The Influence of Ceramic Interphases on the Creep Behavior of Silicon Nitride
Sheldon M. Wiederhorn
In this paper we discuss the role played by the intergranular phases in the creep of silicon nitride, which is completely controlled by the amount and effective viscosity of the intergranular phases. After briefly reviewing the structure and creep behavior of silicon nitride, we discuss two theories developed to rationalize known facts on the creep behavior of this material. One of the theories is based on grain boundary sliding, the other on cavity formation and the flow of the sintering aid away from the cavitation site. A detailed evaluation of each model with regard to transport properties of the sintering aid supports the cavitation model as the explanation for high temperature creep of silicon nitride.