A Study on the Ablation Performance and Mechanisms of G10 Insulators in a Supersonic Plasma Flame

Insulators play a crucial role in the electromagnetic rail launcher. During electromagnetic rail launch tests, molten aluminum produced by the armature-rail can damage the insulators, subsequently reducing their lifespan. However, observing this damage process is challenging owing to the limited visibility in the gun barrel. Therefore, it is essential to investigate the damage process and mechanisms affecting both the sprayed and unsprayed areas of the G10 insulators during the molten aluminum injection process. This study presents two techniques, supersonic plasma aluminum spray ablation and supersonic plasma flame ablation, used to perform equivalent ablation experiments alongside the development of a corresponding numerical model. The findings from experiments and simulations indicate that spalling damage from supersonic plasma flame ablation occurs at the interface between the epoxy resin and the glass fiber. Additionally, the braided structure of the glass fibers leads to the formation of surface cracks that develop into a mesh-like pattern as the number of ablations increases, thereby accelerating the spalling damage. In supersonic plasma aluminum ablation, molten aluminum droplets cause spalling damage to surface insulators and embedded glass fibers through “drop-by-drop spalling.” With successive ablations, an aluminum film accumulates on the insulator surface. The bimodal stress transfer leads to delamination damage in the insulator, fragmenting the epoxy resin between the glass fibers.