Effect of pressure and oxygen content on the ignition and combustion of Al–Mg alloy

Using Al–Mg alloy instead of pure aluminum can improve the agglomeration and combustion characteristics of composite propellants. In this experiment, the effects of oxygen concentration and pressure on the ignition and combustion performance of Al–Mg binary alloy (with a magnesium mass content of 20%) and Al–Mg alloy mixed with ammonium perchlorate (AP) were investigated using a laser ignition test bench. The thermogravimetric results showed that the melting of aluminum, magnesium and intermetallic phases in the alloy powder occurred under argon, producing four heat absorption peaks. Magnesium evaporates at about 580 °C. In air, only one endothermic peak was observed, with oxidation occurring at approximately 510 °C. During the oxidation process, the intermetallic phase decomposes. Laser ignition tests showed that the alloy mainly undergoes gas-phase combustion, exhibiting phenomena such as gas emission, particle fragmentation, and micro-explosions. The introduction of AP promotes ignition and combustion of the alloy, resulting in more intense gas-phase reactions. Both increased pressure and oxygen concentration will promote alloy combustion. There are two reaction zones in the particles during combustion. Filamentary solids were observed in the combustion products of the AP-AM samples, which were primarily the products of the reaction of magnesium with O and Cl.