Charles H. Drummond III, Ph.D. Associate Professor Ph.D., Harvard University, 1974. This includes bulk glasses of scientific and commercial interest and glasses present in crystalline materials. Of interest is the nature of the glassy state and the structure and crystallization of glasses. Properties being studied include the diffusion of ions through the structure and the thermal properties of glasses. The formation of glasses from melts and by other techniques such as sol-gel and as a second phase in other materials is also a research interest.
Current research is focused on the crystallization of yttrium silicate glasses in silicon nitride.
The addition of yttria aids in the densification of silicon nitride but results in the formation of an intergranular glassy phase that softens at high temperatures. This is detrimental to the mechanical properties of components of silicon nitride at use temperatures. The addition of nucleating agents, such as zirconia, and measurement of the viscosity of the glassy phase in silicon nitride is currently being studied. Other materials being investigated for high temperature applications are celsian glass-ceramic matrix composites. The addition of a second phase, such as high strength SiC fibers, results in tough materials capable of withstanding loads at elevated temperatures.