Performance of EPDM Composites Under Thermal Plasma Ablative Tests

Abstract

In this work, a thermal plasma-based ablation test system was used to evaluate the ablative performance of the EPDM composite. The system produces a high enthalpy plasma jet generated by a plasma (DC) torch, operating at atmospheric pressure using compressed air as working gas, enabling the variation of the thermal flux concerned with the studied EPDM composites. The samples were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Fourier-Transform Infrared spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) to investigate the morphology, mass-loss rate, the reaction layer (char formation), and chemical changes of the samples for each thermal flux. For a complete evaluation, the thermal fluxes were varied in 0.30, 0.45, 0.60, 0.75, and 0.90 MW/m² and for each thermal flux, disk-shape samples remained exposed to the plasma jet for 10s. During the plasma jet exposure time, the temperatures of the surface and the back of the samples were collected to verify the formed char layer's insulator capacity and the samples' thermal diffusivity for each experimental condition. The mass loss is continuous under the thermal fluxes of 0.30 and 0.45 MW/m², stabilizing at 60% until 0.75 MW/m². The formed char layer begins to lose its protective capacity, evidenced by the size decrease (from 800 µm to 700 µm), due to the ablation process of the reaction layer from the thermal flux of 0.90 MW/m².

Keywords:
Thermal Plasma; EPDM composite; Ablation; Reaction layer