Resolving 3D microstructure evolution of ceramifiable composites at elevated temperatures using in-situ X-ray computed tomography

Ceramifiable polymer composites suffers significant microstructure change during the polymer-to-ceramic conversion as the environmental temperature increases. The present study employs in-situ X-ray computed tomography (XCT) to reveal the microstructure evolution of high-silica/boron-phenolic composites modified with B₄C and talc (B₄C-talc_HSF/BPR) in three dimensions as the composites is heated to 1000 °C. The cracks are classified based on their locations, and the temporal sequence of their formation is identified. The evolution of internal pore distribution is reconstructed and analyzed quantitatively. Furthermore, the 3D deformation fields of composites during in-situ heating were calculated using digital volume correlation. It is found that the equivalent strain along the thickness direction shows a multi-stage behavior corresponding to the thermal degradation and ceramization transformation processes. The findings provide a 3D visualization of crack propagation and deformation during the polymer-to-ceramic conversion process, which can provide a foundation for further developments in material design.