Carbon composite is widely used in various fields, including the aerospace industry, electrical engineering, transportation engineering, etc. For electrified railways, the pantograph strip utilizes carbon composite as the current collector, which might bear multiple impacts from electrical, mechanical, or thermal aspects, from unwanted arcing, rain, and other diverse operation conditions. In this paper, a thermal shock damage experiment on the carbon composite of a pantograph strip was carried out. The thermal shock processes were realized by the adoption of muffle furnace heating and water cooling. The effect of thermal shock processes on carbon strip porosity, compressive strength, electrical resistivity, and surface topography were studied. In order to verify the mechanism of thermal shock damage to the pantograph strip, the porosity of the pantograph strip is discussed in detail. The results showed that the thermal shock process increased the porosity of the carbon strip and caused reductions in compressive strength and electrical resistivity. The multiple thermal shock processes caused irreversible damage to the pantograph strip, which was attributed to the spillover and scouring of large quantities of water vapor in the pores.

The dielectric relaxation dynamics in polymer composites critically determine their functional performance in advanced electrical systems. This study systematically investigates hybrid epoxy composites comprising neat epoxy resin (EP) and paper-reinforced systems (EIP), modified with 10–50 wt% polypropylene glycol diglycidyl ether (PEGDGE) plasticizer. Through synergistic application of differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (10⁻¹–10⁶ Hz), the quantitative relationships between plasticizer content, glass transition temperature (Tg), and dielectric relaxation processes were established. DSC analysis reveals a linear Tg dependence with increasing PEGDGE content, attributed to enhanced molecular mobility. Dielectric characterization demonstrates three distinct relaxation regimes: α-relaxation below Tg, interfacial polarization at epoxy/PEGDGE boundaries, and paper/epoxy interfacial effects in EIP systems. A quantitative dielectric relaxation model was developed based on complex modulus formalism, coupled with Vogel–Fulcher–Tammann (VFT) analysis of DC conductivity. Activation energy mapping through Arrhenius decomposition reveals three characteristic values: (1) 82.01–87.80 kJ/mol for α-relaxation, (2) 55.96–64.64 kJ/mol for epoxy/PEGDGE interfaces, and (3) 30.88–44.38 kJ/mol for epoxy/paper interfaces. Crucially, the plasticizer content modulates these activation energies, demonstrating its role in tailoring interfacial dynamics.

Electrical contact resistance (ECR) and discharge are the key parameters of electrical contact performance for carbon-copper (C-Cu) contacts in the pantograph-contact line system. The change in physical and chemical properties of the C-Cu interface caused by interface temperature is the main reason for the variation in ECR and discharge. In this paper, an electric contact test platform based on interface temperature control was established. The influence of interface temperature on ECR and the discharge characteristics under different current amplitudes were studied. There are opposite trends in the change in ECR and the discharge characteristics with interface temperature under different currents, which results from the competition between interface oxidation and a softening of the contact spots caused by high temperature. The trend of interface oxidation with temperature was analyzed via the quantitative analysis of the composition and content of the oxides at the C-Cu contact interface and is discussed here. The relationship between interface oxidation, ECR, and discharge characteristics was studied. Furthermore, a finite element simulation model was established for estimating the temperature distribution throughout the C-Cu contact spots. The competitive process of the softening and oxidation of the contact spots at different temperatures and currents was analyzed, and the variation mechanism of the ECR and discharge characteristics with interface temperature was studied.

Previous studies have often observed that moisture can promote the lubricity and wear resistance of carbon-metal contact pairs in purely mechanical conditions. However, the damage to pantograph carbon strips was found to be aggravated in rainfall conditions, leading to a much lower service life than anticipated. This suggests a novel influence mechanism of water on carbon-copper (C-Cu) contacts during current-carrying friction. In this paper, the influence mechanism of water on the current-carrying friction characteristics of carbon-copper contacts, including friction coefficient, wear loss, electrical contact resistance, and arc discharge characteristics, was studied under different current levels by controlling the water content of carbon sliders. The results show that the variation trend of current-carrying tribological parameters of C-Cu contacts with water content at 60–100 A is significantly different from that at 20–40 A, which is mainly the result of the competition of lubrication, cooling, and obstruction of current transmission by moisture. The abnormal wear of carbon sliders in the water environment occurs when the current is greater than 60 A, and the main reason for the abnormal wear is the intensification of discharge erosion. In addition, micro-crack propagation under high water content is an important factor in the deterioration of carbon strip properties.

The pantograph–catenary system (PCS) is a critical component through which electrified railway trains obtain electrical energy, and the current-carrying friction and wear behavior at the pantograph–catenary interface directly affect current collection quality and operational safety. Water environments, particularly icing conditions, may induce contact instability, arc ablation, and abnormal wear. Therefore, this paper provides a comprehensive review of research progress on the current-carrying friction and wear behavior of C/Cu contact pairs under water environments. It focuses on the interfacial evolution characteristics under three different phase states of water and analyzes their influence mechanisms on lubrication conditions, current transmission, and wear behavior. Typical protection strategies, including speed restriction, mechanical de-icing, thermal de-icing, and anti-icing measures, are summarized, and their applicability and current development status are discussed. Finally, it is suggested that future research should focus on the development of high-performance carbon strip materials, accurate monitoring of ice morphology and types, and efficient hybrid anti-/de-icing technologies, thereby ensuring the reliable operation of high-speed railways under icing conditions.

The pantograph–catenary system is the critical pathway for energy collection for high-speed trains, and its interfacial state directly affects current-collection quality and operational safety. Due to the coupled effects of multiple factors, the friction coefficient at the interface exhibits significant nonlinearity, time variability, and stochastic fluctuations, posing substantial challenges for friction-behavior prediction. To improve the prediction accuracy and generalization capability of friction-coefficient models under complex current-carrying conditions, a CNN-LSTM model optimized by a physics-informed Sparrow Search Algorithm, namely PISSA-CNN-LSTM, is proposed in this study. Based on current-carrying friction tests, the effects of current, contact load, and sliding speed on the dynamic evolution of the friction coefficient are analyzed. The physics-based regularities associated with operating conditions are further incorporated into the SSA-based hyperparameter optimization process, enabling directed optimization under physical constraints. The results show that PISSA-CNN-LSTM outperforms CNN-LSTM and SSA-CNN-LSTM in prediction accuracy, convergence speed, and optimization efficiency. The test-set R² reaches 0.9904, and the optimization time is reduced by 49.38% compared with SSA-CNN-LSTM. This work provides a more accurate, robust, and interpretable modeling approach for predicting pantograph–catenary interfacial friction behavior under complex current-carrying conditions.