Engineering Commons^™

A Preliminary Study Of The Effect Of Heat Treatment On The Strength And Microstructure Of A Glass-Ceramic Material, P. D. Ownby

Masters Theses

"The strength and microstructure of a glass-ceramic material of the composition 53 percent SiO₂, 19 percent Al₂O₃, 15 percent MgO, and 13 percent Li₂O were studied. Cylindrical specimens of glass were formed and heat-treated to six different temperature levels for various time periods. The method of strength testing used was a diametral compression loading technique. It was found that the strength of this material increased initially with heat-treatment but then decreased. The strength characteristics of the completely crystallized glass ceramic material were found to be dependent on the initial nucleation period. Some factors which influenced anomalous crystal growth are described. …

Preliminary Investigation Of The Effects Of Seeding Fusion Cast Refractories, Thomas Spencer Montgomery

Masters Theses

"The crystallization process in a zirconia-alumina- silica melt of high viscosity was studied, A system was used of the same composition found in commercial electrocast glass tank refractories. Artificial nucleation was tried in an attempt to control the process of crystallization; the method involved the addition of suitable "seeding" material.

It was found that introduction of nucleation agents consisting of the major component oxides of the system had noted effect upon the course of crystallization. Preferred orientation normally found in unseeded electrocast refractories was diminished with the addition of zirconia grains and amplified with particles of tabular alumina.

Results obtained …