Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

S Ghadami; E Taheri-Nassaj; H R Baharvandi; F Ghadami

doi:10.1038/s41598-021-88566-0

Improvement of mechanical properties of HfB₂-based composites by incorporating in situ SiC reinforcement through pressureless sintering

Sci Rep. 2021 May 10;11(1):9835. doi: 10.1038/s41598-021-88566-0.

Authors

S Ghadami¹, E Taheri-Nassaj², H R Baharvandi³, F Ghadami²

Affiliations

¹ Department of Materials Science and Engineering, Tarbiat Modares University, PO Box 14115-143, Tehran, Iran. s.ghadami@modares.ac.ir.
² Department of Materials Science and Engineering, Tarbiat Modares University, PO Box 14115-143, Tehran, Iran.
³ School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran, Iran.

Abstract

HfB₂, Si, and activated carbon powders were selected to fabricate 0-30 vol% SiC reinforced HfB₂-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB₂ composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB₂-30 vol% SiC and 4.9 MPa.m^1/2 for HfB₂-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB₂ grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.