Carbon nanotube-toughened interlocking buffer layer to improve the adhesion strength and thermal shock resistance of SiC coating for C/C–ZrC–SiC composites

Abstract

For the purpose of improving the interface adhesion strength and thermal shock resistance of SiC coating for C/C–ZrC–SiC composites, a carbon nanotube (CNT)-toughened interlocking buffer layer was constructed between the SiC coating and C/C–ZrC–SiC substrates by pre-oxidation and chemical vapor deposition. After incorporating CNTs, the fracture toughness of the buffer layer increased by 55.7%. The interface adhesion strength between SiC coating and C/C–ZrC–SiC composites was up to 6.8 N, which was 195.7% higher than that of the SiC coated specimens without CNT-toughened interlocking buffer layer. After 25-time thermal shock cycling between 1773 K and room temperature, the mass loss of the coated specimens decreased by 64.4%. The significant enhancement of interface bonding strength and thermal shock resistance of SiC coating was mainly due to the simultaneous existence of micron scale "pinning effect" of the inlaid SiC coating and nanoscale toughing mechanism of CNTs.