Enhanced Strengths and Thermal Shock Resistance of SiC-BN-10 Vol% C_f Composites through ZrB₂ Addition

ABSTRACT

Microstructures, mechanical properties, thermal shock resistance, as well as oxidation resistance of short carbon fiber (C_f) and nano ZrB₂ enhanced SiC-BN ceramics were investigated systematically. Results showed that ZrB₂ induced the structure developments of BN, graphite plates and SiC particles. Consequently, flexural strength reached 378.2 MPa and fracture toughness reached 5.80 MPa.m^1/2. Mechanical properties of ZrB₂ and C_f reinforced SiC-BN ceramics outperformed the properties of C_f and SiC_f reinforced SiC-BN ceramics significantly. SiC-BN/ZrB₂/C_f composites showed good thermal shock resistance below 1000^oC, where a residual strength of 218 MPa can be obtained for the specimen tested at a temperature difference (ΔT) of 800^oC. The enhancing mechanisms can be described as carbon fiber and BN/C plates ‘pull-out’, ‘crack bridging’, etc.

GRAPHICAL ABSTRACT

Keywords:

• SiC-BN ceramics
• Carbon fiber
• ZrB₂
• Mechanical properties
• Thermal shock resistance