A High Strength Alumina-Silicon Carbide-Boron Carbide Triplex Ceramic

Abstract

A ceramic particulate composite composed of oxide, and carbide ceramics was found to have high strength, hardness, and fracture toughness values. A composition consisting of Al2O3 with 15 vol% SiC and 15 vol% B4C additions was produced by hot-pressing at 1650⁰C for 30 min, with full density reached after ~5 min at temperature. Both WB and WB2 were observed, with the W source presumably an impurity from WC milling media, and Al18B4O33 was also detected following densification. Strength was~880 MPa, which is greater than values reported for comparable composites of Al2O3 containing 30 vol% SiC or B4C. Vickers hardness was ~21 GPa, and fracture toughness was ~4.5 MPa m1/2, comparable to values reported for the binary mixtures. The calculated critical flaw size of the material was similar to the size of the SiC/B4C clusters and microcracking at grain boundaries. The latter resulting from thermal expansion mismatch between the Al2O3 matrix and SiC/B4C resuborcing phases.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Aluminum oxide; Boron carbide; Hot-pressing; Microstructure; Silicon carbide; Strength; Binary mixtures; Fracture toughness; Grain boundaries; Hot pressing; Thermal expansion; Vickers hardness

International Standard Serial Number (ISSN)

0272-8842

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2017 Elsevier Ltd, All rights reserved.

Publication Date

01 Jul 2017

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