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Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
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.
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 interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. Tribology is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. People who work in the field of tribology are referred to as tribologists.
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.
In materials science, asperity, defined as "unevenness of surface, roughness, ruggedness", has implications in physics and seismology. Smooth surfaces, even those polished to a mirror finish, are not truly smooth on a microscopic scale. They are rough, with sharp, rough or rugged projections, termed "asperities". Surface asperities exist across multiple scales, often in a self affine or fractal geometry. The fractal dimension of these structures has been correlated with the contact mechanics exhibited at an interface in terms of friction and contact stiffness.
Silver molybdate (Ag2MoO4), a chemical compound, is a yellow, cubic crystalline substance often used in glass. Its crystals present two types of electronic structure, depending on the pressure conditions to which the crystal is subjected. At room temperature, Ag2MoO4 exhibits a spinel-type cubic structure, known as β-Ag2MoO4, which is more stable in nature. However, when exposed to high hydrostatic pressure, the tetragonal α-Ag2MoO4 forms as a metastable phase.
Compacted oxide layer glaze describes the often shiny, wear-protective layer of oxide formed when two metals are slid against each other at high temperature in an oxygen-containing atmosphere. The layer forms on either or both of the surfaces in contact and can protect against wear.
Friction modifiers are added to lubricants in order to reduce friction and wear in machine components. They are particularly important in the boundary lubrication regime, where they can prevent solid surfaces from coming into direct contact, substantially reducing friction and wear.
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.
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.
Chameleon coating, also known as nano composite tribological coating, is an adaptive adhesive that uses nanotechnology to adjust to environmental fluctuations to make living conditions more suitable to the object that the coat has been applied to.
Tribocorrosion is a material degradation process due to the combined effect of corrosion and wear. The name tribocorrosion expresses the underlying disciplines of tribology and corrosion. Tribology is concerned with the study of friction, lubrication and wear and corrosion is concerned with the chemical and electrochemical interactions between a material, normally a metal, and its environment. As a field of research tribocorrosion is relatively new, but tribocorrosion phenomena have been around ever since machines and installations are being used.
Space tribology is a discipline in the field of tribology which deals with tribological systems for spacecraft applications. Research in the field aims to design reliable tribological systems that can withstand the harsh environment of space.
Hugh Alexander Spikes is a British mechanical engineer. as of 2021, 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.
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:
Robert William Carpick is a Canadian mechanical engineer. He is currently director of diversity, equity, and inclusion and John Henry Towne Professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. He is best known for his work in tribology, particularly nanotribology.
Plastic coating is a term that is commonly used in technology but is nevertheless ambiguous. It can be understood to mean the coating of plastic or the coating of other materials with plastics.
Qian Jane Wang is an American professor of mechanical engineering and the Executive Director for the Center for Surface Engineering and Tribology at Northwestern University. She is a tribologist whose research includes work on contact mechanics, lubrication, micromechanics, and solid-state batteries.
References
- 1 2 3 Kapsa, Ph.; Martin, J.M. (1982). "Boundary lubricant films: a review". Tribology International. 15 (1): 37–42. doi:10.1016/0301-679x(82)90110-4.
- ↑ Hsu, S.M.; Gates, R.S. (2005). "Boundary lubricating films: formation and lubrication mechanism". Tribology International. 38 (3): 305–312. doi:10.1016/j.triboint.2004.08.021.
- ↑ Qu, Jun; Chi, Miaofang; Meyer, Harry M.; Blau, Peter J.; Dai, Sheng; Luo, Huimin (2011-08-01). "Nanostructure and Composition of Tribo-Boundary Films Formed in Ionic Liquid Lubrication". Tribology Letters. 43 (2): 205–211. doi:10.1007/s11249-011-9800-z. ISSN 1023-8883. S2CID 137805525.
- ↑ Nyberg, Erik; Mouzon, Johanne; Grahn, Mattias; Minami, Ichiro (2017-04-26). "Formation of Boundary Film from Ionic Liquids Enhanced by Additives". Applied Sciences. 7 (5): 433. doi: 10.3390/app7050433 .
- ↑ Biswas, S.K (2000). "Some mechanisms of tribofilm formation in metal/metal and ceramic/metal sliding interactions". Wear. 245 (1–2): 178–189. doi:10.1016/s0043-1648(00)00477-4.
- ↑ Morina, Ardian; Neville, Anne (2007). "Tribofilms: aspects of formation, stability and removal". Journal of Physics D: Applied Physics. 40 (18): 5476–5487. Bibcode:2007JPhD...40.5476M. doi:10.1088/0022-3727/40/18/s08. S2CID 59488187.
- ↑ Shimizu, Yasunori; Spikes, Hugh A. (2016-12-01). "The Tribofilm Formation of ZDDP Under Reciprocating Pure Sliding Conditions". Tribology Letters. 64 (3): 46. doi: 10.1007/s11249-016-0776-6 . ISSN 1023-8883.
- ↑ Gosvami, N. N.; Bares, J. A.; Mangolini, F.; Konicek, A. R.; Yablon, D. G.; Carpick, R. W. (2015-04-03). "Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts" (PDF). Science. 348 (6230): 102–106. Bibcode:2015Sci...348..102G. doi: 10.1126/science.1258788 . ISSN 0036-8075. PMID 25765069.