Tribo-induced catalytically active oxide surfaces enabling the formation of the durable and high-performance carbon-based tribofilms

Tribocatalysis Induced Carbon-Based Tribofilms—An Emerging Tribological Approach for Sustainable Lubrications

“…However, it fails to explain the formation of the tribofilms at sliding speeds below 0.1 m/s where the boundary lubrication conditions are often tested. In our current work [109], the estimated flash temperature rises at different testing temperatures are small, and they cannot be used solely to explain the formation of the continuous carbon tribofilms as well as tribo-oxide layers. It should be noted that the theory used to calculate flash temperature rises is based on the assumption of a Boltzmann energy distribution at the macroscale, and it may not be true when accounting for the very intense energy dissipation at individual asperity conjunctions.…”

“…These nanomaterials are also famous for their catalytic applications, where many of which are well known as functional catalytic agents to promote the formation of helical carbon nanotubes, carbon nanofibres, and CNT/graphene hybrids from carbon-precursor gases [103][104][105][106]. Therefore, by utilizing both lubrication and catalytic functions of NiAl-CO3 LDH [107,108], we have successfully advanced the tribological performances of CPCa under severe sliding conditions at different temperatures [109]. In this work, extreme boundary rotation tribotests, of On the other hand, the concept of utilizing active elements in promoting and/or controlling in situ carbon-based material has also been applied in current research of 2D nanomaterials like layered double hydroxides (LDHs).…”

“…These nanomaterials are also famous for their catalytic applications, where many of which are well known as functional catalytic agents to promote the formation of helical carbon nanotubes, carbon nanofibres, and CNT/graphene hybrids from carbon-precursor gases [103][104][105][106]. Therefore, by utilizing both lubrication and catalytic functions of NiAl-CO 3 LDH [107,108], we have successfully advanced the tribological performances of CPCa under severe sliding conditions at different temperatures [109]. In this work, extreme boundary rotation tribotests, of which the lambda value was just 0.09, have been carried out under 25 • C, 50 • C and 100 • C. It is clear from the tribotest outcomes (Figure 9) that the combination of 2.5 wt% CPCa and 0.1 wt% NiAl-CO3 LDH in PAO4 ambient (CPCa + 0.1%LDH) results in the best tribological performances at all experimental temperatures.…”

“…Thin tribofilms require careful investigation and examination of the penetration depth as well as peak load to avoid indenting more than 10% of the tribofilm thickness [142,143]. Despite this difficulty, few recent studies have implemented nanoindentation in the context of nanoscratch or nanofriction to qualitatively examine the nanoscale mechanical properties of the surface carbon-based tribofilms [35,109]. In the study by Rouhani et al [35], a long-shaft Berkovich three-sided pyramid diamond indenter specially designed for the xSol stage was used for nanoscratch studies with a ramping load function from 0 to 500 µN at different temperatures.…”

Synergism of TiO2 and Ni on the Growth of a Double-Layered Tribofilm: New Strategy for ZDDP Replacement

“…We assume that the mild abrasion marks on the worn surface can be caused by the TiO 2 particles released at the friction interface or/and protruding peaks on the surface of the tribofilm. From Figure c, only a few abrasion marks are noticed from the worn surface of 5 N /5M/PF, as is ascribed to formation of the carbon-based tribofim. − The worn surface of 3 N /3T/5M/PF is rather smooth and abrasion furrows are rarely observed from Figure d.…”