Ultra-High Temperature Mechanical Properties of a Zirconium Diboride-Zirconium Carbide Ceramic

Abstract

The mechanical properties of a ZrB2-10 vol% ZrC ceramic were measured up to 2300⁰C in an argon atmosphere. Dense billets of ZrB2-9.5 vol% ZrC-0.1 vol% C were produced by hot-pressing at 1900⁰C. The ZrB2 grain size was 4.9 um and ZrC cluster size was 1.8 um. Flexure strength was 695 MPa at ambient, decreasing to 300 MPa at 1600⁰C, increasing to 345 MPa at 1800⁰C and 2000⁰C, and then decreasing to 290 MPa at 2200⁰C and 2300⁰C. Fracture toughness was 4.8 MPa-m1/2 at room temperature, decreasing to 3.4 MPa-m1/2 at 1400⁰C, increasing to 4.5 MPa-m 1/2 at 1800⁰C, and decreasing to 3.6 MPa-m1/2 at 2300⁰C. Elastic modulus calculated from the crosshead displacement was estimated to be 505 GPa at ambient, relatively unchanging to 1200⁰C, then decreasing linearly to 385 GPa at 1600⁰C, more slowly to 345 GPa at 2000⁰C, and then more rapidly to 260 GPa at 2300⁰C. Surface flaws resulting from machining damage were the critical flaw up to 1400⁰C. Above 1400⁰C, plasticity reduced the stress at the crack tip and the surface flaws experienced subcritical crack growth. Above 2000⁰C, microvoid coalescence ahead of the crack tip caused failure.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Carbides; Ceramic materials; Crack propagation; Crack tips; Cracks; Fracture toughness; Hot pressing; Mechanical properties; Argon atmospheres; Critical flaw; Flexure strength; Machining damage; Subcritical crack growth; Ultrahigh temperature; Zirconium carbide; Zirconium diboride; Zirconium compounds

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 Blackwell Publishing Inc., All rights reserved.

Publication Date

01 Feb 2016

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