Anti-wear Properties Research Articles

Tribology performance of diamond-like carbon films on polyether-ether-ketone surfaces

Diamond-like carbon films were deposited on the polymer PEEK surface using a magnetron sputtering system. Experiments were conducted under varying rotational friction speed conditions. Special attention was devoted to assessing the surface condition of spherical spots post-friction experiments. Optical microscopy, friction tester, Raman spectroscopy, XPS analysis, and atomic force microscopy were employed to examine film surface morphology, atomic bonding structure, and surface roughness. The results indicate that thin film wear trace exhibits a graphitization trend that increases and then decreases, peaking around 350 rpm (0.11 m/s). Conversely, for spherical spots, the graphitization pattern is the opposite, suggesting a higher degree of disorder in the transferred film on these spots. XPS analysis reveals multiple chemical bonding structures between carbon and oxygen elements on the spherical spots. Notably, under the optical microscope, spherical spots exhibit clear directional alignment, which is absent on the film surface. This study introduces an innovative approach for producing diamond-like carbon films with lubricating and anti-wear properties. It also provides guidance for designing high-performance polymer tribo-systems in industrial applications.

Insight into the tribological properties of cylinder liner-piston ring under the nano BNNs/Cu composite additive lubrication

To improve the tribological properties of the cylinder liner-piston ring, a two-dimensional hexagonal boron nitride/copper composite lubricant additive was prepared and characterized in detail. The tribological properties and lubrication mechanism of nano hexagonal boron nitride composites with different concentrations were studied through the reciprocating friction test on the Rtec friction and wear tester. The results show that copper is successfully reduced and attached to the surface of h-BN nanosheets through the self-polymerization of dopamine, and the spherical structure promotes the interlayer slip of the nanosheets during the reciprocating friction process. The appropriate concentration of nano composite additives has excellent anti-friction and anti-wear properties. At 1 Hz and 100 N, the friction coefficient and wear quality of the nano composite additive with a concentration of 2 wt% were reduced by 29.07% and 76%, respectively. The surface Sq value and Sz value of the cylinder liner sample decreased by 68.06% and 74.47%. At the same time, under the condition of high speed and heavy load, the average wear depth of the cylinder liner sample is reduced by 61.3%. The nano composite material additive forms an excellent friction protective film on the wear surface of the cylinder liner, which can better enter the wear surface of the cylinder liner and produce a filling and repairing effect. The research results provide a method for the use of nano hexagonal boron nitride composite additives to inhibit the wear of cylinder liner-piston ring of Marine diesel engines.

Revealing the tribological mechanism of synergistic effect between MoDTC and P-containing additives in aluminum-based grease

Purpose This study aims to reveal the tribological mechanism of synergistic effect between MoDTC and P-containing additives in aluminum-based grease. Design/methodology/approach The authors prepared a molybdenum dialkyl dithiocarbamate (MoDTC) and revealed the tribological mechanism of synergistic effect between MoDTC and P-containing additives in aluminum-based grease by combining with ZDDP and P-containing and S-free additives. Findings The MoDTC the authors prepared has good friction-reducing and anti-wear properties in aluminum-based grease and has an obvious synergistic effect with ZDDP. MoDTC and ZDDP have a significant synergistic effect on the tribological properties in aluminum-based grease, mainly because of the formation of phosphates and metaphosphates as well as more MoS2 in the friction film. P element plays a facilitating role in the chemical conversion of MoDTC to MoS2. Originality/value The experiments of MoDTC with tributyl phosphate and trimethylphenyl phosphate confirm that the P element plays a facilitating role in the chemical conversion of MoDTC into MoS2. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0410

Investigating the Wear Mechanism of TiAlN/TiN PVD-Coated WC Inserts in End Milling of Incoloy 925 Under Synergy of Bio-Degradable Fatty Acids and Nano-Metallic Solid Lubricant

Abstract Rapid tool wear in machining difficult-to-cut material is a significant challenge since it is related to tool cost, surface integrity of machined components, and power consumption. The reduction in tool wear may be accomplished by cutting fluids, especially in modern biodegradable fatty acids. Because of its high lubricity, coconut oil is the best choice for lubricating fatty acids. However, this oil has poor heat transfer properties. Hence, to further improve its properties, copper (Cu) nanoparticles (NPs), which have a high thermal conductivity to cost ratio compared to other nanoparticles in addition to anti-frictional and anti-wear properties (due to self-repairing properties caused by their low shear strength and easy deposition on contacting surfaces), have been dispersed in coconut oil, thus creating a nano-lubricant (nanofluid). It is found that synthesized nano-lubricants perform better in thermo-physics and tribology than pure coconut oil. Further, research has been carried out on the combined effects of coconut oil and 0.3 vol% Cu-NPs on Incoloy 925's end milling performance and tool wear mechanism (viz., coating delamination, adhesion, abrasion, and oxidation). It is found that tool wear-rate is reduced, which in turn increases tool life, due to effective cooling and lubrication when nanofluid-based minimum quantity lubrication (NMQL)-assisted machining is performed rather than dry and pure oil-based minimum quantity lubrication (MQL) conditions. Consequently, energy consumption in machining and surface quality of machined components are improved.

Synergistic effect of graphene and nanodiamonds to achieve ultra-low friction on rough DLC coatings

Diamond-like carbon (DLC) with its protective, antiwear and self-lubricant properties represents an outstanding coating material to improve the tribological performance of bare metal-to-metal contacts. The DLC friction response is strictly related to the generation of a carbon-rich transfer layer on the sliding countersurfaces. This key process may benefit from the DLC surface functionalization with carbon nanomaterials, as attested by the recent observation of wearless sliding and ultra-low friction for nanorough model interfaces. In this study, we show by ball-on-disc tribometer that the tribological response of microrough steel-DLC contacts is considerably improved in dry atmosphere through DLC functionalization with graphene sheets (GSs) and nanodiamonds (NDs). The functionalization effectiveness is demonstrated exclusively with both allotropic forms, that synergically lower friction after a unique run-in period. We attribute the enhanced lubricity, with steady coefficient of friction <0.05 at 1 N load, to the formation of a transfer layer which incorporates GSs, NDs and nanoscroll structures self-assembled during sliding. High-resolution electron microscopy and Raman spectroscopy indicate that NDs, besides enabling the erosion of the highest interfacial micro-asperities, do assist the transfer layer development via GSs milling. Our findings contribute to the current quest for superlubricity in realistic tribocontacts meeting industrial standards.

Solid-state deposition of Mo-doped CoCrFeNi high-entropy alloy with excellent wear resistance via cold spray

To improve the wear resistance of CoCrFeNi high-entropy alloys (HEAs) for a wider range of industrial applications, the alloying strategy was applied to CoCrFeNi HEA by doping Mo element in various ratios, and CoCrFeNiMox (x = 0, 0.2, 0.5, and 1.0) HEA deposits were fabricated by cold spray. The microstructure evolution, mechanical properties, and tribological properties of cold-sprayed CoCrFeNiMox HEA deposits were systematically investigated. The results showed that Mo0, Mo0.2, and Mo0.5 deposits have a face-centered-cubic (FCC) single structure, while Mo1.0 deposit was composed of FCC matrix and hard brittle phases. The doping of Mo element into CoCrFeNi HEA deposits significantly increased the hardness due to the enhanced solid solution strengthening and precipitation strengthening. As a result, the anti-wear properties of Mo-doped CoCrFeNi HEA deposits were gradually improved with the increase in Mo ratios. To be specific, the Mo1.0 deposit exhibited the lowest specific wear rate of 5.1 × 10−5 mm3/N·m, which was reduced by 94.9% in comparison to the Mo0 deposit. Overall, the current study proposes a new strategy to manipulate the mechanical properties of cold-sprayed HEA deposits by alloying.

Iron phosphate nanoparticles as oil additives to enhance anti-wear properties

In recent years, nanomaterial lubricant additives have been widely studied in tribology. In this work, a new iron phosphate (FeP) nanoparticle was synthesized to enrich the anti-wear oil-based additives for titanium alloys. A series of tribological experiments were conducted using a reciprocating ball-on-disc tribometer. It has been confirmed that, as additives in polyalphaolefin 8 (PAO8), FeP nanoparticles exhibit excellent friction-reducing and anti-wear properties for TA5 titanium alloys. Compared with the pure PAO8, the friction coefficient (COF) and wear rate (WR) can be significantly reduced by 69.89 % and 99.57 % at a concentration of 30 wt%. The SEM and EDS confirmed that FeP nanoparticles can play a surface repair role and deposit on the titanium alloy surface to form a deposition layer, which was the key to anti-wear property. Besides, XPS characterization demonstrated that the formation of the deposition layer was attributed to the P–O–Ti bond at the interface, through which the phosphate in FeP can bind to and adsorb on the titanium alloy surface. This deposition layer containing FeP can greatly reduce the adhesive wear of the titanium alloy. Meanwhile, the rolling effect of nanoparticles inside the deposition layer promoted the friction-reduction.

Effect of ionic liquid modified indium tin oxide as additive on tribological properties of grease

This study investigates the formulation of composite lubricating greases by incorporating SnO2, ITO, and ATO nanoparticles as additives into a polyurea base grease with excellent additive sensitivity, aiming to explore the physicochemical and tribological properties of the composite lubricating greases. Additionally, two categories of three different ionic liquids were selected to modify the nano metal oxides, and the modified powders were characterized to investigate the tribological properties and conductivity of the polyurea grease after incorporating the ionically modified nano metal oxides. The experimental results demonstrate that the nano metal oxides, when used as lubricating grease additives, can form stable boundary lubrication films, exhibiting excellent anti-wear and anti-friction properties. The ionic liquid-modified nano metal oxides exhibit outstanding anti-friction and anti-wear properties, along with increased conductivity. Particularly, the use of lactate-based ionic liquid for modifying nano metal oxides shows superior degradation, anti-friction, anti-wear, and conductivity properties, holding promising prospects for various applications.

Polycarboxylate superplasticizer modified 3D graphene as long-term-efficient water-based lubricating additive under heavy load conditions

At present, due to the excellent properties of graphene, which can significantly enhance the performance of lubricants, researchers are conducting extensive studies on it. However, the poor dispersion of graphene limits its application in lubrication, which becomes an urgent problem for researchers to solve. Moreover, with the concept of green environmental protection becoming more and more popular, the research on water-based lubricants is of great significance. Therefore, we modify three-dimensional graphene (3DG) by polycarboxylate superplasticizer (PCE) to prepare a water-based lubrication nano-additive with long-term dispersion stability, named PCEG. PCEG nanomaterials can stably disperse in water for more than three months, which effectively solves this problem. Tests show that friction coefficient and wear volume of the lubricant with 0.5 wt% PCEG are reduced by 31.1 % and 23.1 %, respectively, compared to the base fluid at 20 N (2.7 GPa) heavy load conditions. The enhanced lubrication performance is attributed to the fact that PCEG, which has excellent dispersion stability, forms a strong adsorption and continuous dense lubrication film on the friction surface. In addition, it fills and polishes the grooves and pits, thus improving the friction-reduction and anti-wear properties. This study not only greatly solves the problem of poor dispersion stability of graphene and develops a nano-lubricant that is consistently effective under heavy load conditions, but also provides an important reference value for the subsequent development of high-performance and stable graphene-based lubricants.

Friction and self-repairing behaviour of magnesium silicate hydroxide-MoS2 lubricant additives on gray cast iron with Cr-coated steel ball friction pairs

To improve the tribological performance of piston ring assemblies, this work studies the friction and self-repair behavior of magnesium silicate hydroxide(MSH)/MoS2 nanoparticles as PAO6 lubricant additives, whose friction condition is simulated piston ring-cylinder liner operating condition using a friction pair composed of chrome-plated steel balls and gray cast iron. By studying the effect of different concentrations on the friction reduction and anti-wear properties, it was found that the addition of MSH/MoS2 nano-powder to PAO6 could all play a role in the friction reduction and anti-wear effect, with the best friction reduction effect at 0.5 wt% addition. The self-repairing behavior of the lubrications with 0.5 wt% MSH/MoS2 nanopowders was found on grey cast iron specimens after 8 h of friction experiment.

Design and tribological performance of graphene nanofluids dispersed by dragging effect of bicomponent gelator

Nanofluids have excellent lubrication and high thermal conductivity. However, the agglomeration and sedimentation produced by the large surface energy of nanoparticles in base liquid threaten the long-term dispersion stability and impact the wide application of nanofluid. In this work, based on the self-assemble behavior and continuous network structure formed by low molecular weight organic gelator, the uniform clusters were formed through regulating the kinetics behavior in the gelling process. The dragging effect was demonstrated by oleic acid - sodium dodecyl sulfate (OA-SDS) bicomponent gelator and graphene oxide (GO) nanosheets. The results showed that GO nanofluids dispersed by OA-SDS were stable for more than 12 months. The well-dispersed GO nanofluid exhibited better anti-friction and anti-wear properties under both immersion and electrostatic minimum quantity lubrication conditions. Moreover, the lower contact angle, surface tension and droplet size of nanofluids after charging improved the wettability on the frictional interface. The GO adsorption film formed on the friction interface protected the tribochemical reaction film of iron oxide and prevented the occurrence of sintering of base oil.

Amino acid-based ionic liquids as water-ethylene glycol additives towards superior lubricity and corrosion resistance

Two novel amino acid-based ionic liquids (AAILs) were synthesized and their tribological properties as water-ethylene glycol (W-EG) lubricant additives were investigated. The addition of 1 wt% of both AAILs to W-EG can significantly enhance the anti-corrosion, friction-reducing and anti-wear properties of the lubricants. Compared to W-EG, the coefficient of friction and wear volume are reduced by about 50% and 75%, respectively. The physical adsorption film and the tribochemical reaction film derived from AAILs collectively establish a protective barrier at the friction interface, endowing the lubricants with superior lubricity and load-carrying capacity. These two sulfur-free and halogen-free AAILs are promising for application in metal working fluids and hydraulic fluids.

Mechanical properties and current-carrying tribological behaviors of sliver-titanium nitride composite ceramic coating

Current-carrying friction materials with excellent electrical conductivity and anti-wear ability are in constant demand in both academia and industry. In this work, the sliver-titanium nitride (Ag–TiN) composite ceramic coating was fabricated by an arc ion plating method. The microstructure, chemical composition, crystal structure, mechanical properties and current-carrying tribological behaviors of the Ag–TiN composite coating were systematically studied and the worn surfaces were also thoroughly investigated to analyze the possible tribological mechanisms in detail. The results showed that the Ag–TiN composite ceramic coating achieved uniformly distributed co-deposition of Ag and TiN compositions and exhibited excellent mechanical properties and electrical conductivity. The current-carrying tribological tests also revealed that the Ag–TiN composite coating exhibited exceptional friction reducing, anti-wear and conductive properties during the friction process. The analysis of the worn surface showed that the excellent current-carrying tribological behaviors of the Ag–TiN composite ceramic coating were related to the excellent electrical conductivity, the appropriate mechanical properties and the tribo-layer film formed on the worn surface.

Synthesis, tribological properties and oxidative stability of polyol esters base oils containing pentaerythritol complex esters

The performance requirements for extreme pressure and anti-wear properties, as well as oxidative stability, are increasingly stringent for MIL-PRF-23699G Enhanced Ester (EE) for aviation turbine engine lubricants. An oligomerization reaction of pentaerythritol through direct esterification using pentaerythritol and dibasic acid catalyzed by tetrabutyl titanate in xylene solvent, was employed to achieve the low-polymerization reaction of dibasic acid and pentaerythritol. A two-step synthesis process yielded a mixed ester comprising dibasic acid pentaerythritol complex ester and pentaerythritol tetrapentanoate. These mixed esters demonstrate excellent viscosity-temperature performance and good oxidative stability, significantly enhancing the extreme load-carrying properties and anti-wear properties of pentaerythritol tetrapentanoate. Molecular dynamics (MD) calculations indicate that complex esters possess higher adsorption energy and molecular interaction energy, enhancing the possibility of ester molecules adsorbing on metal surfaces and producing stronger oil film that can withstand large loads. The novel 5 mm2/s pentaerythritol ester containing diacid pentaerythritol complex esters exhibits improved viscosity-temperature performance, high-temperature oxidation resistance, and better tribological properties. Therefore, the novel pentaerythritol esters show potential for application in 5 mm2/s EE aircraft engine lubricants.

Enhancing wear resistance and mechanical property of epoxy coating via “roller wheel” liquid metal‐MXene

AbstractThis work presents a design of a unique “roller wheel” structure combining rigid MXene and flexible liquid metal (LM), aiming to construct an epoxy composite coating with simultaneous advanced mechanical strength and lubrication properties. The antiwear property of the epoxy composites is improved by 72.8% when the LM is 0.5 wt% and MXene is 0.03 wt%. The incorporation of LM‐MXene improved the mechanical properties of the epoxy composite coating, resulting in an approximately 136.6% increase in elastic modulus. The unique “roller wheel” structure provides additional mechanical support and leads to lower adhesion between the MXene layers and LM. As a result, LM reduces the stripping and sliding of the interface between MXene layers during the friction process, further enhancing the lubrication performance of the epoxy composite coating.

Mechanical, wear and corrosion behaviours of laser additive manufactured iron-based heterogeneous composite coatings for tillage tools

Steel is commonly used in engineering components, and it has a high tendency to wear and corrosion attacks when exposed to unfavourable working conditions. The use of chromium-vanadium-iron-rich carbide reinforced iron-based hard facings has become more important in improving the corrosion and wear resistance of such steel subjected to abrasive and impact conditions. In this study, the chromium-vanadium-iron carbide reinforced coatings were developed using in-situ by depositing FeCrV15+Cr powder through laser cladding on carbon steel. The influence of the reinforcement on the microstructure of the coating in relation to its laser processing condition and extra chromium addition was investigated. Furthermore, the effect of the coating's reinforcement on the hardness, microstructures, anti-corrosion, and anti-wear properties of the carbon steel used in tillage and mining operations was investigated. The result is a defect free deposits with a solid metallurgical attachment to the substrate and improved microhardness. FeCrV15 deposits had a wear-resistant (with a wear rate of 2.42 × 10−6 mm3/N/m) and anti-corrosion capability (with a corrosion rate of 0.001869 mm/yr) that were several folds higher than the steel substrate (with wear rate of 1.72 × 10−3 mm3/N/m and corrosion rate of 0.1168 mm/yr). The general grain refinement of the FeCrV15 deposits was richly enhanced in the iron base matrix. This resulted in outstanding wear and corrosion resistance attributed to the better production of VC–Cr3C2–Cr7C3 particles and better grain refinement of the microstructural formation.

Tribological performance of ficus carica oil modified with ethylene vinyl acetate and sodium dodecyl benzenesulfonate

PurposeDue to the environmental issues caused by petroleum lubricants used in lubrication, the concept of creating various bio-lubricants requires research globally. Thus, this study aims to develop, characterize and test the base ficus carica oil (fig oil) for its ethylene vinyl acetate copolymer (EVA) and sodium dodecylbenzene sulfonate (SDBS) content.Design/methodology/approachThe sample characterization was done using the Fourier transmission infrared spectrum, whereas the morphologies of the EVA, SDBS particles and lubricated surfaces were carried out under scanning electron microscope equipment. To ensure the homogeneity of the solution (base oil and additives), the formulations were subjected to the sonication process. The anti-friction and anti-wear properties of EVA and SDBS particles as lubricant additives were investigated using a ball on a flat high-frequency reciprocating rig tribo-tester.FindingsAccording to the findings, the base oil’s anti-friction and anti-wear capabilities can be greatly enhanced by the additions. revealed that the best results were obtained when 1.2% EVA + 2% SDBS was applied for the examination of wear (597.8 µm) and friction coefficient (0.106). Commercial references were used, nevertheless, and the results were excellent. This is because the particles in the contact area during lubrication have strong solubility and quickly penetrate the contact zone. The lubricating mechanisms were explained by a tribological model of the EVA + SDBS and SDBS particles.Research limitations/implicationsThe coefficient of friction and wear reduction caused by the use of the additives will certainly enhance system performance and protect the machine components from excessive wear that could cause damage or failure.Originality/valueThe originality and uniqueness of this work are officially affirmed by the authors. The authors’ autonomous and original contribution to the development of sustainable lubrication is represented in this work. To the best of the authors’ knowledge, no other study has been published or made publicly available that duplicates the precise scope and goals of our research, and this conclusion is based on a thorough literature assessment.

Study of low-toxicity copper pyrithione as a multifunctional additive for lithium grease

The feasibility of CuP as a multifunctional additive in lithium grease was evaluated for the first time. The experimental results indicated that the CuP significantly enhanced the friction reduction, antiwear properties, extreme pressure capabilities, and antimicrobial characteristics of lithium greases. The SRV test results suggested that the optimal tribological properties were obtained by adding 3 wt% of CuP to lithium greases, resulting in a decrease of the friction coefficient and wear volume by 28.25% and 34.98%, respectively. The four-ball results confirmed that the extreme pressure performance of the lithium grease with 3 wt% CuP was enhanced by a factor of 3.17. The bacterial inhibition rate of lithium grease with 3 wt% CuP was higher than 99.98%. The lubrication mechanism and antimicrobial mechanism was explained.

Application of Raman Spectroscopy to Evaluate the Structure Changes of Lubricating Grease Modified with Montmorillonite after Tribological Tests

This study shows the experimental data obtained by Raman spectroscopy to evaluate the structural changes of vegetable lubricants modified with montmorillonite after tribological tests. The analysis of the friction factor and limiting load of wear in the test for the examined grease compound shows a substantial effect on this parameter for grease. A change in the evaluated tribo-parameter results in a modification of the structure of the tested lubricant and changes in the protection efficiency of the tribological system. The amount of thickener, oil base and additive in the grease structure has an influence on the value of anti-wear properties, as shown by the data obtained in the tribological test described in this paper. The Raman spectroscopy tests showed that, in the tribological processes, some of the ingredients undergo an oxidative reaction, which leads to the formation of oxygenated organic substances that form an organic layer on the metal surface and counteract the wear of the lubricated contact surfaces. Other compounds come into close contact with the tribological layer, which increases its ability to resist wear and shear. The efficiency of the used additive is based on the formation (during friction) of a low-shear and high-plastic-strength thin film which is chemically highly bonded to the material and has a high level of durability against wear processes. As a consequence of the thermal decomposition of the additive, chemical interactions occur among the ingredients of the material of the substrate and the lubricants.

Microstructure and tribological properties of copper/graphite composites with Ti3AlC2 addition prepared by rapid hot press sintering

Copper/graphite composites are widely used due to their excellent electrical, thermal, and self-lubricating properties. However, their mechanical and anti-wear properties are usually limited by brittle graphite and soft copper matrix. Enhancing the properties of composites by further introducing harder ceramic particles is an effective way. However, these particles are usually poorly wetted to metal and can easily separate from the matrix during friction, causing more severe abrasive wear. Herein, TiCx-reinforced Cu/graphite composites were prepared by rapid hot press sintering of a hybrid powder consisting of Ti3AlC2, Cu-plated graphite, and Cu powder. Al atoms diffused out of Ti3AlC2 and solid-solved into the Cu matrix during the sintering process, forming TiCx and Cu(Al) alloys. Such in situ formed TiCx particles have good interfacial bonding with the matrix. With the increase of Ti3AlC2 addition from 0 to 15 wt%, the average grain size of the composites decreased, the relative density increased, the hardness became larger, the electrical conductivity decreased, and the average coefficient of friction were all maintained at about 0.14, but the wear rate was reduced from 3.6569 × 10−4 mm3·N−1·m−1 to 9.35013 × 10−6 mm3·N−1·m−1. The in situ Ti3AlC2-derived TiCx particles improved the deformation resistance and shear resistance of the Cu/graphite composites, thus contributing to the wear resistance. This research may offer fresh perspectives on how to enhance the properties of copper/graphite composites.