explain how the nature of the two surfaces in contact affect friction between them?
Answers
Answer:
Tungsten Disulfide (WS2) is dry/solid lubricant powder and is one of the most lubricious substance in world. WS2 offers excellant dry lubricity (COF: 0.03) unmatched to any other substance, including Graphite or Molybdenum Disulfide (MoS2).
Tungsten Disulfide (WS2) can also be used in high temperature and high pressure applications. It offers temperature resistance from -450 deg F (-270º C) to 1200 deg F (650º C) in normal atmosphere and from -305 deg F (-188º C) to 2400º F (1316º C) in Vacuum. Load bearing ability of coated film is extremely high at 300,000 psi.
Tungsten Disulfide (WS2) can also be used instaed of Molybdenum Disulfide (MoS2). See comparison of WS2 / MoS2
Since the powder offers one of the lowest Coefficient of Friction (Dynamic @ 0.03 & Static @ 0.07), the applications are unlimited and could be tried with every conceivable idea. .
Two established ways the WS2 powder can be used are:
1) Mixing the WS2 powder with wet lubricants (such as oil, grease & other synthetic lubricants):
The powder can be mixed 1wt% to 15wt% (as required) with grease or oil. This will enhance lubricity of the mixture and also improves High Temperature and Extreme Pressure properties of mixture. During the use, WS2 in the mixture will get coated on mating/moving parts, which in turn reduces friction and improves lubricity and load bearing ability for much longer cycles.
2) Coating the WS2 powder on a substrate requiring (dry) lubricity:
The powder can be coated by spraying (at 120 psi) the substrate with dry (& cool) pneumatic air. It does not require any binders and spraying can be done at normal room temperature. Coated film will be 0.5 micron thick. In an alternative application method, the powder can also be mixed with Isopropyl alcohol and this paste could be buffed to the substrate. The coating applications are already established in many areas such as Automotive parts, Racing Car Engine and other parts, Aerospace parts, Bearings (Linear, Ball, Roller etc), Shafts, Marine parts, Cutting Tools, Blades, Slitters, Knives, Mold release, Precision Gears, Valve components, Pistons, Chains, Machinery components and many other areas.
Explanation:
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Answer:
Friction between two surfaces depends on the smoothness of the surfaces in contact. A greater force is required to move the surfaces past each other when they are rough as compared to when they are smooth.
Also, it is more difficult to move a heavier object on the ground than a lighter one where the two objects are of the same material.
Friction also depends on the value of 'g' or acceleration due to gravity