The Friction and Wear Property of Tungsten Disulfide Nano Powder

The friction and wear property of tungsten disulfide nano powder is a new topic, as a new type of solid lubricating material, tungsten disulfide has excellent lubricating property, it has a layered hexagonal structure, the W and S elements in the layer are combined by covalent bond, and the molecular bond formed by S-S in the layer is combined. Because of the low bond energy of the latter, it is easy to slip during the friction process, so it has lower friction coefficient.

Tungsten disulfide is suitable for lubrication under various harsh conditions such as high temperature, high pressure, strong corrosion and ultra-low temperature. It plays important role in aviation and other national defense industries. Now the research and application of tungsten disulfide in lubricating grease is less. In this paper, tungsten disulfide nano powder is used as additive in lithium base grease, and SRV-Ⅳfriction and wear testing machine is used for comparative test to evaluate the tribological performance of grease and research the lubrication mechanism of this kind of additive.

After the test, it is found that WS2 additive can increase the consistency of lithium-based grease, but it has little effect on its dropping point, it means that it has little influence on the colloidal structure of soap fiber, the following is the analysis of its friction and wear performance from the test.

1.0 Carrying capacity analysis

It can be seen from the load-bearing capacity change curve of lithium-based grease containing different mass fractions of WS2 powder on the four-ball friction tester that WS2 additive can improve the load-bearing capacity of the grease.

2.0 Analysis of friction coefficient

From the friction coefficient change curve of the lithium-based grease with different mass fractions of WS2 powder on the SRV-IV friction and wear testing machine, it shows that the addition of WS2 additives can effectively reduce the friction coefficient compared with the base grease, it will be the best to contain a mass fraction of 2% WS2 grease, with an average friction coefficient of 0.115, 17.3% lower than the base grease.

3.0 Wear analysis

From the influence of WS2 powder containing different mass fractions as grease additive on the wear performance, it can be seen from the wear scar height of the standard disc and the wear scar diameter of the standard ball, the lithium-based grease containing 2% WS2 has the best anti-wear performance, and the wear scar diameter is 0.450 mm, which is 46.8% lower than that of the base grease.

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