Mechanism of Pyrolysis Reaction of Al-Rich Al/PTFE/TiH2 Active Material

Abstract

In order to obtain the chemical reaction mechanism of Al-rich Al/PTFE/TiH₂ composites in argon and oxygen atmosphere, Al/PTFE, PTFE/TiH₂, Al/TiH₂ and Al-rich Al/PTFE/TiH₂ with different contents of TiH₂ composites were prepared by using the wet mixing method. The pyrolysis behavior of the above composites was investigated by thermogravimetric differential scanning calorimeter (TG-DSC). In addition, the calorific value of the above composite was measured by an oxygen bomb calorimeter. The compositions of TG-DSC residues at different peak temperatures and 1000 °C and the residues of oxygen bomb experiment were analyzed by X-ray diffraction (XRD), The results show that the pyrolytic products of Al-rich Al/PTFE/TiH₂ materials under argon atmosphere can be divided into four stages. In the first stage (328.6-378.6 °C), the products are TiH_1.924, (C₂F₄)_n, (CF₂)_n, H₂(g), Al and TiH₂; in the second stage (510.8-534.3 °C), the products are Al, TiH_1.924, (C₂F₄)_n, (CF₂)_n, Ti, AlF₃, TiF₃, TiF₄(g), C and H₂(g). In the third stage (540.8-618.1 °C), the products are Al, C, Ti, (C₂F₄)_n, (CF₂)_n, AlF₃, TiF₃, TiF₄, CF₄(g), C₃F₆(g), C₄F₈(g), C₂F₆(g), Al₅Ti₂ and H₂(g); in the fourth stage (918.5-1000 °C), the products are AlCTi₂, Al₂Ti, AlTi, TiC, AlF₃, Al, TiF₃, TiC_0.957, TiC_0.981 and TiC_0.95. The calorific value of the combustion of Al-rich Al/PTFE/TiH₂ composite with 10% the content of TiH₂ is the highest and is 19,899 J/g, which is 3.776% higher than that of Al-rich Al/PTFE composite. When TiH₂ content is greater than zero and not more than 10%, the chemical reaction mechanism of Al-rich Al/PTFE/TiH₂ is almost the same under oxygen atmosphere. When the content of TiH₂ is higher than 10%, the mechanism of this material is different.