Structure and reactivity of mechanoactivated Mg (Al)/MoO3 nanocomposites

Resumo

X-ray diffraction and thermal analyses, microscopy, and specific surface area measurements are used to study the formation, structure, and reactivity of mechanoactivated Mg/MoO₃ and Al/MoO₃ nanocomposites during slow heating (10°C/min). The optimal mechanoactivation dose is determined. The mechanoactivated Mg/MoO₃ composite is a dense mixture of two nanosized components with a contact surface of ~8 m²/g (upper estimate). The area of the contact surface between the components of the Al/MoO₃ composite is less than 2 m²/g, with the sample consisting of micron-sized aluminum flakes coated with nanoparticles oxide nanoparticles. When heated, the Mg/MoO₃ system explodes, with the temperature of explosion being determined by the heating conditions. The minimum temperature of conversion is ~250°C, close to the temperature of autoignition of fuel–air mixtures promoted by these additives. The Al/MoO₃ system is characterized by a phased progress of the reaction in the temperature range of 200 to 1000°C. The reasons for the differences in the reactivity of the mixtures are discussed.