(Ag,Cu)–Ta–O Ternaries As High-Temperature Solid-Lubricant Coatings

Abstract

Ternary oxides have gained increasing attention due to their potential use as solid lubricants at elevated temperatures. In this work, the tribological properties of three ternary oxides-AgTaO3, CuTaO3, and CuTa2O6-were studied using a combination of density-functional theory (DFT), molecular dynamics (MD) simulations with newly developed empirical potential parameters, and experimental measurements (AgTaO3 and CuTa2O6 only). Our results show that the MD-predicted friction force follows the trend AgTaO3 < CuTaO3 < CuTa2O6, which is consistent with the experimentally measured coefficients of friction. The wear performance from both MD and experiment exhibits the opposite trend, with CuTa2O6 providing the best resistance to wear. The sliding mechanisms are investigated using experimental characterization of the film composition after sliding, quantification of Ag or Cu cluster formation at the interface during the evolution of the film in MD, and DFT energy barriers for atom migration on the material surface. All our observations are consistent with the hypothesis that the formation of metal (or metal oxide) clusters on the surface are responsible for the friction and wear behavior of these materials.

Out-of-Plane Mechanical Properties of 2D Hybrid Organic–Inorganic Perovskites by Nanoindentation

“…can potentially be used as a good solid lubricant [52][53] Furthermore, our study also suggests that the in-plane elastic modulus of 2D HOIPs can be further tuned by selecting organic cations to form stronger or weaker interlayer Van der Waals interactions.…”

Friction and Wear Behavior of an Ag–Mo Co-Implanted GH4169 Alloy via Ion-Beam-Assisted Bombardment

“…Double metal oxides, including titanates, tungstates, molybdate, and vanadates, are effective high-temperature solid lubricants [8][9][10][11]. Among these double metal oxides, more attention has been paid to silver molybdate, which possesses a layer-like structure, because of its excellent lubrication performance, achieving low friction at high temperatures [2,[9][10][11][12][13][14][15][16][17].…”

“…Ag and Mo oxide generates silver molybdate, first proposed by Gulbinski [18], good high-temperature lubrication with a layered structure, which may be considered a mixture of AgO and MoO 3 layers separated by a silver layer. In fact, the lubrication mechanism of silver molybdate can be attributed to weaker Ag-O bridging bonds that are more easily broken to form a rich silver lubrication film when subjected to sliding, which is responsible for the low friction at the sliding interface [9]. Ni-based composites with an addition of lubricious Ag 2 MoO 4 at various temperatures have also been explored.…”

Macroscale Superlubricity Accomplished by Sb2O3-MSH/C Under High Temperature

“…As a result, the justified cases of the superlubricity became very limited in terms of their applications. In efforts to solve the tribological challenges related to high temperature applications, focus was rather directed toward ternary oxides and carbides that are in general incapable of near-zero friction sliding (Gao et al, 2015;Aouadi et al, 2020). A possible solution is to enable adaptive behavior of materials under changes in the testing conditions which was successfully shown in case of graphite-MoS 2 chameleon coatings (Shirani et al, 2020).…”