Effects of doping type of Si on the exothermic characteristics of Si/PTFE energetic composites

In this study, doping type of Si is investigated as a potential factor to modulate the reaction characteristics of Si-based energetic composites. A two-step high-energy ball milling method is used to generate three types of Si powders, namely, n-type, p-type and intrinsic Si (n-Si, p-Si, and i-Si) from respective wafers, which are then physically mixed with PTFE powder to form three kinds of Si/PTFE energetic composites, respectively. Simultaneous thermogravimetric analysis and differential scanning calorimetry are used to compare the heat release characteristics of different energetic composites, while the difference in reaction details is further explored by using coupled thermal analysis and mass spectrometry. Based on the analysis of heat release values and the intensity of several main ion fragments, it is found that p-Si shows apparently a lower tendency toward fluorination than that of n-Si or i-Si, while the latter two show no discernable difference. On the other hand, regardless of doping type, the fluorination of doped Si starts at a lower temperature than that of i-Si, which may be attributed to the extra stain energy accumulated in doped Si.