聚乙烯醇原位包覆铝粉结构表征及活性铝含量测定

In order to solve the decrease in the reactivity of nano-aluminum powder due to the alumina shell on its surface, the nano-aluminum powders were directly encapsulated by polyvinyl alcohol (PVA) during electrical explosion of wires. The apparent morphology of sample was detected by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the particle size distribution was characterized by dynamic laser light scattering particle size analyzer. The valence states of surface elements were analyzed by X-ray photoelectron spectroscope, and the thermal behaviours of micrometer Al, nanometer Al and products were compared by simultaneous thermal analyzer. The combustion heat was measured according to relevant national military standards, and active Al content was measured using NaOH exhaust method. The results show that the average size of coated sample is nearly 200 nm, and the particles form a multi-core structure. The active Al content reaches 84.27% which is 22% higher than that of ordinary nano-Al particles. It was proved that PVA effectively relieves oxidation of nano-Al. The coated products have low onset temperature of oxidation (548.6℃) and can release energy more rapidly compared to micro-Al. The in-situ coated sub-micro Al has high active reactivity and quick energy release rate.