Effect of Zr/Gnp hybrid filler on thermal and ablation properties of carbon‐epoxy composites

In this work, the Zirconia (Zr) particles were coated with graphene nanoplatelets (Gnps) using the wet chemical synthesis process and sintered at 500°C and 900°C. At sintering temperature of 900°C, the Zr coated with 0.25 wt% Gnp fillers exhibited better oxidation resistance. Thus, the carbon epoxy (C‐Ex) composites containing Zr/Gnp, 0.25 wt%, were fabricated by the hand‐layup technique. The prepared composites were characterized by scanning electron microscopy, thermogravimetry analysis (TGA), flexural, and ablation tests. The C‐Ex composites modified with Zr/Gnps fillers showed significant improvement in thermal stability and flexural strength compared with the pristine sample. The composite containing 0.25 wt% Zr/Gnp filler reduced the mass ablation rate to 23%, whereas back‐surface temperature was decreased to 170°C compared with pure C‐Ex composite. The surface morphology of ablated composite samples revealed that the Zr/Gnp produced char droplet spheres on the carbon fibres, which prevented the further oxidation of the matrix and thus improved the ablative performance.