Purpose - This study aims to develop and evaluate copper-free brake pads using an olefin-based elastomer as an alternative to conventional nitrile butadiene rubber (NBR)-based formulations. This research also benchmarks the newly developed pad against the commercial brake pad to determine its viability in real-world applications. Design/methodology/approach - Brake pads were fabricated using an olefin-based elastomer and compared with NBR-based and commercial pads. Following industrial protocols, all samples were tested for physical, chemical, mechanical and acoustic properties. Tribological behavior was assessed using Chase testing in compliance with SAE J661, and damping behavior was measured using an impedance tube. A scanning electron microscope (SEM) was used to examine the worn surface. Findings - The olefin-based elastomer brake pads demonstrated superior fade-recovery performance and wear resistance compared to other brake pads. The olefin-based elastomer brake pads exhibited a higher sound absorption coefficient, indicating improved acoustic damping. SEM analysis confirmed better contact plateaus, which improve tribological performance. Research limitations/implications - The quantitative environmental assessments, including particulate emissions, airborne wear debris and life-cycle analysis, were not performed in this study and should be addressed in future work. Originality/value - This work introduces an olefin-based elastomer as a copper-free alternative to conventional NBR in brake friction materials. This study provides a comprehensive performance benchmark against commercial pads, highlighting the potential of elastomer-based brake pad formulations for next-generation silent automotive braking systems.
Purpose- The cumulative wear of three-lobe semi-floating ring bearings (SFRBs) in marine turbochargers significantly limits their service reliability. This study aims to predict the unsteady wear evolution during frequent start-stop cycles and propose optimization strategies. Design/methodology/approach- A transient lubrication-wear coupled model integrating the energy dissipation principle, asperity contact mechanics and temperature-viscosity effects was established. The model's accuracy was validated through high-fidelity bench tests and microscopic characterization. Findings- The study reveals that the "Edge Effect" driven by fluid end-leakage is a primary wear mechanism. Results indicate that the axial "deep ends, shallow middle" wear distribution is a persistent physical constraint that does not improve with the running-in process. Experimental measurements confirm that wear depths at the edge regions (>16 & micro;m) exceed the sacrificial coating thickness (11.5 & micro;m), causing substrate exposure. Furthermore, a trade-off between rotor dynamic stability and tribological performance is identified; notably, start-up modes with high initial acceleration (e.g. Inverse Sigmoid) are proven to reduce cumulative wear significantly. Originality/value- This paper clarifies the boundary between surface running-in and coating depletion for three-lobe bearings and provides a theoretical basis for optimizing start-up control strategies to extend bearing life.
Purpose - Plunger pairs in emulsion pumps typically operate under extreme boundary lubrication conditions, resulting in severe wear issues. Existing studies have often examined material selection, heat treatment and lubrication independently, without adequately addressing their synergistic interactions. To bridge this gap, this work aims to systematically investigate the combined influence of these factors on tribological performance. Design/methodology/approach - Using QT600 and QT400 ductile irons, specimens with varying hardness were prepared through heat treatment and subsequently paired with nitrided counterparts. Tribological tests were performed under simulated service conditions using gear oil containing 1.5 Wt.% molybdenum dialkyldithiophosphate. Wear mechanisms were characterized via scanning electron microscopy and energy dispersive spectroscopy. Findings - The results indicate that the nitrided layer underwent microfracture and delamination, which aggravated abrasive wear. In contrast, heat treatment significantly enhanced wear resistance. The most favorable performance was observed when the spherical specimen possessed higher hardness than the disc specimen, a configuration that stabilized contact conditions and facilitated the formation of a protective tribofilm. Originality/value - This study highlights the critical roles of mechanical compatibility and surface-lubricant synergy in wear mitigation, demonstrating that tailored heat treatment can effectively optimize the performance of friction pairs and inform the design of advanced lubrication systems.
Purpose - This study aims to provide the comparative analysis of mechanical, microstructural and tribological behaviour of Al6061-ZrB2 nanocomposites fabricated via hot pressing and subjected to T6 heat treatment. The influence of varying ZrB2 nanoparticle content on compression strength, microhardness and wear resistance was systematically evaluated to enhance the performance of Al6061-ZrB2 nanocomposites. The idea is to identify the most effective manufacturing technique. Design/methodology/approach - Al6061-ZrB2 nanocomposites containing 0-2.0 Wt.% ZrB2 nanoparticles (50-100 nm) were produced through hot pressing at 510 degrees C and 35 kg/cm & sup2;, followed by solutionizing (530 degrees C) and artificial aging (175 degrees C). Microstructural characterization was performed using FESEM, while compressive strength, microhardness and tribological behaviour were assessed through mechanical testing and pin-on-disc wear analysis. Findings - FESEM analysis revealed uniform ZrB2 dispersion and refined grains, with the 2 Wt.% composite exhibiting a grain size of similar to 36 nm. The heat-treated 2 Wt.% composite (HT4) achieved the highest compressive strength (106.06 +/- 2 MPa) and hardness (80 +/- 2 HV), reflecting 36% and 86% improvements over unreinforced Al6061. Tribological tests showed significant wear and friction reduction, with HT4 recording a wear depth of 120 & micro;m and a coefficient of friction of 0.18. SEM of wear tracks confirmed reduced surface damage due to ZrB2-induced tribolayer formation. Originality/value - This work highlights the combined effect of hot pressing and T6 heat treatment on ZrB2 reinforced Al6061 composites, offering a high-strength, wear-resistant material suitable for automotive structural applications. Peer review - The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2025-0515/
Purpose During clutch engagement, misalignment errors (parallel and angular) significantly affect the fretting wear characteristics of the engaging spline. Under the premise of obtaining accurate wear coefficients through experiments, this paper aims to investigate the fretting wear behavior of clutch engaging splines based on dynamic torque characteristics and to propose a method for wear prediction considering misalignment errors. Design/methodology/approach Disc-on-disc wear tests on the spline material were conducted to determine the wear mechanism and wear coefficient. Wear progression was implemented in Abaqus using the UMESHMOTION subroutine and the ALE adaptive mesh technique via node displacement control. Comparison between the simulated and experimental wear depths validated the tests. Subsequently, using this wear coefficient and accounting for parallel and angular misalignments, fretting wear models based on dynamic torque characteristics were established to predict the wear behavior of the engaging spline. Findings Based on the wear coefficient K verified by experiment and simulation, fretting wear calculations incorporating dynamic torque characteristics were conducted for splines with two types of misalignment. A parallel misalignment of 0.01 mm produces a uniformly distributed wear depth along the axial direction, peaking at 6.2 & times; 10(-4) & micro;m. An angular misalignment of 0.2 degrees produces a wear depth that decays significantly along the tooth width direction, peaking at 8.5 & times; 10(-4) & micro;m. These results offer quantitative guidance for inferring actual assembly misalignment and controlling wear depth limits. Practical implications These results offer quantitative guidance for inferring actual assembly misalignment and controlling wear depth limits. Originality/value This study provides an effective method for predicting fretting wear of clutch engaging splines considering multiple misalignment errors, offering practical guidance for assembly tolerance control and wear failure assessment.
