Heterogeneous reaction kinetics for oxidation and combustion of boron

摘要: Abstract Non-isothermal thermogravimetric (TG) analysis was used to study the oxidation kinetics for 95% pure amorphous boron powder. Commercial powders were pre-treated with acetonitrile and water reduce thickness of their initial hydrated oxide layer achieve a narrower particle size distribution. The samples oxidized at different heating rates in an oxygen-argon gas mixture. Boron particles comprising aggregates finer primary modeled as spheres porous shells solid cores. Experimental TG traces split among sizes. based on measured distribution accounted fraction mass gain assigned powder bins using core-shell model. Further, reactive shell assumed consist densely packed spherical particles. reaction quantified obtain both activation energy pre-factor describing early stage is well described 148 ± 6 kJ/mol. rate any can be obtained considering introduced structure. model extrapolated range temperatures typical combustion. A change morphology occurring when melts coalesce into single droplet for. Burn times predicted close those burning room air. Comparisons suggest that surface temperature varies 3500–4500 K, approaching boiling point. It concluded same heterogeneous governs low-temperature film small its full-fledged combustion much higher temperatures.