Formation of Wear-Protective Tribofilms on Different Steel Surfaces During Lubricated Sliding

Abstract

We report here the impact of different alloying elements in steels on friction and wear behavior by performing ball-on-at lubricated reciprocating tribotesting experiments on 52100 ball on steel ats with different compositions (52100, 1045, A2, D2, M2, and a specialty Cu-alloyed steel) heat-treated to give similar hardness and microstructure, with polyalphaole n (PAO-4) as the lubricant. There are small variations of coe cient of friction among these alloys. The major observation is that steels containing high concentrations (≥ 10 wt.%) of Cr, Mo, and V gave rise to markedly reduced wear compared with 52100 or plain carbon steels. D2 steel, which contains 11.5 wt.% Cr as the major alloying element was the most wear-resistant. The wear resistance is strongly correlated with the e ciency of formation of carboncontaining oligomeric lms at specimen surfaces as determined by Raman spectroscopy. This correlation holds for steels heat-treated to have higher hardness and with n-dodecane, a much less viscous lubricant compared with PAO-4. Given the strong a nity of chromium to oxygen, chromium should exist as Cr 2 O 3 at the steel surfaces during testing. We have performed molecular dynamics simulation on Cr 2 O 3 and demonstrated its ability to catalyze the formation of carbon-containing oligomeric lms from hydrocarbon molecules, consistent with its known catalytic activity in other hydrocarbon reactions. We believe that chromium-containing alloys, such as D2, and coatings, such as CrN, derive their wear resistance in part from the e cient in-situ formation of wear-protective carbon tribo lms at contacting asperities.

Effect of Cu and Ni Inclusion on Tribological Performance of Tribocatalytically Active Coatings in Hydrocarbon Environments

“…Raman spectroscopy findings suggest that these carbon layers exhibit a combination of D (at approximately 1351 cm −1 ) and G (at approximately 1580 cm −1 ) bands, characteristic of amorphous carbon structures, consistent with our earlier research [13]. The minor fluctuation in the relative intensity of D and G peaks is ascribed to a greater prevalence of incompletely converted tribopolymers, stemming from the fragments of ethanol molecules, as opposed to decane molecules [52].…”

“…In the case of Co7CuP (Figure 7), the carbon-based nature of the formed tribofilms is also summarized with EDS and Raman maps. Interestingly, the Raman results indicate that the nature of the carbon peaks varies depending on the coating composition and the hydrocarbon source [52]. The analysis conducted through Raman spectroscopy, in conjunction with 2D elemental mapping (EDS) as depicted in Figure 6, indicates that the source of the favorable tribological properties of the coating lies in the in situ development of a carbon-rich tribofilm.…”

“…In the case of Co7CuP (Figure 7), the carbon-based nature of the formed tribofilms is also summarized with EDS and Raman maps. Interestingly, the Raman results indicate that the nature of the carbon peaks varies depending on the coating composition and the hydrocarbon source [52]. To further evaluate the variability in the carbon formation, we summarized the changes in the characteristic carbon peaks.…”

Deterioration mechanism and health status prediction of hydrocarbon lubricants under high temperature and humid environment

“…According to the failure research of mechanical equipment, there are three main failure modes of machine parts: Corrosion, Fracture, and Wear [1][2][3], in which wear accounts for the largest proportion, about 60%-80%, and consumes nearly 1/3-1/2 of energy [4,5]. Therefore, the technology of reducing friction resistance and wear is an effective way to save energy, prolong the service life of mechanical equipment, and improve its working reliability [6,7].…”