AW additive
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170750447
2007-11-11T14:21:43Z
Uruiamme
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New category, cleanup
'''AW additives''', or '''antiwear additives''', are [[Oil additive|additives]] for [[lubricants]] to prevent metal-to-metal contact between parts of [[gear]]s.
[[EP additives]] are usually used in applications such as [[transmission (mechanics)|gearboxes]], while AW additives are used with lighter loads such as [[bush (mechanical)|bushings]].
AW additives typically contain [[zinc]] and [[phosphorus]] compounds.
Some popular AW additives are:
* [[zinc dithiophosphate]] (ZDP)
* [[zinc dialkyl dithio phosphate]] (ZDDP), probably the most widely used in formulated [[engine oil]]s, also acts as a [[corrosion inhibitor]] and [[antioxidant]]
* [[Tricresyl phosphate]] (TCP), used for high-temperature operation, often used as an AW and EP additive in turbine engine lubricants, and also in some crankcase oils and [[hydraulic fluid]]s
* [[Halocarbon]]s ([[chlorinated paraffins]]), for extreme pressure operations
* [[Glycerol mono oleate]]
* [[Stearic acid]], adhering to surfaces via reversible adsorption process under 150 °C, which limits its use to mild contact conditions.
Some formulations use [[colloid]]al [[polytetrafluorethylene|PTFE]] ([[Teflon]]), but its efficiency is controversial.
Many AW additives function as EP additives, for example [[organophosphate]]s or [[sulfur]] compounds.
The mechanism of function of TCP and ZDDP is explained in [[EP additive]]s.
Under extreme pressure conditions, the performance of AW additives becomes insufficient and designated [[EP additive]]s are required.
See also:
* [[EP additive]]s
* [[Oil additive]]
[[Category:Lubricants]]
[[Category:Oil additives]]