Sintering Reaction and Pyrolysis Process Analysis of Al/Ta/PTFE

Area of Science:

• Materials Science
• Chemical Engineering
• Solid-state Chemistry

Background:

• Reactive materials containing Aluminum (Al), Tantalum (Ta), and Polytetrafluoroethylene (PTFE) were sintered.
• A soft, fluffy white substance and carbon black were observed after sintering at 360 °C.

Purpose of the Study:

• To investigate the reaction process and mechanisms of Al/Ta/PTFE materials during vacuum sintering.
• To identify the products formed and understand the thermal decomposition and reaction pathways.

Main Methods:

• Preparation of powder samples and molded cylindrical specimens of pure PTFE, Al/PTFE, Ta/PTFE, and Al/Ta/PTFE.
• Thermogravimetric Differential Scanning Calorimetry (TG-DSC) analysis of thermal reactions.
• X-ray Diffraction (XRD) phase analysis of sintering products and TG-DSC residues.

Main Results:

• Tantalum (Ta) reacts with PTFE at the sintering temperature (360 °C) to form tantalum trifluoride (TaF3) and carbon black.
• The reaction causes the formation of a fluffy white substance and carbon black, leading to specimen cracking.
• TaF3 was detected in TG-DSC residues at 350 °C and 360 °C, indicating reaction initiation between 340-350 °C.

Conclusions:

• The reaction mechanism involves PTFE decomposition followed by reaction of fluorine-containing gases with Ta.
• PTFE decomposition is estimated to start before 500 °C, potentially influenced by the presence of Ta.
• The observed cracking is attributed to the expansion caused by the formation of TaF3 and carbon black.