Characteristics of Fe powders prepared by spray pyrolysis from various types of Fe precursors as a heat pellet material

Abstract

Aggregated Fe powders comprising elongated and aggregated particles used in the production of heat pellets for application in thermal batteries were prepared by spray pyrolysis. Iron oxide powders comprising dense and hollow particles were prepared by spray pyrolysis from spray solutions containing various types of Fe precursors. Iron oxide powders prepared from iron chloride and iron nitrate precursors were comprised of spherical and micron-sized particles. On the other hand, iron oxide powders prepared from iron oxalate were comprised of large, hollow, and thin-walled particles. The Brunauer-Emmett-Teller (BET) surface areas of iron oxide powders prepared from iron chloride, iron nitrate, and iron oxalate precursors were 17.5, 71.9, and 78.5 m² g⁻¹, respectively. At a low reduction temperature of 550 °C, iron oxide powders prepared from iron oxalate afforded loosely aggregated Fe powders comprised of elongated and loosely aggregated particles, with a BET surface area of 5.9 m² g⁻¹. The heat pellets prepared from Fe powders reduced at 550 °C and composed of fine primary powders had an ignition sensitivity of 0.9 W and a burn rate of 10 cm s⁻¹.