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A lubricant 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. The property of reducing friction is known as lubricity.
Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, detergents, dispersants, and, for multi-grade oils, viscosity index improvers. The main function of motor oil is to reduce friction and wear on moving parts and to clean the engine from sludge and varnish (detergents). It also neutralizes acids that originate from fuel and from oxidation of the lubricant (detergents), improves the sealing of piston rings, and cools the engine by carrying heat away from moving parts.
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology.
Wear is the damaging, gradual removal or deformation of material at solid surfaces. Causes of wear can be mechanical or chemical. The study of wear and related processes is referred to as tribology.
Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. Subfields of tribology include biotribology, nanotribology and space tribology. It is also related to other areas such as the coupling of corrosion and tribology in tribocorrosion and the contact mechanics of how surfaces in contact deform. Approximately 20% of the total energy expenditure of the world is due to the impact of friction and wear in the transportation, manufacturing, power generation, and residential sectors.
Synthetic oil is a lubricant consisting of chemical compounds that are artificially modified or synthesised. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials. The base material, however, is still overwhelmingly crude oil that is distilled and then modified physically and chemically. The actual synthesis process and composition of additives is generally a commercial trade secret and will vary among producers.
A plain bearing, or more commonly sliding contact bearing and slide bearing, is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.
Oil analysis (OA) is the laboratory analysis of a lubricant's properties, suspended contaminants, and wear debris. OA is performed during routine predictive maintenance to provide meaningful and accurate information on lubricant and machine condition. By tracking oil analysis sample results over the life of a particular machine, trends can be established which can help eliminate costly repairs. The study of wear in machinery is called tribology. Tribologists often perform or interpret oil analysis data.
Zinc dialkyldithiophosphates are a family of coordination compounds developed in the 1940s that feature zinc bound to the anion of a dialkyldithiophosphoric salt. These uncharged compounds are not salts. They are soluble in nonpolar solvents, and the longer-chain derivatives easily dissolve in mineral and synthetic oils used as lubricants. They come under CAS number . In aftermarket oil additives, the percentage of ZDDP ranges approximately between 2 and 15%. Zinc dithiophosphates have many names, including ZDDP, ZnDTP, and ZDP.
Solid film lubricants are paint-like coatings of very fine particles of lubricating pigment blended with a binder and other additives. The lubricant is applied to a substrate by spray, dip or brush methods and, once cured, creates a solid film which repels water, reduces friction and increases the wear life of the substrate to which it has been applied. Certain film lubricants also offer additional properties such as corrosion inhibition. Solid film lubricants are used in the automotive, transportation and aerospace industries. 2 commonly used ones are graphite and molybdenum disulfide.
Oil additives are chemical compounds that improve the lubricant performance of base oil. The manufacturer of many different oils can utilize the same base stock for each formulation and can choose different additives for each specific application. Additives comprise up to 5% by weight of some oils.
The Stribeck curve is a fundamental concept in the field of tribology. It shows that friction in fluid-lubricated contacts is a non-linear function of the contact load, the lubricant viscosity and the lubricant entrainment speed. The discovery and underlying research is usually attributed to Richard Stribeck and Mayo D. Hersey, who studied friction in journal bearings for railway wagon applications during the first half of the 20th century; however, other researchers have arrived at similar conclusions before. The mechanisms along the Stribeck curve have been understood today also on the atomistic level.
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.
Albert Kingsbury was an American engineer, inventor and entrepreneur. He was responsible for over fifty patents obtained between the years 1902 to 1930. Kingsbury is most famous for his hydrodynamic thrust bearing which uses a thin film of oil to support weights of up to 220 tons. This bearing extended the service life of many types of machinery during the early 20th century. It was primarily outfitted on Navy ships during World War I and World War II.
Automotive oil recycling involves the recycling of used oils and the creation of new products from the recycled oils, and includes the recycling of motor oil and hydraulic oil. Oil recycling also benefits the environment: increased opportunities for consumers to recycle oil lessens the likelihood of used oil being dumped on lands and in waterways. For example, one gallon of motor oil dumped into waterways has the potential to pollute one million gallons of water.
Hugh Alexander Spikes is a British mechanical engineer. He is emeritus professor of tribology at Imperial College London. He is the former head of the Tribology Group at Imperial College. Tribology is the science and engineering of friction, lubrication and wear.
Tribofilms are films that form on tribologically stressed surfaces. Tribofilms are mostly solid surface films that result from a chemical reaction of lubricant components or tribological surfaces.
Selda Gunsel is a Turkish-American chemical engineer. She is currently President of Shell Global Solutions and Vice President (VP) for Global Commercial Technology at Royal Dutch Shell.
Extreme tribology refers to tribological situations under extreme operating conditions which can be related to high loads and/or temperatures, or severe environments. Also, they may be related to high transitory contact conditions, or to situations with near-impossible monitoring and maintenance opportunities. In general, extreme conditions can typically be categorized as involving abnormally high or excessive exposure to e.g. cold, heat, pressure, vacuum, voltage, corrosive chemicals, vibration, or dust. The extreme conditions should include any device or system requiring a lubricant operating under any of the following conditions:
White etching cracks (WEC), or white structure flaking or brittle flaking, is a type of rolling contact fatigue (RCF) damage that can occur in bearing steels under certain conditions, such as hydrogen embrittlement, high stress, inadequate lubrication, and high temperature. WEC is characterised by the presence of white areas of microstructural alteration in the material, which can lead to the formation of small cracks that can grow and propagate over time, eventually leading to premature failure of the bearing. WEC has been observed in a variety of applications, including wind turbine gearboxes, automotive engines, and other heavy machinery. The exact mechanism of WEC formation is still a subject of research, but it is believed to be related to a combination of microstructural changes, such as phase transformations and grain boundary degradation, and cyclic loading.
References
- 1 2 3 4 5 Spikes, Hugh (2015-10-01). "Friction Modifier Additives". Tribology Letters. 60 (1): 5. doi:10.1007/s11249-015-0589-z. hdl: 10044/1/25879 . ISSN 1023-8883. S2CID 137884697.
- ↑ Hardy, W. B.; Doubleday, Ida (1922-03-01). "Boundary Lubrication. The Paraffin Series". Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 100 (707): 550–574. Bibcode:1922RSPSA.100..550H. doi: 10.1098/rspa.1922.0017 . ISSN 1364-5021.
- ↑ Braithwaite, E. R.; Greene, A. B. (1978-02-01). "A critical analysis of the performance of molybdenum compounds in motor vehicles". Wear. 46 (2): 405–432. doi:10.1016/0043-1648(78)90044-3.
- ↑ Grossiord, C; Varlot, K; Martin, J. -M; Le Mogne, Th; Esnouf, C; Inoue, K (1998-12-01). "MoS2 single sheet lubrication by molybdenum dithiocarbamate". Tribology International. 31 (12): 737–743. doi:10.1016/S0301-679X(98)00094-2. ISSN 0301-679X.
- ↑ Guangteng, G; Smeeth, M; Cann, P M; Spikes, H A (1996-03-01). "Measurement and Modelling of Boundary Film Properties of Polymeric Lubricant Additives". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology. 210 (1): 1–15. doi:10.1243/PIME_PROC_1996_210_473_02. ISSN 1350-6501. S2CID 136658009.
- ↑ Dai, Wei; Kheireddin, Bassem; Gao, Hong; Liang, Hong (2016-10-01). "Roles of nanoparticles in oil lubrication". Tribology International. 102: 88–98. doi:10.1016/j.triboint.2016.05.020. ISSN 0301-679X.
- ↑ Holmberg, Kenneth; Andersson, Peter; Erdemir, Ali (2012-03-01). "Global energy consumption due to friction in passenger cars". Tribology International. 47 (Supplement C): 221–234. doi:10.1016/j.triboint.2011.11.022.
- ↑ Campen, Sophie; Green, Jonathan; Lamb, Gordon; Atkinson, David; Spikes, Hugh (2012-11-01). "On the Increase in Boundary Friction with Sliding Speed". Tribology Letters. 48 (2): 237–248. doi:10.1007/s11249-012-0019-4. ISSN 1023-8883. S2CID 135749402.
- ↑ Ewen, James P.; Gattinoni, Chiara; Morgan, Neal; Spikes, Hugh A.; Dini, Daniele (2016-05-10). "Nonequilibrium Molecular Dynamics Simulations of Organic Friction Modifiers Adsorbed on Iron Oxide Surfaces". Langmuir. 32 (18): 4450–4463. doi: 10.1021/acs.langmuir.6b00586 . hdl: 10044/1/30875 . ISSN 0743-7463. PMID 27064962.