The Analysis of Molybdenum Disulfide Properties and the Advantages and Disadvantages of Molybdenum Disulfide Grease

- Aug 04, 2020 -

What is molybdenum disulfide?

MoS2 is an inorganic compound that naturally occurs in the mineral molybdenite. The crystal has a layered hexagonal structure similar to graphite. Molybdenum disulfide is known as the "king of high-grade dry lubricant." Molybdenum disulfide is a solid powder made by chemically purifying natural molybdenum concentrate powder after changing its molecular structure. The color of this product is slightly silvery gray, with a metallic luster, and it has a smooth feel when touched. It is insoluble in water. The product has the advantages of excellent dispersibility and non-sticking. It can be added to various greases to form a non-sticky colloid state, which can increase the lubricity and extreme pressure of the lubricant. It is also suitable for high-temperature, high-pressure, high-speed, and high-load mechanical working conditions to extend equipment life.

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Molybdenum disulfide properties

The MoS2 melting point is 1185 ℃, but it begins to sublime at a relatively low temperature of 450 . This property is useful for purifying compounds. Due to its layered structure, hexagonal MoS2, like graphite, is an excellent dry lubricant. It and its tungsten disulfide can be used as mechanical parts (for example, aerospace industry), two-stroke engines (types used for motorcycles), and surface coatings in the barrel (to reduce the friction between bullets and ammunition).

Unlike graphite, the lubrication performance of moly powder does not depend on the adsorbed water or other vapors. It has a maximum temperature of 350 ° C in an oxidizing environment and 1100 ° C in a non-oxidizing atmosphere. Its stability makes it suitable for high-temperature applications where grease is not practical.

It is understood that MoS2 is recognized as the best dry powder lubricant in the world. Still, in the application of lubricating oil, the physical diameter of molybdenum particles is large, which will form a precipitate layer in the engine oil and cannot be evenly fused with the engine oil. Among the greases, this makes the manufacture of molybdenum disulfide lubricants a global problem. Only a few companies in Germany and the United States currently master this technology. China also has many methods available in the field of making molybdenum sulfide grease.


What is molybdenum disulfide grease?

Moly disulfide grease contains solid, semi-fluid, and fluid lubricant of molybdenum disulfide. It has excellent lubricating properties for mechanical friction parts working in extreme-pressure environments but does not have excellent high-temperature resistance. Moly disulfide grease is a molybdenum disulfide extreme pressure grease refined by inorganic thickener thickened synthetic ester oil, containing molybdenum disulfide solid lubricant and various oil additives such as anti-oxidation and anti-corrosion. This high temperature and high-pressure grease are designed for the lubrication of bearings and moving devices under high temperature, high load/impact load, etc., providing long-term anti-wear and corrosion protection.

What is the maximum operating temperature of molybdenum sulfide grease?

First of all, the quality of molybdenum sulfide grease is different between different brands and different brands, so the maximum use temperature is also different. The general-purpose molybdenum sulfide grease has a temperature range of -20-120 ℃.

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What is molybdenum disulfide grease used for?

1. Under high speed, low speed, heavy load or impact load, it is easy to increase the friction between the gears, resulting in wear and other damage, and molybdenum disulfide grease has excellent extreme pressure and wear resistance, can quickly form an oil film on the equipment, reduce Friction and wear, and has a high load-carrying capacity to prevent gluing, thereby protecting the gear unit.

2. When the gear is running, the grease will be agitated violently, the temperature is also higher, and it will contact with air and water vapor, which will accelerate the oxidation speed of the grease, make it deteriorate, and lose the lubrication effect. Molybdenum disulfide grease has excellent oxidation stability, is not easy to generate various precipitates, and can provide long-term lubrication effect for gears.

3. Speeds are often exposed to moisture during operation. If the water resistance and rust resistance of the grease is not excellent, with the participation of water and oxygen, the tooth surface and gearbox will corrode and rust, which will damage the regular operation of the gear. Molybdenum disulfide grease can solve this problem because it does not dilute or emulsify even underwater or other environments, protect the equipment from corrosion and provide adequate lubrication.


Disadvantages of Moly disulfide grease

1. Moly disulfide grease can not be mixed with other lubricants, it will reduce the performance or failure;

2. Moly disulfide grease is not suitable for high speed, light load, and low temperature. Use temperature does not exceed 190 degrees;

3. Molybdenum disulfide has a high content of active sulfur, which is easy to cause corrosion to copper. Besides, when parts made of copper and its alloys need to be lubricated, it is not impossible to choose molybdenum disulfide-containing lubricating products, but it is also necessary to add copper corrosion inhibitors;

4. Molybdenum disulfide must not be mixed with engine oil, physical and chemical reactions will occur, causing grease failure.


Advantages of Molybdenum sulfide grease

1. Long service life

Compared with ordinary grease, molybdenum sulfide grease has more excellent oxidation stability, lubricity, mechanical safety, and extremely low volatility. Even under low temperature, it is not easy to harden or produce deposits, and the service life is long.

2. Reduce noise and meet environmental protection requirements

Moly disulfide grease does not contain silicone, which can avoid contact point failure, effectively reduce the noise from plastic gears, and also has a small seepage flow. It can be used in places where cleanliness is required. The base oil is non-toxic and tasteless and meets environmental protection requirements.

3. Wide range of uses

Molybdenum sulfide grease is suitable for the lubrication and protection of high-speed bearings, gears, chains, and other transmission devices in automobiles, electrical equipment, precision equipment, audio-visual equipment, office equipment, textile, printing and dyeing, metallurgy, mining and other industries with plastic components.

4. Outstanding anti-wear performance

Anti-friction: The particle size of molybdenum disulfide produced by supersonic airflow crushing reaches 325-2500 mesh, micro-particle hardness 1-1.5, friction coefficient 0.05-0.1, so it can be used in friction materials to reduce friction.

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. 

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