Tribological Behavior Research Articles

Surface mechanical rolling treatment-introduced gradient nanostructured Inconel 625 alloy with enhanced high-temperature wear resistance

Heterogeneous gradient nanostructures induced through surface treatment of nickel-based superalloys hold significant promise for enhancing wear resistance. In this study, a 700 µm ultra-thick gradient nanostructured (GNS) strengthening layer was fabricated on the surface of an Inconel 625 alloy plate via surface mechanical rolling treatment (SMRT). Subsequently, the tribological behaviors and wear resistance mechanisms of coarse-grained (CG) and GNS samples at temperatures ranging from 25 ℃ to 800 ℃ were comparatively investigated. The results indicated that the gradient nanostructures significantly enhanced the high-temperature wear resistance of the samples, which wear characterized by low coefficient of friction (COF), wear rate and thin friction layer. This enhancement was attributable to the stability and excellent hot hardness of the gradient nanostructures during friction.

Understanding the Influence of Carbon Interlayers on Material Removal and Tribochemical Evolution in Multilayer Coatings Through In-Situ Analysis

The carbon interlayers in the multilayer coatings can improve the load-bearing capacity and oxidation resistance, promote the layer-by-layer wear mechanism, and extend the lifespan of the multilayer coating, which is crucial to improving their tribological properties. To investigate the role of C interlayers in the competitive relationship between tribochemistry and material removal in multilayer coatings, this study comprehensively examines the tribological behavior of single layer MoS2 and multilayer MoS2/C coatings through in-situ tribotests and nanoscratch tests. Key findings reveal that the C interlayers enhance the tribological behavior by reducing the oxidation rate of MoS2, improving the load distribution, and delaying the onset of coating failure. Specifically, the single layer MoS2 coating demonstrated a lifespan of 55,000 cycles, whereas the multilayer MoS2/C coating achieved 80,000 cycles, reflecting a 45% enhancement. The critical load increased from 8 mN to 18 mN, indicating a 125% improvement in removal resistance. The presence of C layers results in a more stable and enduring tribofilm, which leads to reduced friction and wear. This study underscores the importance of in-situ analysis by combining nanoscratch with Raman mapping to elucidate the complex tribological behavior of coatings. These insights are crucial for designing efficient, wear-resistant, low-friction multilayer coatings for diverse industrial applications.

The tribological properties and synergistic lubrication mechanism of MoS2/AlOOH nanosheets as lubricant additives

The MoS2/AlOOH nanocomposites were prepared through a facile one-pot hydrothermal method and subsequently employed as lubricating oil additives to improve the tribological properties of PAO4 base oil. The structure, composition, morphology, tribological properties, and lubrication mechanism of the MoS2/AlOOH nanocomposites have been investigated. The results demonstrated that the in-situ assembly of MoS2 on the surface of AlOOH change their microstructure, resulting in enhanced dispersion and a reduction in friction and wear. At 0.5 wt% concentrations of MoS2/AlOOH nanocomposites, the average COF, WSD, and wear volume were decreased by 50.47 %, 42.34 %, and 86.57 % compared to base oil, respectively. Moreover, the tribological behaviors of the PAO4 containing MoS2/AlOOH nanocomposites under various conditions were explored as well. Furthermore, based on the analysis of micromorphology and composition of wear surfaces, a synergistic lubrication mechanism for MoS2/AlOOH nanocomposites has been proposed, which involves the formation of a tribochemical film composed of Fe2O3, Fe3O4, MoS2, and Al2O3 and demonstrates remarkable capabilities in reducing friction and wear. This research might provide new insight into enhancing the tribological properties of MoS2-based additives through the composite method and promote the application of MoS2/AlOOH nanocomposites as additives.

Investigation on the mechanical and tribological behavior of tungsten-reinforced Ti-5Al-2.5Sn composites

Investigation on the mechanical and tribological behavior of tungsten-reinforced Ti-5Al-2.5Sn composites

Mechanical properties and tribological behavior of hard phase doped Pb/MoS2 composite films

MoS2 is commonly used as a lubricant in spacecraft applications, and it is necessary to improve the vacuum tribological properties of MoS2 films. Thus, in the current study, hard phase (Ta, Ti, and TiN) and soft metal (Pb) double-doped MoS2 composite films were designed and prepared using an unbalanced magnetron sputtering system. The microstructures and mechanical and tribological properties of the hard-soft phase doped Pb/MoS2 composite films were systematically investigated. The results showed that the synergistic effect of the hard and soft metals gave a denser MoS2 structure denser. In addition, an amorphous structure was generated along with fine crystals, leading to a structure typical of nanocrystals embedded in an amorphous phase. Furthermore, compared with the Ti-doped Pb/MoS2 film, the doped alternative hard phase (i.e. Ta and TiN) improves the mechanical properties, among which the adhesion strength of Ta-Pb/MoS2 film is the highest, and the hardness of TiN-Pb/MoS2 film is the highest. Importantly, the soft metal Pb and its sulfide are excellent lubricants, while the hard phase ensures the long-term reliability of the films. Overall, these soft-hard bimetallic-doped MoS2 films exhibit superior tribological properties to their un-doped equivalents.

Tribological behavior of TiN, AlTiN, and AlTiCrN coatings in atmospheric and vacuum environments

In this study, the tribological characteristics of TiN, AlTiN, and AlTiCrN coatings sliding against a SUS420J1 stainless steel pin were investigated in atmospheric and vacuum environments. The coatings were deposited on SUS440C substrates using the arc-physical vapor deposition technique. The friction and wear behavior of the coatings were evaluated based on the systematic analyses of the friction coefficient data as well as the physical and chemical state of the wear track. The results revealed that the friction coefficients of the SUS440C specimen and AlTiCrN coatings increased, whereas those of the TiN and AlTiN coatings decreased when the environment was changed from atmospheric to vacuum. It was confirmed that the formation of an oxide layer and adsorption of oxides on the surface were dominant factors that influenced the tribological behavior in the atmospheric environment. On the other hand, the compatibility, oxidation inhibition, and droplets of the surface mainly affected the frictional characteristics in the vacuum environment. The results of this work are expected to aid in the selection of proper coating materials for tribological systems operating in a vacuum.

Investigations on tribological behavior under lubricated condition of post heat treated additively manufactured SS316L parts

PurposeThe purpose of this paper is to investigate the friction and wear mechanisms in lubricated sliding conditions of additively manufactured SS316L parts. The different viscous oils 5W30, 15W40, 20W50 and SAE140 are used. These investigations provide a theoretical basis for the high performance of printed and postheattreated SS316L.Design/methodology/approachTribological tests were carried out on selective laser melting-made SS316L printed specimens and heat-treated specimens. The parameters in 15 min of test duration are 20 N of load, 200 rpm, 8 mm of pin diameter, 25 mm length, 80 mm of track diameter and EN31 counter disc body. This work presented the phenomena of lubrication regimes and their characterization, as identified by the Stribeck curve, and these regimes affect the tribological properties of additively manufactured SS316L under the influence of industrial viscous lubricants. The results are observed using Scanning electron microscope (SEM), X-ray diffraction (XRD) and wear tests.FindingsThe observations indicate that additively manufactured SS316L shows a reduced coefficient of friction (COF) and specific wear rate (SWR). This is credited to the utilization of different viscous lubricants.Originality/valueThis exclusive research demonstrates how various viscous lubricants affect the COF and SWR of printed and post-heat-treated SS316L parts. Lambda (λ), lubricant film thickness (h0), surface roughness and wear mechanisms are studied and reported.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0110/

Effect on Ti/Mg isothermal oxidation of refinement microstructure and tribological behaviour of pure aluminium alloy by plasma spray coating

Effect on Ti/Mg isothermal oxidation of refinement microstructure and tribological behaviour of pure aluminium alloy by plasma spray coating

Comparative study on tribological behaviors of interproximal tooth enamel against zirconia under fretting and sliding conditions

Interproximal contact loss (ICL) between zirconia crown and adjacent natural teeth is a common complication that could lead food impaction and compromise the periodontal/peri-implant tissue health and patient’s satisfaction. Both fretting and sliding wear mode can be found in the frictional pair between zirconia crown and interproximal enamel during mastication. In this study, fretting and sliding wear behavior of interproximal enamel against zirconia in artificial silva was investigated. The wear damage of the interproximal enamel in a sliding movement was higher than in a fretting movement. In fretting mode, the running condition fretting map (RCFM) composed of partial slip regime (PSR), gross slip regime (GSR), and mixed fretting regime (MFR) was constructed depending on different normal loads and displacement amplitudes. Intact surface was observed in the PSR. Plastic deformation at contact center and microcracks at contact margin were detected in the MSR. Severe wear damage occurred in the GSR, predominated by microfracture, brittle deformation. Macroparticles generation, fatigue delamination and abrasive wear prevailed in sliding mode. In contrast, enamel debris could be transferred on zirconia surface while the material loss of the antagonist zirconia was negligible in both fretting and sliding test.

Pin-on-disc tribological characterization of single ingredients used in a brake pad friction material

Researchers have long been studying the effects of the modification of friction material compositions on their tribological properties. Predictive models have also been developed, but they are of limited use in the design of new compositions. Therefore, this research aims to investigate the tribological behaviour of single ingredients in friction materials to develop a tribological dataset. This dataset could then be used as a foundation for a cellular automaton (CA) predictive model, intended to be a tool for designing friction materials. Tribological samples were almost entirely composed of four distinct friction material ingredients, and one sample composed of their mixture was successfully produced. Pin-on-disc (PoD) tribometer testing and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDXS) analysis were used for the tribological characterization. Each material showed distinct tribological properties and evolution of the contact surface features, and the synergistic effect of their mutual interaction was also demonstrated by their mixture.

Tribological Behavior and In‐Vitro Biocompatibility of a Newly Designed TiZrNbMoTa High‐Entropy Alloy

A novel Ti35Zr15Nb25Mo15Ta10 high‐entropy alloy has been designed, fabricated, and characterized as a viable substitute for the conventional Ti‐6Al‐4V alloy in biomaterial applications. Alloy design is conducted based on various parameters including mixing enthalpy (ΔHmix), omega parameter (Ω), delta parameter (δ), valence electron concentration (VEC), and biocompatibility aspects of its constituent elements with CALPHAD approach. The fabricated Ti35Zr15Nb25Mo15Ta10 alloy demonstrated a body‐centered‐cubic (BCC) solid solution phase with no evidence of intermetallics. Nanoindentation investigations exhibited high hardness of ≈5.1 GPa and a young modulus of ≈140 GPa. The alloy proposed better surface properties and tribological behaviour in comparison with the Ti‐6Al‐4V alloy in dry and wet (under PBS solution) conditions. Furthermore, the newly designed alloy revealed promising behaviour after investigation of in‐vitro biocompatibility compared to the Ti‐6Al‐4V alloy. These initial benefits of the Ti35Zr15Nb25Mo15Ta10 alloy concerning mechanical properties and wear resistance over the conventional Ti‐6Al‐4V alloy present an avenue for exploring novel orthopedic implant alloys.

Unveiling the tribological and corrosion characteristics of Ti20-Al16-V16-Fe16-Ni16-Cr16 high-entropy alloy developed via spark plasma sintering

This research explores the corrosion resistance and anti-wear property of near-equimolar Ti20-Al16-V16-Fe16-Ni16-Cr16 High Entropy Alloys (HEAs), fabricated at varying temperatures through spark plasma sintering (SPS) procedure. The alloy powders were processed and sintered at temperatures ranging from 700°C to 1100°C, and the resulting HEAs underwent comprehensive characterization. The tribological behavior of these sintered HEAs and their corrosion response in sulfuric and chloride environments were systematically investigated. Microstructural analyses were conducted before and after exposure to corrosive media using a scanning electron microscope. Notably, the assessments in both acid and salt media revealed that HEAs sintered at 1100°C exhibited the highest corrosion resistance, whereas those sintered at 700°C displayed the least resistance. The wear rate is improved by 130% over Inconel 718 alloy in the created HEA. This research signifies the potential of Ti20-Al16-V16-Fe16-Ni16-Cr16 HEA prepared through tailored SPS procedures, as corrosion and wear resistance alternatives surpass the performance of Ti6AlV4 and traditional alloys.

Effect of pv factor on carbo-graphite and copper impregnated carbo-graphite material under dry conditions

This study investigates the tribological behaviour of copper-impregnated carbo-graphite (ICG) compared to plain carbo-graphite (CG) under various parameter-product (PV) values and temperatures. Impregnation significantly enhanced ICG's hardness (70%) and reduced porosity (98.6%) compared to CG. The CoF for CG was lower than that for ICG attributed to the formation of a lubricating graphite-rich tribo-film that facilitated easy shearing at the contact interface. The wear mechanisms for CG at elevated temperatures were identified as adhesion, oxidation and delamination, likely exacerbated by the material's softening. In contrast, ICG exhibited superior wear resistance, attributed to its higher hardness and the formation of a protective tribo-layer containing copper and graphite. This tribo-layer offered a low-shear interface at lower PV values, reducing friction. However, at higher PV values, ICG wear increased due to abrasion and adhesion. Overall, copper impregnation offers a promising strategy to improve the wear resistance of carbo-graphite, particularly at elevated temperatures.

Mechanical, corrosion and tribological behavior of friction stir processed AZ31B/egg shell /WS2 hybrid surface composite

In the present work, egg shell and Tungsten disulphide particles are reinforced in AZ31B alloy using friction stir process. Initially, the ES and WS2 particles are mixed at different weight ratios (25/75, 50/50 and 75/25) then are reinforced in AZ31B plates using a taper threaded FSP tool at rotation speed of 1000 rpm, axial load of 6 kN and traverse speed of 10 mm/min in hole method. The post macroscopic analysis showed that defect free hybrid surface composite is obtained with 75wt %ES and 25wt % WS2 particles reinforced in AZ31B alloy. The grain size is reduced from 15 µm to 5 µm due to the addition of 75wt% ES and 25wt% WS2 particles through FSP. The mechanical, corrosion and tribological responses of AZ31B/75ES/25WS2 hybrid surface composite are observed and are compared with FSPed AZ31B alloy without reinforcements and AZ31B base alloy. The microhardness is improved by 66% and 83% in FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite respectively compared to the AZ31B base alloy. Similarly, the ultimate tensile strength is improved by 16% and 31% in FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite respectively compared to the AZ31B base alloy but the % of elongation is decreased by 70% and 78% in FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite respectively compared to the AZ31B base alloy. The corrosion rates of FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite are decreased by 22% and 48% respectively compared to AZ31B base alloy. The dry sliding friction and wear responses are observed for AZ31B base alloy and AZ31B/75ES/25WS2 hybrid surface composite by varying the applied load (10 N, 20 N and 30 N) and sliding velocity (1.5 m/s, 2.6 m/s and 3.6 m/s) with constant sliding distance of 2000 m. In AZ31B base alloy, the wear mechanism is initially dominated by delamination and ploughing phenomena but at high sliding condition, the delaminated and worn out debris based tribolayer reduced the wear rate. In AZ31B/75ES/25WS2 hybrid surface composite, the wear mechanism is dominated by adhesive and delamination phenomena and the formed tribolayer decreased the wear rate at high sliding condition.

Mechanical and Tribological Behaviours of Aluminium Metal Matrix Composite Reinforced with Bamboo Powder and Iron Filings

Mechanical and Tribological Behaviours of Aluminium Metal Matrix Composite Reinforced with Bamboo Powder and Iron Filings

Augmenting microstructure and tribological performance of wire arc additive manufactured PH13-8Mo stainless steel via TiC/TiB2 nano-particles incorporation

This study aimed to investigate the effect of TiC and TiB2 nano-inoculants addition on the microstructure and tribological behavior of PH13-8Mo stainless steel processed through wire arc additive manufacturing (WAAM). The incorporation of TiC/TiB2 inoculants demonstrated notable efficiency in mitigating the anisotropic wear and scratch response and enhancing wear resistance observed in the as-printed state. This improvement was ascribed to the refinement of the grain structure, disruption of the columnar structure, and increased content of the retained austenite. Notably, TiB2 inoculation exhibited superior grain refinement and achieved the highest hardness. However, the TiC-inoculated condition demonstrated the best wear resistance, attributed to its excellent combination of hardness and fracture resistance, and a higher contribution of strain-induced martensite transformation during wear testing. Additionally, the implementation of post-printing solutionizing and aging treatment was found to improve the scratch and wear resistance of the alloy, attributed to the formation of nano-sized β-NiAl precipitates. The main wear mechanism observed involved oxidation wear, adhesive wear, and three-body abrasive wear. The findings of this study highlight the significant potential of incorporating ceramic-based nano-particles for improving the wear resistance of WAAM PH13-8Mo components, particularly in demanding applications like injection molding dies where superior abrasion resistance is paramount.

Fabrication and tribological behavior of laser cladding Cu/Ti3SiC2 reinforced CoCrW matrix composite coatings on Inconel718 surface

To satisfy the need for high wear resistance of Inconel718 alloy under harsh working conditions, laser cladding technique was adopted to fabricate the Cu/Ti3SiC2-CoCrW metal matrix composite coatings on that surface. The phase composition, microstructure, microhardness, surface energy, and tribological properties of the composite coatings were systematically analyzed by characterization methods such as XRD/ SEM/ EDS/ XPS and performance test methods such as high-temperature friction and wear test, and the wear mechanism at different temperatures was deeply discussed. The research results indicate that the microhardness of coatings is increased by 2.2–2.9 times compared to the substrate, which is mainly owing to the solid solution strengthening effect and the diffusely distributed hard reinforcing phases such as Cr7C3, WCx, and TiC. Regarding the wear resistance, the wear rate of coatings is significantly reduced by 1–2 orders of magnitude over the substrate. Among them, the Co-based coating adding 10 wt% Cu - 10 wt% Ti3SiC2 exhibited the lowest wear rates at room and high temperatures, which were 0.22 and 3.23 × 10−5 mm3/ N·m, respectively, with 98.22 % and 88.19 % reductions in comparison with the substrate. The low surface energy (27.94 mN/m) was one of the main reasons for the good tribological properties. When the friction environment changes from room temperature to 600 °C, the primary wear mechanism of coatings changes from abrasive and adhesive wear to oxidative wear.

Microstructure, Mechanical Properties and Tribological Behavior of Wire Electron Beam Additive Manufactured Eutectic Al–12Si Alloy

Microstructure, Mechanical Properties and Tribological Behavior of Wire Electron Beam Additive Manufactured Eutectic Al–12Si Alloy

Lubrication of polyphthalamide (PPA) and polyetheretherketone (PEEK) with biodegradable synthetic esters: Effects of base oil polarity, temperature and polymer aging

This study aims to evaluate the tribological behavior of polyphthalamide (PPA) and polyetheretherketone (PEEK) lubricated with biodegradable synthetic esters. Tribological tests were performed at 23 °C and 100 °C with new and aged samples to assess the effects of increased temperature and polymer aging on friction and wear. The results of tests at room temperature and the SEM images of the wear scars show that synthetic esters provide better wear resistance to PEEK than synthetic mineral oil (polyalphaolefin, PAO). FTIR and XPS analyses suggest the formation of a physisorbed protective film by the esters. Trimethylolpropane-based ester (TMP) was shown to adsorb better to both polymers than propylene glycol-based ester (PG), but this did not translate into a better tribological performance. When compared to room temperature, tests at 100 °C showed a higher wear coefficient for both polymers, irrespective of the oil. However, the friction coefficient increased for PEEK due to a higher adhesion, while it decreased for PPA because of the material’s softening. The aging of samples at 100 °C degraded the tribological performance of the polymers, especially aging in PG ester, which caused an increase in friction for PEEK and an increase in friction and wear for PPA. PG ester was found to have caused oxidation of both polymers to a greater extent than PAO or TMP ester.

Comparative analysis of pin-on-disc and inertia-dynamometer sliding tests on a friction material

The development of modern brake systems requires the assessment of multiple aspects. Among these, parameters related to the tribological behaviour, vibration, and particulate matter emission are typically evaluated using inertia dynamometers and tribometers. While these two testing systems have been previously compared regarding emissions and tribological behaviours, vibrations were not compared, nor have all these aspects been examined simultaneously. This study investigates the scale effects between a pin-on-disc tribometer and a reduced-scale dynamometer operating under dragging conditions with two levels of pressure and velocity, and a disc temperature not exceeding 260 °C. Regarding the vibration, the pin-on-disc exhibited higher and broader values in the normal direction, 1.3–15.5 m/s2, than the reduced-scale dynamometer, 0.37–0.42 m/s2, while the tangential vibrations exceeded those in the normal direction in both systems. The wear rates in the two systems were overall similar, in the range of 1–4 e−14 m2/N. During the tests the disc temperature in the dynamometer increased at a higher rate compared to the pin-on-disc, affecting the tribological and emission behaviours: steady state values were obtained only in the pin-on-disc tests. The particulate concentration values observed during dynamometer tests better correlated with the peak values from pin-on-disc tests rather than with the steady-state values. This study highlights the importance of including transient values in the evaluation of pin-on-disc testing.