Structural Reliability of Yttria-Doped, Hot-Pressed Silicon Nitride at Elevated Temperatures.

摘要

The strength of yttria-doped, hot-pressed silicon nitride was investigated as a function of temperature and applied load. Data collected 1200 degrees C are presented in the form of a strength degradation diagram for an applied load of 350 MPa. At this temperature, the behavior of the yttria-doped material is found to be superior to that of magnesia-doped silicon nitride, in which creep results in the formation of microcracks that lead to strength degradation. By contrast, the ytrria-doped material does not suffer from microcrack formation, or strength degradation at 1200 degrees C. At higher temperatures strength degradation does occur, and as a consequence, an upper limit of 1200 degrees C is recommended for ytrria-doped, hot-pressed silicon nitride in structural application. (Author)