ABSTRACT
In order to determine the equilibrium phase relations of a two, three or four component system it is necessary to establish the phases existing at various temperatures for selected compositions within the system. When oxide containers such as fused silica, alumina, zirconia, mullite, zircon or thoria are used at high temperatures, it is absolutely essential to make chemical analyses of the compositions after the time-temperature equilibrium heat treatment. After equilibrium or non-equilibrium heat treatment of compositions in one-component and especially multicomponent systems are made, it is frequently necessary to chemically analyze the final product. The history of phase equilibrium studies of sluggish silicate systems by the Geophysical Laboratory of the Carnegie Institution of Washington, D.C. is extremely classical. Rapid chemical and metallurgical reactions had been studied in conventional ways for many years before the Geophysical Lab introduced the "quench" furnace, the "quench" technique and many other techniques for the phase equilibrium determination of sluggish silicate systems.
