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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