Reduction In Friction Coefficient Research Articles

Evaluation of the effects of the application of Ti−C:H DLC coatings obtained by PVD techniques in the kinematic pairs of internal combustion engines and powertrain systems.

The article attempts to analyze the possible effects of using Ti−C:H DLC carbon coatings produced by pulsed magnetron sputtering (PVD) to reduce friction coefficient and wear in kinematic pairs found in internal combustion engines and powertrain systems used in automotive vehicles. The aim of such action is primarily to reduce internal losses in the aforementioned units. The coatings were deposited on heat-treated bearing steel 100Cr6, examined using a scanning electron microscope FEI Quanta 200 Mark II with the chemical analyzer EDS EDAX Genesis XM 2i, tribotester T−01M examining the friction coefficient in the ball-disc correlation and Hommel Werke T8000 profilometers, additionally, in order to check the coating thickness, studies were carried out using the Calotest method. The results obtained indicate that both the friction coefficient and wear are drastically reduced in relation to samples on which no DLC coatings were applied.

The influence of laser texturing on the tribological behavior of titanium alloy Ti6Al4V in medical applications

This paper analyzes the tribological behavior of the Ti6Al4V ELI alloy subjected to laser texturization for medical purposes. Laser texturing enables one to observe specific patterns of the material surface at established depths. Microtexturing of the samples was performed using a 355 nm picosecond laser. The influence of the microtexturing process (depending on the process parameters) on the geometric parameters of the proposed laser texturing pattern was evaluated. Selected samples were subjected to tribological testing using the ball-on-plate technique in dry and lubricant-sliding methods (in Ringer solution). The wear properties were evaluated by comparing the coefficient friction, wear volumes, and wear ratio. A scanning electron microscope characterized the morphologies of the wear scar and the wear mechanism. The experimental results show that the surface texturing and the changes in microgrooves can reduce wear. The results indicate, that samples after laser texturing were characterized by 15% higher microhardness, compared to those in the initial state. It was found, a 26% reduction in friction coefficient and 29% in the wear volume compared to the smooth, untextured surface samples under lubricated conditions. The decrease in value of the coefficient friction and wear volume for the samples after the laser texturing process is an effect of synergistic of entrapped wear debris in micro-grooves and increased hardness for samples after laser textured.

An Experimental Study to Assessing the Efficacy of Oil to Prevent Differential Stuck Pipe Incidents in Zubair Oil Field, Southern Iraq

This study focuses on the important role of drilling mud in successful drilling operations, particularly in preventing and treating differential stuck pipes. Differential pipe sticking (DSP) is a common challenge when drilling through a pay zone with water-based drilling mud containing bentonite clay. However, using oil as an additive in a water-based mud (WBM) system offers distinct advantages and can significantly improve drilling performance. The research utilizes the Fann VG meter, a self-fabricated tester, and a tester of stickance to investigate the impact of oil on water-based drilling mud (WBM) and controlling DSP to address this challenge. The empirical study demonstrates that adding oil to the drilling fluid enables it to maintain its rheological properties (PV, YP, and API fluid loss) while reducing filtration loss from 7 to 4.8 cc and friction coefficient from 0.30 to 0.05. This indicates that emulsion mud can mitigate the risks of differential sticking by maintaining the oil concentration within the recommended limit (not exceeding 3%). Balancing the maintenance of rheological properties with the reduction of friction coefficient is essential to reaching optimal drilling performance and preventing differential pipe sticking.

Atomic layer deposited TiO2 nanofilm on titanium implant for reduced the release of particles.

Objective: Titanium implants are widely used in surgeries for their biocompatibility and mechanical properties. However, excessive titanium particle release can cause implant failure. This study explores Atomic Layer Deposition (ALD) to coat commercially pure titanium (Cp-Ti) with TiO2, aiming to improve its frictional and corrosion resistance while reducing particle release. By comparing TiO2 films with varying ALD cycle numbers, we assess surface properties, particle release, friction, and corrosion performance, providing insights into mitigating particle release from implants. Methods: Cp-Ti surfaces were prepared and coated with TiO2 films of 100, 300, and 500 ALD cycles. Surface characterization involved SEM, EDX, and XRD. Friction was tested using SEM, nanoindentation, and ICP-MS. Corrosion resistance was evaluated through immersion tests and electrochemical analysis. Cytotoxicity was assessed using BMSCs. Results: Surface characterization revealed smoother surfaces with increased ALD cycles, confirming successful TiO2 deposition. Friction testing showed reduced friction coefficients with higher ALD cycles, supported by nanoindentation results. Corrosion resistance improved with increasing ALD cycles, as evidenced by electrochemical tests and reduced titanium release. Cytotoxicity studies showed no significant cytotoxic effects. Conclusion: ALD-coated TiO2 films significantly enhance frictional and corrosion resistance of titanium implants while reducing particle release. The study underscores the importance of ALD cycle numbers in optimizing film performance, offering insights for designing implants with improved properties.

Supramolecular self‐assembled nanoparticles for targeted therapy of myocardial infarction by enhancing cardiomyocyte mitophagy

AbstractMyocardial infarction accompanied by diabetes mellitus is accepted as the most serious type of coronary heart disease, and among the current treatment strategies, the precise delivery of protective drugs for inhibiting cardiomyocyte apoptosis is still a challenge. In this study, we developed a biodegradable nanoparticles‐based delivery system with excellent macrophage escape, cardiac targeting, and drug release properties to achieve targeted therapy of myocardial infarction. Specifically, a copolymer of p(DMA–MPC–CD) combining self‐adhesion, hydration lubrication, and targeting peptide binding site was successfully prepared by free radical copolymerization, and it was self‐assembled on the surface of melatonin‐loaded dendritic mesoporous silica nanoparticles (bMSNs) following the integration of adamantane‐modified cardiac homing peptide (CHP) based on supramolecular host–guest interaction. Importantly, a hydration layer formed around the zwitterionic phosphorylcholine groups of the multifunctional nanoparticles, which was confirmed by the enhancement in hydration lubrication and reduction in coefficient of friction, prevented the nanoparticles from phagocytosis by the macrophages. The in vivo bioluminescence imaging test indicated that the nanoparticles were endowed with satisfied cardiac targeting capability, and the in vivo mice study demonstrated that the intravenous injection of drug‐loaded nanoparticles (namely bMSNs–Mel@PDMC–CHP) effectively reduced cardiomyocyte apoptosis, alleviated myocardial interstitial fibrosis, and enhanced cardiac function.

Design of experiments coupled with Bayesian optimisation for nanolubricant formulation

Nanoparticle-enhanced lubricants (nanolubricants) achieve tribological properties that can signficantly outperform the unmodified base oil. However, this performance enhancement is known to be extremely senstive to the concentration of nanoparticles used. Here, we introduce a new approach to optimizing nanolubricants combining design of experiments (DOE) with machine learning, addressing the challenge of determining optimal nanoparticle concentration in base oils and demonstrating significant performance improvements. Combining Box-Behnken design with Bayesian optimization, we identify an optimal concentration of 0.04 wt% copper oxide (CuO) nanoparticles in a standard engine oil (SAE 20W50), resulting in a 42% reduction in coefficient of friction (COF) relative to the base oil. Surface analysis (AFM, SEM) confirmed improvement of anti-wear and anti-friction characteristics. Signficant enhacements of thermophysical properties were observed (demonstrated by increased flash and pour points, by 10% and 7% respectively), signifying greater thermal stability. The dynamic viscosity remained consistent, with a beneficial reduction observed under conditions of high temperature and shear, which aligns with the demands of engine lubricant standards for PC-12B oils, with a reduction from 3.49 to 3.18 cP (8%). This research introduces a novel hybrid optimization technique that provides a versatile framework for optimizing nanofluids, addressing the critical challenge of determining optimal nanoparticle concentration.

Tribological characteristics and film behaviour of polytetrafluoroethylene in jatropha with sodium dodecyl sulphate as surfactant

In this research, a bio lubricant was developed utilising eco-friendly constituents of jatropha oil, polytetrafluoroethylene (PTFE) and sodium dodecyl benzenesulphonate (SDBS), characterised and tested with four-ball tribometer under ASTM D2783 standard. The tribological performance in terms of friction, wear, load carrying ability and evaluation of the film behaviour on stability and strength was conducted. According to Fourier transform infrared spectroscopy (FT-IR) of the study, the presence of the two additives in base jatropha oil demonstrated good functional groups desired for lubricant lubricity. In comparison to base jatropha under 40 kg and 1200 rpm, blended 1 wt-% PTFE + 0.8 wt-% SDBS additives produced an outstanding reduction in coefficient of friction (61.4%) and good load carrying strength among all the samples tested, but commercial shell oil (CSO) outperformed under wear resisting potential. Scanning electron microscopy (SEM) and a 3D surface profilometer were used to examine the rubbed surfaces. Findings indicate that the boundary film on the worn surface was made up of PTFE and SDBS nanoparticles that deposited film elements of sulphur and higher carbon content. The decrease in the percentage of iron (Fe) indicates that tribo-pairs were separated from direct contact under additives usage. According to the research, adding an anti-wear substance to the new formulation could increase wear protection, thus effectively making it comparable with CSO counterpart.

A Study of Water-Based Nanolubricants Using Hexagonal Boron Nitride (hBN)-Based Nanocomposites as Lubricant Additives

An Rtec ball-on-disk tribometer was used to investigate the tribological performance of the synthesised water-based nanolubricants containing hBN/TiO2 nanocomposite at room temperature. The water-based nanolubricants with different concentrations were prepared by adding glycerol and sodium dodecyl benzene sulfonate (SDBS) under ultrasonication. These as-prepared nanolubricants demonstrated exceptional dispersion stability for 7 days without distinct sedimentation. The results indicate that the water-based nanolubricants with an overall concentration of 1.0 wt% at different ratios (hBN: TiO2 = (1:0), (0.7:0.3), (0.5:0.5), (0.3:0.7), (0:1)) can effectively reduce the coefficient of friction (COF) and the wear of the ball and disk. In particular, the water-based nanolubricant containing 0.5 wt% hBN and 0.5 wt% TiO2 exhibited the best tribological performance, leading to a significant reduction in COF up to 70%, and decreased the wear area of the ball and disk by up to 79.57% and 60.40%, respectively, compared to those obtained using distilled water. The lubrication mechanisms were mainly attributed to the formation of a protective film, and the mending, polishing, rolling, and synergistic effects of the hBN nanosheets and TiO2 nanoparticles.

Covalently Bonded Heterostructures with Mixed-Dimensional Carbons for Suppressing Mechanochemical Wear of Diamond under Heavy Loads.

Diamond is widely acknowledged as the hardest naturally occurring material. Nevertheless, when exposed to friction against ferrous metals, it is prone to graphitization or amorphization, which limits the utilization of its extremely high hardness and wear resistance. These issues have persisted for decades without an effective solution. Here, we report that a covalently bonded heterostructure with mixed-dimensional carbons as a high-performance solid lubricant could effectively reduce diamond surface friction and mechanochemical wear with excellent load capacity and durability. When subjected to dry friction and heavy loads (20-150 N), the heterostructure exhibited a notable improvement over pristine diamond with reduced friction coefficients and relative wear rates by 22-45 and 67-91%, respectively. Especially under a 20 N load, the relative wear rate was an order of magnitude lower than that of pristine diamond. Additionally, experiments and molecular dynamics simulations revealed that the heterostructure integrated the outstanding properties of diamond (three-dimensional (3D)), nanographite (3D), and graphene (two-dimensional (2D)), resulting in improved lubrication and antiwear performance that could not be achieved by the individual carbon materials. The findings in this work will be beneficial to overcome the ferrous metal forbidden zone of diamond and are expected to expand the applications of engineered diamond surfaces and graphite/graphene in tribology, mechanics, and electronic fields.

Friction and wear behavior of C implanted copper via ion beam-assisted bombardment

This work modified the surface of copper using physical vapor deposition and investigated the wear behavior of the modified copper at low load and sliding speed. The results of the study showed that the adhesion between the thin film prepared using the ion beam deposition technique and the substrate was insufficient, leading to an increased wear rate of copper after surface modification. However, when carbon particles were injected using ion beam-assisted bombardment, the friction properties of copper were significantly improved, with a decrease in wear rate from 1.6 × 10−4 to 8 × 10−6 mm3/N m and a 40% reduction in friction coefficient. This improvement can be attributed to the amorphous carbon layer on the copper surface, as well as the injection of carbon particles into the substrate, which enhanced the adhesion between the film and the substrate. Furthermore, a continuous copper oxide film formed during the friction and wear process, providing lubrication and protection to the substrate in conjunction with the amorphous carbon layer. Additionally, the primary wear mechanism of copper shifted from abrasive and adhesive wear to oxidation wear after ion beam-assisted bombardment with carbon injection. This study provides new insights and methods for material design and engineering applications by investigating the effects of ion beam-assisted bombardment technology on the wear resistance of copper materials.

Effects of aluminizing on the microstructure and wear resistance of AISI 321 steel

To enhance the surface properties, particularly hardness and wear resistance, of AISI 321 steel, an aluminizing coating was introduced through pack cementation treatment. Microstructure characterization and wear resistance tests were conducted to elucidate the intricate relationship between the microstructure and wear behaviors. A thorough analysis on the structure and compositions revealed the incorporation of FeAl(Cr) phases, aluminum oxides, titanium compounds and B2-NiAl phases in the coating, which resulted in a remarkable 192 % increase on the surface hardness, elevating it from 226 HV to an impressive 662 HV. In comparison to the uncoated 321 steel, the aluminized counterpart exhibited a pronounced reduction in coefficients of friction (COFs), wear volume losses, and wear rates. The wear mechanisms of both the uncoated 321 steel and aluminized steel were intricately analyzed. The uncoated 321 steel endured severe adhesive and oxidation wear, characterized by pronounced plastic deformation, the presence of wear debris and flaking oxides. In contrast, the aluminized steel predominantly underwent abrasive wear, showcasing a relatively smooth worn surface and dense continuous oxides. These findings not only reveal the significant enhancement of tribological properties by aluminized coatings, but also provide valuable insights into their fundamental behavior during wear.

Study on the tribological characteristics of surface triangular textured TC4 alloy prepared by SLM technology

Surface Triangular Textured TC4 Alloy specimens were prepared by 3D printing technology (SLM technology: selective laser fusion). Effects of wedge-shaped triangular textures with different texture area occupancy on hardness, friction and wear of the 3D printed TC4 alloy specimens were studied, in comparison with non- textured specimens. SFT -2 M pin-disc friction and wear testing machine was used to perform friction and wear experiments under 46 # mechanical oil lubrication conditions, and MH-500 Vickers hardness tester was used to measure hardness of the specimens. Scanning electron microscope (SEM), energy spectrometer (EDS), and electronic balance instrument were used to characterize the wear scar morphology, element content, wear amount, etc. of the specimens. Using the Fluent module in ANSYS Workbench software, we studied the mechanism for the reduction in the friction coefficient between friction pairs during the relative movement in lubricating oil. Results of the study show that the hardness of the 3D printing specimen is significantly greater than that of the non- textured one. In each group of experiments, the wedge triangular textured specimens showed better tribological properties, and the 3D printed specimen with an area occupancy of 22. 53 % exhibited the smallest average friction coefficient (0.17) and higher wear resistance than other specimens. The dynamic pressure effect due to the wedge triangle texture inside the lubricating oil film is the main reason for the reduced friction coefficient between the friction pairs.

Empirical investigation of the effect of adding nanoparticles to HB-80 gas turbine oil: Evaluation of thermophysical behaviors

The current study aims to conduct an empirical investigation on the performance of copper (II) oxide (CuO), Graphene Oxide (GO), and Molybdenum (VI) Oxide (MoO3) nanoparticles as additives for HB-80 base lubricant and their effects on essential characteristics such as density, flashpoint and flammability, cloud point and pour point, viscosity and viscosity indicators, thermal conductivity coefficient, friction coefficient and wear. The test results show that nanoparticles have minor effects on density and viscosity but managed to improve viscosity indicators. Flashpoint, flammability, cloud point, and pour point all increased after the addition of nanoparticles. The increase in the concentration of nanoparticles also improved and increased the lubricant's thermal conductivity coefficient; the highest increase was 11.3 % compared to the base oil with the addition of 1 wt% CuO. Adding nanoparticles to lubricant decreases wear and friction coefficient by creating a lubricant film, especially at lower nanoparticle concentrations, which leads to a more stable lubricant film by nanoparticles. Copper (II) Oxide nanoparticles had the best performance in reducing friction coefficient and wear at 0.2 wt% with 22.86 % and 63.92 % reduction compared to the base oil, respectively.

Enhancing the Elastohydrodynamic Lubrication and Vibration Behavior of Rolling Bearings Using a Hybrid Bio-Grease Blended with Activated Carbon Nanoparticles

In recent years, bio-lubricants have received a growing interest for industrial applications. Still, a full-scale implementation in machinery lubrication requires a thorough evaluation of their performance through tribological and operational tests to stand upon their performance. Additionally, the promising outcomes achieved by nanoadditives in improving the performance of synthetic lubricants have prompted research efforts to identify suitable nanoadditives for bio-grease. This paper introduces a bio-grease from a hybrid vegetable oil and glycerol monostearate as a thickener for the lubrication of rolling bearings. Activated carbon nanoparticles (ACNPs) as nanoadditives were synthesized, characterized, and incorporated into the bio-grease at concentrations of 0.5, 1, and 2% by weight. Tribo-tests were conducted on these bio-grease blends, and running tests were carried out using 6006 ball bearings on a custom test rig. Throughout a 30-min test run under a radial load of 10% of the bearing’s dynamic load rating, mechanical vibrations and power consumption were measured and analyzed for each bearing. The bio-grease with ACNPs exhibited a substantial reduction in wear scar diameter (WSD) and coefficient of friction (COF), achieving improvements of up to 73.6 and 65%, respectively, in comparison to lithium grease. Furthermore, the load carrying capacity was enhanced by 200%. The study revealed a strong correlation between measured vibration amplitudes and the viscosity of the bio-grease. The absence of high frequency resonant bands in vibration spectra indicated that the test grease samples satisfied the conditions of elastohydrodynamic lubrication, and these findings were corroborated through calculations of the minimum oil film thickness.

Effect of Heat Treatment on the Electrochemical and Tribological Properties of Aluminum-Bronze Coatings Deposited Used the Thermal Spraying Process

The corrosion and wear resistance of aluminum-bronze coatings deposited by thermal flame spraying were investigated after a 10 h heat treatment at 500 °C in a nitrogen atmosphere. The coatings were characterized by SEM, EDS, XRD, and XRF. Corrosion resistance was evaluated by Tafel and EIS tests, while wear resistance was assessed using a ball-on-disc test. Results showed the heat treatment compacted the coating microstructure, increased oxide content, and improved splat bonding through diffusion mechanisms. This led to enhanced corrosion resistance, evidenced by reduced corrosion current density in electrochemical tests, resulting from densification impeding electrolyte penetration. Heat treatment also increased wear resistance, as indicated by lower wear rates in ball-on-disc tests, attributable to increased hardness, reduced friction coefficients, and annealing-induced microstructural changes. Overall, the heat treatment optimizes the anticorrosive and tribological properties of thermally sprayed aluminum-bronze coatings via favorable alterations in composition, morphology, and physical characteristics. The research provides a new understanding of how thermal spray parameters and post-deposition heat treatment can be utilized to enhance the corrosion and wear resistance of aluminum-bronze coatings for marine applications.

Synthesis and application of silicone-modified polyurethane as a slip-elastic finishing agent for polyamide fabrics

Despite the wide application of polyamide in clothing and home textiles, its inherent stiffness hardly meets consumers' preference for a smooth and elastic hand feel. In this study, a new hydroxyl silane coupling agent (KHS), 1-(4-(4-(4-(trimethoxysilyl)butyl)piperazin-1-yl)-3-(3-(trimethoxysilyl)propoxy) propan-2-ol, was synthesized and used to prepare a series of silicone-modified polyurethane (KHS-PU). KHS-PU then was finished onto the polyamide fabric via a pad-dry-cure procedure. The finishing process was optimized using the Minitab software. The morphology and elemental distribution of KHS-PU finished polyamide fabric were characterized using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The hand evaluation tests demonstrated that KHS-PU not only significantly enhanced the fabric's smooth and elastic properties, specifically evidenced by a 23 % reduction in surface friction coefficient, a 13 % decrease in bending average stiffness, a 10 % reduction in compression work, and a 40 % increase in compression recovery rate, but also exhibited good wash durability. In addition, the thermal and mechanical properties of KHS-PU finished fabric were further investigated. This work provides a valuable contribution to the field of surface science and textile engineering, offering insights into advanced fabric finishing techniques.

Recycling Automotive Plastic Waste: Residual Polyvinyl Butyral (rPVB) as Solid Lubricant in Polyoxymethylene (POM) Blends

Polyoxymethylene (POM) is an engineering thermoplastic commonly used in tribological applications due to its low friction and auto-lubrication properties. To improve its performance further and broaden its applications to higher sliding speeds and loads, it is commonly reinforced with different particles, fibers, or solid lubricants. In this study, the effect of adding residual polyvinyl butyral (rPVB) from automotive windshields production lines on the tribological performance of POM during pin-on-disk wear tests at different loads (12, 15, and 18 N) and sliding speeds (0.25, 0.50, and 0.75 m/s) is investigated. It was found that rPVB acts as a solid lubricant, reducing the coefficient of friction (CoF) up to 50%. It is suggested that the formation of a protective layer of adhered material on the wear track is the mechanism behind CoF reduction. Melt flow index, Shore D hardness and elastic properties decrease linearly with rPVB content. However, the reduction in tensile strength, and thus shear strength of the blends, seems to be more significant on their CoF behavior than the reduction in hardness. No trend was found for wear resistance. Under certain sliding conditions rPVB decreased volume loss, but in other cases it increased it. It is suggested that, for the conditions analyzed in this study, adding 10 wt% of rPVB to a POM matrix results in the best balance of tribological performance, with an overall CoF reduction of 36%, and an average volume loss increase of only 1%.

Tribology Evaluation on a Four-Ball Tribometer Lubricated by Al2O3/PAG Nanolubricants

Nanolubricants can improve the tribological properties for application in automotive systems. By reducing the friction rate of the internal components with nanolubricants, the service life of a compressor used in automotive air conditioning (AAC) can be extended. The investigation aims to determine the optimal volume concentration of nanolubricants for achieving the highest performance in tribological properties. Al2O3 nanoparticles dispersed in a polyalkylene glycol (PAG ND12) base at volume concentrations of 0.01%, 0.03%, and 0.05% were investigated to improve the lubrication system in the AAC compressor. The stability investigations were carried out by comparing absorbance conditions using a UV-Vis Spectrophotometer at each volume concentration for 210 days. Koehler's four-ball tribometer was used to measure coefficient of friction (COF) and friction torque at a load of 40.0 kg and a speed of 1200 rpm. The stability study of nanolubricant yielded average absorbance values of 0.752, 0.755, and 0.684, respectively. The average COF values of the nanolubricants of 0.01%, 0.03%, and 0.05% were 0.104, 0.078, and 0.117, while the pure lubricant was 0.095. Further investigation on friction torque resulted in a decrease in the pure lubricant of 0.064%, and for nanolubricant Al2O3/PAG ND12, a decrease of 0.087%, 0.057%, and 0.092%, respectively. The results indicated that a concentration of 0.03% produced the greatest reduction in COF and torque, namely 0.0078% and 0.0578%, correspondingly. Therefore, it is recommended to use Al2O3/PAG ND12 nanolubricant at a volume concentration of 0.03% because it is the most optimal in terms of stability and has the highest COF and frictional torque reduction.

Robust wear performance of graphene-reinforced high entropy alloy composites

The expected excellent tribological performance of high-entropy alloys (HEAs) is rarely achieved due to the absence of self-lubricating ability on the worn surface. In particular, the situation is more challenging in HEAs with face-centered cubic structure because of the inferior yield strength when used in dry sliding conditions. Unlike conventional soft-solid lubricants, which deteriorate the mechanical properties of HEA matrix, in this study we demonstrate in a protocol model alloy that the proper incorporation of few-layer graphene as reinforcement in CoCrFeNiMn can lead to both surface strengthening and lubrication. This is achieved by a partially chemical interface reaction between graphene and HEA via a tunable fabrication process, resulting in a reduction of wear rate and friction coefficient of 86.03% and 23.87%, respectively. As a result of the interfacial in-situ carbide strengthening together with the self-lubrication of graphene, this tailored composite structure also exhibits superior tribological properties over most HEA-based self-lubrication composites. Besides, the subsurface structure evolution and deformation mechanisms that influence the wear resistance are systematically clarified through microscopic exploration and atomistic simulation. The present study presents an effective strategy for the development of innovative HEA composites suitable for safety-critical applications, which overcomes the inherent compromise and achieves exceptional tribological performance, i.e., self-lubricating and anti-wear.

The impact of synergistic action of methacrylic acid/zinc oxide/carbon nanotubes on metal Friction and wear

The continuous operation of essential refining equipment, internal mixers, leads to wear on their end faces, resulting in an increased gap between the mixer chamber and the end face. This, in turn, causes material leakage, reducing mixing efficiency and adversely impacting rubber performance. Therefore, investigating metal wear on the mixer's end face during the mixing process is essential. Scholars have introduced dynamic covalent bonds into rubber molecular chains, bestowing self-repairing capabilities upon the materials. This innovation has significant implications for extending rubber lifespan and lowering production costs. It involves adding methacrylic acid (MAA) and excess zinc oxide (ZnO) to construct an ionic crosslinking network, limiting covalent crosslinking of rubber molecules and enabling in-situ polymerization of MAA/ZnO, resulting in self-repairing properties. However, it is crucial to consider corrosive wear induced by MAA's strong acidity on metals. This study combines MAA, ZnO, and multi-walled carbon nanotubes (MWCNTs) through mechanical mixing to create a composite material called zinc methacrylate (ZDMA)/MWCNTs/rubber. The research investigates the in-situ synthesis mechanism of MAA and ZnO and the synergistic mechanism of ZDMA and MWCNTs. The study analyzes the impact of MWCNTs additive amount on the frictional wear of the internal mixer's metal end face. During the mixing process, ZDMA is grafted and polymerized onto rubber's macromolecular chains, forming ionic pairs with strong electrostatic interactions, creating a primarily reversible supramolecular network dominated by ion crosslinking. This ion crosslinking network, along with the three-dimensional mesh structure of MWCNTs, establishes a stable spatial structure within the rubber matrix. The study reveals that increasing the MWCNTs content to 3 phr reduces the aggregation of SiO2 particles and ZDMA granules within the rubber matrix, resulting in reduced friction coefficients, roughness, and wear rates of the metal. However, exceeding 3 phr of MAA content leads to excessive MWCNT aggregation within the rubber matrix, increasing wear rates, roughness, and friction coefficients due to hindrance of rubber macromolecular chain crosslinking and reduced SiO2 particle dispersion within the rubber matrix. These findings provide valuable insights into the dynamics of frictional wear in internal mixers.