To obtain the influence of the Bi₂O₃ particle content of a PTFE/Al/Bi₂O₃ reactive material (later referred to as PAB) on its shock-induced chemical reaction (SICR) characteristics, five kinds of PAB with different Bi₂O₃ 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 Bi₂O₃ content, the shock-induced chemical reaction duration and the sensitivity of PAB increase, and then decrease. When the Bi₂O₃ 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/Bi₂O₃ reaction, an Al/Bi₂O₃ reaction, pyrolysis of the melted PTFE, and a C₂F₄/Al reaction; moreover, the presence of Bi₂O₃ 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.

Polytetrafluoroethylene (PTFE)/Al reactive material with different aluminum particle sizes were prepared by molding and sintering, and the effect of aluminum particle size on the impact behavior of PTFE/Al reactive material with a mass ratio of 50:50 was investigated. The results show that aluminum particle size has significant effects on the shock-reduced reaction diffusion, reaction speed, and degree of reaction of the PTFE/Al reactive material. At a moderate strain rate, the reaction delay of PTFE/Al increased, and the reaction duration and degree decreased, with the increase of aluminum particle size. Under the strong impact of explosive loading, aluminum particle size has little effect on the reaction delay, which maintains at about 1.5 μs–2.5 μs, but the reaction durability and degree of reaction of PTFE/Al decrease with increasing aluminum particle size. There is also a strain rate threshold for the shock-induced reaction of PTFE/Al reactive material, which is closely related to aluminum particle size. The shock-induced reaction occurs when the strain rate threshold is exceeded.