Influence of surface roughness and running-in on the lubrication of steel surfaces with oil containing MoS2 nanotubes in all lubrication regimes

MoS2/WS2 Quantum Dots as High‐Performance Lubricant Additive in Polyalkylene Glycol for Steel/Steel Contact at Elevated Temperature

“…All these results suggest that the addition of 0.5 wt% MoS 2 /WS 2 QDs in PAG is the optimum content to provide significant friction reduction and AW properties for steel/steel contacts at 150 °C, and the fact that MoS 2 /WS 2 QDs added in PAG exhibits lower friction and wear behaviors than MoS 2 / WS 2 nano may be explained as follows: MoS 2 /WS 2 QDs with smaller particles sizes will be able to easily enter the ball-disk www.advmatinterfaces.de contact interface and establish an effective protective film that acts to reduce friction and wear. [27][28][29] The film can be either in the form of a thick, patchy boundary film composed of compacted MoS 2 /WS 2 QDs aggregates and other tribochemical products, or formed directly by the adhesion of small MoS 2 / WS 2 QDs to the surface. [27][28][29] In addition, the tribochemical reactions between MoS 2 /WS 2 particles and the contact surface are also affected by size and shape of the additives and surface roughness.…”

“…[27][28][29] The film can be either in the form of a thick, patchy boundary film composed of compacted MoS 2 /WS 2 QDs aggregates and other tribochemical products, or formed directly by the adhesion of small MoS 2 / WS 2 QDs to the surface. [27][28][29] In addition, the tribochemical reactions between MoS 2 /WS 2 particles and the contact surface are also affected by size and shape of the additives and surface roughness. [27][28][29] As shown in Figure 12B-a, MoS 2 /WS 2 QDs that are smaller than the surface roughness of lower disk (Ra = 45 nm) will "fill" the asperity valleys and form a thin, smooth film between the contacting asperities.…”

“…[27][28][29] In addition, the tribochemical reactions between MoS 2 /WS 2 particles and the contact surface are also affected by size and shape of the additives and surface roughness. [27][28][29] As shown in Figure 12B-a, MoS 2 /WS 2 QDs that are smaller than the surface roughness of lower disk (Ra = 45 nm) will "fill" the asperity valleys and form a thin, smooth film between the contacting asperities. [27,28] By contrast, MoS 2 /WS 2 nano with the larger particles size (≈90 nm) decrease friction and wear by carrying some of the load between contact surfaces ( Figure 12B-b), but most them tend to be pushed away with some being squeezed into the contact interface, demonstrating their diminishing tribological advantage as compared to MoS 2 /WS 2 QDs.…”

“…[27][28][29] As shown in Figure 12B-a, MoS 2 /WS 2 QDs that are smaller than the surface roughness of lower disk (Ra = 45 nm) will "fill" the asperity valleys and form a thin, smooth film between the contacting asperities. [27,28] By contrast, MoS 2 /WS 2 nano with the larger particles size (≈90 nm) decrease friction and wear by carrying some of the load between contact surfaces ( Figure 12B-b), but most them tend to be pushed away with some being squeezed into the contact interface, demonstrating their diminishing tribological advantage as compared to MoS 2 /WS 2 QDs. [19,[27][28][29] The corresponding wear surfaces of lower steel disks lubricated by pure PAG, and PAG containing 0.1, 0.5, and 1.0 wt% MoS 2 /WS 2 QDs were further checked with 3D surface mapping profilometer.…”

“…[27,28] By contrast, MoS 2 /WS 2 nano with the larger particles size (≈90 nm) decrease friction and wear by carrying some of the load between contact surfaces ( Figure 12B-b), but most them tend to be pushed away with some being squeezed into the contact interface, demonstrating their diminishing tribological advantage as compared to MoS 2 /WS 2 QDs. [19,[27][28][29] The corresponding wear surfaces of lower steel disks lubricated by pure PAG, and PAG containing 0.1, 0.5, and 1.0 wt% MoS 2 /WS 2 QDs were further checked with 3D surface mapping profilometer. As shown in Figure 7A,a-a' and B,a- Figure 7A,d-d', or B,d-d').…”