Abstract:
An investigation of the feasibility of rapidly producing fused silica glass parts from powder compacts using Pulsed Electric Current Sintering was carried out. This sintering method was found to be inherently non-isothermal and inhomogeneous, specifically when processing electrically-insulating glass samples. It was evident that significant temperature variation within the die ensemble does not equilibrate during the time the sample is being processed. Amorphous silica powder compacts fused according to the thermal gradients within the die ensemble, resulting in an axially graded porous microstructure for intermediately sintered samples, and extensive macroscopic defects (trapped bubbles, devitrification) in nominally fully consolidated glass parts. The results of this study indicate that in order to consistently attain a pristine amorphous silica part using Pulsed Electric Current Sintering, extreme care must be taken to avoid significant thermal gradients within the die ensemble, thus identifying future design challenges in this area.
Description:
Dissertation completed in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Glass Science at the Inamori School of Engineering, New York State College of Ceramics at Alfred University
