MoS₂ formation induced by amorphous MoS₃ species under lubricated friction

Abstract

In order to investigate the decomposition mechanism of amide molybdate, two series of experimental friction tests have been performed, varying the temperature and pressure.

Mo(VI) dithiocarbamate with no pre-existing Mo–S–Mo core as an active lubricant additive

“…The two MoS2 characteristic Raman shifts 1 and 1 at 373 cm -1 and 405 cm -1 , respectively, are detected, in agreement with Raman analyses of MoDTC tribofilms [10,14,25]. The presence of amorphous MoS3 compound [26] could explain the background shape near 2 1 and 1 . The presence of Fe(MoO4) is suggested by the presence of the Raman peak at 925 cm -1 [7] and is consistent with the Mo (+VI) oxide contribution detected by XPS at 232.3 eV on Mo3d peak.…”

Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature

“…The MRS spectrum of the unworn coating (area A1, Figure 8) was attributable to its amorphous structure, in which there were regions of local atomic ordering into lamellar clusters (layer-type MoS 2 ); this was evidenced by narrow peaks at 410 and 370 cm −1 , which stood out clearly against the wide bands of the amorphous MoS 2 . These peaks were caused by the vibrations of A 1g and E 2g 1 , respectively, in the hexagonal 2H-MoS 2 structure [34,35,41].…”

“…Nanomaterials 2020, 10, x FOR PEER REVIEW 12 of 21 were caused by the vibrations of A1g and E2g 1 , respectively, in the hexagonal 2H-MoS2 structure [34,35,41]. For the MoS2 coating, in the regions of the sliding track that were not subject to substantial wear (area A2, Figure 8), the peak intensity grew significantly at 410 cm −1 ; this points to an increased content of lamellar material and/or increased crystallinity in these regions.…”

“…S 2− and S 2 2− ligands mold the Mo atoms into a curved chain. MoS 3 -based nanomaterials may exhibit better antifriction behavior at normal temperatures and humidity when they are in the form of coatings or additives (to hydrocarbon lubricants) [33][34][35]. The tribo-induced formation of a tribo-film with a 2H-MoS 2 lamellar structure was found on the contact surface of these nanomaterials in normal environmental conditions (in terms of sliding friction).…”

Влияние химического состава и локальной атомной упаковки твердосмазочных нанопокрытий MoS-=SUB=-x-=/SUB=- и MoSe-=SUB=-x-=/SUB=- на их трибологические свойства в осложненных условиях

“…Проведенные исследования позволяют предположить, что причина обнаруженного явления обусловлена особенностями химического состояния атомов S и специфической локальной упаковкой атомов в соединении MoS 3 . Нельзя исключить, что при трении поверхностный слой этого покрытия претерпевает трансформацию с формированием слоистой атомной упаковки [9]. Однако эти изменения могут протекать в очень тонком поверхностном слое, что исключало возможность эффективного проникновения молекул H 2 O и O 2 в объем MoS 3 .…”