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Creep and Creep Rupture of Nonoxide Ceramics: Silicon Nitride and Silicon Carbide

Published

Author(s)

Sheldon M. Wiederhorn

Abstract

Because SiC and Si3N4 are covalently bonded, they are also among the most creep resistant of ceramic materials and, therefore, are used in applications such as kiln furniture, heat exchangers, gas turbines and cutting tools where resistance to high-temperature deformation is required. Covalent bonded solids require higher temperatures than ionic solids for the motion of the vacancies and other atomic defects that control creep and, consequently, need higher temperatures for creep. It is for this reason that creep-resistant, sintered SiC and hot pressed Si3N4 requires temperatures greater than 1500 C and 1400 C, respectively, to creep, Fig. 1. By contrast, Al2O3 and ZrO2 which are ionic solids, creep at temperatures of 1300 C or less, Fig. 1. The same relative temperature differences are observed for the sintering of covalently and ionically bonded ceramics. In this article, we emphasize this relationship between creep and processing temperatures and show how different processing techniques affect the creep of Si3N4 and SiC.
Citation
Encyclopedia of Materials

Keywords

ceramics, creep, creep rupture, high temperatures, silicon carbide, silicon nitride

Citation

Wiederhorn, S. (2008), Creep and Creep Rupture of Nonoxide Ceramics: Silicon Nitride and Silicon Carbide, Encyclopedia of Materials (Accessed June 24, 2024)

Issues

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Created October 16, 2008