Effect of Guanidine Carbonate on the Optical Properties of KClO3–Lactose-Based Orange Smoke-Generating Composition

Abstract To investigate the influence of the nitrogen-rich additive guanidine carbonate (GC) on the optical performance of orange-colored smoke compositions, pyrotechnic formulations with varying GC contents were evaluated using a self-made sealed smoke chamber. A stroboscopic spectrum analyzer and Fourier-transform infrared spectroscopy (FTIR) were employed to characterize the optical properties of smoke aerosol and compositions of combustion residue and thus elucidate the mechanism by which GC modulates the optical performance of KClO3–lactose-based orange-colored smoke compositions. The results showed that at GC contents of 0–4 wt %, the aerosol exhibited low broadband transmittance, with ΔT suppressed to approximately 1.45%. At a GC content of 8–12 wt %, the early endothermic decomposition and gas evolution of GC eliminate the high-temperature exothermic stage of the system and shorten the time the dye resides in the high-temperature region, which is hypothesized to minimize the thermal degradation of the dye during vaporization. Consequently, ΔT increased sharply to 8.06–8.34%, yielding orange-colored smoke compositions with high color rendering purity. However, at a GC content of 16 wt %, excessive endothermic cooling caused thermal quenching and interrupted combustion, and FTIR confirmed that the characteristic peaks of the dye were retained in the residue. Overall, a GC content of 8–12 wt % provided the optimal balance between thermal regulation and dye sublimation, offering a quantitative basis for the formulation and design of orange-smoke agents with high colorimetric purity.