High Tribological Performance Research Articles

2D mica as a new additive for nanolubricants with high tribological performance

This article presents 2D mica nanoplatelets as a novel additive to produce a stable engine lubricant. The planar structure and excellent mechanical properties of 2D mica contribute significantly to the improvements in tribological performance when evaluated under pure sliding and rolling/sliding contact configurations. The wear rate is reduced by 72 %, and the coefficient of friction (COF) decreases by 28 % when 2D mica is added to engine oil under pure sliding conditions. No tribological improvement was observed under rolling/sliding conditions. Our results also showed that nanosheet loading plays a significant role in nanolubricant performance, where 0.2 wt% is the optimum. These findings demonstrate superior performance to other 2D material nanoadditives and indicate the potential for commercial applications of 2D mica-based nanolubricants.

High tribological performance of quenched–tempered 40Cr steel treated by plasma oxynitriding

Alloy steel 40Cr was treated by plasma oxynitriding after quenching and tempering. The microstructures, mechanical properties, and tribological performances of plasma oxidized–nitrided layer at tempering temperatures of 500, 520, and 540 °C were investigated. The typical tempered sorbite structure was present when the 40Cr alloy steel was treated by quenching at 900 °C and tempering. A special structure of mixed oxide–nitride layer along with the veinlike nitride phase was formed after plasma oxynitriding. The surface hardness of the quenched–tempered 40Cr alloy steel was significantly improved. The quenched 40Cr alloy steel tempered at 520 °C exhibited the highest hardness of approximately 973 HV0.2 and the lowest wear rate of about 1.72 × 10−14 m3 N−1 m−1 than the samples tempered at 500 and 540 °C. The oxide and nitride phases inside the plasma oxidized–nitrided layer played important roles in the improvement of the surface mechanical properties and the tribological performance of the quenched–tempered alloy steel.

A Review on Abrasive Wear of Aluminum Composites: Mechanisms and Influencing Factors

Aluminum matrix composites (AMCs) find extensive use across diverse industries such as automotive, aerospace, marine, and electronics, owing to their remarkable strength-to-weight ratio, corrosion resistance, and mechanical properties. However, their limited wear resistance poses a challenge for applications requiring high tribological performance. Abrasive wear emerges as the predominant form of wear encountered by AMCs in various industrial settings, prompting significant research efforts aimed at enhancing their wear resistance. Over the past decades, extensive research has investigated the influence of various reinforcements on the abrasive wear behavior of AMCs. This paper presents a comprehensive review of the impact of different variables on the wear and tribological response of aluminum composites. This review explores possible wear mechanisms across various tribosystems, providing examples drawn from the analysis of existing literature. Through detailed discussions on the effects of each variable, conclusions are drawn to offer insights into optimizing the wear performance of AMCs.

Enhanced tribological performance of laser directed energy deposited Inconel 625 achieved through laser surface remelting

Inconel 625 (IN625) is an essential material for the manufacture of turbine blades and seals, aircraft ducting systems, engine components, and pressure valves. Laser Directed Energy Deposition (LDED) process has shown the potential to fabricate IN625 parts with superior mechanical properties and higher corrosion resistance when compared to those fabricated using conventional manufacturing techniques. However, the poor surface quality limits the practical application of LDED fabricated parts, especially in sectors that demand high tribological performance. To this end, this study focuses on improving the surface quality and tribological performance of LDED fabricated IN625 components using Laser Surface Remelting (LSR) as a postprocessing operation. The tribological performance was evaluated using a linear reciprocating ball-on-flat wear test setup. The surface roughness, remelting depth (RD), microstructure, hardness, and tribological performance (coefficient of friction and wear rate) of the remelted (RM) samples were compared with that of as-deposited (AD) samples. Microstructural characterization revealed that LSR resulted in grain refinement, reduced dendrite size, and primary dendritic arm spacing (PDAS). Laser scanning speed effects RD, dendrite size and PDAS via its effect on cooling rates. SEM + EDS analysis confirmed the presence of Laves phase in both AD and RM samples. XRD analysis of RM samples showed an increase in the amount of Laves phase. The refinement in microstructural features and the increased amount of Laves phase among the RM samples led to improvement in microhardness when compared to AD samples. Wear test results revealed a reduction in the coefficient of friction (COF) and wear rate after LSR with wear mechanism being either abrasive or delamination. Reduction in the size of dendrites and refinement in grain size are attributed to the enhanced tribological performance after LSR.

A Polytetrafluoroethylene@Polyacrylonitrile core-shell composite with high tribological performance

As a lubricating additive, polytetrafluoroethylene (PTFE) exhibited poor wear resistance, high wear rate and weak adhesion strength, which restricted its application in the area of lubrication and wear protection. In this paper, we prepared a PTFE-based core-shell composite (PTFE@PAN) composed of PTFE core and polyacrylonitrile (PAN) shell through an emulsion polymerization method. The PTFE core with diameter of about 80–100 nm was wrapped by the PAN shell with the thickness of about 50–60 nm. The PTFE@PAN core-shell composite present better dispersion stability in lubricating oil (poly-α-olefin 6, PAO6) than PTFE. Additionally, the PTFE@PAN composite dispersed in PAO6 exhibited significantly reduction in friction coefficient and wear scar width up to 50 % and 25 % compared to PTFE, respectively. Meanwhile, the wear volume of PTFE@PAN composite under a load of 200 N was 4.855 × 104 μm3, was merely one twenty-seventh of that of PTFE (130.6 × 104 μm3). In comparison to conventional oil lubricants, this enhanced tribological properties of PTFE@PAN composite were conducive to a homogeneous transfer film composed of the dual-phase hard polymer (PAN) and soft PTFE polymer (PTFE). Compared with PTFE, the lower surface hardness and better flexibility of PAN shell led to deformation and gap filling with the entanglement and motion of the molecular chains, which could reduce the scratches and decline the abrasive wear of the rubbing surface significantly in the course of the friction process on a rough surface under the high load. That results also suggested that the PTFE@PAN core-shell composite will be a potential lubricating and wear-resistant additive.

Effect of reinforced diverse synthetic and agricultural-industrial waste materials on the microstructural and mechanical performance of hybrid metal matrix composite

This report provided a thorough analysis of previous research on the topic under consideration from the previous year's research. This research work focuses on the microstructural and mechanical performance of hybrid metal matrix composite (HMMC) reinforced with different synthetic and agricultural-industrial wastes. By varying the wt% of Synthetic (i.e. carbon allotropes, AlB2 TiB2, CeO2, B4C, SiC, MgO, TiC, TiC, WC, and TiB2, etc.) + Industrial–Agricultural Wastes materials (i.e. Bean shell ash (BSA), Sugarcane bagasse, Neem seed, Wheat husk ash (WHA), rice husk ash (RHA), Corn cob ash (CCA), bamboo leaf ash (BLA), palm kernel shell ash (PKSA), etc.) reinforced in the metal matrix to create HMMC using solid andliquid-state processing. Result of that, the material properties, microstructure, and wear parameters, etc of composite materials, were examined, and found improvement in microstructural and mechanical performance. But Agro-Industrial Wastes be prominent due to their low density, reduce the overall cost as well as helps to overcome the addition of synthetic reinforcement cost, eliminate the problem of a landfill, and improve the strength of a composite, because they have elements such as MgO, K2O, ZnO, MnO, Na2O, Fe2O3, SiO2, CaO, SO3, P2O5, Al2O3, Li2O, SO3, SrO, TiO2, etc. To fabricate the high Tribological performance and high mechanical strength HMMC uses them as reinforcements to make them attractive. The purpose of this review is to examine the most effective Synthetic + Industrial agricultural waste materials and their percentage effect on mechanical and tribological properties.

Ti3C2 MXene induced high tribological performance of polyimide/polyurea copolymer at a wide temperature range

Copolymers of polyimide and polyuria with different fractions were synthesized. Furthermore, Ti3C2 MXene two-dimensional material was obtained by etching Ti3AlC2 with hydrofluoric acid. It was demonstrated that the copolymers displayed outstanding tribological performance than that of pure polymers and the as-synthesized Ti3C2 MXene were endowed with outstanding dispersion in above copolymer. Importantly, when used as a solid lubricant additive at different temperatures, the two-dimensional material showed excellent friction reducing and antiwear properties. That is, blending even a small fraction of Ti3C2 MXene into the copolymer dramatically reduced the friction and wear of the friction pair. SEM mappings and XPS analyses revealed that a continuous tribofilm consisting of a high fraction of tribo-chemical products and TiO2 was established on the rubbed surfaces, which were significant in improving the lubrication performance at different temperatures.

Directional diffusion of carbon atoms and lattice distortion in the high-speed changing dynamic temperature field – A novel method to manufacture high tribological performance cermets

The research was aiming at exploring a novel approach to manufacture high tribological performance cermets by treating in a high-speed changing dynamic temperature field. Results showed that with the method, carbon atoms migrated from the subsurface region to the surface region. Atoms escaped from the crystals and large-angle boundaries (>10°) and dislocation were formed. During ball-on-disk wear tests at 800 °C, fine furrows with a smallest depth of 8 μm was obtained on the cermets after treated for 30 cycles, which showed highest Vicker hardness of 1810 HV30 and best toughness of 9.7 MPa.m1/2 due to the strengthening effect of large angle boundaries and dislocations. The cermets after treated for 100 cycles displayed the lowest COF of 0.17 due to graphite phase formed by carbon atoms migration.

Molecules with a TEMPO-based head group as high-performance organic friction modifiers

High-performance organic friction modifiers (OFMs) added to lubricating oils are crucial for reducing energy loss and carbon footprint. To establish a new class of OFMs, we measured the friction and wear properties of N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)dodecaneamide referred to as C12Amide-TEMPO. The effect of its head group chemistry, which is characterized by a rigid six-membered ring sandwiched by an amide group and a terminal free oxygen radical, was also investigated with both experiments and quantum mechanical (QM) calculations. The measurement results show that C12Amide-TEMPO outperforms the conventional OFMs of glyceryl monooleate (GMO) and stearic acid, particularly for load-carrying capacity, wear reduction, and stability of friction over time. The friction and wear reduction effect of C12Amide-TEMPO is also greatly superior to those of C12Ester-TEMPO and C12Amino-TEMPO, in which ester and amino groups replace the amide group, highlighting the critical role of the amide group. The QM calculation results suggest that, in contrast to C12Ester-TEMPO, C12Amino-TEMPO, and the conventional OFMs of GMO and stearic acid, C12Amide-TEMPO can form effective boundary films on iron oxide surfaces with a unique double-layer structure: a strong surface adsorption layer owing to the chemical interactions of the amide oxygen and free radical with iron oxide surfaces, and an upper layer owing to the interlayer hydrogen-bonding between the amide hydrogen and free radical or between the amide hydrogen and oxygen. Moreover, the intralayer hydrogen-bonding in each of the two layers is also possible. We suggest that in addition to strong surface adsorption, the interlayer and intralayer hydrogen-bonding also increases the strength of the boundary films by enhancing the cohesion strength, thereby resulting in the high tribological performance of C12Amide-TEMPO. The findings in this study are expected to provide new hints for the optimal molecular design of OFMs.

Effect of He and N2 gas on the mechanical and tribological assessment of SS316L coating deposited by cold spraying process

In this study, simulation and experimental methods were used to investigate the influence of cold spray conditions on AISI 316L stainless steel coatings. The effect of both helium and nitrogen gases used was investigated. The temperature, particle sizes of spraying powder, and distance from the nozzle throat to the impinging point were estimated by using the Kinetics Spray Solutions GmbH software. The 316L stainless steel (SS) coatings were examined by X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray Microanalysis. The tribological behavior was evaluated under different loads (2 N and 5 N) in dry conditions. It was found that the nitrogen and helium propellant gas with high speed and fine particles led to produce good coatings with dense microstructures. From the nanoindentation experiments, the Young's modulus and hardness of the SS 316L samples were enhanced of about 8% with helium due to the high particle velocity. It was shown that the wear resistance of SS 316L produced with helium was higher than that of the standard SS 316L coatings. The coatings produced with helium revealed lower friction coefficient (0.65) and wear rate (6.9 × 10–4 mm3/Nm) under 2 N applied load than that obtained nitrogen. It was also found that the SS 316L cold sprayed by helium with dense structure presents high hardness and good tribological performance that can be suggested for several applications.Graphical

Microstructure, Mechanical and Tribological Properties of Advanced Layered WN/MeN (Me = Zr, Cr, Mo, Nb) Nanocomposite Coatings.

Due to the increased demands for drilling and cutting tools working at extreme machining conditions, protective coatings are extensively utilized to prolong the tool life and eliminate the need for lubricants. The present work reports on the effect of a second MeN (Me = Zr, Cr, Mo, Nb) layer in WN-based nanocomposite multilayers on microstructure, phase composition, and mechanical and tribological properties. The WN/MoN multilayers have not been studied yet, and cathodic-arc physical vapor deposition (CA-PVD) has been used to fabricate studied coating systems for the first time. Moreover, first-principles calculations were performed to gain more insight into the properties of deposited multilayers. Two types of coating microstructure with different kinds of lattices were observed: (i) face-centered cubic (fcc) on fcc-W2N (WN/CrN and WN/ZrN) and (ii) a combination of hexagonal and fcc on fcc-W2N (WN/MoN and WN/NbN). Among the four studied systems, the WN/NbN had superior properties: the lowest specific wear rate (1.7 × 10−6 mm3/Nm) and high hardness (36 GPa) and plasticity index H/E (0.93). Low surface roughness, high elastic strain to failure, Nb2O5 and WO3 tribofilms forming during sliding, ductile behavior of NbN, and nanocomposite structure contributed to high tribological performance. The results indicated the suitability of WN/NbN as a protective coating operating in challenging conditions.

Growth, mechanical properties, and tribological performance of TiAlN/NbN and NbN/TiAlN bilayer coatings

Three different coatings, namely TiAlN, TiAlN (external)/NbN (internal) and NbN (external)/TiAlN (internal), were deposited on cemented carbides by arc ion plating. The comparative investigation conducted in this study elucidates the effect of the NbN layer and coating systems on the growth, mechanical properties, and tribological performance of the coatings. The results showed that the surface of the TiAlN and TiAlN/NbN coatings was smoother when TiAlN served as the external layer. The NbN/TiAlN coating, wherein NbN formed the external layer, had a much rougher but more symmetrical surface. With the introduction of the NbN layer, the increased micro stress induced a lower adhesion strength in the TiAlN/NbN and NbN/TiAlN coatings. The TiAlN/NbN and NbN/TiAlN coatings exhibited higher hardness and hardness/effective elastic modulus (H/E*). During the friction test, when the temperature was elevated to 700 °C, the tribological performance of the monolayer TiAlN coating was the lowest because of the TiO2-induced breakage of the dense tribo-oxide film. The NbN layer participated in the formation of a NbOx film at elevated temperatures, which was responsible for the high tribological performance of the two bilayer coatings. When the NbN layer was on the outermost layer and in direct contact with the elevated temperature atmosphere, the NbN/TiAlN coating generated a tribo-oxide film with high integrity, and its coefficient of friction decreased by 27% of that at room temperature. Therefore, the NbN/TiAlN coating exhibited the highest wear resistance at 700 °C.

High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates.

Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE-UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a significant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomography, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction coefficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.

Tribological and mechanical behaviors of mollusk shell‐ultrahigh molecular weight polyethylene bio‐composite

AbstractThis work is focused on the study of the tribological and mechanical properties of mollusk shell (MS)‐ultrahigh molecular weight polyethylene (UHMWPE) biocomposite against stainless steel. Wear tests were carried out on a reciprocating pin on disc apparatus. Tensile tests were achieved using a computerized universal traction machine, model EZ‐20 LLOYD. Rockwell hardness of the bio‐reinforced composite was carried out using an AFFRI universal hardness test. The coefficient of friction and wear rate were measured after tribological tests. From tensile tests, the ultimate strength, Young's modulus, fracture strain, and fracture strength were determined. It is found that wear tests of MS‐UHMWPE biocomposites achieved high tribological performance in terms of specific wear rate and coefficient of friction compared to pure UHMWPE. The mechanical properties of UHMWPE were enhanced by the addition of MS particles. The correlation between the mechanical and tribological properties of MS‐UHMWPE biocomposites was investigated. It is established that there is no solid confirmation of a strong correlation between the mechanical properties and the specific wear rate of MS‐UHMWPE biocomposites. However, the coefficient of friction gives a reasonable correlation with the hardness, fracture strain, fracture strength, and Young's modulus of the MS‐UHMWPE.

BN–SiC ensembles to form tribofilm with excellent shielding effects in PEEK- stainless steel contacts for artificial joint

Developing more reliable joint prostheses is crucial for minimizing impact of end-stage arthritis. In this work, SiC-BN hybrid nanoparticles were compounded into PEEK and their roles in tribocorrosion behaviors of PEEK sliding against a 316L steel in simulated body fluid were explored. Our results manifest that the addition of SiC and BN nanoparticles enhances synergistically tribological performance of the friction pairs. Tribofilm growth and tribo-chemistry at the friction interface were thoroughly investigated. It is demonstrated that hydrolysis products of SiC and easy-slippery characteristic of BN released onto the interface endow the tribofilm with shielding and boundary lubrication effects. Hence, when sliding takes place with the PEEK composite filled with SiC/BN hybrids, the friction pairs exhibit high tribological and anti-corrosion performance.

Hybrid PTFE-glass hierarchical braided/epoxy composites with self-lubricating and high tribological performance

In this study hybrid polytetrafluoroethylene (PTFE)/glass fibers were employed in hierarchical braided structure as a composite reinforcement. PTFE-covered glass fibers were braided to achieve the hierarchical structure, then the composites were prepared through vacuum assisted resin transfer molding (VARTM) process. Tribological experiments were performed on the composites. The results showed self-lubricating and lower dynamic friction coefficient due to the PTFE transfer film formation. SEM micrographs confirmed the transfer film formation. Friction coefficient of 0.112, 0.105 and 0.096 were obtained under loading of 20, 30 and 40 N forces, respectively. The experimental coefficient of friction results were confirmed by mixture theory. The self-lubricating feature of PTFE-glass braided epoxy composite along with its mechanical characteristics makes it a feasible alternative for traditional wet bearing parts.

Improvement of the milling process performance by using cutting fluids prepared with nano-silver and boric acid

Today, it is aimed to produce high quality products and reduce energy consumption in metal cutting processes. For this purpose, it is necessary to use cutting fluids with high tribological performance in metal cutting processes. With the use of these fluids, the lubrication and cooling functions required in metal removal processes will be provided effectively. In addition, minimal and effective use of fluids will reduce processing costs and energy consumption. In this study, tribological performances of cutting fluids consisted of nano-silver and boric acid were investigated comprehensively in the milling process of AA7075-T6 material. First, colloidal suspensions were prepared in ethylene glycol medium using nano-silver as a cooling and surface film-forming agent and boric acid as a lubricating agent. Secondly, milling experiments were performed according to semi factorial design method. Surface roughness (Ra) and cutting forces were considered as performance criteria. Visual and elemental analyses of chips were performed via scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. Tool wear and build-up-edge (BUE) formation was examined by optical microscope. According to the results, the cutting fluid prepared with nano-silver (nAg) and boric acid (BA) in a medium of ethylene glycol (EG) decreased surface roughness by 14.59% more than the nAg and EG mixture and by 5.27% more than the BA and EG mixture. In addition, cutting forces of EG + BA + nAg was observed 0.846% and 0.115% lower than the EG + nAg and EG + BA, respectively. In terms of tool wear and chip morphology, EG + BA + nAg cutting fluid showed better results than other cutting fluids.

Influence of deposition parameters on the residual stresses of WC-Wo sputtered thin films

AbstractControl and manipulation of residual stresses in thin films is a key for attaining coatings with high mechanical and tribological performance. It is therefore imperative to have reliable residual stress measurements methods to further understand the dynamics involved. The sin2ψ method of X-ray diffraction was used to investigate the residual stresses on the tungsten carbide cobalt thin films deposited on a mild steel surface to understand the how the deposition parameters influence the generation of residual stresses within the substrate surface. X-ray spectra of the surface revealed an amorphous phase of the thin film therefore the stress measured was of the substrate surface and the effects of sputtering parameters on residual stress were analysed. Compressive stresses were identified within all samples studied. The results reveal that as the sputtering parameters are varied, the residual stresses also change. Optimum deposition parameters in terms of residual stresses were suggested.

Effects of cutting fluids with nano-silver and borax additives on milling performance of aluminium alloys

The development of tribological properties of cutting fluids is important to ensure cutting efficiency in metal cutting processes. It is expected that the nano-cutting fluids obtained using nanoparticles as a tribological agent will provide high tribological performance. In this study, the suspension of borax - ethylene glycol and colloidal suspension of borax - ethylene glycol – nano-silver particles were used as cutting fluid for milling of AA7075 - T6 material and their tribological properties were investigated. The originality of this paper is the improvement of the lubrication function and heat transfer properties of cutting fluids by using borax and nano-silver additives. In the experimental part of the current study, borax was used for lubrication, and nano-silver particles were employed to improve the heat transfer properties of nano-cutting fluids. Both additives were synthesised using ethylene glycol which has high penetration ability. The prepared cutting fluids were applied to the cutting zone in pulverised form by minimum quantity of lubricant (MQL) technique due to the lower environmental and health impacts. In the experimental section, surface roughness values and cutting forces were measured and analysed according to the response surface method (RSM). Besides, chip morphologies were examined in microscale using SEM and EDX, and the effects of additives were discussed in detail. As a result, it was determined that the silver nano-particle additive reduced the surface roughness up to 13.88 %. However, any sufficient effect reducing the cutting forces was not observed.

Wear-resistant carbon nanorod-embedded poly(vinylidene fluoride) composites with excellent tribological performance

High-tribological performance composites were prepared by incorporating wear-resistant carbon nanorod (CNR) fillers into a poly(vinylidene fluoride) (PVDF) matrix. CNRs with a diameter of 300 nm were synthesized via electrospinning a polyacrylonitrile solution followed by pyrolysis. The incorporation of the CNR filler increased the fraction of the non-polar α-phase in the PVDF matrix, which improved the friction and interfacial adhesion properties of the composites. The composites showed excellent frictional performance and wear resistance owing to self-lubricating property and scaffold effect of the CNR filler. The lowest friction coefficient was obtained at the CNR loading of 10 wt%. Compared to neat PVDF, the friction coefficient and wear rate of the PVDF/CNR composite with 10 wt% CNR loading decreased significantly from 0.43 to 0.03 and 8.43 × 10−5 to 3.70 × 10−5 mm3/N m, respectively. These values represent excellent tribological performances for polymer-based composites.