Real-time quantitative imaging of RTV silicone pyrolysis

Quantitative microstructural analysis of Room Temperature Vulcanized (RTV) silicone pyrolysis at high temperatures is presented. RTV is used as a bonding agent in multiple industries, particularly filling gaps in ablative tiles for hypersonic (re-)entry vehicles and fire prevention. Decomposition of RTV is resolved in real time using in situ high-temperature X-ray computed micro-tomography. Full tomographies are acquired every 90~seconds for four different linear heating rates ranging from 7 to 54 C/min. The microstructure is resolved below 5 micro-meters/pixel, allowing for a full quantitative analysis of the micro-structural evolution and porous network development. Results are highly heating rate dependent, and are evaluated for bulk sample volume change, porosity, pore network size, and observed densification from X-ray attenuation. The outcome of this work is critical to develop multi-physics models for thermal response.