Experimental study on high-temperature thermal oxidation and laser ignition of aged boron powder

Abstract

To investigate the effect of the initial surface oxide layer on boron regarding high-temperature thermal oxidation and ignition combustion performance, boron powder was subjected to aging under varying temperature and humidity conditions. The thickness of the surface oxide layer was analyzed and quantified using transmission electron microscopy (TEM) and digital microscopy software. The thermal oxidation characteristics, including the starting and ending temperatures, initiation temperature of rapid oxidation, and activation energy of the aged boron powder, were investigated through thermogravimetric analysis (TG). Additionally, the ignition delay time, flame morphology, and emission spectrum characteristics of the aged boron powder were assessed using a laser ignition experimental system. The results indicated that the surface oxide layer of boron developed gradually across different storage environments characterized by temperature and humidity. As the thickness of the initial oxide layer increased, the starting and ending temperatures of thermal oxidation exhibited minimal variation; however, both the initiation temperature of rapid oxidation and activation energy increased. Furthermore, the emission spectrum's intensity during the ignition phase of the aged boron powder diminished with an increase in oxide layer thickness, while the ignition delay time was prolonged.