Analysis of synthetic parameters for coating aluminum powders with phenyltriethoxysilane coupling agent and their effects on powder flow behavior

Though silanization of aluminum powder is currently used to improve its flow properties, for use as an alternative fuel source, there are a wide range of experimental parameters for the process and not all of them have been thoroughly explored. Until this is complete, it is unknown if the process is optimized in terms of time, efficiency, and effect. Herein, we report on a study into the effects of changes in humidity, degree of agitation, reaction temperature, and curing time upon the deposition of phenyl triethoxysilane into 20 μm (d₅₀) aluminum particles. We confirm the deposition of the coating via diffuse reflectance infrared spectroscopy and x-ray photoelectron spectroscopy. We then characterize the coated particles using apparent density measurements and Carney flow methods. Using analysis of variance, we find that, of the parameters explored, only changes in cure time and reaction temperature provide meaningful changes to the apparent density, while none of our parameters produced statistically significant changes in Carney flow values. Thus, we conclude that, when optimizing silanization of aluminum particles, environmental control of humidity is unneeded and that the reaction can be run with minimal agitation. The ability to largely ignore these parameters is a benefit to large-scale processing.