Views: 2 Author: Site Editor Publish Time: 2023-01-13 Origin: Site
Molybdenum disulfide is an inorganic substance with the chemical formula MoS2, which is the main component of molybdenite.
Chemical formula: MoS2
Molecular weight: 160.07
Melting point: 2375°C
Appearance: Black solid powder
Mohs hardness: 1.0~1.5.
Molybdenum disulfide is a black solid powder with a metallic luster. 1370°C starts to decompose and decomposes into metallic molybdenum and sulfur at 1600°C. 315°C starts to be oxidized when heated in air, and the oxidation reaction is accelerated when the temperature rises. Molybdenum disulfide is insoluble in water, dilute acid and concentrated sulfuric acid, generally insoluble in other acids, bases and organic solvents, but soluble in aqua regia and boiling concentrated sulfuric acid. 400 ℃ slow oxidation occurs, generating molybdenum trioxide: 2MoS2+ 7 O2→ 2 MoO3 + 4 SO2
The generated molybdenum trioxide can be tested with a titanium-iron reagent. The product is first treated with sodium or potassium hydroxide solution (the principle is to convert molybdenum trioxide into molybdate), and then a drop of titanium-iron reagent solution is added, which will react with the resulting sodium or potassium molybdate to produce a golden yellow solution. This method is very sensitive, and trace amounts of molybdate can be detected. And if no molybdenum trioxide is generated, the solution will not produce a golden color because molybdenum disulfide does not react with sodium or potassium hydroxide solution.
Molybdenum disulfide can be heated to react with chlorine to produce molybdenum pentachloride: 2 MoS2+ 7 Cl2→ 2 MoCl5+ 2 S2Cl2
Molybdenum disulfide reacts with alkyl lithium in a controlled manner to form the embedded compound (intercalation compound) LixMoS2. if it reacts with butyl lithium, then the product is LiMoS2.
Molybdenum disulfide has a high content of active sulfur, which tends to corrode copper, and is discussed in many books and papers on lubricant additives. In addition, when there are parts made of copper and its alloys that need lubrication, it is not impossible to choose lubrication products containing molybdenum disulfide, but it is also necessary to add anti-copper corrosion agents.
Molybdenum disulfide concentrate is produced by repeatedly stirring the process with hydrochloric acid and hydrofluoric acid under direct steam heating, washing with hot water, centrifuging, drying and crushing. Ammonium molybdate solution is passed through hydrogen sulfide gas to produce ammonium molybdate thiosulfide. Add hydrochloric acid to transform into molybdenum trisulfide precipitate, followed by centrifugation, washing, drying and crushing. Finally heated to 950 ° C desulfurization can be produced.
Molybdenum disulfide is an important solid lubricant, particularly suitable for use at high temperatures and pressures. It is also antimagnetic and can be used as a linear photoconductor and as a semiconductor displaying P- or N-type conductivity with rectification and commutation. Molybdenum disulfide is also used as a catalyst for the dehydrogenation of complex hydrocarbons.
It is also known as the "King of Advanced Solid Lubricants". Molybdenum disulfide is a solid powder made from natural molybdenum concentrate powder that has been chemically purified and its molecular structure changed. The product is black with silvery gray color, metallic luster, slippery to touch, insoluble in water. The product has the advantages of good dispersion and non-bonding, and can be added to various greases to form a colloidal state of no bonding, which can increase the lubricity and extreme pressure of grease. It is also suitable for high temperature, high pressure, high speed and high load mechanical working condition to extend the life of equipment.
Molybdenum disulfide for friction materials is the main function of low-temperature friction reduction, high-temperature friction increase, small burn loss, easy to volatilize in the friction material.
Friction reduction: molybdenum disulfide processed by supersonic airflow has a particle size of 325-2500 mesh, a micro-particle hardness of 1-1.5, and a friction coefficient of 0.05-0.1, so it can be used in friction materials to reduce friction.
Increase friction: molybdenum disulfide does not conduct electricity, the presence of molybdenum disulfide, molybdenum trisulfide and molybdenum trioxide copolymer. When the friction material due to friction and a sharp rise in temperature, the copolymer of molybdenum trisulfide particles with the temperature and expansion, playing a role in increasing friction; anti-oxidation:
molybdenum disulfide is a chemical purification of the comprehensive reaction, its pH value of 7-8, slightly alkaline. It covers the surface of the friction material, can protect other materials, to prevent them from being oxidized, especially so that other materials are not easy to fall off, the adhesion force is enhanced.
Fineness: 325 mesh - 2500 mesh ;
PH value: 7-8;
Friction coefficient: 0.05-0.09.
In addition, molybdenum disulfide can be a new material for making transistors. Compared with graphene, which is also a two-dimensional material, molybdenum disulfide has an energy band gap of 1.8 eV, while graphene does not have an energy band gap, so molybdenum disulfide may have a wide range of applications in the field of nanotransistors. Moreover, the electron mobility of single-layer molybdenum disulfide transistors can reach up to about 500 cm^2/(V-s), and the current switching rate reaches 1×10^8.