Abstract
When the Al/Ta/PTFE reactive material was sintered at 360 °C in a vacuum sintering furnace, it was found that the material reacted to form a soft fluffy white substance and carbon black. To explore the reaction process further, powder samples of pure PTFE, Al/PTFE, Ta/PTFE and Al/Ta/PTFE, and molded cylindrical specimens were prepared. A TG-DSC test was carried out on the thermal reaction of four reactive materials, and XRD phase analysis was conducted on the white product, formed by the sintering reaction and the residue of the TG-DSC test sample, based on which of the pyrolysis processes and reaction mechanisms were analyzed. The results show that Ta and PTFE could have a chemical reaction at sintering temperature (360 °C) to form soft and fluffy white material TaF3 and carbon black, which can overflow the surface of the specimen and cause cracking of the specimen, which is tightly pressed. Since no obvious exothermic peak showed up on the TG-DSC curve, the composition of the residue of TG-DSC sample at different temperatures was tested and TaF3 was detected in the residue at 350 °C and 360 °C, indicating that Ta began to react with PTFE at a temperature range of 340–350 °C. According to the chemical properties and product formation of Ta, it could be speculated that the reaction mechanism between Ta and PTFE involves the PTFE decomposing first, then the fluorine-containing gas product reacting with metal Ta. According to the temperature range of the reaction, it is estimated that PTFE starts to decompose before 500 °C, but it is not detected effectively by TG-DSC, and the introduction of Ta could also affect the decomposition process of PTFE.
Highlights
Metal fluoropolymer, generally referred to as a reactive material, is known as impact-induced energetic material
Starting from 509 °C, the TG curve shows a sharp drop in sample mass and the loss is 100%, and peak B starts at 514.02 ◦ C, the TG curve shows a sharp drop in sample mass and the loss is 100%, and peak B starts at 514.02 °C, indicating that peak B is the endothermic decomposition peak of PTFE, and the decomposition product indicating that peak B is the endothermic decomposition peak of PTFE, and the decomposition is gaseous product
The results show that TaF3 exists only in the sample residue at the temperature of 350 ◦ C and above, indicating that Ta and PTFE begin to react within 340–350 ◦ C, and produce TaF3
Summary
Generally referred to as a reactive material, is known as impact-induced energetic material. PTFE, the chemical has the highest fluorine content in all fluoropolymers, up to 75% [6] When it is decomposed by heat, PTFE will release highly oxidizing fluorine-containing radical, which could react intensely with various metals. Many scholars have conducted a lot of research on the key problems of PTFE-based metal reactive materials, including mechanical properties, preparation technology, reaction mechanisms, and energy release characteristics. Due to its excellent physical and chemical properties, Ta was initially introduced into Al/PTFE reactive material as an additive in order to improve the mechanical properties of the material, and to explore its effects on the reaction characteristics and energy release levels of the reactive materials. During the preparation of vacuum sintering (sintering temperature is 360 ◦ C), the reactive material could have a significant chemical reaction and produce a white product. The reaction process and mechanism of the Al/Ta/PTFE system are analyzed based on the test results
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