What is a strong lubricant?
A solid lubricant is a form of fabric that reduces the friction coefficient and put on by means of preventing direct touch of friction components under regular use or excessive load. In super instances wherein liquid lubricants consisting of oil and grease can’t be used, stable lubricants have a first-rate utility market. Except, the stable lubricant is also an additive cloth for high-performance anti-chunk and anti-put on coatings. It’s far regularly mixed with grease and lubricating oil in the form of powder particles to play a sliding function. This type of special solid lubricant will slip when the friction pair slides distinctly Fill out tough surfaces. Consequently, below excessive working conditions, strong lubricant gives enough boundary lubrication situations, thereby decreasing the friction coefficient and decreasing wear. Generally talking, stable lubricants have a higher benefit than liquid oils beneath high vacuum situations beneath 10-2 Pa and near atmospheric stress above 104 Pa, and coffee temperatures beneath 0℃and excessive temperatures above 177℃.
There are five foremost varieties of solid lubricants: carbon-based materials, transition metallic disulfides (including mos2 and ws2), polymers (which include PTFE lubricant), soft metallic, and ceramic excessive-temperature lubricating materials. among them, carbon-based materials and transition metal disulfides belong to the standard layered structure solid lubricant.
(1) Carbon-based lubricating fabric
Graphite is a regular carbon-based lubricating fabric with excessive-temperature resistance and corrosion resistance and is thought for its dependable lubrication characteristics. Graphite has a layered solid with a hexagonal lattice. The atoms within the carbon base plane are bonded collectively by way of robust covalent bonds, at the same time as the bottom planes are blended via vulnerable Van der Waals forces, ensuing in a broken mechanical dating among the plane. The presence of water vapor and oxygen within the surroundings can promote the shear movement between graphite crystal layers. When the bottom floor is worn, those lively edges are neutralized (passivated) by way of adsorbing water or other vapors. Graphite also can keep low friction. This is genuine for different carbon-based solid lubricants. Carbon-primarily based lubricants also consist of various sorts of DLC coatings and occasional-friction carbon coatings (NFC).
(2) Transition metal organization disulfide (TMD) lubricating materials
Within the TMD own family, MoS2 and WS2 have broadly used for their reliable lubrication overall performance. The number one mechanism for achieving low shear resistance on the interface is a base surface oriented parallel to the sliding course and a switch movie fashioned at the friction couple. MoS2 and WS2 coatings do now not oxidize or react with water vapor in a dry gas or extremely-high vacuum, thereby maintaining their dependable inner lubrication. However, in humid air, friction oxides along with MoO3 and WO3 may be formed because of the dangling or unsaturated bonds on the edge of the base surface reacting with water vapor or oxygen in the surroundings. Presently, the sliding friction coefficient is pretty excessive (0.15 ~ 0.2), and the wear lifestyles are likewise concise.
(3) PTFE lubricant:
Polymer strong lubricant is usually deposited inside the shape of a coating (movie) at the surface of a substrate (inclusive of polymer-primarily based engine bearing cowl). The molecular shape of those substances includes long chains parallel to every difference, and the bond strength between molecules susceptible might also slip beneath low shear pressure. PTFE is common for such solid lubricants. In contrast to another solid lubricant, PTFE does not have a layered structure, however PTFE macromolecules without difficulty slide, just like a layered shape. The minimum static and dynamic coefficient of friction of PTFE can be decreased to 0.04. The PTFE-lined metal can be used beneath the harsh temperature, stress, and medium, and may attain an extended protection period. Polymer-based total nanocomposites, together with PTFE / nano Al2O3, also show top-notch friction overall performance beneath distinctive test conditions.
(4) soft steel lubricating materials
Due to low shear strength and high plasticity, some smooth metals additionally have lubricating homes inclusive of lead, tin, bismuth, indium, zinc, cadmium, and precious metals, including gold and silver. For example, Zn and Sn had been used in sliding bearings, while valuable metals inclusive of gold and silver have started inside the aerospace industry. In daily life, smooth metals are widely used as stable lubricants in engine bearing substances.
Gentle metals used as strong lubricant substances generally have a face-focused cubic lattice, so their crystals are all isotropic. Consequently, those smooth metals do no longer have a high bearing potential, and the external load can best be borne with the aid of the substrate. Some other advantage of face-focused cubic crystals is that there’s no low-temperature brittleness, and the lubricating houses will now not be misplaced in low-temperature environments.
(5) excessive temperature resistant lubricating substances
Certain oxides, which include B2O3, MoO2, MoO3, ZnO, Re2O7, TiO2, V2O5, and PbO, etc., have decrease melting factors, soften at high temperatures, and feature better homes.