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Parfenova Maria, Speaker at Chemical Engineering Conferences
Siberian Branch of the Russian Academy of Sciences, Russian Federation
Title : Crystallization processes in Li,M,K||Cl (M=Nd,Pr) systems: Digital twins of phase diagrams, cross-validation of horizontal and vertical material balances, DTA spectrum simulation

Abstract:

In many cases the chloride ternary systems are used as the catalytic materials. The publication of the graphics for the phase diagrams (PD) of many ternary systems makes it urgent to accelerate the training of students and more experienced specialists for the perception and understanding of such information. The manual «Development of Technical Specifications for Prototyping Disassemblable T-x-y Diagrams (EXCEL + AutoCAD Technology) of Maria Parfenova et al (Buryat State University, Ulan-Ude, Russia, 2021) may be very useful for this purpose. Two variants (A. Prince and M. Parfenova) of disassemblable PD of the ternary systems are using in this technology: to show all phase regions of PD or their compressed variant – a puzzle with a complex element of the known origin. For the second variant 13 phase regions of the eutectic-type diagram have been transformed into a puzzle of 4 typical phase regions (L+i and L+i+j - with melt, i and i+j – without melt), a unique 3-phase subsolidus region and a complex element with the rest 8 regions. Next opportunity to understand the whole family of this eutectic-type diagram is to show its variants with different degree of the phase regions degeneration (a merging with the edges and side planes of the PD’ trigonal prism).  A 3D computer model of an isobaric LiCl-PrCl3-KCl PD with 2 compounds (K2PrCl5 – incongruently melting and K3PrCl6 – congruently melting and decomposing above the ternary eutectics) was constructed, the quality of which was estimated by comparison with experimentally obtained isoplethic and isothermal sections, as well as with 33 DTA spectra. The model was corrected accounting for the mutual solubility of lithium and potassium chlorides. To verify the model, a coherence analysis (cross validation) of the horizontal (on a polythermal section at a fixed temperature) and vertical (for some compositions of this isopleth) material balances was carried out. For a similar LiCl-NdCl3-KCl PD there were elaborated 2 variants of the 3D computer models: with and without 2 binary compounds: LiNd2Cl7 and KNd2Cl7 incongruently melting and decomposing above the ternary eutectics. Along with an expansion of the opportunities of computer design, it is pertinent that 3D models of PD (both for real systems and their prototypes) are helpful to recognize the graphic errors in erroneous interpretation of experimental and computational (thermodynamic or ab initio) data. E.g., within T-x-y diagram with 3-phase equilibrium comprising as few as six phase regions, two binary eutectic points are erroneously connected by two lines, rather than one. The Ag–Cu–Ni PD, comprising in addition 3 new phase regions, namely L1+L2, L1+L2+B(C), and B+C), is derived from such a diagram. For this diagram it has been shown (likewise erroneously) the Ag+Cu+Ni three-phase subsolidus region, while the phase reaction scheme forbids its existence

Biography:

Materials CAD Laboratory engineer and Ph.D. student in IPMS SB RAS. Participated in conferences: CALPHAD GLOBAL CONFERENCE: 14th Conference for Young Scientists in Ceramics (CYSC-2021), October 20-23, 2021. Novi Sad, Serbia; 10th International Conference on Materials Science (ICMS2021). November 19-20 2021. Ulaanbaatar, Mongolia; III International Scientific and Practical Conference «Society and Science. Problems and Prospects». January 25-28 2022, London, England; 2022 Sustainable Industrial Processing Submit, SIPS-2022., November 27 - December 1. Phuket, Thailand; V International Conference "Modeling of synthesis and destruction of advanced materials'' (MSDAM-2022) October 12-14, Minsk, Belarus.

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