ) was 84.3% more than the base fat.

2.Friction coefficient: compared with base grease, the addition of WS2 additive can effectively reduce the friction coefficient, in which the grease with mass fraction of 2%WS2 is the best, the average friction coefficient is 0.115, which is lower than that of base grease 17.3%.

3.Effect of wear quantity, WS2 powder with different mass fraction as lubricating grease additive on wear performance.

It can be found that tungsten sulfide plays a critical role in the lithium complex grease agent, in the process of friction, two tungsten sulfide powder can play the effect of nano scale adsorption and deposition on the friction surface pits, so as to repair; At the same time, under high temperature and high load conditions, WS2 nanoparticle penetrating layer is formed, and the tungsten disulfide nano-powder chemically reacts with the surface of the friction pair to form a chemical protective film containing WO3 and Fe3O4 so as to improve the lubricating effect. This is why tungsten disulfide can become a high-end precision industrial lubricants.

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Tungsten Trioxide

Tungsten trioxide (WO3) is a product of tungstate or calcining ammonium paratungstate, is an important intermediate compound of high purity tungsten.

The general appearance of yellow powder, insoluble in water, soluble in alkaline solution, slightly soluble in acid. The crystal structure of tungsten trioxide has four kinds, the crystal type: it mainly depends on the temperature at 24 °C into ammonium metatungstate, heated to 300 °C and 350 °C, transformed into amorphous material (ammonium tungsten bronze), heated to 400 °C, into six party crystal WO3, when the temperature reached 500 °C, it became triclinic WO3. When the temperature reached 750 °C, the crystal was recrystallized. Crystal is not the same, WO3 surface area and average particle size is not the same.


The basic principle of preparation of tungsten trioxide mainly has three kinds: one is composed of tungsten and soda to eutectic ammonium paratungstate, plus roasting and acid decomposition and tungsten trioxide; The two is precipitated with calcium tungstate tungstic acid and hydrochloric acid reaction, the high temperature decomposition into tungsten trioxide and tungstate water, in addition to two tungsten oxide hydrogenation reduction of tungsten trioxide. Along with the progress of the process, were also derived from two other forms of W02.90 and W2.72 (tungsten blue and violet tungsten), blue tungsten is mainly used in the manufacture of hard alloy, purple tungsten for mainly for preparing ultrafine tungsten powder.

Tungsten trioxide is a major category of China's tungsten products export trade, except for the tungsten or tungsten carbide hard alloy production reduction products, were also used in industrial chemical catalyst or catalyst, a small amount of colorant for yellow ceramic is also used in industrial production. Tungsten oxide is used as an important anticorrosive paint and coating material in shipbuilding industry.

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2021年5月19日星期三

Nano Tungsten Oxide for Semiconductor Memory

The reason why semiconductor memory chooses nano tungsten oxide material to produce storage media is that it is a very important semiconductor material with good electrochemical performance, and its resistance value can undergo reversible transformation under the action of an electric field. Next, let's take a look at the manufacturing method of a storage device based on a tungsten oxide storage element.

Manufacturing method (1)

The storage device includes a plug that extends upward from the top surface of the substrate through a dielectric layer. A bottom electrode, the outer surface of the bottom electrode has tungsten, the bottom electrode extends upward from the top surface of the plug. An insulating material, the insulating material surrounds the bottom electrode is in contact with tungsten on the outer surface of the bottom electrode. The storage element is located on the upper surface of the bottom electrode, the storage element includes a tungsten oxide compound, and the storage element can be programmed to at least two resistance states. And the top electrode, the top electrode overlay and contact the storage element. In addition, the plug has a first lateral dimension, the bottom electrode has a lateral dimension, the lateral dimension is parallel to the first lateral dimension of the plug, and the lateral dimension is smaller than the first lateral dimension of the plug.

Manufacturing method (2)

The tungsten oxide storage part is formed using a non-critical mask tungsten oxide material, or in some embodiments, it may be formed without any mask. The memory device disclosed herein includes a bottom electrode and a memory element, and the memory element is located on the bottom electrode. The memory element includes a tungsten oxide compound and has more than two resistance states; the upper electrode includes a barrier material located on the memory element, and the purpose of the barrier material is to prevent metal ions from moving from the upper electrode into the memory.

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Compared with traditional semiconductor storage devices, tungsten oxide storage devices have better response performance.

Preparation Method of White Tungsten Oxide

 Tungsten oxide is a very classic low-dimensional transition metal oxide material, which is attracted by its special physical and chemical properties (such as electrochromism, photochromism, catalytic activity, superconductivity and large load capacity, etc.) A large number of materials, semiconductor devices, and physics and chemistry researchers are paying attention. However, there is no report on white tungsten oxide and its preparation method.

The chemical formula of white tungsten oxide is the same as that of purple tungsten oxide, which is W18O49. It can be excited to become blue under the irradiation of ultraviolet light, and it can be restored to white after removing the ultraviolet light. It is widely used in construction, automobiles and other fields.

A method of producing white W18O49, there are the following steps:

Disperse the tungsten hexachloride ultrasonically in anhydrous n-butanol, of which 150ml anhydrous n-butanol is used per gram of tungsten hexachloride. When the system turns from yellow to blue during the ultrasonic process, stop the ultrasound, and then add it to the system Sodium nitrate, the amount of sodium nitrate is 1.5-3 times the mass of tungsten hexachloride, put the mixed system into the reaction kettle, control the reaction temperature at 180-220°C, and control the reaction time at 6-12 hours; wait for the end of the reaction After cooling to room temperature, the obtained product was washed with water and ethanol, centrifuged, and dried to obtain powdery white W18O49.

This method uses tungsten hexachloride and n-butanol as reactants. The color of the reaction product W18O49 can be adjusted by controlling the amount of sodium nitrate added. When the mass ratio of sodium nitrate and tungsten hexachloride is more than 3:2, white 118049 can be obtained. . The advantage is that by adding sodium nitrate to the system to modify the surface of the tungsten oxide, white tungsten oxide is obtained, which is obviously different from the W18O49 obtained by the general solvothermal method in appearance and color; and the production is simple and easy.

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Tungsten Trioxide for Mulch

 In addition to the production of tungsten trioxide (WO3) ultrafine particles, they can be used to produce tungsten powder, tungsten carbide powder, yellow ceramics, electrode materials for energy storage batteries, anti-corrosion paints and coatings, and can also be used to make multifunctional mulch films. Compared with ordinary agricultural film, the agricultural film containing tungsten oxide additives has higher comprehensive performance, which is mainly manifested in better heat insulation effect and better light transmission performance.

In areas with strong sunlight, when the temperature is too high, it is easy to produce drought and cell dehydration, which affects the physiological and metabolic activities of plants, such as photosynthesis, water metabolism, endogenous hormones, and thermal stability of cell membranes, which in turn leads to the appearance and growth of plants abnormal. Therefore, it is of practical significance to produce agricultural film with good heat insulation effect. However, a film with excellent heat insulation effect means that it has better near-infrared absorption performance.

In addition to good heat release effect, the new thermal insulation film also needs to have excellent light transmittance, so that it is convenient for managers to observe the production of crops at any time, without lifting the film, which improves the work efficiency of managers. At the same time, it can also reduce the rate of film breakage. The agricultural film with excellent light transmittance means that it has a higher transmittance to visible light.

WO3 is a classic transition metal n-type semiconductor material. It has excellent optical properties, that is, it has a significant absorption effect on near-infrared light in the 1400~1600nm and 1900~2200nm bands, and it also has high permeability to visible light. Therefore, it is favored by materials researchers at home and abroad. It is often used as a key modifier for commercial mulch films, which can significantly increase the near-infrared absorption capacity and light transmittance of the product, which is more conducive to the growth of crops.

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New Production Process of Tungstic Acid

Tungstic acid is made of artificial white tungsten (CaWO4) and concentrated acid under heating and cooking conditions. Artificial white tungsten is prepared by removing molybdenum (Mo) from industrial sodium tungstate solution by sodium sulfide method and adding calcium chloride. If the process is not treated by the sodium sulfide method, there will be no molybdenum removal effect, and the sodium sulfide method for removing molybdenum is more troublesome. Because the process needs to be produced under high temperature and high acidity conditions, it has high energy consumption and high acid consumption. The corrosiveness is strong, and the yield is not high. Therefore, the following will introduce a new production process of tungstic acid. The specific steps are as follows:

Add hydrogen peroxide (H2O2) complexing agent to industrial sodium tungstate (concentration between 0.2N and 1N). The amount of complexing agent is the molar ratio of tungsten: hydrogen peroxide of 2:1 to 2:2, add hydrochloric acid in the room temperature range of 10℃ to 28℃ to make the solution acidity between 0.5N and 2N (if the content of chromium and molybdenum impurities in sodium tungstate is high, the acidity of the solution should be adjusted to 2N), and then pass sulfur dioxide or add sulfite or bisulfite to directly prepare tungstic acid. The prepared tungstic acid is washed sequentially with 1N HCl, 0.5N HCl and absolute ethanol to obtain a pure product. Note: The amount of sulfur dioxide or sulfite or bisulfite is that the molar ratio of sulfur dioxide or sulfite or bisulfite: hydrogen peroxide is between 1:0.7 and 1:1.3.

Compared with the existing production method, the advantages of this technology are that in addition to the classic sodium sulfide removal of molybdenum process and the process of preparing artificial white tungsten with calcium chloride; since concentrated acid is no longer needed, it consumes less acid and consumes less energy and wastes; the production efficiency can be 98%, which is 10% higher than the existing process, and the molybdenum removal effect can reach 70% to 80%.

In general, the new technology has the advantages of simple operation, high yield, weak corrosiveness, less three wastes, high purity and high activity.

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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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2021年2月25日星期四

Corrosion Inhibition Mechanism of Sodium Tungstate

In order to protect the environment, human efforts to develop new, efficient, low toxicity, pollution-free corrosion inhibitors, sodium tungstate quickly favored by people.

Sodium tungstate was first used as a corrosion inhibitor for organic antifreeze, and subsequently developed in other functional packages. Tungstic acid can be used in different corrosive media, such as fresh water cooling water, seawater cooling water, oil recovery in the oil field, molten salt, water-cooled internal combustion engine antifreeze, adsorption type refrigerant circulating fluid and coal slurry. You can also add anti-rust paint and mold resin material from the role of corrosion inhibition.


Sodium tungstate alone has some inhibition, but the corrosion rate is not high, and the amount is large, the cost is difficult to control, therefore, sodium tungstate is mixed with other organic compounds in general industry, which can significantly improve the corrosion inhibition performance and reduce the cost of sodium tungstate.

Sodium tungstate can not only inhibit the uniform corrosion of metals, but also inhibit the pitting corrosion. Before the metal is immersed in the solution, the coverage of the surface metal oxide is quite high due to the action of oxygen in the air, and the oxidation rate is further increased after entering the solution, so that the anode area decreases and the anode current density increases. While WO42- can discharge rapidly at high current density, at this time, its oxidation ability is very strong, Fe2+ can be oxidized to Fe3+, which promotes the formation of iron oxide film, therefore, tungstate does not play a major role in the formation of metal passive film. It only acts as the maintenance and repair function of the film.

In addition to the oxidizing sodium tungstate inhibitor has in common, its specificity can not be ignored, such as: the oxidation of tungstate is relatively low, and the atomic weight of tungsten is larger; Tungstate can form a very small salt with many metal ions. Therefore, whether the passivation film theory or the characteristic adsorption theory, we only need to know that sodium tungstate has good metal corrosion inhibition, and it is the ideal material to inhibit metal corrosion, so that is enough.

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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...