Examining the Aging Characteristics of Fluoropolymer-Coated Boron using Heat Flow Calorimetry

Boron (B) is a remarkable metal fuel offering significant potential in terms of both theoretical gravimetric and volumetric energy. However, realizing its complete experimental potential has been challenging due to the existence of a diffusion-limiting boric oxide layer. Consequently, numerous strategies have been devised over time, primarily aiming to disrupt the boric oxide shell and effectively activate boron for enhanced combustion reactions. Our approach relied on the application of a low molecular weight fluoropolymer (FP) coating, which we developed in-house, to enhance the combustion of boron to elevated levels. In this method, the activation process is initiated by the fluorination reaction, which leads to the disruption of the boric oxide shell. Additionally, the hydrophobic nature of FP is expected to provide a passivating effect on boron by preventing aging reactions caused by humidity and temperature. However, this aspect has not been thoroughly investigated yet. The present study focuses on examining the aging characteristics of FP coated B using heat flow calorimetry (HFC) experiments. We comprehensively investigate the aging process as a function of the percentage of FP coating, relative humidity, and temperature to gain a deeper understanding of the behaviour and stability of FP-coated B over time. We believe that this research will provide insights for optimizing the performance and utilization of activated boron as a metal fuel, thereby creating new possibilities for its practical applications.