Anti-wear additives form protective 'tribofilms' on metal parts, suppressing wear.Corrosion inhibitors (rust inhibitors) are usually alkaline materials, such as alkylsulfonate salts, that absorb acids that would corrode metal parts.Detergents ensure the cleanliness of engine components by preventing the formation of deposits on contact surfaces at high temperatures.In the latter application the additives are called metal deactivators.
At temperatures >90 ☌, where the metals catalyze the oxidation process, dithiophosphates are more useful.
#HIGH VISCOSITY LIQUID FILLING MACHINE FREE#
At low temperatures, free radical inhibitors such as hindered phenols are used, e.g.
Antioxidants suppress the rate of oxidative degradation of the hydrocarbon molecules within the lubricant. Typical VIIs are polyacrylates and butadiene. Viscosity index improvers (VIIs) are compounds that allow lubricants to remain viscous at higher temperatures. Anti-foaming agents are typically silicone compounds which increase surface tension in order to discourage foam formation. Long chain alkylbenzenes adhere to small crystallites of wax, preventing crystal growth. Pour point depressants are compounds that prevent crystallization of waxes. Modern automotive lubricants contain as many as ten additives, comprising up to 20% of the lubricant, the main families of additives are: Limited interest has been shown in low friction properties of compacted oxide glaze layers formed at several hundred degrees Celsius in metallic sliding systems, however, practical use is still many years away due to their physically unstable nature.Ī large number of additives are used to impart performance characteristics to the lubricants. Dry lubricants such as graphite, molybdenum disulphide and tungsten disulphide also offer lubrication at temperatures (up to 350 ☌) higher than liquid and oil-based lubricants are able to operate. Non-liquid lubricants include powders (dry graphite, PTFE, molybdenum disulphide, tungsten disulphide, etc.), PTFE tape used in plumbing, air cushion and others. Additives deliver reduced friction and wear, increased viscosity, improved viscosity index, resistance to corrosion and oxidation, aging or contamination, etc. Vegetable oils or synthetic liquids such as hydrogenated polyolefins, esters, silicones, fluorocarbons and many others are sometimes used as base oils. Typically lubricants contain 90% base oil (most often petroleum fractions, called mineral oils) and less than 10% additives. Pour Point (the minimum temperature at which oil will flow under prescribed test conditions). A high boiling point and low freezing point (in order to stay liquid within a wide range of temperature). 
Properties Ī good lubricant generally possesses the following characteristics: This technology allowed the purification of very nonvolatile substances, which are common in many lubricants. A breakthrough came with the development of vacuum distillation of petroleum, as described by the Vacuum Oil Company. Relying initially on natural oils, needs for such machinery shifted toward petroleum-based materials early in the 1900s. The growth of lubrication accelerated in the Industrial Revolution with the accompanying use of metal-based machinery. In the Roman era, lubricants were based on olive oil and rapeseed oil, as well as animal fats. Building stones were slid on oil-impregnated lumber in the time of the pyramids. Calcium soaps have been identified on the axles of chariots dated to 1400 BC. Lubricants have been in some use for thousands of years. It is mainly used to reduce friction and to contribute to a better and efficient functioning of a mechanism. Other uses include cooking ( oils and fats in use in frying pans, in baking to prevent food sticking), bioapplications on humans (e.g., lubricants for artificial joints), ultrasound examination, medical examination, and sexual intercourse. In addition to industrial applications, lubricants are used for many other purposes. The property of reducing friction is known as lubricity. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces.
JSTOR ( March 2023) ( Learn how and when to remove this template message)Ī 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. Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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