Synthesis of hafnium carbide (HfC) via one-step selective laser reaction pyrolysis from liquid polymer precursor

Abstract

This study introduces a novel one-step selective laser reaction pyrolysis (SLRP) method for synthesizing hafnium carbide (HfC), an ultrahigh-temperature ceramic (UHTC). Unlike conventional methods that involve multiple steps, including crosslinking and pyrolysis, this approach combines both processes into a single laser-driven step, reducing time and energy consumption. The CO2 infrared (IR) laser (λ = 10.6 µm) used in this technique enables localized heating up to 2000°C within seconds, facilitating the conversion of a liquid polymer precursor into HfC. Material characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) confirmed the crystallinity and phase purity of the synthesized HfC powder. To study energy absorption, thermal and photo-activators were added to the precursor before laser exposure. The thermal activator had a negligible impact on reflectivity but yielded a pure HfC phase, demonstrating the potential for optimized precursor formulations to enhance efficiency without compromising purity. The one-step process was successfully applied for additive manufacturing, depositing HfC coatings onto carbon–carbon (C/C) composite substrates. This technique eliminates the need for high-temperature furnaces, enabling rapid fabrication of UHTC components and advancing scalable, energy-efficient manufacturing. The study highlights its potential for energy, aerospace, and other extreme environment applications.