PSI - Issue 77

Fabian Jung et al. / Procedia Structural Integrity 77 (2026) 308–315 Author name / Structural Integrity Procedia 00 (2026) 000–000

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4. Results & Discussion 4.1. Microstructural and Phase Analysis

We characterized the morphology and chemical composition of the MAXCarbon hybrid fibers using SEM, light microscopy, and EDX. Cross-sectional SEM images revealed a continuous, homogeneous boundary layer surrounding the carbon fiber core (Figure 4.1). The interface between the MAX- phase Ti₃SiC₂ layer and the carbon core appeared sharp and well-defined, confirming the formation of a reaction boundary. Image analysis determined the average thickness of the boundary layer to be 1.744 µm, resulting in a total filament diameter of 8.022 µm, compared to the original diameter of 7 µm. This corresponds to a reduction in the diameter of the carbon fiber core to 6.277 µm. The resulting volume fractions of the hybrid fiber were calculated to be 61.24% carbon fiber core and 38.76% Ti₃SiC₂ boundary layer.

Figure 4.1: Synthesized hybrid fibres (left) and EDX spectrum of Ti₃SiC₂ at measuring point A (right) EDX analysis confirmed the presence of titanium, silicon, and carbon in stoichiometric ratios consistent with Ti₃SiC₂. The element distribution maps demonstrated robust signals for Ti and Si, which were confined to the surface region, while the core exhibited a carbon-dominant composition. This further validated the successful formation of the MAX phase.

4.2. Thermal Stability and Oxidation Resistance

Figure 4.2:

Test setup for thermal stability and oxidation resistance