Fabrication of Metallic Powders for Energy-Intensive Combustible Compositions by Mechanochemical Treatment: 1. Peculiarities of the Structure and State of Aluminum Powder Particles Formed by Mechanochemical Treatment

Abstract

The morphology, dispersion, structure, and average particle size of aluminum powders after mechanochemical treatment with different organic modifiers (graphite, stearic acid, and polyvinyl alcohol) are investigated by electron force microscopy, X-ray phase analysis, IR spectroscopy, EDX, and granulometric analysis, which show significant changes in the particle surface layer. It is stated that the mechanochemical treatment of aluminum with organic additives leads to the partial reduction of the surface oxide layer and several types of active centers able to enter chemical reactions when using these composites in the composition of various combustible mixtures are formed. It is found that upon an increase in the content of modifiers, i.e., graphite and polyvinyl alcohol, in the composite with these additives, the activity of aluminum increases. The increment of the activity index falls with an increase in the content of stearic acid in the Al composite. This may be because a dense encapsulating layer poorly soluble in alkali is formed when grinding the Al–C1₇H₃₅COOH mixture with a large amount of stearic acid (more than 5%). Both the accumulation and redistribution of defects over the particle bulk, an increase in amount of active aluminum, and the formation of active centers and the encapsulating layer based on organic modifiers occur during the mechanical action in powders of the compositions under study.