Wear behavior of UHMWPE composites under oxidative effect

Synergistic Enhancement of the High-Temperature Friction and Wear Behavior of PTFE Matrix Composites with the Addition of CF, PEEK, and TiC

With the rapid development of the aerospace, automobile, and ocean industries, there is an urgent need for the fabrication of high-performance polymer matrix composites with low friction and wear in wide temperature ranges. In this paper, polytetrafluoroethylenes (PTFEs) doped with polyether-ether-ketone (PEEK), carbon fiber (CF), and TiC were prepared, and the effects of testing temperatures from room temperature to 250 °C in air conditions were investigated. The results showed that the friction coefficient of the PTFE matrix composites had no obviously changing trend, while the wear resistance properties were significantly improved. Due to the synergistic lubrication and enhancement of CF, PEEK, and TiC, the wear rate for composites with these particles decreased from (2.04-2.72) × 10-3 mm3/Nm for pure PTFE to (0.67-1.96) × 10-4 mm3/Nm. Moreover, the SEM analysis results showed that the main wear mechanisms are fatigue and abrasive wear for the PTFE matrix composites. The results obtained in this study will provide data and technical support for the development of high-performance polymer matrix composites with low friction and wear that can be used over a wide temperature range.

Synergistic Enhancement of the Friction and Wear Performance for UHMWPE Composites under Different Aging Times

With the rapid development of the pipeline transportation and exploitation of mineral resources, there is an urgent requirement for high-performance polymer matrix composites with low friction and wear, especially under oxidative and prolonged working conditions. In this work, ultra-high-molecular-weight polyethylene (UHMWPE) matrix composites with the addition of carbon fibers (CFs), TiC, and MoS2 were prepared by the hot press sintering method. The influence of thermal oxygen aging time (90 °C, 0 h-64 h) on their mechanical and frictional performance was investigated. The results showed that TiC ceramic particles can increase wear resistance, especially by aging times up to 32 and 64 h. The wear mechanisms were analyzed based on the results of SEM images, EDS, and Raman spectra. The knowledge obtained herein will facilitate the design of long-service-life polymer matrix composites with promising low friction and wear performances.

Wear simulation of UHMWPE against the different counterface roughness in reciprocating unidirectional sliding motion

Wear simulations of UHMWPE can economically and conveniently predict the performance of wear resistant bushings used for sealing or other reciprocating unidirectional sliding motion. In this study, pin on plate tribological experiments and microscopic analysis was done to obtained the wear profiles, wear volume and wear mechanism of UHMWPE against the counterface with different surface roughness of which Ra range is 0.03 ~ 2 μm. Meanwhile, the 3D wear simulation model of the pin on plate tribological experiments was established to discuss the adaptability of the energy and Archard wear model by analyzing the difference of wear profiles and wear volume between the experiment and simulation. The results indicate that with an increase in the counterface roughness, the wear simulation of UHMWPE estimated by the energy model were more accurate in reciprocating unidirectional sliding motion.

Investigation of the effects of irradiation and aging on the tribological behavior of ultra-high molecular weight polyethylene/graphene oxide composites under water lubrication

Ultra-high molecular weight polyethylene/graphene oxide (PE-UHMW/GO) composites have demonstrated potential in artificial joint applications. The tribological behavior of irradiated PE-UHMW/GO composites under water lubrication remained unclear, which limited their application range. In this study, the PE-UHMW/GO composites were gamma irradiated at 100 KGy in a vacuum and subsequently aged at 80 °C for 21 days in air. We assessed their water absorption, and mechanical and tribological properties post-treatment. Notably, gamma irradiation markedly enhanced the mechanical and tribological performance of PE-UHMW/GO composites. Irradiated composites had a 6.11% increase in compressive strength and a 25.72% increase in yield strength compared to unirradiated composites. Additionally, under water lubrication, the irradiated composites showed improved wear resistance and a reduced friction coefficient. The irradiation enhancement can be attributed to the irradiation-induced strengthening of the interface bonding between GO and PE-UHMW. Conversely, accelerated aging led to oxidative degradation, negatively impacting these properties. Aged composites exhibited lower compressive and yield strengths, higher friction coefficients, and diminished anti-wear properties compared to the irradiated composites. The wear mechanism evolved from predominantly fatigue wear in irradiated PE-UHMW/GO to a mix of abrasive and fatigue wear post-aging. While GO and aging influenced water absorption, irradiation had a minimal effect. These insights significantly contribute to the application potential of irradiated PE-UHMW/GO composites in artificial joints.

Enhancing Wear Resistance of UHMWPE Composites with Micro MoS2 and Nano Graphite: A Taguchi-DOE Approach

This study presents an in-depth investigation into the wear characteristics of ultrahigh-molecular-weight polyethylene (UHMWPE) composites reinforced with microsized MoS2 and nanosized graphite particles. The objective is to enhance the wear resistance of the UHMWPE by examining the effects of various parameters and optimizing the wear performance. To achieve this goal, wet wear tests were conducted under controlled conditions, and the results were compared between composites with micro MoS2 and nano graphite reinforcements. The Taguchi method was employed to design the experiments (DOE) using an L9 orthogonal array. Four key parameters, namely, reinforcement percentage, load, speed, and track radius, were varied systematically to analyze their impact on wear characteristics, including wear rate, frictional forces, and the coefficient of friction (COF). The data obtained from the experiments were subjected to analysis of variance (ANOVA) to identify the significant factors affecting wear behavior. Subsequently, the optimal wear parameters were determined through regression analysis, allowing for the prediction of wear characteristics under the optimum conditions. This research not only provides insights into the comparative performance of micro MoS2 and nano graphite reinforcements in UHMWPE composites but also offers a comprehensive approach to optimizing wear resistance by employing advanced statistical and experimental techniques. The findings contribute to the development of more durable and wear-resistant materials with potential applications in various industries, such as those investigated in the study, which are commonly employed, such as automotive, aerospace, medical devices, or manufacturing.

Effects of UV sensitivity and accelerated photo-aging on stab resistance of ρ-aramid fabrics impregnated with shear thickening fluids (STFs)

The use of Kevlar in the field of ballistic and stabbing protection has been studied by researchers in polymeric composites for this purpose. This study presents complementary knowledge on energy absorption and dissipation in ρ-aramid fabric impregnated with shear thickening fluids (STFs), especially aiming to obtain better protection against impacts that are deeply associated with STFs, as well as color change, accelerated aging (QUV), and penetration depth (drop tower test). In addition, Scanning Electron Microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) was performed. The research shows that there was a good distribution of STF particles on the ρ-Aramid fabric surface, promoting increased friction between the interfilament and the yarns, further increasing performance and, consequently, improving the energy absorption and dissipation mechanism and, also, the penetration effectiveness in relation to non-impregnated ρ-Aramid fabric. Regarding the protection efficiency against UV exposure (250-400 nm region), there was a significantly decreased compared to those non-impregnated Kevlar® woven with STFs. The FTIR analysis showed that the conditions of aging, after exposure to UV, did not produce new functional groups, that is, there was no chemical modification. Finally, Kevlar fabric impregnated with STFs improved penetration depth performance with the blades independent of the blade type with up to 81% increase in resistance. This result was improved due to interactions between the nanoparticles present in STFs, yarns, and even high-performance woven impregnated with shear-thickening fluids.

Wear Behaviour of Multilayer Al-PVD-Coated Polymer Gears

A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. Three different thicknesses of aluminium (Al) coatings were investigated and deposited by the Physical Vapour Deposition (PVD) process. The Al coating was deposited in three steps: By plasma activation, metallisation of the aluminium by the magnetron sputtering process, and plasma polymerisation. The wear of the gears was tested on an in-house developed testing rig for different torques (16, 20, and 24 Nm) and a rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness and, consequently, the wear of the tooth flank were recorded. The experimental results showed that the influence of metallisation with aluminium surface coatings on the wear behaviour of the analysed polymer gear is not significantly important. The results also showed that the gears with a thicker aluminium coating showed greater wear than gears with a thinner coating or even without a coating. This is probably due to the fact that the aluminium particles that started to deviate during gear operation represented the abrasive material, which led to the faster wear of the contacting surfaces of the meshing gear flanks.

Crystallization and Melting Behavior of UHMWPE Composites Filled by Different Carbon Materials

In order to understand the effect of different carbon materials on the crystallization and melting behavior of ultrahigh molecular weight polyethylene (UHMWPE), UHMWPE composites were prepared by different carbon materials through solution mixing in this paper. UHMWPE was oxidized to improve the interfacial interaction between UHMWPE and carbon materials. The UHMWPE composites and oxidized UHMWPE composites were prepared using granular graphite particle (GP), graphite nanoplatelets (GNP), and flaky graphene oxide (GO) as fillers. The effect of the type and the content of carbon materials and the oxidization of UHMWPE on crystallization and melting temperatures, crystallinity, and crystal form of UHMWPE and oxidized UHMWPE composites was investigated by differential scanning calorimetry, X-ray diffraction, scanning electron microscope, X-ray photoelectron spectrum, and Fourier transform infrared spectroscopy. The results indicated that there are coexistence of the heterogeneous nucleation and the hindering effect of crystal growth by carbon materials for UHMWPE crystallization. The different influence of carbon materials on the crystallization and melting behavior of UHMWPE was discussed by the heterogeneous nucleation of carbon materials and the restriction of the macromolecular chain motion of UHMWPE by carbon materials.