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Mechanisms of varnish formation and implications for the use of varnish-removal technology

TitleMechanisms of varnish formation and implications for the use of varnish-removal technology
Publication TypeConference Paper
Year of Publication2017
AuthorsHobbs, MG, Dufresne, P, Behyan, S, Kennepohl, P
Conference Name72nd Annual Meeting and Exhibition of the Society of Tribologists and Lubrication Engineers, STLE 2017
KeywordsElectron Paramagnetic Resonance Spectroscopy, Radical chemistry
Abstract

Thermo-oxidative lubricant breakdown leads to varnish formation. Radical process. EPR study of radical intermediates involved in oxidation revealed:•Initiation of breakdown does not require O2 as previously thought.Oil hydrocarbons form radicals on their own. Role of O 2 : trap which promotes radical propagation. Results in O 2 incorporation to form polar breakdown products. Polar products result in varnish formation.2 Strategies to mitigate the risk of lubricant varnishing: 1.Don't allow polar breakdown products to form: • Limit lubricant exposure to O 2 using inert N 2 blanket. 2. Remove any polar breakdown products which do form: • Use resin to remove soluble polar species before they can form varnish. Improve lubricant condition and maintain it even under degrading conditions.