No abstract

The paper investigated the effect of metal nanopowders additive on the combustion properties of HMX/CL‐20/AP/polyvinyltetrazole binder/Al propellants. Using thermal analysis, the authors described the effect of aluminum, boron, zinc, nickel, copper, and molybdenum and identified the combustion in a pressure range from 4 to 10 MPa with a pressure step of 1 MPa. No significant correlation between the oxidation properties of the n‐Me powders and the combustion properties of propellants was discovered. An addition of nanopowders caused an increase in the propellant burning rate by approximately 30 % for n‐Al, n‐B, n‐Ni, and n‐Mo independent from the pressure values. An addition of n‐Cu resulted in a burning rate increase by a factor of 4.9 due to coppers’ probable catalytic activity during interaction with nitroesters and cyclic nitramines in a solid phase. n‐Zn additive increased the propellant burning rate by factors 2.3 and 3.6 at 4 and 10 MPa, respectively, due to catalytic activity of zinc in a gaseous phase.

Nanoaluminum powder (nAl, nominal size of particles 50 nm and 100 nm), obtained by electrical explosion of wires, was passivated by air and coated by several different protective organic reagents to assess the effects on ballistics of nAl-loaded hydroxyl-terminated polybutadiene (HTPB)-based solid fuel with respect to pure HTPB baseline. The nAl samples were characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and chemical analysis on active aluminum content (Al°) content and added to HTPB-based solid fuels for hybrid propulsion. Combustion tests were carried out burning central-perforated single-port cylindrical samples in a 2D radial burner. Data analysis was performed to obtain a continuous time-resolved regression rate. Coated nAl particles may significantly improve the ballistics of HTPB + nAl formulations burning in gaseous oxygen, with respect to pure HTPB. All investigated formulations with nAl exhibit increase of instantaneous regression rate (up to 89% maximum), depending on coatings and oxidizer mass flux G ox . Fluoroelastomer and fluorine-containing chemicals used for coating show a good compromise between increase in regression rate and low sensitivity to G ox variation under the implemented operating conditions