Reduction In Wear Rate Research Articles

A combined approach of melt pool ultrasonic vibration and inter-pass laser re-melting for achieving superior mechanical properties by controlling microstructure and phases in L-DED of Inconel 625

Abstract Laser Direct Energy Deposition (DED) is an additive manufacturing technique used in aerospace, automotive, nuclear industries. However, challenges such as porosity, cracks, microstructural inhomogeneity, elemental segregation, usually affect the mechanical properties of fabricated components. This study proposes the synergistic application of ultrasonic vibration and inter-pass laser re-melting in DED of Inconel 625 to effectively address these issues. Ultrasonic vibration to the melt pool results in equiaxed structures and reduces micro-pores by inducing acoustic streaming and cavitation effects, whereas inter-pass laser re-melting selectively melts the previously deposited layers and reduces porosity. Both the techniques influence the formation and distribution of intermetallic within the deposition. A synergistic application of these methods led to minimal porosity and equiaxed grains with thinner grain boundaries. Phase analysis revealed significant presence of similar intermetallic compounds in as-deposited and vibration-assisted samples, with (γ′) phase appearing specifically in re-melted and combined techniques. Further, intermetallic compounds, which were randomly distributed in as-deposited and re-melted conditions, were found predominantly near the grain boundaries when vibration was applied alone or with re-melting, resulting in better mechanical properties. The synergistic effect led to ∼20% increase in micro-hardness, ∼75% reduction in wear rate, ∼32% higher ultimate tensile strength, ∼25% increase in strain, and significantly enhanced corrosion resistance compared to as-deposited samples. This study underscores the potential of using ultrasonic vibration and inter-pass re-melting synergistically to enhance overall performance of DED-fabricated Inconel 625 components, outperforming their individual effect.

Oxidized Zirconium Femoral Components in Total Knee Arthroplasty: A Retrieval Study of the Tibial Bearing.

Advanced materials for total knee arthroplasty (TKA), including crosslinked bearings and Cobalt-Chrome-Molybdenum-alternative components, show promise for reducing wear rates and improving outcomes. The objective of the current study was to test whether an alternative femoral-bearing material achieved these goals. An Institutional Review Board-approved retrieval database was searched to identify 137 oxidized zirconium femoral TKA components from 2004 to 2023; 75 had a tibial bearing of never-irradiated polyethylene (PE) and 62 had a bearing of cross-linked polyethylene (XL). All had a polished tibial tray. The mean duration of implantation was 58 months for the PE group and 34 months for the XL group. The most common reasons for retrieval were instability and infection in the XL group and instability in the PE group. Dimensional change (creep plus wear) was measured from the thickness of the polyethylene insert using short-duration (<16 months) and never-implanted devices as a reference. Oxidation (maximum ketone oxidation index) was measured via FTIR using a cross-section of the medial condyle of the polyethylene at < three months post-explant. Statistical analyses were conducted using groups matched for in vivo duration. A P < 0.05 was considered significant. Dimensional change rate and in vivo oxidation rate were statistically indistinguishable between the two bearing types. The mean dimensional change rate for the PE group was 0.018 ± 0.024 mm/year, and 0.021 ± 0.030 mm/year for the XL group (P = 0.64). Mean oxidation rates were also not statistically different, with the mean rate for the PE group being 0.051 ± 0.052 arbitrary units (a.u.)/year and the mean value for the XL group being 0.064 ± 0.055 a.u./year (P = 0.19). Only one device (PE) exceeded the oxidation threshold, marking a decrease in mechanical properties. The dimensional change rate and oxidation rate for tibial inserts against oxidized zirconium femoral components were low and consistent with previously reported literature values. The XL did not demonstrate superiority to PE in this analysis.

Investigation of tribological performance of PAI and PAI/graphite/PTFE composites under different mediums and working conditions

Purpose This study aims to investigate the tribological performance of neat polyamide-imide (PAI) and PAI composite (PAI + 12% graphite + 3% polytetrafluoroethylene [PTFE]) under varying mediums and conditions, including dry sliding, distilled water and seawater lubrication, to determine their suitability for high-stress applications. Design/methodology/approach Tribological tests were conducted using a pin-on-disc setup with AISI 316 L stainless steel (SS) as counterface. Experiments were carried out under loads of 150 and 300 N and sliding speeds of 1.5 and 3.0 m/s. Values of temperatures, friction coefficients and wear rates were recorded to analyze the effect of fillers and lubrication mediums. Findings The PAI composite outperformed the neat PAI under all conditions, showing significant reductions in friction coefficients and wear rates. Seawater lubrication yielded the best results, achieving friction coefficients of 0.05 and 0.01 and specific wear rates of 18.10−16 m²/N and 1.10 −15 m²/N, for neat PAI and PAI composite, respectively. Graphite and PTFE fillers enhanced lubrication, reduced surface temperatures and mitigated abrasive and adhesive wear mechanisms. Superior cooling and lubrication effects of the seawater contributed to these improvements. Originality/value Previous studies mainly focused on dry sliding and distilled water lubrication for the PAI and its composites, with no research on the seawater conditions. This study compares the tribological behaviors of the neat PAI and PAI composite against AISI 316 L SS under dry sliding, distilled water and seawater lubrication. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0302/

Effect of Recovery Treatment on the Microstructure and Tribological Properties of Ultrasonic Impacted Al2FeCoNiCrW0.5 High-Entropy Alloy Coatings

To investigate the effect of recovery treatment on the microstructure and tribological properties of ultrasonic impact-treated Al2FeCoNiCrW0.5 high-entropy alloy coatings, laser cladding technology was used to fabricate coatings on a G10450 steel substrate, followed by ultrasonic impact treatment (UIT) and recovery treatment (HR, 300 °C). The results showed that the Al2FeCoNiCrW0.5 high-entropy alloy coating consisted of BCC and FCC phases. Ultrasonic impact treatment slightly broadened the XRD diffraction peaks, while the recovery treatment had minimal effect on them. Ultrasonic impact also refined the coating grains. Ultrasonic impact treatment increased the coating hardness from 738 HV0.5 to 856 HV0.5. Although the subsequent post-annealing slightly reduced the hardness to 806 HV0.5, it significantly improved wear resistance, with wear loss decreasing from 3.273 mm3 to 2.881 mm3, representing a 15% reduction in wear rate. The improvement in wear resistance was attributed to a change in the wear mechanism of the high-entropy alloy coating. Before and after post-annealing, the mechanism transitioned from abrasive wear, adhesive wear, and oxidative wear to primarily abrasive wear and oxidative wear. Additionally, the recovery treatment transformed the surface from hard and brittle to ductile and resilient.

Comprehensive Analysis of Wear, Friction, and Thermal Resistance in PVDF/Nanoclay Composites Using Taguchi Methodology for Enhanced Tribological Performance

This study discusses the tribological characteristics of Polyvinylidene Fluoride (PVDF)/nanoclay composites, focusing on the effects of nanoclay content (0, 1, 2 and 3 wt.%), load, sliding speed, and sliding distance on the wear rate, friction coefficient, specific wear rate, and temperature. A Taguchi Design of Experiments technique was applied to optimize and assess these aspects. The results demonstrated that nanoclay addition considerably improved the wear resistance and frictional stability of the PVDF composites. Specifically, a nanoclay concentration of 3 wt.% gave the lowest wear rate (0.05 mg/m) with a 10 N load and 100 m sliding distance, lowering wear by roughly 23% compared to unreinforced PVDF. The friction coefficient was similarly lowered by 12% with 3 wt.% nanoclay, reaching a value of 0.38 at the highest load of 40 N. Interaction effects demonstrate that load and sliding distance are key elements impacting wear performance, with large loads and long distances virtually tripling the wear rate. ANOVA results quantify nanoclay’s contribution to a wear rate reduction of 51.29%, whereas load and sliding distance contributed 22.47% and 16.98%, respectively. Temperature increases due to frictional heating reached 10 °C under rigorous test conditions, although nanoclay treatment decreased this increase by an average of 15%. Characterization by XRD and FTIR verified the nanoclay dispersion inside the PVDF matrix, whereas the SEM images demonstrated smoother surfaces and fewer wear tracks in the nanoclay-reinforced samples. These findings illustrate the efficiency of nanoclay in increasing the wear resistance of PVDF, making these composites appropriate for high-performance applications. This research provides useful insights into enhancing PVDF/nanoclay composites, with possible uses in situations that demand endurance and thermal stability.

MECHANICAL AND MICROSTRUCTURAL BEHAVIOR OF ZE41 MAGNESIUM ALLOY REINFORCED WITH INCONEL FOR HIGH-PERFORMANCE APPLICATIONS

Abstract Magnesium alloys are known for their lightweight and desirable properties, as they hold significant potential for innovative engineering applications. The present study investigated the mechanical and microstructural characteristics of a magnesium alloy (ZE41) reinforced with Inconel ceramic particulates. The Magnesium Metal Matrix Composites (MMMC) were fabricated using the stir casting method, with varying weight percentages (wt. %) of Inconel (0, 2, 4, 6, 8, 10, 12 wt. %). The microstructural examinations of the MMMC specimens were performed using SEM, SEM+EDS analyses, and Optical Microscopy (OM), which revealed a strong interfacial bond well-defined between the Magnesium matrix and the Inconel particulates. This uniform distribution of reinforcement particulates significantly enhanced the mechanical properties of the composite materials. The tensile tests showed that the Ultimate Tensile Strength (UTS) improved progressively with up to 8% Inconel reinforcement, achieving a maximum UTS of 202.56 MPa, a 24.47% improvement compared to the base Magnesium alloy. However, the UTS decreased beyond 8% Inconel due to increased brittleness. Hardness tests indicated that the highest hardness value of 76.1 HV was achieved for the composite containing 12 wt.% Inconel, marking an 18.85% increase over the base alloy. Additionally, the wear rate decreased with increasing Inconel reinforcement, demonstrating improved wear resistance. Specifically, the wear rate dropped from 2.58 × 10-7 g/mm at 0% Inconel to 0.84 × 10-7 g/mm at 12% Inconel, showing a 67.44% reduction in wear rate compared to the pure AA6082 matrix. The findings from the present work, indicate the potential of Inconel-reinforced ZE41 composites towards achieving optimized strength and hardness levels for applications requiring high-performance materials. The present research is a contribution to the body of knowledge on the development of magnesium composites and highlights the importance of reinforcement compositions for enhancing their mechanical and microstructural characteristics.

Research on the design of the working parts of vertical roller mills for grinding granulated slag

Abstract. This research focuses on optimizing the design, parameters, and operational modes of vertical roller mills (VRMs) for grinding granulated slag, which are crucial in industries such as cement, mining, and energy. VRMs are widely recognized for their energy efficiency and ability to grind various materials with minimal energy consumption. However, the challenge lies in designing mills that can operate efficiently under harsh conditions of intense friction, impact loads, and abrasive particles, especially when processing hard materials like granulated slag. To address these challenges, advanced materials and protective coatings are being utilized to improve wear resistance. Additionally, the research explores the use of polymer-metal composites in the construction of mill components, which significantly reduce wear rates and extend the lifespan of the mill, ultimately leading to cost savings and reduced maintenance needs. Furthermore, the study examines the integration of intelligent control systems that optimize operational parameters in real-time, thus enhancing grinding efficiency and minimizing energy consumption. The findings also emphasize the importance of reducing vibrations and improving the stability of equipment to ensure reliable performance. The research identifies the key parameters that affect VRM performance, such as roller pressure, material moisture content, and rotational speed, and proposes methods for optimizing these factors to achieve maximum efficienc. The development of VRMs is especially important in post-war Ukraine, where cement production has significantly declined due to infrastructure damage. Vertical roller mills are considered the only viable technological solution for new high-capacity cement plants, capable of enhancing cement quality and reducing CO₂ emissions. This research aims to further develop VRM technology, ensuring its ability to meet the demands of the cement, metallurgy, and coal industries by improving energy efficiency, wear resistance, and grinding quality, making it a vital tool for sustainable industrial production

Increasing the Wear Resistance of Stamping Tools for Coordinate Punching of Sheet Steel Using CrAlSiN and DLC:Si Coatings

The punching of holes or recesses on computer numerical control coordinate presses occurs in sheets at high speeds (up to 1200 strokes/min) with an accuracy of ~0.05 mm. One of the most effective approaches to the wear rate reduction of stamping tools is the use of solid lubricants, such as wear-resistant coatings, where the bulk properties of the tool are combined with high microhardness and lubricating ability to eliminate waste disposal and remove oil contaminants from liquid lubricants. This work describes the efficiency of complex CrAlSiN/DLC:Si coatings deposited using a hybrid unit combining physical vapor deposition and plasma-assisted chemical vapor deposition technologies to increase the wear resistance of a punch tool made of X165CrMoV12 die steel during coordinate punching of 4.0 mm thick 41Cr4 carbon structural steel sheets. The antifriction layer of DLC:Si allows for minimizing the wear under thermal exposure of 200 °C. The wear criterion of the lateral surface was 250 μm. The tribological tests allow us to consider the CrAlSiN/DLC:Si coatings as effective in increasing the wear resistance of stamping tools (21,000 strokes for the uncoated tool and 48,000 strokes for the coated one) when solving a wide range of technological problems in sheet stamping of structural steels.

Enhanced Tribological and Mechanical Properties of Copper-Modified Basalt-Reinforced Epoxy Composites.

The increasing demand for high-performance materials in industrial applications highlights the need for composites with enhanced mechanical and tribological properties. Basalt fiber-reinforced polymers (BFRP) are promising materials due to their superior strength-to-weight ratio and environmental benefits, yet their wear resistance and tensile performance often require further optimization. This study examines how adding copper (Cu) powder to epoxy resin influences the mechanical and tribological properties of BFRP composites. Epoxy matrices, modified with 5%, 10%, and 15% weight fractions (wf.%) of copper powder, were reinforced with BFRP-type fabric, using a vacuum bag manufacturing method. Mechanical tests, including bending and tensile tests, showed notable improvements in tensile strength and flexural modulus due to copper addition, with higher copper (Cu) content enhancing ductility. Tribological tests using a pin-on-disk tribometer revealed reduced wear rates and an optimized coefficient of friction. Statistical analysis and 3D microscopy identified wear mechanisms such as delamination and protective copper film formation. The results highlight the significant potential of copper-modified BFRP composites for applications demanding superior mechanical and tribological performance.

Corrosion and wear resistance of ultrasonic vibration-assisted laser cladded Fe-based crystal/amorphous composite coatings

The ultrasonic vibration (UV) is applied during the laser cladding process of Fe88.83Si6.21B2.51Cr2.45 (wt. %) amorphous powders. The microstructure evolution and properties of the Fe-based crystal/amorphous composite coatings with and without UV were investigated in detail. The results reveal a significant decrease of 55.8% in the average grain size within the UV coating, accompanied by a 35.9% reduction in the length of columnar grains at the interface, which is primarily attributed to the acoustic streaming and cavitation effects of ultrasound. The average microhardness value of coatings rises from 659 ±33 HV0.2 to 873 ±48 HV0.2. Meanwhile, the coatings with UV exhibit outstanding wear resistance, with a 38.2% reduction in wear rate compared to normal coatings. The corrosion mechanism of the coatings is pitting corrosion and the corroded surface of the coating with UV displays a relatively smaller pitting area. The enhancement mechanism for properties by U V can be the cooperative effect of the fine-grain strengthening and the amorphous phase strengthening.

Microstructure Evolution and Wear Behavior of Stellite12 Coating Prepared by Laser-Directed Energy Deposition on H13 Steel

Laser-directed energy deposition (LDED) was employed to apply a Stellite12 coating onto an H13 steel substrate. This study explored the effects of processing parameters on the dimensions of the deposited tracks. Comprehensive examinations were conducted on the coatings to assess their phase composition, microstructure, and wear resistance properties. The relationship between microstructural characteristics and thermal field was investigated through a synergy of numerical simulations and experimental analyses. The findings revealed that the Stellite12 coating displayed a heterogeneous microstructure with epitaxial growth and a slight texture across successive layers. The primary phase comprised a γ-Co solid solution and M23C6 carbides, contributing to a significant enhancement in hardness, which was observed to be 2.2 times higher than that of the substrate. The coating demonstrated superior performance in terms of lower friction coefficients and reduced wear rates at both room and elevated temperatures. The predominant wear mechanisms identified were oxidative wear. These results underscore the promising applications of Stellite12 coatings in industrial contexts facilitated by LDED technology.

Dependence of mechanical and surface properties on crystallographic orientation, twin boundaries, and temperature in CoCrFeMn0.3Ni high-entropy alloys

The CoCrFeMnNi high-entropy alloy (HEA) has been widely studied for its mechanical properties and thermal stability, yet its tribological behaviour remains under explored. In this article, we investigate the effects of temperature and twin boundary spacing on the surface nanotribological properties and subsurface damage of CoCrFeMn0.3Ni HEA through molecular dynamics simulations. Among the orientations, [001] exhibits the highest friction coefficient, indicating the greatest restriction to indenter movement. Higher temperatures reduce wear rates, showing good thermal stability, likely due to thermal softening that decreases high-stress regions and the driving force for dislocation nucleation. Monocrystalline HEA shows lower scratch resistance than twinned workpieces. The loading force correlates with twin boundary distance, with twins increasing strength but excessive twins causing softening. Material removal becomes easier in large twinned workpieces. In monocrystalline HEA, plastic deformation is dominated by partial dislocation slip. However, in twinned workpieces, there are not only partial dislocation slips but also dislocation slips parallel to the twin and twin migration. These findings have important implications for HEA design and their applications in extreme conditions.

A study on the effect of nanoclay addition on the erosion wear characteristics of S-glass/sisal reinforced hybrid polymer composites

This study investigated the erosion wear behaviors of S-glass (G) and sisal (S) fibers reinforced with nanoclay (NC). Samples were fabricated using epoxy and polyester matrices through a hand lay-up process, consisting of four fiber layers (GSSG) with varying NC weight percentages (2, 4, 6 wt.%). Tests were conducted at room temperature using angular-shaped silica sand erodents impacting at 148 m/s at angles of 30°, 60°, and 90°. The results showed that erosion wear was highest at a 60° impact angle, indicating a semi-ductile nature of the composites. The hybrid NC polymer composite with 2 wt.% NC exhibited the highest erosion wear resistance at a 90° impingement angle. A significant reduction in wear rate was observed at 2 wt.% NC, with a 43% decrease in Polyester/GSSG and an 18% decrease in Epoxy/GSSG when comparing 60° and 90° impact angles. Polyester-reinforced composites demonstrated superior wear resistance compared to epoxy-reinforced ones. SEM analysis of the eroded surfaces revealed the wear mechanisms involved. These composites are anticipated to be used as high-speed machinery or aggressive environments, enhancing resistance to erosion wear.

Enhancing biodiesel production and tribocorrosion resistance with MWCNT–COOH @TiO2 nanocatalysts

This study marks a significant advancement in sustainable energy by demonstrating the potential of novel nanocatalysts to efficiently transesterify used cooking oils into biodiesel. A nanocatalyst consisting of titanium dioxide and functionalized multiwalled carbon nanotubes (MWCNTs) was selected for its large specific surface area and high catalytic efficiency in biodiesel production. Prepared through impregnation followed by calcination, the nanocatalyst was thoroughly characterized using advanced techniques such as Brunauer–Emmett–Teller (BET) surface area analysis, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), High-Resolution Field Emission Scanning Electron Microscopy (HR–FESEM), and Atomic Force Microscopy (AFM). The optimum parameters of the transesterification process were determined by Taguchi method as 30 min of reaction at a temperature of 50 °C a stirrer speed of 600 rpm with a nanocatalyst concentration of 400 mg and the oil-to-methanol ratio 1:6. Under these conditions, this nanocatalyst afforded a 98.4 % biodiesel yield, effectively converting waste oil into renewable energy. The biodiesel, with a flash point of 148 °C and a viscosity of 4.2 mm2/s, met the required specifications according to American Society for Testing and Materials (ASTM) standards for applications. Furthermore, the nanocatalyst reusability 91.2 % efficiency after three cycles.The nanocatalyst was reported to reduce wear rates by 9.46%, 10%, and 14.3% compared to functionalized multi-walled carbon nanotubes, according to ASTM G99 standards on a wear test. The wear resistance is enhanced by the formation of a protective oxide layer, which provides smoothness to the surface with solid protection against wear. Combining a high biodiesel yield and low wear provides a route to increase the efficiency and sustainability of energy processes. This highly efficient and durable nanocatalyst can be applied in the transesterification of waste cooking oil as an economical and eco-friendly procedure to produce biodiesel.

Brake pads performance analysis: Influence of polydimethylsiloxane (PDMS) viscosity on tribological efficiency

Friction materials are crucial in engineering, particularly in the automotive and industrial sectors where they are extensively used in brake systems. Lubricants are essential in these brake pad materials because they provide friction stability and reduce wear, especially at high temperatures. Polydimethylsiloxane (PDMS), known for its thermal stability and low volatility, is a lubricant in automotive brake pads. However, the effect of PDMS viscosity on the tribological behaviour of brake pads and their overall braking effectiveness is not well understood. This study examines the effect of PDMS viscosity on the tribological properties of eco-friendly brake pads reinforced with benzoyl-treated Pseudoxytenanthera stocksii (P. stocksii) bamboo rhizomes. Brake pads were fabricated with varying viscosities of PDMS and subjected to detailed physical, chemical, mechanical, and tribological testing. Tribological tests were conducted using a CHASE tribometer under controlled conditions, following SAE J661a standards. The results reveal a significant relationship between PDMS viscosity and the tribological properties of the brake pads. Specifically, low-viscosity PDMS emerged as a highly effective additive, demonstrating superior tribological performance compared to higher-viscosity variants. Conversely, higher-viscosity PDMS improved lubrication, leading to a lower coefficient of friction and reduced wear rates. This research underscores the importance of PDMS, particularly in its low-viscosity form, in enhancing the tribological properties of friction composites in brake pad formulations.

A novel environmentally friendly thermochemical process for Ti64 alloy surface modification for biomedical implants

This study develops an environmentally friendly novel thermochemical surface modification process of Ti64 alloy by utilizing citric acid and hydrogen peroxide to improve the mechanical properties, biocompatibility, and bioactivity for biomedical applications. The novel process was developed thermochemically, followed by simulated mineralization in Hanks Balanced Salt Solution (HBSS). The study investigates the effects of thermochemicals on surface characteristics by evaluating the influence of eco-friendly chemicals on modifying surfaces and finding the optimal pH value. The findings demonstrated that the modification effectively enhanced the Ti64 alloy mechanical properties with a significant increase in average microhardness by approximately 71 % and a reduction in wear rate by approximately 64.29 %, compared to untreated Ti64 alloy. The surface modification with pH (5,7, and 9) revealed absorptive properties as evidenced by a contact angle below 90°, indicating a hydrophilic surface, enhancing cells' attachment to biomaterials. After soaking Ti64 alloy in HBSS, a uniform coating layer of around 20.5 μm formed, leading to increased bioactivity, as evidenced by a Ca/P ratio of 1.67, comparable to hydroxyapatite in human bone. The hemolysis ratio of 0.027 % at pH 7 indicates little red blood cell (RBC) lysis, indicating increased biocompatibility. The corrosion rate was enhanced with pH (5,7, and 9) approximately (1.975 × 10−2, 1.078 × 10−2, and 1.615 × 10−2) mm/year, respectively. These findings indicate that the novel process with neutral pH (7) is optimal for surface modification as it is the most effective in enhancing the biocompatibility and bioactivity of the Ti64 alloy, making it suitable for biomedical implants.

Microstructure and tribological properties of atmospheric plasma-sprayed TiO2 coatings reinforced by boron nitride nanosheets

ABSTRACT In this study, boron nitride nanosheets (BNNSs)/TiO2 composite coatings were fabricated using atmospheric plasma spraying. The phase composition and microstructure of composite coatings were characterized through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, tribological tests were conducted using a ball-on-disc tribometer under dry sliding conditions. XRD analysis reveals the transformation of partial anatase TiO2 to rutile TiO2. SEM images demonstrate that the incorporation of BNNSs has no discernible impact on the coating’s morphology. The TiO2-BNNSs coating exhibited a reduction in both volume loss and wear rate by approximately 71.5% and 55.9%, respectively, in comparison to the TiO2 coating. The potential strengthening mechanisms of the composite coating are further discussed.

Wear-resistance triboelectric nanogenerator based on metal-organic framework modified short carbon fiber reinforced polyphenylene sulfide

In aerospace, automobile transportation, disaster warning and other fields, triboelectric nanogenerators (TENGs) are a new type of energy harvesting device that converts mechanical energy into electrical energy. It is especially suitable for monitoring and early warning systems in harsh environments. This paper reported a TENG based on composites reinforced polyphenylene sulfide (PPS) by the metal–organic frameworks (MOFs) are constructed on the surface of short carbon fibers (SCF). The friction properties of the composites were investigated by using two different friction methods. The composites demonstrated excellent wear resistance, with reduced wear rates to 8.16 × 10-7 mm3/Nm and 2.512 × 10-7 mm3/Nm, respectively. Additionally, it exhibited outstanding high-temperature stability (445.9 °C). Therefore, the study highlights the potential of TENGs to serve as a sustainable solution for real-time environmental monitoring, paving the way for the development of robust and energy-efficient systems in harsh environment applications.

Synthesis, fabrication and tribo-mechanical studies of microcapsules filled and Al2O3/glass fibre reinforced UHMWPE based self-lubricating and self-healing composites

Development of composites containing both self-lubricating and self-healing (SLSH) characteristics is a nascent area of research for applications where direct lubrication is discouraged such as marine, textile, and food processing industries. For instance, SLSH composites may enhance the longevity of propeller shafts, bearings, and other dynamic components in such applications. The present work focuses on the synthesis of microcapsules with molybdenum disulfide (MoS2) as a core and polysulfone as a shell material, using the solvent evaporation method. The composites were fabricated by blending synthesized microcapsules in ultra-high molecular weight polyethylene (UHMWPE) matrix via injection moulding technique. Aluminum oxide (Al2O3) nanoparticles (3–12 wt.%) and glass fibres (10 wt.%) were also used as reinforcements. Flexural and tensile tests of the fabricated composites were conducted to evaluate their mechanical properties. Tribological behaviour was also investigated using a pin-on-disc tribometer. The polymer composites with a constant dose of 10 wt.% glass fibre and 5 wt.% microcapsules along with 6 wt.% Al2O3 exhibit the best performance. The maximum reductions in wear rate and coefficient of friction (COF) are 45.28% and 54.47%, respectively, as compared to the base matrix. Moreover, flexural and tensile strength increased by 43.55% and 39.77%, respectively. The worn surfaces exhibited fractured microcapsules which acted as SLSH agents, due to the high thermal stability of the polysulfone shell and release of the solid core. Various analytical tools, including optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), are employed in this study.

A study of the friction and thermal properties of epoxy composites synergistically reinforced by open-celled Cu foams and carboxylated CNTs

Epoxy resin (EP) plays an important role in the field of friction, but its poor thermal conductivity limits its mature development in industry. To solve this problem, open cell copper foam (Cuf) and carboxylated carbon nanotubes (C-CNTs) were incorporated into the epoxy group as co-intensifiers to improve its thermal conductivity and frictional properties. The results demonstrate that increasing the pore density of Cuf/EP composite copper foam leads to a 33.6 % reduction in wear rate and 23.2 times increase in thermal conductivity when reaching 130 Pores Per Inch (PPI). Furthermore, increasing the content of C-CNTs in Cuf®(C-CNTs/EP) composites resulted in decreased friction coefficient and wear rate; at 0.75 wt% C-CNTs content, the friction coefficient decreased by 9.5 % and the wear rate decreased by 40.6 % compared to that of the (130PPICuf)/EP composites while also achieving a 54.8 % increase in thermal conductivity.