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Composite performance evaluation of lithium tungsten disulfide grease

2021-10-20 14:50:50  Knowledge

What is tungsten disulfide WS2?

As a new type of solid lubricating material, tungsten disulfide has excellent lubricating properties and environmental strain capacity, and is a lubricating material for high-end precision industries. Tungsten disulfide has a layered hexagonal crystal structure. The W and S elements in the layer are combined by covalent bonds, and the molecular bonds formed by SS between the layers are combined. Because the latter has a low bond energy, it is easy to slip during friction. , So it has a lower coefficient of friction.

The properties of tungsten disulfide WS2

Studies have shown that the W element in tungsten disulfide has an empty orbital in the 4f electron layer, and the nano-tungsten disulfide powder has a larger specific surface area. The two work together to make it easier for tungsten disulfide to be adsorbed on the metal surface. , Its better performance provides favorable conditions. Tungsten disulfide is suitable for lubrication under various harsh conditions such as high temperature, heavy load, high pressure, high vacuum, high speed, high radiation, strong corrosion and ultra-low temperature. It is used in aviation, aerospace and The defense industry and other fields have important application value.

Most paired with tungsten disulfide WS2 are high temperature lithium grease. Lithium grease is made of natural fatty acid (stearic acid or 12-hydroxystearic acid) lithium soap, thickened medium viscosity mineral lubricating oil or synthetic lubricating oil, added with antioxidants, rust inhibitors and extreme pressure It becomes a multi-effect long-life general-purpose grease after it is applied, which can replace calcium-based grease and sodium-based grease, and is used for bearing lubrication of aircraft, automobiles, tanks, machine tools and various mechanical equipment. Undoubtedly, lithium-based grease (oil) is an ideal carrier for tungsten disulfide. Adding tungsten disulfide lubrication to high-temperature lithium-based grease (oil) can greatly improve the lubricating performance.

How much is the performance of grease (oil) added with tungsten disulfide?

According to the method, a four-ball friction tester is used to test the bearing capacity of the grease. In the test, it was found that tungsten disulfide has advantages.

1. Bearing capacity, WS2 additives can improve the bearing capacity of grease. Among them, the grease containing 2% WS2 additive in terms of maximum seizure load (PB) is 112.8% higher than that of base grease. ) Is 84.3% higher than the base fat.

2. Friction coefficient: Compared with the base grease, the addition of WS2 additives can effectively reduce the friction coefficient. The grease containing 2% WS2 by mass is the best. The average friction coefficient is 0.115, which is 17.3% lower than the base grease. If WS2 is added in a large amount, a very dense chemical reaction film is gradually formed on the surface of the friction pair, and the hardness of the surface layer is too high, resulting in adhesive wear.

3. Wear volume, the effect of different mass fractions of WS2 powder as a grease additive on wear performance. The lithium-based grease containing 2% WS2 has the best anti-wear performance. The wear scar diameter is 0.450 mm, which is 46.8% lower than that of the base grease.

The role of tungsten disulfide WS2 in lithium-based grease compound

Through research, it can be found that tungsten disulfide plays a vital role in the lithium-based grease compound. In the friction process, tungsten disulfide powder can exert a nano-scale effect to adsorb and deposit in the pits of the friction pair, thereby acting as a surface Repairing effect; At the same time, under high temperature and high load conditions, a WS2 nanoparticle penetration layer is formed, and the tungsten disulfide nanopowder chemically reacts with the surface of the friction pair to form a chemical protective film containing WO3 and Fe3O4, thereby enhancing the lubricating effect. That is why tungsten disulfide WS2 can become a lubricating material for high-end precision industries.

Infomak is dedicated to the technology development of special oil additives, combined the Technology of nanomaterials developed dry lubricant and oil additives two series. Our products can significantly improve the performance of lubricating oil, improve energy efficiency, effectively protect the lubrication device and extend the oil change cycle, which can satisfy the lubrication oil constantly upgrading for high-end engine oil additives. Contact us.





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