Tribological Mechanisms Research Articles

Nano-scale wear: A critical review on its measuring methods and parameters affecting nano-tribology

This paper presents a critical review on the measuring methods and parameters affecting nano-tribology in the context of nano-scale wear. Nano-scale wear phenomena play a crucial role in various industries, including micro/nano-systems, electronics, and biotechnology. The review begins by discussing the significance of nano-scale wear and its impact on device performance, lifespan, durability, energy efficiency, cost savings, and environmental sustainability. It then delves into the measuring methods employed to assess nano-scale wear, including scanning probe microscopy (SPM) techniques such as atomic force microscopy (AFM) and friction force microscopy (FFM). The capabilities of AFM and FFM in studying the roughness of surface, adhesion, friction, scratch, abrasion, and nano-scale material transfer are highlighted. Additionally, the review explores the parameters affecting nano-wear, such as lubrication strategies, stress levels, sliding velocity, and atomic-scale reactions. The article concludes by emphasizing the importance of advanced microscopy techniques in understanding tribological mechanisms at different scales, bridging the gap between macro and nano-tribology studies.

Phenomenological modeling of wear mechanisms between nickel-based superalloy blades and ceramic-based abradable coatings in turbomachines

The tribological behavior and wear mechanism between K417G nickel-based superalloy blades and 8 wt% yttria-stabilized zirconia poly-p-hydroxybenzoate ceramic-based abradable coatings were investigated using a high-speed rubbing test machine simulating actual operating conditions. Two main influencing factors (linear velocity and incursion rate) were varied, and their effects on the system were determined. The wear mechanism of the system was attempted to be characterized. A significant correlation was found between all test results and the linear velocity, indicating that the linear velocity was the primary influence driving the friction. The incursion rate became a secondary factor. A linear mathematical model based on the proposed wear mechanism was developed to explain the wear mechanism and to predict the test results. The excellent fit and normally distributed residual results indicated the excellent performance of the model. This work can be used as an aid to understanding the present results and as a basis for further research on these phenomena in the future.

Comparative study on tribological performance and mechanism of eco-friendly solvent-free covalent MXene nanofluids in glycerin and polyethylene glycol

Solvent-free covalent MXene nanofluids (MXene NFs) were prepared as eco-friendly additives to improve the dispersibility of MXene and the tribological performance of lubricants. Here, the tribological properties and tribo-mechanisms of MXene NFs additives in glycerin and polyethylene glycol (PEG 400) were evaluated, and pronounced differences were observed. In glycerin, the excellent anti-friction (28.9%) and anti-wear (98.0%) properties were realized after 0.5 wt% MXene NFs addition, for MXene NFs preferentially adsorbing onto the surface of friction pair and participating in the formation of tribofilm. However, in PEG 400, the poor friction-reducing and negative anti-wear performance were related to PEG 400 exhibiting high affinity towards steel substrate. This work provides a new approach for fabricating eco-friendly additives with excellent dispersion and lubricity.

Tribological behavior and wear mechanism of nanomultilayer AlCrN/AlTiSiN coatings at elevated temperatures

Wear resistance is a critical property of tool coatings for high-speed machining, which depends on mechanical properties and oxidation resistance of the coatings. Many works have demonstrated that AlTiSiN coating has good mechanical properties. Additionally, AlCrN coating exhibits excellent oxidation resistance. The multilayered structure has proved to improve comprehensive properties of the coatings. Therefore, AlCrN/AlTiSiN multilayer coating has a high potential to be used in machining applications. This paper focuses on the high-temperature tribological behavior of AlCrN/AlTiSiN multilayer coating. The results show that AlCrN/AlTiSiN coating exhibits good to acceptable wear resistance up to 800 °C. Meanwhile, AlCrN/AlTiSiN coating also displays the lowest friction coefficient of ∼0.5 and a wear rate of 1.8 × 10−6 mm3/N m at 800 °C, which is about 58.13% and 64.0% lower than that of AlCrN and AlTiSiN coatings, respectively. The imaging and composition analysis of the high-temperature wear tracks allowed for explaining the differences in wear mechanisms. At 800 °C, a dense thin tribofilm is formed on the surface of AlCrN/AlTiSiN coating, which acts as a glaze layer to impede wear. It provides a strategy for enhancing the wear resistance of monolayer coating in high temperatures, which combines the advantages of both high oxidation resistance of one layer and high hardness of the other layer.

Nitrogen-doped carbon quantum dots assembled on layered Ti3C2Tx exhibit excellent tribological properties

Nitrogen-doped carbon quantum dots (NCQDs) as a lubricant additive, is limited by its single tribological mechanisms and difficult to surface functionalization. Therefore, it will be anticipated to combine NCQDs with two-dimensional layered materials, so as to improve lubrication and interface bonding performance. Due to the active groups existing on the surface of Ti3C2Tx, the NCQDs is assembled on the two-dimensional material Ti3C2Tx, thus the NCQDs@Ti3C2Tx composite can be used as a favorable lubricant additive. The NCQDs@Ti3C2Tx composite can exert synergistic lubrication and chemical reactions during the friction process in comparison to NCQDs as lubricant additives, resulting in forming a friction transfer film between the surface. Therefore, this study confirms that NCQDs@Ti3C2Tx composite exhibits enormous potential as a lubricant additive.

Ultra-low wear in multifunctional Ti3C2Tx/PI composite films induced by tribo-chemistry mechanism

Ti3C2Tx MXene was cooperated with polyimide (PI) to improve the wear resistance of the PI matrix under complex working conditions. Compared to the pristine PI, the Ti3C2Tx/PI composites have excellent frictional properties, specifically, the coefficient of friction is 0.32 and the wear rate is 0.62 × 10−5 mm3/(N·m). The composites formed a transfer film on the contact surface during the friction process, and the transfer film prevents direct contact between tribo-couples. The results studied by Raman and XPS showed that the transfer film contains TiO2 that is derived from oxidized Ti3C2Tx. Moreover, the tribological mechanism has been summarized as two aspects: On one hand, the relative sliding of the Ti3C2Tx lamellae transfers the sliding stress. On the other hand, a transfer film is created between Ti3C2Tx/PI composites and steel ball during friction that prevents further wear of the material. All in all, two-dimensional MXene can effectively improve the wear resistance of the polymer matrix and has the potential to be used in friction-protective layers under complex working conditions.

Surface tension, wettability and tribological properties of a low viscosity oil using CaCO3 and CeF3 nanoparticles as additives

The rise of the electric vehicles as a more sustainable transport alternative makes it necessary to study new transmission fluids that adapt to their needs and improve their efficiency. The thermophysical properties (contact angle, surface tension and rheology) and tribological properties (friction and wear) of potential PAO8 transmission nanofluids using CaCO3 and CeF3 nanoparticles as additives are evaluated at mass concentrations of 0.05, 0.10, 0.15 and 0.20 wt%. Low contact angle and surface tension values are obtained, indicating good wettability. When the nanoparticles are used as PAO8 additives, small reductions in surface tension are achieved, but no differences in contact angle are observed. All nanolubricants and base oil exhibit Newtonian behavior. Concerning the tribological behavior, reductions in the friction coefficient are achieved for both types of nanoparticles, with the largest reductions comparing to PAO8 base oil being 13 % and 10 % for nanolubricants containing 0.05 wt% CaCO3 and 0.10 wt% CeF3 nanoparticles (NPs), respectively. In terms of antiwear performance, maximum reductions are obtained for the CaCO3 nanolubricant of 28 % (0.15 wt%), 41 % (0.10 wt%) and 59 % (0.15 wt%) and for the CeF3 nanolubricant of 19 % (0.20 wt%), 53 % (0.10 wt%) and 58 % (0.20 wt%) for the parameters of diameter, depth, and area of the worn track, respectively. Through Raman microscopy, the tribological mechanisms of tribofilm formation, repairing, and rolling can be proposed. A discontinuous tribofilm formed by the CaCO3 and CeF3 nanoparticles reduces the contact area between the two surfaces protecting them.

Tribological characteristics and wear mechanisms of reinforced composites against steel

To explore the potential wear performance of commonly utilized hydraulic system polymer components, we investigated the effects of different working conditions on the frictional and wear behaviors of three polymer sealing materials in this study. Polytetrafluoroethylene (PTFE), nylon (PA), and polypropylene (PP) composites were prepared using copper (Cu) and glass fiber (GF) as fillers. The tribological and wear properties (wear rate, surface appearance, wear patterns) of the sealing composites were evaluated. The results showed consistent trends toward increasing average coefficient of friction as load and speed increased for PTFE. The incorporation of filler improved the wear resistance of the composites. The addition of Cu particles showed lower coefficient under higher load and sliding speed. PA with continuous glass fiber (CGF) sealing composites showed lower coefficient, less wear volume, and relatively smoother wear zone surfaces than PTFE-based composites or PP with short glass fiber (SGF). We propose that PA-CGF outperforms other materials in regards to fatigue and friction and wear even under extremely high silding speed,as well as sealing properties.

Effect of Dehydroxylation on Tribological Performances of Synthetic Magnesium Silicate Hydroxide as Lubricant Additive

Abstract The heat-treated nanoparticle heat-treated magnesium silicate hydroxide (MSHH) was obtained based on the synthesis of lamellar nanoparticle magnesium silicate hydroxide (MSH) and analysis of thermal stability, and the morphology, phase composition, and chemical groups of nanoparticles were subsequently characterized. The heat treatment process induces partial dehydroxylation of MSHH, while preserving the layered structure. Compared with MSH, the tribological performances of MSHH as a lubricant additive have been greatly improved. The mechanical properties of MSH and MSHH are analyzed by calculation of elastic constants using density functional theory (DFT). The interactions among dispersant oleic acid (OA), nanoparticles (MSH and MSHH), and Fe tribopairs were investigated by simulations of classical molecular dynamics (CMD) from the views of adsorption energy and confined shear. The tribological mechanism of MSHH as a lubricant additive is proposed based on the decreased shear strength and weakened agglomeration.

Study of the Effect of ZnO Functionalization on the Performance of a Fully Formulated Engine Oil.

The automotive sector is demanding higher specifications to achieve maximum efficiency; in this sense a new generation of lubricants with higher thermo-oxidative stability and superior tribological properties is being explored. The formulation of nanolubricants based on the nature of different nanomaterials is one of the most recent approaches, with several gaps to cover, such as dispersion stability, related to the compatibility of proposed nanomaterials with conventional additives and baseoils used in lubricant formulation. This study evaluated the effect of ZnO nanomaterial dispersed in a commercial engine oil using two different approaches; the use of surfactant and nanomaterial surface functionalization to promote higher stability and lower cluster size. Experimental evidence shows a synergetic effect between the tribological protection mechanism and the antioxidant properties in the lubricant. The effect of nanoparticle cluster size, functionalization level, and nanomaterial content are presented.

Tribological properties and wear prediction of various ceramic friction pairs under seawater lubrication condition of different medium characteristics using CNN-LSTM method

The tribological performance and wear mechanism of polyetheretherketone (PEEK)/17–4PH stainless steel, PEEK/silicon carbide (SiC), WC-6Ni (YN6X)/SiC and SiC/polycrystalline diamond composite (PCD) tribopairs sliding in seawater at different temperatures (ranged from 25 °C to 70 °C) and salinities (20‰, 35‰ and 50‰) was investigated. A deep neural network model was used to predict the coefficient of friction, combining a one-dimensional CNN and an LSTM. The experiment results showed that increasing salinity led to a decrease in tribological performance of the tribopairs, while the performance effectively improved within the temperature range of 25–55 °C. The CNN-LSTM model demonstrated high accuracy in predicting results, which is significant for analyzing the tribological characteristics of tribopairs in seawater hydraulic components.

Friction and wear mechanism of artificial joint composite material PEEK/ZnO under different decomposition motion modes of knee joint

According to the standard of knee joint movement and actual working conditions, the complex movement of knee joint can be decomposed into three movement modes: sliding, swinging and twisting. The friction and wear mechanism of PEEK and PEEK/ZnO composites in sliding, swinging and twisting modes was studied on knee joint simulator. The result shows that the friction coefficient and wear of the PEEK/ZnO composite are lower than those of PEEK, and the addition of ZnO can effectively improve the wear resistance of the PEEK composite. The relevant data has deepened people's understanding of the tribological behavior and wear mechanism of artificial knee joints.

Nanotribological Properties of Oxidized Diamond/Silica Interfaces: Insights into the Atomistic Mechanisms of Wear and Friction by Ab Initio Molecular Dynamics Simulations.

Controlling friction and wear at silica-diamond interfaces is crucial for their relevant applications in tribology such as micro-electromechanical systems and atomic force microscopes. However, the tribological performance on diamond surfaces is highly affected by the working environment where atmospheric gases are present. In this work, we investigate the effects of adsorbed oxygen on the friction and wear of diamond surfaces sliding against silica by massive ab initio molecular dynamics simulations. Different surface orientations, O-coverages, and tribological conditions are considered. The results suggest that diamond surfaces with full oxygen passivation are very effective in preventing surface adhesion, and as a result present extremely low friction and wear. At low oxygen coverage, Si-O-C bond formation was observed as well as atomistic wear initiated from C-C bond breaking at extreme pressure. The analysis of electronic structures of the configurations resulting from key tribochemical reactions clarifies the mechanisms of friction reduction and atomistic wear. Overall, our accurate in silico experiments shed light on the influence of adsorbed oxygen on the tribological properties and wear mechanisms of diamond against silica.

The influence of corrosive medium on the selected tribological properties of ZrSi-based nitride and oxynitride deposited on 316L stainless steel

Targeting to restore the function of load-bearing joints which are subjected to high levels of friction and wear during the normal activity, the aim of the current study was to assess the extent of the role played by the corrosive environment on the underlaying tribological mechanism. In this study we deposited by reactive cathodic arc evaporation technique ∼ 1 μm thick, stoichiometric ZrSi-based nitrides and oxynitrides coatings, either as monolayer or double-layer structure on 316L steel substrates. Tribological tests were conducted in dry and two commonly used corrosive environments: Ringer and 0.9 % NaCl solutions. We demonstrate that the ZrSiN and ZrSi(N,O) coatings improved the wear performance of 316L stainless steel in biological environments, reaching even ∼ 94 % improvement as compared with the bare substrate for the ZrSi(N,O) coating.

Interfacial adsorption and tribological response of various functional groups on titanium surface: In-depth research conducted on the lubricating mechanism of liquid lubricants

Lubricating materials for highly reactive titanium alloys are not sufficiently abundant, limiting their wide practical applications. In this work, the tribological properties for various lubricants on titanium alloy surfaces are investigated, as well as their physicochemical and adsorption properties in terms of structural composition. The results indicated that high polarity, long alkyl chain length and small spatial site resistance will be positively correlated with the tribological properties. The FIB-TEM analysis further illustrates that the film-forming mechanism of strong polar adsorption and tribo-chemical reaction is vital to high-performance lubricants on titanium alloys. This work shows great instructive significance to investigate the tribological properties and interaction mechanisms on titanium alloy surfaces from the perspective of molecular design.

Effect of CaF2 nanoparticles on the microstructure evolution, mechanical properties and tribological behavior of Cu-Ni alloy/cBN self-lubricating composites

This research study presents the effect of CaF2 reinforcement on the microstructure, mechanical and self-lubricating (SL) tribological properties of Cu-Ni alloy/cBN metal matrix composite (MMC). The composite of Cu-Ni (CN) alloy/cBN reinforced with CaF2 nanoparticles (2–6 wt%) was developed by powder metallurgy, using pressure-less sintering without any additive. Microstructure studies proved uniform dispersion of cBN/ CaF2 particles in the Cu-Ni matrix. The maximum density and hardness were obtained at reinforcement of 2 wt% CaF2. The minimum coefficient of friction (0.15) and higher wear resistance were obtained for 4 wt% CaF2 reinforcement in CN alloy/cBN composite. Tribo-chemical reactions culminated in the formation of oxides of Cu, Ni, Fe and B at the interface, which significantly influenced the tribological properties and wear mechanisms. The worn surface analysis indicated that adhesive wear, oxidative wear and delamination are the predominated wear mechanism of CN alloy-cBN-CaF2 composite.

The Effects of Electrochemical Hydrogen Charging on Charpy Impact Toughness and Dry Sliding Tribological Behavior of AISI 316H Stainless Steel

In this work, solution-annealed AISI 316H grade austenitic stainless steel was studied in terms of investigating the electrolytic hydrogen charging effects on the resulting Charpy impact toughness and dry sliding tribological behavior. Conventional Charpy impact bending tests were employed to study the mechanical response of the investigated material to dynamic loading conditions, whereas dry linear sliding tribological tests were used to study material friction and wear behavior. The obtained mechanical and tribological properties were correlated with corresponding fracture and tribological mechanisms, which were determined from morphological observations of fracture surfaces and tribological tracks. The applied testing procedures were individually carried out for the non-hydrogenated, hydrogen-charged, and dehydrogenated material conditions. The observed changes in individual properties due to applied hydrogen charging were rather small, which indicated the good resistance of solution-annealed AISI 316H steel against material degradation in currently used electrolytic hydrogenation conditions.

Effects of Nitrogen Modification of Porous PVD–MoS2 Coatings on the Tribological Behavior under Rolling–Sliding Conditions in Vacuum

In order to improve the tribological performance of PVD–MoS2 coatings, which are frequently used as a solid lubricant for operating in challenging environments, e.g., in a vacuum, they can be modified with nitrogen. This work evaluates the tribological behavior and a possible compaction occurring during the initial tribological load in the rolling contact for pure and nitrogen-modified PVD–MoS2 coatings in a vacuum. Short-running tests (1000 cycles) of coated steel discs paired with uncoated steel discs made from 100Cr6 (1.3505, AISI 52100) were conducted on a two-disc tribometer. The slide-to-roll ratio of 10.5% was kept constant, while the load was varied in two steps from 1.1 GPa to 1.6 GPa. Subsequently, a comparison was made between the worn and the pristine coatings by means of nanoindentation and an optical analysis of the wear track. The formation of a load-bearing solid lubrication was achieved for both MoS2-variants. The main differences affected the material transfer and wear mechanisms. The worn coatings reached a similar wear coefficient of 4 × 10−6 mm3N−1m−1 and a possible compaction of the coatings was found, indicated through an increased indentation hardness (for MoS2 1158% and MoS2:N 96% at a 1.1 GPa load). The assumed tribological mechanism changed with nitrogen modification, but scales with increasing load. The nitrogen-modified MoS2 coating showed less compaction than pure MoS2, while the frictional behavior was improved by a 17% reduction of the coefficient of friction.

THE TRIBOLOGICAL CHARACTERISTIC OF WEAR IN ALLOY STEEL COMPOSITE MATERIAL

This abstract provides a concise overview of the tribological characteristics of wear in alloy steel composite materials. Alloy steel composites, consisting of steel and alloying elements, exhibit improved mechanical properties and wear resistance. This study investigates the tribological behavior, wear mechanisms, and influential factors of alloy steel composites. Experimental tests, including pin-on-disk and abrasive wear tests, analyze friction coefficients, wear rates, and microstructural observations. The research identifies adhesive, abrasive, and fatigue wear as dominant mechanisms and explores the role of protective oxide layers and solid lubricants. The findings contribute to material selection and design for enhanced wear resistance in alloy steel composite applications..

The Tribological Mechanism of Chromium at Extreme Stress-temperature Conditions Simulating the Interior Ballistic Environment in Artillery Barrels

The tribological mechanism of bulk chromium materials has been investigated at high-temperature and high-stress conditions simulating the interior ballistic environment in gun barrels. The results show a higher level of weight change after testing at 1, 000 °C as compared to that at 600 °C. The topographical difference is more evident in the friction surface after testing at 1, 000 °C than that at 600 °C. The detailed analysis of surface morphology and chemistry indicates a tribological mechanism combining oxidative wear, abrasive wear, and adhesive wear at a testing temperature of 600 °C, whilst the tribological mechanism is combined with adhesive wear and oxidative wear at a testing temperature of 1, 000 °C.