AW additive 3155665 170750447 2007-11-11T14:21:43Z Uruiamme 1540803 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]]