Most electric locomotives currently draw power from overhead contact lines. As train speeds continue to increase, irregularities in the contact wire cause system vibrations, leading to frequent pantograph-catenary arc discharges. The presence of arcing imparts distinctive friction, wear, and erosion product characteristics to the current-carrying friction process. Carbon/copper materials subjected to arc erosion exhibit significant differences in surface morphology and physicochemical properties compared to those resulting from pure mechanical wear. In this study, the phenomenon of arcing due to contact wire irregularities under simulated service conditions was investigated to examine the effects of arcing on the current-carrying wear behavior of carbon strips in pantograph-catenary systems and the resulting erosion products. The results indicate that current magnitude is positively correlated with the friction coefficient, temperature, arc ignition rate, and arc energy. Increased current shifts the dominant wear mechanism from abrasive wear to arc-induced erosion. Moreover, higher current levels promote the emission of particles, especially small-sized ones, while the proportion of medium and large-sized particles also increases. However, sustained intense arcing slightly reduces the total particle count due to material sublimation. The microscopic morphology of the particles is predominantly characterized by onion-like carbon spheres encapsulated with copper nanoparticles and multi-walled carbon nanotubes. Additionally, arc erosion significantly enhances the crystallinity and graphitization degree of the carbon material. This study provides an in-depth analysis of arc-induced erosion products and contributes to the theoretical understanding of the microstructural evolution and graphitization behavior of carbon materials under arcing conditions.

The pantograph-catenary system bears the crucial task of supplying electrical energy to high-speed trains. However, as train speeds continue to increase, irregularities in the contact wire exacerbate vibrations within the pantograph-catenary system, frequently triggering pantograph arcs. To delve deeper into the characteristics and erosion mechanisms of these arcs, this study employed high-speed cameras and photodiodes to precisely capture the evolution of the arc morphology and fluctuations in the arc intensity triggered by contact pair irregularities. By adjusting the current intensity, we further analyzed the impact of arc discharge on the friction and wear performance of the carbon strips, as well as their current-carrying efficiency. The study revealed that when the current is sufficiently high, the arc column of the old arc, which forms when the contact pair separates, connects with the arc root of the new arc that is yet to make contact, leading to the formation of a continuous arc. Additionally, under the same current conditions, the arc intensity prior to contact between tribo-pairs is notably weaker than that at the moment of separation. Furthermore, parameters such as the arc ignition rate, wear volume, and temperature are positively correlated with the current intensity. Severe arc discharge not only deteriorates the electrical performance of the system, causing current distortion, but also exacerbates the instability of system operation. Abrupt changes in the friction coefficient can serve as harbors of intense arcs between the contact pair. Arc erosion causes severe damage to current-carrying tribo-pairs, with ablation pits eliminating thermal cracks and pores and leaving behind numerous molten copper particles, significantly increasing the wear volume. This study provides strong support for understanding the arc erosion process caused by contact wire irregularities and the mechanisms underlying the abnormal wear of carbon strips.

The ceramic green bodies with different structures can be formed via binder micro-jetting and bonding additive manufacturing technology. However, the density, strength and surface quality of the sintered ceramic bodies are low. The nanozirconia suspension was used as a jet solution to substitute a conventional organic binder, and the effect of nanozirconia suspension jet amount on the properties of additive manufactured zirconia ceramics after sintering was investigated. When the nanozirconia suspension jet amount increases from 0 to 175%, the line shrinkage and surface roughness of sintered zirconia ceramics decrease significantly, and the reduction rates are 6%–8% and 57%, respectively, while the relative density, flexural strength and hardness increase considerably, and the increase rates are 18.1%, 124.0%, and 187.0%. The nano-sized zirconia particles can fill in the pores of the zirconia powder layer after introducing the nanozirconia suspension, thus improving the green density and the sintering quality of the zirconia ceramic. This provides an effective method for rapid manufacturing complex and compact ceramic parts.