The pressure effect study on the burning rate of ammonium nitrate-HTPB-based propellant with the influence catalysts

Abstract

The burning rate of AN–HTPB-based propellant catalysed with chromium salt has been studied using conventional strand burner under the various pressure range, i.e. from atmospheric pressure to 6.897 MPa and verified with Piobert law, i.e. r = aPn. At atmospheric pressure, the burning rate AN–HTPB propellant was being accelerated with the chromium-based catalysts used. In case of lead chromate-catalysed system, burning rate was observed 2.655 times higher than burning rate (r = 0.200 mm s−1) of virgin AN–HTPB propellant sample. However, the Copper chromate-catalysed propellant burned with slower rate (r = 0.160 mm s−1) than the virgin AN–HTPB propellant sample. The burning rate of all catalysed propellant samples are found to be the pressure sensitive and accelerated higher with rise of pressure. The highest burning rate (r = 2.422 mm s−1) was recorded with ammonium dichromate and lowest (r = 1.40 mm s−1) with lead chromate-catalysed propellant sample with the rise of pressure up to 6.897 MPa at different pressures. A linear relationship was observed between the burning rate and pressure rise which followed the Piobert law, i.e. r = aPn. The pressure index (n) values of AN–HTPB-based samples were calculated higher when catalysed with ammonium dichromate, Copper Chromate, Cr2O3, Potassium dichromate (n = 0.525, 0.555, 0.429, and 0.408 respectively) and lower (n = 0.226) with lead chromate compared to virgin sample (n = 0.405). Higher value indicates the positive effect on accelerating the burning rate with catalyst at higher pressure ranges.