Anti-wear Properties Research Articles

Facile fabrication of continuous graphene nanolayer in epoxy coating towards efficient corrosion/wear protection

A combination of graphene and resin has been recognized as a good strategy for anti-corrosion and anti-wear applications. However, the discontinuity of shielding layer and lubricating film restricts the performance enhancements of graphene/epoxy coating. Hence, to maximize the structure and property advantages of graphene, a continuous graphene nanolayer with parallel distribution was fabricated in the epoxy coating by the Marangoni effect. Meanwhile, the introduction of microarc oxidation layer enhances the adhesion strength of epoxy coating and prevents galvanic corrosion of graphene. The multilayer coating exhibits a large enhancement of lowest-frequency impedance value increased by two orders of magnitude and excellent long-term chlorine resistance, with pure epoxy coating as a comparison, attributing to the outstanding barrier effect of multilayer structure and continuous impermeable graphene layer to corrosion media. Meanwhile, its wear rate (6.94 × 10−8 mm3/N·mm) is decreased by 43.11% compared with pure epoxy coating (1.22 × 10−7 mm3/N·mm) due to the graphene layer preventing the counterpart ball from directly contacting the epoxy coating and providing easy shear in the contact interface. Therefore, the as-prepared multilayer coating with excellent anti-corrosion and anti-wear properties has great application prospects in the corrosion and wear fields.

Effect of nanoparticles additives on tribological behaviour of advanced biofuels

The energy crisis and climate change have brought attention to developing alternative fuels. Waste tire pyrolysis oil is one of the most effective and renewable alternative fuels. Still, the TPO fuel had poor anti-wear properties than either biodiesel or diesel fuel, resulting in the studies conducted with nanoparticles. The lubricity of fuel is one of the important properties since it is the only lubricant in an engine injection system. Nanoparticles can be used as fuel additives to enhance better lubrication performance. This study presents the tribological behaviour of filtered tire pyrolysis oil (FTPO)-biodiesel-diesel blended fuel with the addition of various types of nanoparticles, including magnesium oxide (MgO), graphene (G), aluminium oxide (Al2O3). The tribological experiments were conducted with Four ball tribo-tester, according to the ASTM-D4172 standard at 40 kg, 1200 RPM constant speed and 75 °C temperature. Low concentration for all types of nanoparticle additives provides better performance on anti-friction in the blended fuel due to the protective film formed between the contact surface. 0.1 wt% of Al2O3 nano-fuel showed the best anti-wear performance, which improved by 2.83% compared to the base fuel Al2O3-0.1 and Al2O3-0.2, both reduced 22.09% and 18.33% of WSD, respectively, in compared to PB20FTPO10. The study results indicate that the addition of 0.2 wt% MgO nanoparticles performs well in obtaining smooth surface roughness. The Scanning Electron Microscope and Alicona images show lesser wear and damage to the surface with 0.1 wt% concentration of nano-fuel.

Experimental investigation into the effects of electric discharge surface modification process parameters on the biocompatibility of Ti6Al4V

Titanium alloys especially Ti6Al4V is extensively used in the fabrication of biomedical implant due to its similar mechanical properties as of bone, bio compatibility, high strength to weight ratio, better resistance to the body fluid and corrosion resistance etc. However, in order to further improve the osteointegration, anti-bacterial, anti-corrosion, and anti-wear properties, various surface modification or coating methods are often essential. Moreover, the biological behavior of surrounding cells on the implants depends on its various surface properties like surface roughness and wettability, etc. Therefore, in this paper a comprehensive experimental investigation is planned to investigate the influence of electric discharge-based surface modification process parameters on the bio-compatibility of Ti–6Al–4V. The important process parameters such as current and pulse ON time was varied at three different levels with double deionized water as the dielectric fluid to generate different functional surfaces. The areal surface roughness, wettability, surface elemental composition and morphology, etc. were analyzed in detail using scanning electron microscopy (SEM), X-Ray Diffractometry (XRD), Energy Dispersive x-ray spectroscopy (EDS). It is observed that the surface roughness values varied between 2.9 µm to 5.4 µm with respect to the variation in the pulse ON time and current. Similarly, the contact angle also varied between the hydrophilic to hydrophobic with respect to the number of days from the development of the surfaces. In addition, it is observed that a good amount of oxygen got deposited on the surface and formed various bio active titanium oxides which enhances the cell viability, cell adhesion and proliferation. The cytocompatibility tests with L929 fibroblast cells as per the ISO 10993-5, showed a maximum of cell viability up to 84.69% with 70.6633% of cell survival.

The Current Situation and Future Direction of Nanoparticles Lubricant Additives in China

Nanoparticles as lubricant additives demonstrate powerful friction reduction and antiwear properties and are potential alternatives to traditional additives in line with green and environmentally friendly requirements. However, the vast majority of currently available research focuses on the tribological properties of various nanoparticles in base oils at laboratory, which has a large gap with their application in engineering. To cope with the rapid economic and industrial development in China, there is a need to improve the tribological properties of nanoparticles. This paper highlights the current status and development trend of nanoparticles as lubricant additives in China. The factors influencing the tribological properties of nanoparticles, such as their composition, particle size and morphology, as well as the base stocks and their combination with other additives, are summarized. Furthermore, the research progress in the lubrication mechanism of nanoparticles is discussed, and the issues concerning the application of nanoparticles as lubricant additives as well as their future directions are discussed. This review is expected to provide an impetus to guide the design of high-performance, fully formulated lubricant systems containing nanoparticles as the lubricant additive.

Tribological mechanisms of the synergistic effect between sulfur- and phosphorus-free organic molybdenum and ZDDP

In this work, three environmentally friendly sulfur- and phosphorus-free organic molybdenums, MODE (amide type), MGMO (ester type) and MGME (ether type) with different structures were prepared, and the relationship between molecular structure and tribological properties was investigated. Furthermore, the tribological properties and mechanisms after compounding with conventional zinc dialkyldithiophosphate (ZDDP) were also investigated, indicating that the synergistic effect on antiwear and antifriction properties has the following order: MODE+ZDDP > MGMO+ZDDP > MGME+ZDDP. We further explored the tribological mechanisms through the in-depth surface and cross-sectional analyses, which manifests that the formation of homogeneous and compact tribofilm composed of molybdenum disulfide, molybdenum oxide, sulfate, phosphate, and polyphosphate with the thickness of 50–200 nm is contributed to the excellent synergistic effect.

Preparation of FeCo/C-N and FeNi/C-N Nanocomposites from Acrylamide Co-Crystallizates and Their Use as Lubricant Additives.

FeCo and FeNi nanoalloy particles encapsulated in a nitrogen-doped carbonized shell (FeCo/C-N and FeNi/C-N) were synthesized by thermolysis at 400 °C of polyacrylamide complexes after frontal polymerization of co-crystallizate of Fe and Co or Ni nitrates and acrylamide. During the thermolysis of polyacrylamide complexes in a self-generated atmosphere, Co(II) or Ni(II) and Fe(III) cations are reduced to form FeCo and FeNi nanoalloy particles, while polyacrylamide simultaneously forms a nitrogen-doped carbon shell layer. This unique architecture provides high chemical and thermal stability of the resulting nanocomposites. The average crystallite size of FeCo and FeNi nanoparticles is 10 and 12 nm, respectively. The nanocomposites were studied by X-ray diffraction, atomic force microscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The nanocomposites have been tested as antifriction and antiwear additives in lubricating oils. The optimal concentrations of nanoparticles were determined, at which the antifriction and antiwear properties of the lubricant manifest themselves in the best possible way.

Natural Cholesterol-Derived Ionic Liquids Enhancing the Antiwear Property and Biodegradability of Mineral/Vegetable Oils

Natural Cholesterol-Derived Ionic Liquids Enhancing the Antiwear Property and Biodegradability of Mineral/Vegetable Oils

Preparation and Tribological Properties of a Multilayer Graphene-Reinforced TiO2 Composite Nanolubricant Additive

The unique structure and physical properties of graphene and anatase TiO2 make them suitable for use as additives for engine lubricants. This study describes the use of dielectric barrier discharge plasma-assisted ball milling to synthesize a multilayer graphene-reinforced TiO2 composite nanolubricant additive (MGTC). A variety of physical and chemical tests were performed to characterize the resulting experimental materials, including X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Four-ball friction and wear testing machines were used to study the tribological properties and extreme pressure anti-wear properties of a base oil containing 0.1, 0.5, 1.0, and 1.5 wt % of the modified TiO2. Raman spectroscopy, XPS, SEM, and energy-dispersive spectrometry (EDS) analyses were used to examine and analyze the microstructure of the friction pairs. As a result of the plasma-assisted ball milling process, expanded graphite was successfully separated into multilayer graphene nanosheets, and spherical TiO2 was successfully bonded to the nanosheets of the multilayer graphene. The 1.0 wt % composite oil was found to provide good friction reduction and wear resistance. It had a film thickness of 27.5 nm, which was 167% thicker than base oil. Due to its excellent dispersion stability, the MGTC nanocomposite exhibited excellent lubrication performance, which was attributed to the formation of carbon protective films, titanium dioxide deposition films, transfer films, and the occurrence of nano ball effects on the surface of friction pairs.

Interactions Balancing Competition and Cooperation between Covalent-Organic Framework Additives and PEG Base Oil toward Advanced Lubrication.

Severe competition between nanolubricant additives and polar lubricating oil molecules for the formation of lubricant films has been hindering the progress of green and advanced lubricants. In this work, based on the tautomerism of cyanuric acid molecule (trione and triol configurations), two kinds of triazine-based covalent-organic frameworks (COFs), that is, Ton-COFs and Tol-COFs, were synthesized as additives of the polar PEG 400 oil, realizing compromise between them by providing delicate interactions. The triazine matrix bonding with intense polar groups in the framework of additives offers more powerful interactions to competitively form the adsorbed lubricant film on the surface of the metal substrate over PEG 400 oil and also bolts PEG 400 oil molecules by the hydrogen bonding inside the pore of the framework to cooperatively bear against the load. Molecular quantum chemical calculations further confirm that Ton-COFs can produce a more intense interaction with Fe atoms in the form of coordination and ions···π than Tol-COFs, far beyond PEG 400, and the cross-sectional profile of the worn surface definitely exhibits a protective lubricant film only composed of Ton-COFs. Consequently, at the low concentration of 0.3 wt %, the excellent friction reduction (41.2%) and antiwear property (97.4%) are achieved for the Ton-COFs compared to pure PEG 400 oil; moreover, 28.6% and 79.0% for Tol-COFs at the essential concentration of 0.7 wt % are achieved. This finding provides a novel insight from molecules to materials into guiding the development of additives for advanced lubricants.

Tribological performance study of oil‐soluble ILs as lubricant additives by the four‐ball method

AbstractFour oil‐soluble ionic liquids (ILs) with different structures were synthesised: N88816‐Doss (N/S), P88816‐Doss (P/S), N88816 phosphate (N/P) and P88816 phosphate (P/P). The effects of the four ILs synthesised with conventional lubricating additives isobutylene sulfide (T321), zinc dialkyl dithiophosphate (ZDDP) and tricresyl phosphate (T306) as PAO10 additives on the physicochemical properties of the prepared oil samples were systematically investigated at the same dosing rates. The antifriction and antiwear properties and extreme pressure performance of oil samples prepared by four ILs and three conventional additives were investigated by a four‐ball friction and a wear testing machine. The results showed that P/S improved the thermal stability of PAO10. The addition of N/S significantly improved the tribological performance of PAO10 at room temperature and under heavy loading. The coefficient of friction was reduced by 90%, the wear spot diameter is decreased by 28%, the last non‐seizure load PB is doubled, and the resistance to sintering did not improve.

Flake Graphene as an Innovative Additive to Grease with Improved Tribological Properties.

The paper presents the results of research on the use of flake graphene as an additive to plastic grease in order to improve its tribological properties. The influence of concentration (0.25-5.00 wt.%) and the form of graphene (graphene oxide, reduced graphene oxide) on selected properties of the base grease were investigated. It has been found that the addition of graphene flakes improves the anti-wear properties of the lubricant. The greatest improvement in the properties of the lubricant was achieved by using graphene at a concentration of 4.00 wt.%; the reduction in the average diameter of the wear scar was almost 70% for GO and RGO, compared to the base lubricant without the addition of graphene.

Tribological Behaviors of Inconel 718–Tungsten Carbide Friction Pair with Sulfur Additive Lubrication

This work investigated the lubricating and anti-wear properties of several sulfur additives for a nickel-based superalloy–tungsten carbide friction pair. Compared with PAO40 without any active chemical compounds, the three kinds of sulfur additives could decrease the friction coefficient from 0.2 to 0.1 and the wear volume by 90%. Sulfurized fatty acid ester had the best performance under high temperature and heavy load with COF below 0.1 and the smallest wear volume. Furthermore, the lubricating mechanism was investigated by XPS. The physical adsorptive film and the tribochemical film together enhanced the friction-reducing and anti-wear performances of the lubricants. This effective lubricant for Inconel 718 can be applied to the machining of nickel-based alloy.

Effect of Perfluoropolymers on the Anti-Wear Properties of Carbon Fiber/Polyphenylene Sulfide Composites: A Comparative Study

In this work, several perfluoropolymers (PFP), including commercial polytetrafluoroethylene (PTFE), perfluorinated ethylene-propylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and irradiated PTFE (iPTFE) were used as additives to lubricate carbon fiber (CF)-reinforced polyphenylene sulfide (PPS) composites. The tribological properties of the yielding composites were studied and correlated with the melt processability of PFPs. Although the neat FEP and PFA have higher friction coefficients when compared with neat PTFE, the composites filled with FEP and PFA additives were found to exhibit a lower friction coefficient compared to PTFE at PFP content below 10 wt %. Moreover, the iPTFE-filled composites also showed similar results as FEP or PFA filled ones, very different from PTFE at low additions. Based on the morphological investigation, we postulate that FEP, PFA, and iPTFE are melt-kneaded with PPS due to their melt processability at processing temperature, leading to the good dispersion in composites in the form of smaller deformed spheres and/or fibril bands. The well-dispersion of PFPs in composites promotes the formation and growth of the transfer film on the counterface during sliding.

Effects of electrostatic catalysis on the formation of chemical reaction films with charged lubricant containing sulfurized isobutylene additive

Tribochemical reactions between lubricant additives and friction interface can be initiated or catalyzed by self-excited electrons during friction. To explore the effects of static electricity-stimulated artificial electrons on chemical activity of additives, tribological properties of steel/steel interface and static chemisorption on steel surface were investigated with white oil containing sulfurized isobutylene additive (WO+T321) under electrostatic minimum quantity lubrication (EMQL). The results show that charged WO+T321 lubricant exhibits improved anti-friction (AF) and anti-wear (AW) properties, and chemical reaction films contain higher concentrations of S element on the worn and static chemisorption steel ball surface. This is attributed to the electrostatic catalysis induced by artificial electrons which ionize T321 molecule into anions and free radicals, promoting the formation of lubricating film enriched in S element.

1,3,4-THIADIAZOLE AND ITS DERIVATIVES: AN OVERVIEW ON CRYSTAL STRUCTURE AND TRIBOLOGY ACTIVITIES

1,3,4-thiadiazole derivatives has been attracted great attention due to application in various areas. Synthesis and crystal structure is briefly investigated. Their application in high temperature and high pressure as anti-friction and antiwear, and improve the anti-wear and extreme pressure properties have been described. The effect of various 1,3,4-thiadiazole additives on the tribological properties of base oils is studied. This paper aims to present an overview of the role of 1,3,4-thiadiazole and its derivative in improving the tribological properties of base oils.

Alkylated Polyphenyl Ethers as High-Performance Synthetic Lubricants

Lubricants exhibiting both thermal and chemical stability that consequently generate less hydrogen during friction are required to avoid the hydrogen embrittlement of moving mechanical components. The present work studied the effects of the length and number of alkyl chains on the tribological properties of polyphenyl ethers (PPEs), which feature good thermal and radiation resistance. PPEs were found to have much lower friction coefficients compared with a poly-alpha-olefin and alkyldiphenyl ether, and the effect of the running-in process on friction appeared to be negligible. The formation of polymers on the friction track evidently decreased the friction coefficients of the lubricants and the wear rates were almost zero for all the PPEs, indicating excellent anti-wear properties. Analyses with a quadrupole mass spectrometer connected to a friction tester under vacuum indicated negligible hydrogen generation from 4P2E, which had no alkyl chains, after the running-in. R1-4P2E, having a C16H33 chain, showed hydrogen desorption similar to that of the alkyldiphenyl ether, which had a C18H37 alkyl chain. R2-4P2E, with two C16H33 chains, produced significant hydrogen, but with a long induction period; thus, it provided good wear protection. Although alkyl chains increased the risk of hydrogen generation, PPEs with such chains may have applications as standard lubricants.

Versatile Medium Entropy Ti-Based Bulk Metallic Glass Composites.

An ultra-strong Ti-based bulk metallic glass composite was developed via the transformation-induced plasticity (TRIP) effect to enhance both the ductility and work-hardening capability of the amorphous matrix. The functionally graded composites with a continuous gradient microstructure were obtained. It was found that the austenitic center possesses good plasticity and toughness. Furthermore, the amorphous surface exhibited high strength and hardness, as well as excellent wear corrosion resistance. Compared with the Ti-6Al-4V alloy, bulk metallic glass composites (BMGCs) exhibit better spontaneous passivation behavior during the potential dynamic polarization. No crystallization was observed on the friction surface, indicating their good friction-reduction and anti-wear properties.

Investigation on anti-wear and corrosion-resistance behavior of steel-steel friction pair enhanced by ionic liquid additives under conductive conditions

Wear and corrosion are one of the main causes of material loss and equipment failure in mechanical equipment, especially under current-carrying friction conditions, which interact and exacerbate each other. Herein, a new ionic liquid additive (IL-16) was studied to simultaneously improve the anti-wear and anti-corrosion properties of steel-steel friction pair under conductive conditions. The coefficient of friction decreased by 58.8% at 1.6 wt% IL-16 content under the load current of 1.5 A, the wear was reduced 10 times, and the contact resistance was only 37 mΩ, owing to the IL-16 ionic liquids additive forming a stable physical adsorption film on the surface of the friction pair to hinder the transfer of charges and products related to the corrosion reaction.

Preparation of WS2 with Varying Thickness and Its Enhanced Anti-wear Property in Resin-Based Carbon Composites

Preparation of WS2 with Varying Thickness and Its Enhanced Anti-wear Property in Resin-Based Carbon Composites

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.