Lubricant
Other uses include cooking (oils and fats in use in frying pans and baking to prevent food sticking), to reduce rusting and friction in machinery, through the use of motor oil and grease, bioapplications on humans (e.g., lubricants for artificial joints), ultrasound examination, medical examination, and sexual intercourse.
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.
Lubricants are generally composed of a majority of base oil plus a variety of additives to impart desirable characteristics.
Its usable temperature range up to 350 °C and chemical inertness make it a useful additive in special greases, where it can function both as a thickener and a lubricant.
The use of some such materials is sometimes restricted by their poor resistance to oxidation (e.g., molybdenum disulfide degrades above 350 °C in air, but 1100 °C in reducing environments.
Many vegetable oils are often hydrolyzed to yield the acids which are subsequently combined selectively to form specialist synthetic esters.
[10] Whale oil was a historically important lubricant, with some uses up to the latter part of the 20th century as a friction modifier additive for automatic transmission fluid.
Grain-growers trialling the product have welcomed the innovation, with one describing it as needing very little refining, biodegradable, a bioenergy and biofuel.
In most common greases, the thickener is a light or alkali metal soap, forming a sponge-like structure that encapsulates the oil droplets.
This is analogous to hydroplaning, the loss of friction observed when a car tire is separated from the road surface by moving through standing water.
High flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the lubricant.
The primary drawback is that high flows typically require larger sumps and bigger cooling units.
Turbochargers get red hot during operation and the oil that is cooling them only survives as its residence time in the system is very short (i.e. high flow rate).
Over time these deposits can completely block the oil ways, reducing the cooling with the result that the turbo charger experiences total failure, typically with seized bearings.
In closed systems such as gear boxes the filter may be supplemented by a magnet to attract any iron fines that get created.
Poor automotive filters significantly reduce the life of the machine (engine) as well as make the system inefficient.
Many lubricants are formulated with additives that form chemical bonds with surfaces or that exclude moisture, to prevent corrosion and rust.
A further phenomenon that has undergone investigation in relation to high-temperature wear prevention and lubrication is that of a compacted oxide layer glaze formation.
Due to the elimination of metallic contact and adhesion by the generation of oxide, friction and wear is reduced.
[citation needed] Burning the lubricant as fuel, typically to generate electricity, is also governed by regulations mainly on account of the relatively high level of additives present.
Burning generates both airborne pollutants and ash rich in toxic materials, mainly heavy metal compounds.
Other direct contamination sources include runoff from roadways, accidental spillages, natural or man-made disasters, and pipeline leakages.
Improvement in filtration technologies and processes has now made recycling a viable option (with the rising price of base stock and crude oil).
Typically various filtration systems remove particulates, additives, and oxidation products and recover the base oil.
Basestock fractionally vacuum distilled from used lubricants has superior properties to all-natural oils, but cost-effectiveness depends on many factors.
Cost prohibits carrying out both filtration (soot, additives removal) and re-refining (distilling, isomerization, hydrocrack, etc.)
however the primary hindrance to recycling still remains the collection of fluids as refineries need continuous supply in amounts measured in cisterns, rail tanks.
