What is Molybdenum Disulfide and why is it showing a good lubricating behavior?

Molybdenum Disulfide, also known as Molybdenum Disulphide, MoS2 and Moly, is one of the most widely used solid film lubricants. Like graphite and tungsten disulfide (WS2), MoS2 is a dichalcogenide. The lubricating properties of molybdenum disulfide lubricant are due to a weak atomic interaction (Van der Waals Force) of the sulfide anions, while the covalent bond within the molybdenum is strong.

Which are the easiest and widely recognized ways of applying MoS2 coating?

There are a number of ways to apply MoS2 low friction coatings to the desired substrate. These include:

  • Rubbing and burnishing
  • Impingement with or without inorganic binder
  • Spraying or dipping paint like substance containing the molybdenum disulfide as a lubricant
  • Physical vapor deposition

Some of the specifications covering this application are; MIL-PRF-46010, AS5272, AMS2526.

Why molybdenum disulfide coating is considered unbeatable in comparison to its competitors?

In moving/mating components, the friction causes considerable loss of energy, poorer performance, and limits the wear life of the components. Molybdenum Disulfide can provide a low coefficient of friction, sometimes as low as 0.05 COF. This will be dependent on the humidity, cleanliness, and sliding conditions of your application.

Also, the molybdenum disulfide dry lubricant can:

  • Operate in a wide range of temperatures up to 600 deg F and maintain its lubricity in high load, high-speed conditions.
  • Be very effective in inhibiting corrosion as well when combined with the proper resins and binders.

Lubrication relies on the slippage along with the sulfur atoms. All of the properties of the lamella structure are intrinsic and no external form of moisture is required (as it is with graphite). Mos2 performs best when water vapor is not present, making molybdenum disulfide coating ideal for vacuum applications.

Coating Specifications

Silver Grey
Coefficient of Friction0.06 to 0.15
SubstratesAll ferrous or non-ferrous metal
Man-made solids & plastics
Cure TimeNo cure time is required when applied at ambient temperature
ApplicationsChucks, Collets and Tools
Circuit Breakers and Switches
Compressors and Rheostats
Cryogenic Pumps
Electrical Connectors
Engine and Drive Train Parts
High Vacuum Applications
Machine tools, Pins, Taps
Magnetic Heads
Pilot Valves, Chain Saws
Rubber Gaskets, “O” Ring Seals
Seamer Rolls
Slide Mechanisms

Environmental Specifications

Relative Load Carrying250,000 PSI
Ambient Temperature Range-185 to 350 ºC
Vacuum Temperature Range-185 to 1100°C at 10-14 Torr
Chemical StabilityInert, non-toxic, corrosion resistant

Material Specifications

Molecular Weight160.08
Density4.8 g/cc
Hardness1.0 on Mohs Test
Electrical PropertiesHas semiconductor properties