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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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...