Energy Release Characteristics and Reaction Mechanism of PTFE/Al/BiO Reactive Materials under Drop-Hammer Test.

To obtain the influence of the BiO particle content of a PTFE/Al/BiO reactive material (later referred to as PAB) on its shock-induced chemical reaction (SICR) characteristics, five kinds of PAB with different BiO contents were prepared; the reaction process in a drop-hammer test, recorded using a high-speed camera, was analyzed. The ignition and reaction mechanisms of PAB under mechanical impact were analyzed based on the thermochemical reaction characteristics and the microstructure. The results show that with an increase in BiO content, the shock-induced chemical reaction duration and the sensitivity of PAB increase, and then decrease. When the BiO content is 9%, the impact sensitivity is the highest and the reaction duration is the longest. The heating at the crack tip is responsible for PAB ignition under long-pulse low-velocity impact. During ignition, PAB undergoes several physicochemical changes such as the melting of PTFE, a PTFE/BiO reaction, an Al/BiO reaction, pyrolysis of the melted PTFE, and a CF/Al reaction; moreover, the presence of BiO decreases the excitation threshold of the reactive material, which facilitates the propagation of the reaction and improves the degree of the reaction and overall energy release of the reactive material.