Iron oxide as solid propellant catalyst: A detailed characterization

Abstract

Hematite represents the most common burning rate modifier used in propellant production. The tuning of burning rate is obtained even for amounts ranging below 1 wt% of the total composition. Different studies have evidenced a role in ammonium perchlorate dissociation while there are not enough literature documents to clearly support or oppose its capability to enhance binder decomposition. The acceptance of such ingredient in an industrial environment is based mostly on the verification of few parameters, relevant to catalytic action (namely, particle size, specific surface area). The complexity of the iron oxide family shows a wide set of features, neglected in standard quality check but important for a detailed characterization. Such properties assist in defining a unique fingerprint of the material and can be used for detailed identification of batch-to-batch reproducibility, for new supplier qualification, or for improvement of basic knowledge. The present paper is an extract of a detailed characterization activity performed on different batches of nominally identical propellant-grade hematite. Reported results show peculiar properties of the ingredients and characterization methodologies specifically employed for the scope, proposing an end-to-end batch analysis for full ingredient back-trace capability in the supply chain.