# Sustainable Pyrotechnics: Combustion Behavior of B4C/Bi2O3 for Delay Compositions

## TL;DR

This study investigates B4C and Bi2O3 as eco-friendly alternatives for pyrotechnic delay compositions, analyzing their combustion behavior and performance.

## Contribution

The paper introduces B4C/Bi2O3 as a sustainable alternative for pyrotechnics and provides insights into their combustion mechanisms.

## Key findings

- Increasing compaction reduces burning rates due to decreased porosity.
- Combustion occurs in multiple stages, starting with a solid–solid preignition phase.
- Particle and granule size influence the burning profile up to certain limits.

## Abstract

Understanding the combustion behavior of greener pyrotechnic
delay
compositions is key to developing more sustainable and efficient materials
for practical applications. This study explores B4C, a
high-reactivity fuel, and Bi2O3, an efficient
oxidizer, as eco-friendly alternatives to traditional formulations.
Thermodynamic calculations guided formulation design, predicting major
combustion products. After formulation, the compositions were granulated,
pressed at varying pressures (64–385 MPa), burned, and analyzed
for their burning rates. Results show that increasing compaction leads
to a progressive decrease in burning rates, as reduced porosity shifts
combustion from convective to conductive. Particle size influences
combustion up to a certain limit, while the granule size of the final
composition alters the burning profile. The reaction unfolds in multiple
stages, starting with a solid–solid preignition phase, then
moving to a solid–liquid phase, and eventually reaching a gas
stage. Complementary analyses of solid residues and combustion gases
supported the proposed reaction pathway. These findings provide crucial
insights into optimizing both performance and environmental impact
reinforcing the viability of B4C/Bi2O3 formulations for practical applications.