Metal Oxides and Dichromate Salts Application as Burning Catalysts for the Modern Aluminized Ammonium Nitrate–Based Solid Propellants

ABSTRACT This study is devoted to the investigation of combustion characteristics of aluminized solid propellants (SPs) with ammonium nitrate (SP4, 44 wt.% and SP5, 66 wt.%), ammonium perchlorate (5 wt.%), and inert (butyl rubber) and active (polyvinyl tetrazole) binders. The experimental SP formulations were compared with their analogs, both with and without ammonium nitrate included in their compositions. Among ammonium nitrate–contained SPs, the following row of burning rates was found (ammonium nitrate content in brackets, wt.%): SP3 (0) > SP2 (44) ∼ SP4 (44) > SP1 (51) > SP5 (66). The studied SPs were modified by additives of micron‐sized oxide powders (Co 3 O 4 , V 2 O 5 , MnO 2 , Fe 2 O 3 , CuO) and bichromate salts (K 2 Cr 2 O 7 , Na 2 Cr 2 O 7 , (NH 4 ) 2 Cr 2 O 7 ) or potassium bichromate in combination with the second salt of different origin: oxalates (NH 4 ) 2 C 2 O 4 , La 2 (C 2 O 4 ) 3 , and Na 2 C 2 O 4 and chlorides NaCl, KCl, and BaCl 2 . Micron‐sized oxide powders were added into the formulation SP4 with 44 wt.% of ammonium nitrate. It was found that there was a 20–30% improvement in the burning rate. CuO exhibited the most pronounced catalytic effect, increasing the burning rate by up to 270% compared to the SPs without additives. K 2 Cr 2 O 7 was the effective combustion modifier for ammonium nitrate–based SPs, enhancing the burning rate by up to 100% in the pressure range above 4 MPa. The addition of BaCl 2 and La 2 (C 2 O 4 ) 3 in the pressure range from 2 to 5 MPa had a promoting effect on K 2 Cr 2 O 7 . The studied salt mixtures based on K 2 Cr 2 O 7 were found to be effective catalysts for AN‐based SP combustion.