Influence of Cyclic Current on the Fretting Wear Behavior of T2-Y Copper

The results demonstrated that cyclic current significantly alters the dynamic response and electrical contact resistance (ECR) of the fretting interface. Under lower load conditions, the friction coefficient during the peak current phase gradually increased (reaching a maximum of 1.58), followed by a gradual decrease in the friction coefficient during the baseline current phase. In contrast, under higher load conditions, the friction coefficient in the peak current phase progressively decreased (to a minimum of 0.65), after which the friction coefficient in the baseline current phase rapidly recovered to a stable value.

The maximum temperature rose in the fretting contact zone reached 178.6 °C, leading to accelerated oxidative wear and increased ECR (as well as fluctuation, with a fluctuation index of up to 246.9%) during the reference current phases, the accumulation of oxide was the primary mechanism leading to the degradation of electrical contact performance. Furthermore, ECR fluctuation can serve as a sensitive indicator of electrical damage and was directly associated with the ablation.

Micromorphology analysis revealed that cyclic current exacerbates material degradation, including melting, ablation, and crack initiation. As the peak current increased, the oxide in the contact zone transitioned from Cu2O to CuO, while the dominant damage mechanisms shifted from delamination and oxidative wear to a combined mode of delamination, ablation, and oxidative wear. Notably, ablation was more severe under low-load conditions.

The findings provided a theoretical foundation for optimizing the design of electrical contact pairs under non-constant current conditions, offering critical insights for improving the reliability of high-current connectors in practical applications