Metal-Based Iodine Bearing Materials Prepared by Mechanical Milling
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Metal-Based Iodine Bearing Materials Prepared by Mechanical Milling Song Wang, Amy Corcoran, Victoria Leybova, Edward L. Dreizin New Jersey Institute of Technology Newark, NJ 07102 ABSTRACT Recent research has demonstrated that ternary aluminum-boron-iodine (Al-B-I2) materials prepared by mechanical milling are effective in generating biocidal combustion products. Such reactive materials are of interest for the munitions aimed to defeat stockpiles of biological weapons. In this research, ternary Mg·B·I2 composites were synthesized using two-stage milling. The first stage consisted of a binary B·I2 powder prepared by mechanical milling, followed by addition of magnesium for iodine stabilization. Specific compositions for each ternary material were varied. Stability of the samples was assessed by their heating in argon at a constant rate using Thermo Gravimetric Analysis (TGA) and observing weight loss. Oxidation of the prepared powders was also studied by TGA. Ternary Mg·B·I2 composite powders prepared by two-stage milling were more stable than any of the previously prepared iodine-bearing materials with the same concentration of iodine (20 wt %). Particle size distributions were measured using low-angle laser light scattering. Powders were ignited using in an air-acetylene flame and in a constant volume explosion apparatus. Particle burn times and temperatures were measured optically. Substantially longer burn times and lower temperatures were observed for the prepared materials compared to the reference pure Mg powder. INTRODUCTION Reactive materials capable of releasing halogens upon ignition are of interest for munitions aimed to defeat stockpiles of biological weapons [1]. Previous work focused on aluminum-based powders containing iodine, designed to replace pure aluminum powders in energetic compositions [2-5]. In this project, iodine is incorporated in a composite Mg·B powder prepared by mechanical milling. Preparation and properties of the new material are presented in this paper. MATERIALS Mechanically alloyed Mg·B·I2 composites were prepared with iodine concentration of 20 wt%. Stating materials were magnesium powder, -325 Mesh, by Hart metals, Inc., amorphous boron powder, 95-97% pure, by SB Boron, and iodine chips (approximately 1–5 mm in size), 99% pure, from Sigma Aldrich. Six different composite samples were prepared and listed in Table1. Ball milling at room temperature was performed using a shaker mill (SPEX Certiprep, 8000 series) with two 50-ml flat-ended steel vials cooled by an air jet. All materials were milled with a fixed ball to powder mass ratio (BPR) of 10 using 3/8”-diameter case hardened carbon steel balls. Each vial contained 5 grams of powder. The vials were loaded and sealed inside an argonfilled glovebox. Materials were prepared by two-step milling, which included one-hour milling of boron and iodine, followed by an additional three-hour milling step with magnesium added. The powder inside the milling vial was chilled in dry ice during 30 min between the first and second milling st
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