Thermal barrier coating for carbon fiber-reinforced composite material for drone applications

Carbon fiber-reinforced polymer (CFRP) composites, despite their excellent strength-to-weight ratio, suffer from severe thermal degradation under high-temperature conditions. This study introduces a hybrid thermal barrier coating (TBC) system incorporating α-Al₂O₃ and YSZ nanoparticles dispersed in an epoxy matrix, applied to CFRP substrates through a combination of hand lay-up, nanoparticle spraying, and Vacuum-Assisted Resin Transfer Molding (VARTM). Designed for applications such as firefighting drones, the multilayered TBC architecture aims to significantly enhance flame resistance, thermal stability, and mechanical integrity, thereby extending the operational capability of CFRP-based structural components in extreme environments.

Experimental evaluation under direct flame exposure up to 750 °C demonstrated that coated samples limited heat transfer to 190–235 °C. Flexural strength retention reached 50 % even after severe thermal loading, compared to over 90 % loss in uncoated CFRP. FTIR analysis confirmed crosslinking through N–H bending, aromatic C=C stretching (1580 cm⁻¹), and C–O–C vibrations (1200–1300 cm⁻¹). DSC revealed a high melting temperature (375–400 °C) with thermal degradation onset beyond 420 °C. TGA indicated a retained mass above 22 % at 500 °C, while thermal conductivity improved to 4.29 W/m⋅K (7.27 × over neat CFRP). Surface temperature control remained consistent across thermal cycles, and post-exposure failure load reduction was limited to 12–50 % across 550–750 °C. These results confirm the TBC-CFRP composite as a robust, scalable solution for high-temperature aerospace and firefighting applications.