Evaluation of phase diagrams for the Al 2O 3-CaO-SrO system by in-situ observation using confocal laser microscope

Abstract

Phase relations for the Al 2O 3-CaO-SrO ternary oxide system were clarified. This ternary system has a high liquidus temperature in most compositions and contained many types of solid solutions with a wide composition range. Hence, it was difficult to predict the precise phase diagrams by using conventional techniques such as chemical equilibration method. In fact, the phase diagram reported formerly contains a considerable amount of prediction and surmise and is far from satisfaction. In the present study, an in-situ observation at increasing temperatures was performed using a high temperature observational system that included a confocal scanning laser microscope (CSLM) in combination with an infrared image furnace as a heating device. As a result, definite images of the samples during melting were obtained, and the advantages of this method for the measurement of this type of ternary oxide system were confirmed. Further, a more appropriate ternary phase diagram and its 1973 K isothermal cross section were predicted. © 2009 The Japan Institute of Metals.