The Investigation On Digital Phase Diagram Of Ternary Oxide System

Phase diagram is a geometry description about the relation among system's composition, phase and external conditions in the balanced state, which is a important date to study the phase state, property, separation and purification of relative material, and is also a necessary tool in the field of metallurgy, material, physics, chemistry and geology. In a constant pressure, it is needed a 3-dimension to show the relationship completely among the component for ternary phase diagram, while the conventional ternary phase diagram are all the projection drawing, which can't include enough information and need a great imagination to restore the 3D data in plan sketch to three-dimensional system of coordinate, so it great reduced the efficiency to solve problems, moreover, it is not convenient to save and use for conventional paper-made phase diagram. Now, there are a lot of work has been done about the digital phase diagram ,and the used main software are Thermo-Calc and Fact, but the phase diagram we got is also a projection drawing, so it is necessary to learn how to get 3D phase diagram, how to build a digital system to increase the efficiency of phase diagram. There is not only component content but also temperature in the projection drawing of ternary system. The key of plotting 3D phase diagram is how to restore the 3D data in a planner graph to 3D system of coordinate. And take Al₂O₃-SiO₂-TiO₂ system and CaO-Al2O3-SiO2 system for example. Firstly, the original phase diagrams are analyzed according to thermodynamically consistent theory, the ternary phase diagrams and relative binary phase diagrams which are sufficed to thermodynamic self-consistency are selected. Secondly, the basic data are obtained by interpolation. Finally, the 3D phase diagrams are plotted by means of the function in programming language Matlab, and Al₂O₃-SiO₂-TiO₂ system is analyzed initiatively by means of multiple linear regression. Main conclusions are shown as follows: 1. For Al₂O₃-SiO₂-TiO₂ system, the 3D phase diagram is plotted directly according to basic data, the projection drawing and isothermal section of phase diagram are obtained. The result indicates that all surface of liquid phase has not sharp rise or sharp drop in 3D phase diagram, the intersection between different phase and the tendency of isothermal section complied with original phase diagram,and the result is more accurate than that got by FACT. While the intersection and isothermal section somehow are not smooth. 2. Due to mentioned problems, the equations of all surface of liquid phase are gotten by means of multiple linear regression, and plot 3D phase diagram with Matlab. The intersection between different phases are smooth in projection drawing. 3. For CaO-Al2O3-SiO2 system, the 3D phase diagram, top view and the isothermal section of phase diagram are obtained. The results abided by original phase diagram very well, and the result is more accurate than that got by FACT. 4 By the mean of object-orentied programming, combined with VB and Matlab, a user-friendly and covenient software is developed. In conclusion, on the basis of the study on Al2O3-SiO2-TiO2 system and CaO-Al2O3-SiO2 system, the results present that this method could be applied to construct 3D phase diagrams.