Mechanical, tribological and thermal properties of hot pressed ZrB₂–SiC composite with SiC of different morphology

Abstract

ZrB₂–SiC composites were prepared by hot pressing with different sources of SiC to study the effect of SiC with different morphology on densification, microstructure, phase composition and mechanical properties like hardness, fracture toughness and tribological properties (namely, scratch resistance, wear parameters) and thermal behaviour of the composites. Three different ZrB₂–SiC composites, i.e. ZrB₂–SiC_P (polycarbosilane derived SiC), ZrB₂–SiC_C (SiC from CUMI, India) and ZrB₂–SiC_H (SiC from H. C. Starck, Germany), were studied. It is found that ZrB₂–SiC_C composite shows highest hardness (19·13 GPa) and fracture toughness (5·30 MPa m^1/2 at 1 kgf load) in comparison with other composites. Interconnected network, better contiguity between grains of ZrB₂–SiC composites and impurity content in starting powders can play significant roles for achieving high mechanical, tribological and thermal properties of the composites. Coefficient of friction and wear parameters of all ZrB₂–SiC composites are very low, and thermal conductivity of ZrB₂–SiC composites varied from 52·71 to 65·53 W (m K)⁻¹ (ZrB₂–SiC_P), 54·30 to 71·55 W (m K)⁻¹ (ZrB₂–SiC_C) and 64·25 to 88·02 W (m K)⁻¹ (ZrB₂–SiC_H), respectively and also calculate the interfacial resistance of all the composites.

Keywords:

• Zirconium diboride
• UHTC
• Silicon carbide
• Hot pressing
• Tribology
• Thermal property

Acknowledgements

The authors would like to thank the Director, CSIR-CGCRI, for permission of the work. The authors are also thankful to Director, DMSRDE, Kanpur, for financial support. Thanks are also due to SEM and CSIR, New Delhi. XRD sections and to NOCCD for helping in the experiments. Special thanks to Dr J. Ghosh, scientist, AMMCD, CSIR-CGCRI, for Rietveld analysis.