Elevated Temperature Strength Enhancement of ZrB₂-30 vol% SiC Ceramics by Postsintering Thermal Annealing

Abstract

The mechanical properties of dense, hot-pressed ZrB2-30 vol% SiC ceramics were characterized from room temperature up to 1600⁰C in air. Specimens were tested as hot-pressed or after hot-pressing followed by heat treatment at 1400⁰C, 1500⁰C, 1600⁰C, or 1800⁰C for 10 h. Annealing at 1400⁰C resulted in the largest increases in flexure strengths at the highest test temperatures, with strengths of 470 MPa at 1400⁰C, 385 MPa at 1500⁰C, and 425 MPa at 1600⁰C, corresponding to increases of 7%, 8%, and 12% compared to as hot-pressed ZrB2-SiC tested at the same temperatures. Thermal treatment at 1500⁰C resulted in the largest increase in elastic modulus, with values of 270 GPa at 1400⁰C, 240 GPa at 1500⁰C, and 120 GPa at 1600⁰C, which were increases of 6%, 12%, and 18% compared to as hot-pressed ZrB2-SiC. Neither ZrB2 grain size nor SiC cluster size changed for these heat-treatment temperatures. Microstructural analysis suggested additional phases may have formed during heat treatment and/or dislocation density may have changed. This study demonstrated that thermal annealing may be a useful method for improving the elevated temperature mechanical properties of ZrB2-based ceramics.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Annealing; Ceramic materials; Hot pressing; Mechanical properties; Silicon carbide; Dislocation densities; Elevated temperature mechanical property; Elevated temperature strength; Flexure strength; Heat treatment temperature; Microstructural analysis; Test temperatures; Thermal-annealing; Heat treatment

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 Mar 2016

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