Publication: Effects of HfB2 addition on the oxidation resistance, microstructure, and mechanical properties of pressureless sintered ZrB2-SiC composite
Date
2021
Authors
Mashhadi M.
Salimi I.G.
Golieskardi M.
Journal Title
Journal ISSN
Volume Title
Publisher
Begell House Inc.
Abstract
In order to improve oxidation resistance and mechanical properties of ZrB2-based composites, 10% silicon carbide (SiC) nano-sized particles were used as a reinforcing phase and 4% MoSi2 as a synthesizer aid. In this work, the effects of HfB2 addition (0, 5, 10, 15, 20, and 25%) on Vickers hardness, bulk density, oxidation resistance, and microstructure of the ZrB2-SiC-based ceramics were investigated. The results revealed that the samples consisting of 10% HfB2 have the highest relative density (98.4%). The lowest apparent porosity (i.e., 15%) and the highest hardness (i.e., 15.24 GPa) of the samples were achieved by the addition of 20% HfB2. The X-ray diffraction (XRD) analysis indicated that prolonging the oxidation period resulted in the production of more oxide compounds. The sample containing 25% HfB2 in addition to the lowest relative density due to the oxidized surface erosion and the formation of a poor layer of porous SiC exhibited the maximum oxygen penetration into the sample, the highest gain in mass, and the least oxidation resistance even compared to the ZrB2-SiC composite without the HfB2 addition. It was concluded that by increasing the temperature and time, solid solution formation increases. � 2020 by Begell House, Inc.
Description
Microstructure; Molybdenum compounds; Oxidation resistance; Particle size; Silicon carbide; Vickers hardness; X ray diffraction analysis; Zirconium compounds; Nano-sized particles; Oxidized surfaces; Oxygen penetration; Pressureless-sintered; Reinforcing phase; SiC-based ceramics; Silicon carbides (SiC); Solid solution formation; Hafnium compounds