The Effect of Aluminum in Its Mixtures With Ammonium Nitrate on the Ignition of Burning and Its Transition to the Convective Burning Regime

The ignition of the normal layer-by-layer burning (LB) and its transition to the convective burning (CB) regime in mixtures of ammonium nitrate (AN) with bulk density aluminum are studied. Experiments in a constant-volume bomb with pressure registration are carried out. The porosity of the samples is 0.55–0.59, the particle size of the AN varies from 20–40 to 250–630 µm, and the aluminum content varies from 8 to 47 wt %. Two brands of aluminum were used: ASD-4 and PAP-2. It is shown that the mixtures are capable of being ignited when the igniter pressure is close to or above the critical (minimum) value. The values of the critical pressure of the igniter, the pressure, and the time at which LB and CB occurs for mixtures with different particle sizes of AN and aluminum and different concentrations are measured. The replacement of aluminum ASD-4 with PAP‑2 leads to a significant (by an order of magnitude or even more) decrease in the values of critical pressure and pressures at which LB and CB begins.