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Particulate Ceramic Composites: Their High-Temperature Creep Behavior

Published

Author(s)

Sheldon M. Wiederhorn

Abstract

Particulate composites, such as liquid-phase sintered silicon nitride and reaction-bonded silicon carbide, are being considered for use in applications where superior chemical and mechanical behavior at high temperatures are essential. Superior strength, creep resistance and oxidation resistance will decide whether particulate composites will find commercial acceptance in such applications. Creep degradation provides an upper thermal limit to the use of these materials. Mechanisms of creep must be understood to project material behavior to the long lifetimes required in applications such as gas turbines and heat exchangers. Therefore, we discuss the high-temperature behavior of particulate ceramics with regard to their creep behavior. Creep deformation in tension and compression are essentially different. In tension, creep is controlled by cavity formation, in compression by solution-precipitation. For both mechanisms, however, the most important property controlling creep resistance is the refractoriness of the phases located at the grain boundaries of these materials: the more refractory these phases, the more resistant the material is to creep. The volume fraction of second phase contained in the material is also critical to high-temperature creep resistance: a lower volume fraction second phase leads to a higher creep resistance.
Citation
Engineering

Keywords

creep, high temperature, silicon carbide, silicon nitride

Citation

Wiederhorn, S. (2017), Particulate Ceramic Composites: Their High-Temperature Creep Behavior, Engineering (Accessed April 17, 2024)
Created February 19, 2017