Lubricants are substances, usually organic, which are introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surface moves. It can also have the function of sending forces, transporting foreign particles, or heating or cooling surfaces. The reduced friction properties are known as lubricants.
In addition to industrial applications, lubricants are used for many other purposes. Other uses include cooking (oils and fats used in frying pans, roasting to prevent food from sticking), human bioapplications (eg lubricants for artificial joints), ultrasound examinations, medical examinations.
Video Lubricant
Histori
Lubicants have been used for thousands of years. Calcium soap has been identified on the dating wagons dating up to 1400 BC. The building blocks slip on the oil-treated wood at the time of the pyramid. In the Roman era, lubricants were based on olive oil and rapeseed oil, as well as animal fats. Lubricant growth accelerated in the Industrial Revolution with the use of accompanying metal-based machinery. Relying initially on natural oils, the need for such machinery shifted toward petroleum-based materials in the early 1900s. The breakthrough came with the development of petroleum vacuum distillation, as described by the Vaccum Oil Company. This technology allows the purification of highly non-flammable substances, which are common in many lubricants.
Maps Lubricant
Properties
A good lubricant generally has the following characteristics:
- High boiling point and freezing point (to remain liquid at various temperatures)
- High viscosity index
- Thermal stability
- Hydraulic stability
- Demulsibility
- Corrosion Prevention
- High resistance to oxidation
Formulation
Usually the lubricant contains 90% base oil (most often the petroleum fraction, called mineral oil) and less than 10% of the additives. Vegetable oils or synthetic liquids such as hydrogenated polyolefins, esters, silicon, fluorocarbons and many others are sometimes used as base oils. Additives produce reduced friction and wear, increase viscosity, increase viscosity index, corrosion resistance and oxidation, aging or contamination, etc.
Non-liquid lubricants include powder (dry graphite, PTFE, molybdenum disulfide, tungsten disulfide, etc.), PTFE tape used in pipes, air cushions and others. Dry lubricants such as graphite, molybdenum disulfide and tungsten disulfide also offer lubricants at temperatures (up to 350 ° C) higher than lubricated and oil-based lubricants that can operate. Limited interest has been shown in the low friction properties of a compacted oxide glaze layer that forms at several hundred degrees Celsius in a metallic shear system, but practical use is still many years away due to its unstable physical properties.
Additive
A large number of additives are used to implant performance characteristics into the lubricant. Modern automotive lubricant contains as many as ten additives, comprising up to 20% lubricant, the main additive family is:
- The depressant pour point is a compound that prevents wax crystallization. The long chain of alkylbenzenes attaches to the small crystals of the wax, preventing the growth of crystals.
- Anti-foaming agents are usually silicon compounds that reduce surface tension to prevent foam formation.
- Viscosity index improvers (VIIs) are compounds that allow lubricants to stay viscous at higher temperatures. Typical VII are polyacrylates and butadiene.
- Antioxidants suppress the oxidative degradation rate of hydrocarbon molecules in the lubricant. At low temperatures, free radical inhibitors such as blocked phenols are used, for example hydroxytoluene butylation. At temperature & gt; 90 Â ° C, in which the metal catalyzes the oxidation process, the dithiophosphate is more useful. In the last application the additive is called a metal deactivator.
- The detergent ensures the cleanliness of machine components by preventing the formation of precipitates on the contact surface at high temperatures.
- Corrosion inhibitors (rust inhibitors) are usually alkaline materials, such as alkylsulphonic salts, which absorb acids that will corrode metal parts.
- Anti-wear additives form a tribofilms protector on metal parts, depressing wear. They come in two classes depending on the forces that bind them to the surface. Popular examples include ester phosphate and zinc dithiophosphates.
- An extreme pressure additive (anti-scuffing) forms a protective film on the slipping metal parts. These agents are often sulfur compounds, such as dithiophosphates.
- The friction modifier reduces friction and wear, especially in the boundary lubrication regime where the surface becomes a direct contact.
Type of lubricant
In 1999, an estimated 37.3 million tonnes of lubricants were consumed worldwide. Automotive applications dominate, but industrial, marine, and other metal applications are also big consumers of lubricants. Although air lubricants and other gaseous lubricants are known (for example, in fluid bearings), liquid lubricants dominate the market, followed by solid lubricants.
Lubricants generally comprise most of the base oil plus various additives to provide the desired characteristics. Although most lubricants are based on one type of base oil, a mixture of base oil is also used to meet performance requirements.
Mineral oil
The term "mineral oil" is used to refer to lubricating oil derived from crude oil. The American Petroleum Institute (API) establishes several types of base oil lubricants:
- Group I - Saturation & lt; 90% and/or sulfur & gt; 0.03%, and the viscosity index of the Society of Automotive Engineers (SAE) (VI) 80 to 120
- Manufactured by solvent extraction, solvent or catalytic dewaxing, and a hydro finishing process. Common Group I base oils are 150SN (neutral solvent), 500SN, and 150BS (brightstock)
- Group II - Saturation & gt; 90% and sulfur & lt; 0.03%, and the viscosity index of SAE 80 to 120
- Produced by hydrocracking and solvent or catalytic dewaxing processes. The base group II oil has superior anti-oxidation properties because almost all of the hydrocarbon molecules are saturated. It's white-water.
- Group III - Saturation & gt; 90%, sulfur & lt; 0.03%, and the SAE viscosity index more than 120
- Produced by special processes such as isohydromerization. Can be made from base oil or slax wax from dewaxing process.
- Group IV 3 b- Polyalphaolefins (PAO)
- Group V - All others not included above such as naphthenics, PAG, l 80esters.
Lubricating industry generally extends the terminology of this group to include:
- Group I with a viscosity index of 103-108
- Group II with a viscosity index of 113-119
- Group III with a minimum viscosity index of 140
Can also be classified into three categories depending on the applicable composition:
- Paraffin
- Naphthenic
- Aromatic
Synthetic oil
Oil derivative lubricants can also be produced using synthetic hydrocarbons (derived from petroleum). These include:
- Polyalpha-olefin (PAO)
- Synthetic esters
- Polyalkylene glycols (PAG)
- Esther phosphate
- Naphthalene Alkylation (AN)
- Silicate ester
- Ionic Liquids
- Duplicate alkylated cyclopentane (MAC)
Solid lubricant
PTFE: polytetrafluoroethylene (PTFE) is usually used as a coating layer on, for example, cooking utensils to provide a non-stick surface. The temperature range that can be used up to 350 Â ° C and chemical inertia makes it a useful additive in special greases. Under extreme pressure, PTFE powder or solids have small values ​​because they are soft and flow away from the contact area. Ceramic or metal or alloy lubricants should be used later.
Inorganic solids: Graphite, hexagonal boron nitride, molybdenum disulfide and tungsten disulfide are examples of solid lubricants. Some retain their lubrication to a very high temperature. The use of some of these materials is sometimes limited by their poor resistance to oxidation (eg, molybdenum disulfide degraded above 350 ° C in air, but 1100 ° C in reducing the environment.
Metals/alloys: Metallic alloys, composites, and pure metals may be used as fat additives or sole surface components and shear bearings. Cadmium and gold are used for surface plating which gives them good corrosion resistance and shear properties. Lead, lead, zinc alloy and various bronze alloys are used as shear pads, or their powder can be used to lubricate the shear surface only.
Aqueous lubricant
Aqueous lubricants are attractive in a number of technological applications. A strong hydrated brushing polymer such as PEG can serve as a lubricant in a liquid solid interface. With the continuous rapid exchange of water bound to other free water molecules, this polymer film keeps the surface separate apart while maintaining high fluidity at the brush interface at high compression, thus leading to a very low coefficient of friction.
Biolubricants
Biolubrition comes from vegetable oils and other renewable sources. They are usually triglyceride esters (fats derived from plants and animals.For lubricants using basic oils, vegetable derivatives are preferred) The common ones include high canola oleic oil, castor oil, palm oil, sunflower seed oil and rapeseed oil from vegetables, and high oil from tree sources Many vegetable oils are often hydrolyzed to produce acids which are then selectively coupled to form a special synthetic ester. Other natural derived lubricants include lanolin (wool fat, natural water repellent).
Whale oil is an historically important lubricant, with several uses up to the latter part of the 20th century as a frictional change additive for automatic fluid transmission.
In 2008, the biolubricant market accounted for about 1% of UK lubricant sales in the total lubricant market of 840,000 tonnes/year.
Lubricant function
One of the biggest applications for lubricants, in the form of motor oil, is to protect internal combustion engines in motor vehicles and powered equipment.
Lubricant vs. Anti-tack Layer
Anti-tack or anti-stick layers are designed to reduce the adhesive condition of the given material. The rubber, hoses, and wire and cable industries are the largest consumer of anti-tack products but almost every industry uses some form of anti-sticking agent. The anti-stick agent is different from the lubricant because they are designed to reduce the adhesive quality of the particular compound while the lubricant is designed to reduce friction between two surfaces.
Keep separate the different parts
Lubrication is usually used to separate moving parts in a system. This separation has the benefit of reducing friction and surface fatigue, along with heat reduction, noise operation and vibration. Lubricants achieve this in several ways. The most common is to form a physical barrier that is, a thin layer of lubricant separates the moving parts. This is analogous to hydroplaning, the friction loss observed when a car tire is separated from the road surface by moving through a puddle. This is called hydrodynamic lubrication. In case of high pressure or surface temperature, the fluid film is much thinner and some forces are transmitted between the surfaces through the lubricant.
Decrease friction
Usually the lubricant-to-surface friction is much smaller than the surface friction to the surface in the system without lubrication. Thus the use of lubricants reduces overall system friction. Less friction has the benefit of reducing heat formation and reducing the formation of wear particles and improving efficiency. Lubricants may contain additives known as frictional modifiers that are chemically bonded to metal surfaces to reduce surface friction even when there is not sufficient bulk lubrication for hydrodynamic lubrication, eg. protect the valve train in car engine at startup.
Transfer heat
Gas and liquid lubricants can transfer heat. However, liquid lubricants are much more effective because of their high specific heat capacity. Usually the liquid lubricant is constantly circulated to and from the cooler parts of the system, although the lubricant can be used to warm and cool when the regulated temperature is required. This flow of circulation also determines the amount of heat carried over in any given time unit. High flow systems can carry a lot of heat and have the added benefit of reducing thermal pressures in lubricants. So a lower cost liquid lubricant can be used. The main drawback is that high currents usually require larger cooling units and larger cooling units. A secondary drawback is that a high flow system that depends on the flow rate to protect the lubricant from the thermal stress is susceptible to catastrophic failure during a sudden shutdown system. An automotive oil cooled turbocharger is a typical example. Turbochargers become red hot during operation and the oil cools them only because their staying time in the system is very short (ie high flow rate). If the system is turned off unexpectedly (pulls into the service area after high speed drive and stops the engine), the oil on the turbo charger will immediately oxidize and will clog oil with the sediment. Over time, these deposits can completely block the oil path, reducing cooling with the result that turbo chargers fail completely, usually with seized cushions. Non-flowing lubricants such as greases and pastes are not effective in heat transfer although they contribute by reducing heat generation in the first place.
Bring contaminants and debris
The lubricant circulation system has the benefit of carrying internally generated debris and external contaminants that are inserted into the system onto a filter where they can be removed. Lubricants for machines that regularly produce debris or contaminants such as automotive engines usually contain detergent and dispersant additives to assist in debris and transport of contaminants to filters and removals. Over time, the filter gets clogged and needs to be cleaned or replaced, then a recommendation to replace the car oil filter at the same time by changing the oil. In a closed system such as a filter gearbox may be equipped with magnets to attract the iron fines made.
It is clear that in the circulatory system, oil will be as clean as the filter that can make it, so it is unfortunate that there is no industry standard where consumers can easily assess the filtering ability of various automotive filters. Poor automotive filters significantly reduce machine life (engine) and make the system inefficient.
Transmit power
Lubricants known as hydraulic fluids are used as working fluids in hydrostatic power transmission. Hydraulic fluid consists of most of all the lubricants produced in the world. Automatic transmission torque converter is another important application for power transmission with lubricant.
Protect from wear
The lubricant prevents wear and tear by keeping the moving parts apart. Lubricants can also contain anti-wear or extreme pressure additives to improve their performance against wear and tiredness.
Prevents corrosion
Many lubricants are formulated with additives that form chemical bonds with surfaces or those that exclude water vapor, to prevent corrosion and rust. It reduces the corrosion between two metal surfaces and avoids contact between these surfaces to avoid submerged corrosion.
Seals for gas
The lubricant will occupy the distance between the moving parts through the capillary forces, thus sealing the clearance. This effect can be used to seal pistons and shafts.
Liquid type
- Automotive
- engine oil
- Engine oil (Gasoline)
- Diesel engine oil
- Automatic transmission fluid
- Fluid gearbox
- Brake fluid
- hydraulic fluid
- engine oil
- Tractors (one lubricant for all systems)
- Universal Tractor Transmission Oil - UTTO
- Super Tractor Oil Universal - STOU - including engines
- Other motor
- 2-stroke engine oil
- Industry
- Hydraulic oil
- Air compressor oil
- Food Grade Lubricant
- Gas Compressor Oil
- gear oil
- System oil pads and circulation
- Cooling compressor oil
- Steam and oil gas turbine
- Flights
- gas turbine engine oil
- Piston engine oil
- Marine
- Crosshead cylinder oils
- Crankcase Crosshead Oil
- Trunk piston engine oil
- Strong tube lubricant
Formation "Glaze" (using high temperature)
A further phenomenon that has undergone investigations in relation to the prevention of wear and high-temperature lubrication, is that the formation of glazed layers of oxide layer is compacted. Such glazing is produced by sintering a compacted oxide layer. Such a glaze is a crystal, in contrast to the amorphous glazes seen in pottery. The required high temperatures arise from the metal surfaces that glide against each other (or the metal surface against the ceramic surface). Due to the removal of metal contacts and adhesion by the generation of oxides, friction and wear are reduced. Effectively, such surfaces lubricate themselves.
Since the "ice sheet" is already an oxide, it can survive at very high temperatures in the air or oxidizing environments. However, it is impaired by the need for basic metals (or ceramics) to have to undergo some wear and tear in advance to produce enough oxide debris.
Disposal and environmental impact
It is estimated that 40% of all lubricants are released into the environment. Common disposal methods include recycling, burning, landfills, and discharges into water, although usually landfill and disposal into water are strictly regulated in most countries, since even small amounts of lubricants can contaminate large amounts of water. Most regulations permit possible threshold levels of lubricants in the waste stream and companies spend hundreds of millions of dollars each year in treating their waste water to reach acceptable levels.
Burning lubricants as fuel, usually to generate electricity, is also regulated by regulation mainly due to the relatively high additive rate. Combustion produces air pollutants and ash rich in toxic materials, especially heavy metal compounds. So the combustion of lubricants takes place in special facilities that have incorporated a special scrubber to remove air pollutants and have access to a landfill site with permission to handle toxic ash.
Unfortunately, most of the lubricants that end up directly in the environment are because the general public releases them to the ground, to the sewer and directly to landfills as waste. Other direct contamination sources include runoff from highways, accidental spills, natural or man-made disasters and pipeline leaks.
Improved technology and filtration processes have now recycled feasible options (with rising stock prices of base and crude oil). Normally various filtration systems remove particulates, additives and oxidizing products and restore base oils. Oil can be smooth during the process. These base oils are then treated just like basic pure oils but there is considerable reluctance to use recycled oil because they are generally considered lower. Basestock fractionally vacuum distilled from used lubricants has superior properties for all natural oils, but the cost effectiveness depends on many factors. Used lubricants can also be used as raw material for refineries to be part of the crude oil. Again, there is considerable reluctance to use this because additives, soot and metal wear will seriously poison/deactivate important catalysts in the process. The cost of prohibiting screening (soot, additive removal) and refining (refining, isomerization, hydrocracking, etc.) But the main obstacle to recycling remains a collection of liquids because refineries require a steady supply in quantities measured in water tanks, tank.
Sometimes, unused lubricants require disposal. The best action in such situations is to return it to the factory where it can be processed as part of the new batch.
Environment: New and used lubricants can cause enormous damage to the environment primarily because of the potential for serious water pollution. Further additives usually contained in lubricants can be toxic to flora and fauna. In the liquid used oxidation products can be toxic as well. The moisture content in the environment is heavily dependent on the basic liquid, but if a toxic additive is used they can affect the negative persistence. The non-toxic Lanolin lubricant makes it an environmentally safe alternative for users and the environment.
Society and industry body
- American Petroleum Institute (API)
- The Society of Tribologists and Lubrication Engineers (STLE)
- National Lubricating Grease Institute (NLGI)
- Society of Automotive Engineers (SAE)
- Independent Manufacturers' Lubricant Association (ILMA)
- The European Car Manufacturers Association (ACEA)
- Japan Automotive Standards Organization (JASO)
- Petroleum Packaging Council (PPC)
Main publication
- Peer reviews
- Lubricant
- Tribology International
- Tribology Transactions
- Synthetic Lubricant Journal
- Tribology Letter
- Lubrication Science
- Commerce periodically
- Tribology and Lubrication Technology
- Fuel & amp; Lubes International
- Oiltrends
- Lubes n 'Grease
- Compounds
- Chemical Market Reviews
- Machine lubrication
See also
- Fat (lubricant)
- Lubrication
- Motor oil
- Oil analysis
- Translucent oil
- The Association of Tribologists and Lubrication Engineers
- Tribology
References
Note
Source
- API 1509, Engine Oil Licensing and Certification Systems, 15th Edition, 2002. Appendix E, Basic API Oil Adjustment Guidelines for Passenger Car Engines and Diesel Engine Oil (revised)
- Boughton and Horvath, 2003, Environmental Assessment of Used Oil, Environmental Science and Technology Methods, V38
- I.A. Inman. Created Oxide Layer Formation under Limited Lost Retention Conditions on the Cushioned Interface during High Frequency Superalloy Shear Use , Ph.D. Thesis (2003), University of Northumbria ISBNÃ, 1-58112-321-3
- Mercedes-Benz oil recommendations, extracted from factory manuals and personal research
- Measure the backup alkalinity and evaluation of wear dependencies
- Testing uses oil quality, a list of possible measurements
- Lubricant Additives: Chemicals and Applications, Leslie R. Rudnick, CRC Press.
External links
- SAE-ISO-AGMA viscosity conversion graph
- Gravity API Chart and Specific Gravity
Source of the article : Wikipedia
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