Session: 03-09-01: Materials for Extreme Environments

Paper Number: 182656

182656 - Formation and Evolution of Protective Oxide Scales in Hfc-Sic-Tac Ceramics Under Extended High-Temperature Ablation 

Note: This abstract is a placeholder.

This work explores the evolution of protective oxide layers in HfC-SiC-TaC ultra-high-temperature ceramics subjected to prolonged oxyacetylene ablation at approximately 2400 °C. Building upon prior studies that optimized TaC reinforcement, this investigation advances into the next phase by examining the influence of decreasing SiC content on oxide formation mechanisms and long-duration ablation performance. Composites with reduced SiC levels (5-20wt.%) were fabricated via pressureless sintering and evaluated under extended ablation durtions of up to 25 mins to capture the progressive evolution of surface chemistry and morphology.

            Microstructural and compositional analyses revealed the sequential formation of complex, multilayered oxide scales composed of HfSiO₄, Hf₆Ta₂O₁₇, and SiO₂-rich amorphous regions, along with dispersed Ta₂C nanoparticles within the outer layer. The interaction between Hf–Ta–Si oxides generated a dense and adherent barrier that restricted oxygen diffusion and suppressed volatile SiO release, preserving structural integrity under extreme thermal flux. As SiC content decreased, the resulting oxide network exhibited greater compositional stability, reduced spallation, and improved retention of the substrate microstructure.

            Post-ablation characterization confirmed that the cooperative formation of mixed hafnium-tantalum oxides and Si-rich glassy phases sealed surface porosity and mitigated mass loss, collectively enhancing thermal protection efficiency. These findings highlight the critical role of oxide-scale chemistry in defining the durability and longevity of ultra-high-temperature ceramics during prolonged ablation exposure.

            The novelty of this work lies in establishing the relationship between SiC depletion and oxide-scale evolution under realistic high-temperature conditions. Insights gained from this study provide a foundation for predicting modelling and future compositional optimization of HfC-based systems for next-generation hypersonic and re-entry vehicle applications.

Presenting Author: Naomy Serrano University of North Texas - Discovery Park

Presenting Author Biography: I received my B.S. in Materials Science from University of North Texas in May 2025 and am currently pursuing my Ph.D. in the same department. My research centers on the development and characterization of ultra-high temperature ceramics (UHTCs) for aerospace and hypersonic flight applications, with an emphasis on oxidation resistance and thermal stability. I have published my first paper in October 2025 and continue to contribute to the field through my work on advanced materials for extreme environments. Beyond research, I am passionate about STEM outreach and inspiring the next generation of scientists and engineers.