Effect of purity and surface functionalization on stability and oxidation kinetics of boron powders

Document Type

Conference Proceeding

Publication Date

1-1-2017

Abstract

A commercial 95-% pure boron was ultrasonicated in acetonitrile and then in toluene to remove the surface layer of boron oxide and boric acid. The powder suspended in acetonitrile forms stratified layers, with the bottom layer containing most of the material with the least amount of boron oxide and boric acid. The stability of different powders was characterized using isothermal calorimetry employing a thermal activity monitor TAM III with a perfusion ampoule. The surface of the processed boron powder was functionalized with a protective layer, making it more stable in room temperature humid oxidizing environment than the reference 95-% pure commercial boron. Oxidation of the surface functionalized boron powders was studied using thermal gravimetry and compared to oxidation of both 99 and 95-% pure commercial powders. Upon heating, the 99-% boron begins oxidizing at a lower temperature than all the 95-% pure powders. However, the activation energy of oxidation at elevated temperatures obtained using a model-free isoconversion methodology is lowest among all tested powders for the 95-% pure powder processed in both acetonitrile and toluene. It is expected that the latter powder is the most attractive as a fuel, which will be characterized by the shortest ignition delays.

Identifier

85049029187 (Scopus)

Publication Title

10th U S National Combustion Meeting

Volume

2017-April

Fund Ref

Defense Threat Reduction Agency

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