International Journal of Applied Ceramic Technology· 2026Q2
Influence of Surface Microcracks on Mass Change in Hf and B Modified SiCN‐Carbon Fiber Minicomposites
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- Q2SCImago
- 2026year
Short summary
SiHfBCN coatings on carbon fibers (CFs) retained 25.7% fiber mass after 550°C oxidation, significantly higher than SiCN (12%) and SiBCN (9.2%), due to reduced crack width (5.6 ± 1.5 µm) and increased spacing (38.5 ± 10.9 µm).
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Key points
- SiHfBCN coatings on carbon fibers (CFs) show the lowest average crack width (5.6 ± 1.5 µm) and highest crack spacing (38.5 ± 10.9 µm) after 550°C oxidation.
- At 36% ceramic mass loading, SiHfBCN coatings retained 25.7% of the original fiber mass.
- SiCN and SiBCN coatings retained significantly less fiber mass (12% and 9.2%, respectively) under the same conditions.
- Uncoated CFs retained only 2.9% of their mass, highlighting the protective role of the coatings.
- The findings provide mechanistic insights into how coating defects and microcrack evolution influence CF degradation.
AI-generated from the title and abstract; the full text is not read.
Abstract
ABSTRACT Polymer‐derived ceramic (PDC) coatings on carbon fibers (CFs) protect against high‐temperature oxidation; however, thermomechanical stress and cracking during precursor pyrolysis can expose fiber surfaces, creating pathways for oxygen ingress. In this study, a boron‐ and hafnium‐modified polysilazane precursor is used to prepare PDC coatings on CF single plies via a modified polymer infiltration and pyrolysis (PIP) process. Rather than studying high‐temperature stability limits of SiHfBCN‐coated CF composites, we track macroscale mass changes and localized crack evolution. Up to three PIP cycles for fabrication and an oxidation temperature of 550°C were used as a model system to investigate defects in PDC coating, oxygen ingress, and CF degradation. The relationship among coating layers, crack width, crack spacing, ceramic mass loading, and fiber mass retention is investigated using electron microscopy. After oxidation at 550°C for over an hour, SiHfBCN‐coated samples exhibited the lowest average crack width of 5.6 ± 1.5 µm and the highest crack spacing of 38.5 ± 10.9 µm compared to SiBCN and SiCN coatings. At 36% ceramic mass loading, SiHfBCN retained 25.7% of the fiber mass, compared with 12% for SiCN, 9.2% for SiBCN, and 2.9% for uncoated CFs. These findings provide mechanistic insights into coating defects, microcrack evolution, and CF degradation in PDC‐CF composites.
The authors' abstract, as published at the source. International Journal of Applied Ceramic Technology, 2026 · DOI ↗
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Field: Ceramics and Composites
Ceramics and CompositesMaterials Science