Low-Interfacial-Defect Carbon Aerogel/Carbon Fiber Composites with In situ Repair-Induced Ultrahigh Compressive...

Area of Science:

• Materials Science
• Composite Materials
• Nanotechnology

Background:

• Carbon aerogel/carbon fiber composites (CACFs) possess good thermal stability but suffer from limited compressive strength due to interfacial defects.
• These defects arise from mismatched shrinkage during carbonization between fibers and the matrix.

Purpose of the Study:

• To develop robust CACFs (RCACFs) with significantly reduced interfacial defects.
• To enhance both high-temperature insulation and structural integrity of CACFs.
• To evaluate the performance of RCACFs under extreme conditions.

Main Methods:

• An in situ repair route was employed to address interfacial defects in CACFs.
• X-ray micro computed tomography (micro-CT) was used to quantify interfacial defects before and after repair.
• High-temperature tensile testing and ablation tests were conducted to assess material performance.

Main Results:

• The repair process reduced interfacial defects from 22.4% to 4.6%.
• RCACFs exhibited a 180.4% increase in compressive strength (14.3 MPa vs. 5.1 MPa).
• RCACFs demonstrated excellent thermal-mechanical stability at 1200 °C, low thermal conductivity (0.173 W·m⁻¹·K⁻¹ at 25 °C, 0.901 W·m⁻¹·K⁻¹ at 1200 °C), negligible shrinkage at 1600 °C, and superior ablation resistance (1.3 μm·s⁻¹ at 1800 °C).

Conclusions:

• The in situ repair strategy effectively mitigates interfacial defects, significantly enhancing the mechanical properties of CACFs.
• RCACFs exhibit exceptional thermal insulation, structural integrity, and resistance to extreme temperatures and ablation.
• These findings position RCACFs as highly promising materials for demanding applications in extreme environments.