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A true grease consists of an oil or other fluid lubricant that is mixed with a thickener, typically a soap, to form a solid or semisolid. [1] Greases are usually shear-thinning or pseudo-plastic fluids, which means that the viscosity of the fluid is reduced under shear stress.
A tube of commercial graphite powder lubricant with molybdenum disulfide additive (called "molybdenum") [33] Due to weak van der Waals interactions between the sheets of sulfide atoms, MoS 2 has a low coefficient of friction. MoS 2 in particle sizes in the range of 1–100 μm is a common dry lubricant. [34]
Motor oil, a common lubricant. A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces.
Synthetic lubricants were first made in significant quantities as replacements for mineral lubricants (and fuels) by German scientists in the late 1930s and early 1940s, because of their insufficient quantities of crude needed to fight in World War II.
Dry lubricants or solid lubricants are materials that, despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid oil medium. [1] The two main dry lubricants are graphite and molybdenum disulfide. They offer lubrication at temperatures higher than liquid and oil ...
Most computerized databases will create a table of thermodynamic values using the values from the datafile. For MgCl 2 (c,l,g) at 1 atm pressure: Thermodynamic properties table for MgCl 2 (c,l,g), from the FREED datafile. Some values have truncated significant figures for display purposes. The table format is a common way to display ...
Organo-molybdenum compounds, were initially developed as antiwear additives but were later recognized to be very effective in reducing boundary friction. [3] They are currently used in many engine oils and, more recently, in gear oils. [1] They reduce friction by forming two-dimensional molybdenum disulphide layers on rubbing surfaces. [4]
Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species. Within a mineral species there may be variation in physical properties or minor amounts of impurities that are recognized by mineralogists or wider society as a mineral variety.