# A Study on the Pantograph Slide Wear Model Based on Energy Dissipation
## 6 Discussion
### Wear Morphology of the Pantograph Slide Surface  
The wear morphology of the pantograph slide surface was observed using a metallographic microscope to further analyze the wear mechanism of the strip and to clarify the applicability of the proposed wear model. Figure 9 presents the surface wear morphology of the pantograph slide under different operating conditions. Figure 9a shows the original surface morphology of the copper-impregnated carbon pantograph slide, where the black regions represent carbon and the small white particles correspond to metallic copper. The original surface appears relatively smooth, with copper particles randomly embedded within the carbon matrix. Figure 8: The variation law of the pantograph–catenary current-carrying friction dissipation energy under different sliding speeds. As shown in Figure 9b, under a sliding speed of 80 km/h, contact pressure of 90 N, and contact current of 100 A, distinct plowing marks aligned with the sliding direction are observed, indicating that the dominant wear mechanism is abrasive wear. As seen in Figure 9c, when the contact current increases to 150 A, flake-like adhesive material and metal oxides of varying sizes are found on the worn surface. This is attributed to the increased energy generated by electrical work, which, in combination with frictional effects, rapidly raises the surface temperature. The elevated temperature induces the oxidation of the contact surface material, and, under sliding friction, material transfer occurs, leading to adhesive wear. When the contact current reaches 200 A, as suggested by the energy diagram in Figure 6, the energy generated by electrical work increases significantly, initiating arc-induced ablation on the pantograph slide surface. In Figure 9d, arc erosion pits are observed; these pits are irregular in shape, with uneven edges, rougher than the surrounding unaffected areas, and exhibit signs of material melting. Additionally, cracks are present on the surface. Under the combined effects of mechanical action and thermal stress concentration, these cracks tend to propagate, further accelerating material loss and intensifying wear. This also indicates that, with an increasing contact current, the erosive effect of arc discharges on the pantograph slide surface becomes more pronounced and should not be neglected. Due to the high energy contained in arc discharges during loss of contact, the ablation effect on the pantograph slide material is significant, leading to deviations between the predicted and actual wear values. The mathematical model for pantograph slide wear was developed under conditions where the contact current is below 250 A and does not account for the influence of arc energy. Clearly, neglecting the impact of arc discharges reduces the model's predictive accuracy. In future work, parameters representing arc energy will be introduced to develop a segmented wear model for the pantograph slide, aiming to  
Figure 9: Wear morphology of pantograph slide surface: (**a**) original surface morphology of pantograph slide; (**b**) 80 km/h, 90 N, 100 A; (**c**) 80 km/h, 90 N, 150 A; (**d**) 80 km/h, 90 N, 200 A.  
achieve more accurate predictions. Therefore, the wear model proposed in this study is applicable for the prediction of wear dominated by abrasive wear, adhesive wear, and mild arc ablation wear. From the perspective of energy dissipation, the proposed wear model for the pantograph slide is characterized by using a single variable--pantograph-catenary current-carrying frictional energy dissipation--to represent the wear amount. This results in a simpler model structure. Since the energy dissipation is directly related to operational parameters such as the contact current, contact pressure, and sliding speed, the computational process is significantly simplified. Moreover, most conventional wear models do not consider the influence of the friction coefficient on pantograph slide wear.