Surface-activated boron powder via atomic layer deposited titania: enhanced ignition and thermal oxidation performances

Boron has emerged as a highly attractive high-energy fuel/additive for multi-scenario applications including powder ramjet engines and rocket propellants, owing to its exceptional calorific value. However, the inherent surface oxide layer impedes oxygen diffusion during combustion, resulting in ignition difficulties and incomplete combustion. This study provides a methodology for constructing titanium oxide activation layers on boron particles via atomic layer deposition (ALD), with systematic investigation of how coating thickness (precisely controlled at 0.046 nm/cycle) influences thermal oxidation behavior and ignition characteristics through multi-technique characterizations. It is demonstrated that complete and uniform encapsulation of boron particles was achieved by TiO₂ nano-coatings. Compared to pristine boron, ALD TiO₂-activated specimens exhibit significant performance enhancements including reduced oxidation temperature (ΔTp = 133 °C), shortened laser ignition delay (32 % reduction), minimized ignition energy of dust clouds (over 90 % decrease), and accelerated flame propagation velocity in dust clouds (one order of magnitude increase). Mechanistic analysis reveals that these improvements originate from a synergistic oxygen transport mechanism between oxygen vacancies in TiO₂ and B₂O₃-TiO₂ solid-solution interfaces. The uniformly distributed TiO₂ surface modification layer establishes sustainable oxygen transport channels through surface vacancy defects, maintaining stable oxygen concentration at reaction interfaces and thereby accelerating boron oxidation kinetics. This work provides both theoretical foundations and practical engineering solutions for overcoming critical bottlenecks in boron-based energy applications.