Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy

Abstract Molybdenum dialkyl dithiocarbamate (MoDTC) is a friction reducing additive commonly used in lubricants. MoDTC works by forming a low-friction molybdenum disulphide (MoS2) film (tribofilm) on rubbed surfaces. MoDTC-induced MoS2 tribofilms have been studied extensively ex-situ; however, there...

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Autores principales:	Carlos E. Garcia, Mao Ueda, Hugh Spikes, Janet S. S. Wong
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/26a7a65dd8df4ac8945cb459624ea34c
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spelling	oai:doaj.org-article:26a7a65dd8df4ac8945cb459624ea34c2021-12-02T14:26:54ZTemperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy10.1038/s41598-021-81326-02045-2322https://doaj.org/article/26a7a65dd8df4ac8945cb459624ea34c2021-02-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-81326-0https://doaj.org/toc/2045-2322Abstract Molybdenum dialkyl dithiocarbamate (MoDTC) is a friction reducing additive commonly used in lubricants. MoDTC works by forming a low-friction molybdenum disulphide (MoS2) film (tribofilm) on rubbed surfaces. MoDTC-induced MoS2 tribofilms have been studied extensively ex-situ; however, there is no consensus on the chemical mechanism of its formation process. By combining Raman spectroscopy with a tribometer, effects of temperature and shear stress on MoS2 tribofilm formation in steel-steel contacts were examined. Time-resolved Raman spectra of the tribofilm were acquired, together with the instantaneous friction coefficient. The tribofilm is constantly being formed and removed mechanically during rubbing. Increasing shear stress promotes MoS2 formation. The nature of the tribofilm is temperature-dependent, with high-temperature tribofilms giving a higher friction than lower temperature films. Below a critical temperature T c, a small amount of MoS2 gives significant friction reduction. Above T c, a patchy film with more MoS2, together with a substantial amount of amorphous carbon attributed to base oil degradation, forms. The composition of this tribofilm evolves during rubbing and a temporal correlation is found between carbon signal intensity and friction. Our results highlight the mechanochemical nature of tribofilm formation process and the role of oil degradation in the effectiveness of friction modifier MoDTC.Carlos E. GarciaMao UedaHugh SpikesJanet S. S. WongNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-13 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Carlos E. Garcia Mao Ueda Hugh Spikes Janet S. S. Wong Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy
description	Abstract Molybdenum dialkyl dithiocarbamate (MoDTC) is a friction reducing additive commonly used in lubricants. MoDTC works by forming a low-friction molybdenum disulphide (MoS2) film (tribofilm) on rubbed surfaces. MoDTC-induced MoS2 tribofilms have been studied extensively ex-situ; however, there is no consensus on the chemical mechanism of its formation process. By combining Raman spectroscopy with a tribometer, effects of temperature and shear stress on MoS2 tribofilm formation in steel-steel contacts were examined. Time-resolved Raman spectra of the tribofilm were acquired, together with the instantaneous friction coefficient. The tribofilm is constantly being formed and removed mechanically during rubbing. Increasing shear stress promotes MoS2 formation. The nature of the tribofilm is temperature-dependent, with high-temperature tribofilms giving a higher friction than lower temperature films. Below a critical temperature T c, a small amount of MoS2 gives significant friction reduction. Above T c, a patchy film with more MoS2, together with a substantial amount of amorphous carbon attributed to base oil degradation, forms. The composition of this tribofilm evolves during rubbing and a temporal correlation is found between carbon signal intensity and friction. Our results highlight the mechanochemical nature of tribofilm formation process and the role of oil degradation in the effectiveness of friction modifier MoDTC.
format	article
author	Carlos E. Garcia Mao Ueda Hugh Spikes Janet S. S. Wong
author_facet	Carlos E. Garcia Mao Ueda Hugh Spikes Janet S. S. Wong
author_sort	Carlos E. Garcia
title	Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy
title_short	Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy
title_full	Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy
title_fullStr	Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy
title_full_unstemmed	Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy
title_sort	temperature dependence of molybdenum dialkyl dithiocarbamate (modtc) tribofilms via time-resolved raman spectroscopy
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/26a7a65dd8df4ac8945cb459624ea34c
work_keys_str_mv	AT carlosegarcia temperaturedependenceofmolybdenumdialkyldithiocarbamatemodtctribofilmsviatimeresolvedramanspectroscopy AT maoueda temperaturedependenceofmolybdenumdialkyldithiocarbamatemodtctribofilmsviatimeresolvedramanspectroscopy AT hughspikes temperaturedependenceofmolybdenumdialkyldithiocarbamatemodtctribofilmsviatimeresolvedramanspectroscopy AT janetsswong temperaturedependenceofmolybdenumdialkyldithiocarbamatemodtctribofilmsviatimeresolvedramanspectroscopy
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Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy

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