Enhancing ignition and thermal oxidation performances of boron powder via tungsten surface activation layers fabricated by atomic layer deposition

Boron (B) powder has outstanding theoretical gravimetric and volumetric calorific values, with broad application potential in fuel-rich propellants and powder ramjet engines. However, ignition difficulty and low combustion efficiency hinder practical applications. Surface activation is an effective strategy to improve the oxidation and ignition performances of boron. In this work, ultra-thin tungsten (W) activation layers were deposited on boron powder via atomic layer deposition (ALD), and their effects on ignition and thermal oxidation performances were investigated. The results demonstrate that the W activation layers uniformly cover the B particles, lower the oxidation temperature by 137 °C, and shorten the ignition delay time by up to 47%. Kinetic analyses reveal that the increased reaction rate is mainly attributable to the increase in the pre-exponential factor. A cooperative mechanism is proposed to explain the improvement: the tungsten trioxide (WO 3 ) layer formed on the W coating undergoes stress-induced cracking, generating WO 3 /boron oxide (B 2 O 3 ) interfacial gaps that facilitate oxygen ingress toward the B core, while WO 3 fragments dispersed in molten B 2 O 3 further mitigate the diffusion barrier. This surface-activation strategy provides a novel and efficient technical route to enhance the ignition and thermal oxidation performances of boron fuels, supporting applications in defense and aerospace sectors.