Title : Phase diagrams 3D computer models as a novel tool to design the catalytic materials
Abstract:
The method of assembling an isobaric phase diagram from surfaces and phase regions represents the construction of a 3D object in the coordinates "concentration (x-y) - temperature (T)" in such a way that the result is a 3D computer model of the phase diagram constructed exclusively geometrically, as if without the use of thermodynamics, which is certainly not the case. Therefore, for brevity, the described approach is positioned as a geometric one, unlike the thermodynamic calculations in CALPHAD-technology. The thermodynamic description of a ternary system requires all the necessary data from special databases. A geometric 3D model can be constructed with a minimum of information: based on hypothetical data, a virtual prototype model is constructed, which gradually turns into a perfect model of a real system phase diagram as new information becomes available. The prototype takes into account all surfaces and phase regions, including those that then are degenerated in a phase diagram of real system. Such degenerations lead to the errors, sometimes serious, and the use of a prototype helps to avoid these inaccuracies. Compounds are another problem that researchers encounter when using thermodynamic programs. The corresponding calculations cannot be performed if the required parameters are unknown, whereas geometrically a 3D model can be constructed from "invented", virtual values of temperature dependencies of its homogeneity boundaries, replacing them later with real ones. The computer models of phase diagrams have been elaborated on the basis of PD DESIGNER and NEDITOR software of the authors. They allow, in addition to the obvious tasks of excellent visualization, to perform calculations of mass balances at all stages of crystallization, to restore the history of the formation of microstructure by studying the qualitative and quantitative composition of coexisting phases, and, in general, to find out the conditions for the formation of a material with specified properties. Based on the models of phase diagrams, commercial products will be developed in the form of a special program for each system, equipped with options for visualizing both the phase diagram itself and the results of crystallization calculations occurring in the corresponding system. Work on each system will be carried out in 4 stages: 1) Critical analysis of the initial data; 2) Construction of 3D computer models for various variants of phase diagrams; 3) Development of a final, verified and consistent 3D model of the phase diagram (assembled from surfaces and phase regions) describing the formation of microstructure; 4) Digitization - creation of commercial products - 3D computer models of verified phase diagrams with the patent support. Thus, completed 3D model of each phase diagram will be made in the form of an independent object (including a commercial product protected by a patent), which can be offered to users in the form of a complete description of all possible phase transformations in a ternary system equipped with extensive capabilities for visualizing all fragments of the phase diagram and the results of calculations of crystallization processes occurring in the system. Examples for the catalytic materials will be shown.
