Phase diagrams of metal systems with highly volatile components: Simulation and experiments

A critical analysis is performed of existing literature data on the melting diagrams of systems whose components are a low-volatile metal and a high-volatile component. Models for the р–Т phase diagrams of binary systems are developed, and characteristic isobaric sections (partial state diagrams) are presented that correspond to the experimental data for real systems.     

直接氯化法测定LiCL熔盐体系相图的研究及LiCI-KCI-LiF三元相图的制作

首次成功地将NH4Cl直接氯化Li2CO3的反应引入热分析, 制作含LiCl 的二元、三元体系熔盐相图, 避免LiCl吸水性给相图绘制带来的困难, 三个二元体系LiCl-KCl、NaCl-LiCl和LiCl-LiF 的测定结果与文献吻合很好, 并在此基础上制作了LiCl-KCl-LiF三元相     

Models of phase diagrams of one-and two-component systems with heterophase equilibria in the critical and supercritical regions of the coexistence of liquid and vapor

Formal model phase diagrams of one-and two-component systems with heterophase equilibria in the region of critical vapor-liquid states are constructed. The diagrams take into account the existence of the fluid phase.     

Positions of steady states in two-component chemical systems

The general kinetic equation for two-component chemical systems is analyzed. It is shown that the positions of steady states in concentration spaces can be detected by a qualitative analysis of the chemical mechanism.

---

. , .

     

Modeling the state diagrams of ternary reciprocal systems

A model p-T diagram of a eutectic-type ternary reciprocal system is presented. An isobaric cross section in the form of a projection onto a concentration diagram is shown. Isothermic and polythermic cross sections of a eutectic-type ternary reciprocal fusibility diagram with swept faces of a tetrahedral prism are created. A projection of the diagram of a ternary reciprocal system with solid solutions based on initial components with a ternary nonstoichiometric intermediate phase is considered.     

On the structure of the melting diagrams of quaternary systems

Topological and geometric images of invariant and monovariant reactions with the participation of melt in quaternary systems were presented. A network of invariant points and monovariant lines characterizes the structure of the liquidus hypersurface. Each invariant reaction produces an association of four solid phases, which is an element of the solidus hypersurface. Its topology is conveniently described by a graph of adjacency of tetrahedra that partition the composition tetrahedron of a system with a given set of binary, ternary, and quaternary compounds. It was demonstrated that it is possible to construct a spatial network of invariant points and monovariant lines on the liquidus hypersurface using the tetrahedron incidence graph with consideration for the phase reactions occurring in the system.     

Solubility diagrams in solvent-antisolvent systems by titration calorimetry

Isothermal titration calorimetry (ITC) has been used to develop a method to construct the solid-liquid equilibrium line in ternary systems containing the solute to precipitate and an aqueous mixed solvent. The method consists in measuring the heat of dissolution of a solid component (the solute) during successive additions of the liquid solvent. The cumulated heat, resulting from the successive heat peaks obtained for the different injections of known volumes of solvent, plotted vs. the ratio of the numbers of moles n _solvent/n _solute is represented by two nearly straight lines. The intercept of the two lines gives the solubility limit and the corresponding enthalpy of dissolution of the solute in the solvent. Solubility diagrams have been established at 303.15 K in binary mixed solvents ethanol-water over the whole concentration range for seven compounds of pharmaceutical interest, namely: urea, phenylurea, l-valine, dl-valine, l-valine ethyl ester hydrochloride, tris(hydroxymethyl)amino methane.     

State diagrams of perfluorocarbon/solvent systems

The phase behaviour of perfluorocarbons in various solvents has been investigated. In case of perfluorohexadecane the state diagrams with trichlorotrifluoroethylene (CF₂Cl-CFCl₂) known also as Freon F113 and hexafluorobenzene (C₆F₆) as solvents could be determined in the total concentration range and also at temperatures far below the melting temperatures of the pure components. Beside the normal melt transitions in this binary systems some not yet known intramolecular phase transitions were found. From the course of the liquidus curve the Flory-Huggins interaction parameter of these systems could be determined. So statements about the quality of these solvents can be made. The investigated substances are suitable solvents for all perfluorocarbons which are actually available. The high molecular polytetrafluoroethylene (PTFE) cannot entirely be dissolved by these solvents, although traces are soluble. The reason is that the boiling points and critical temperatures of the solvents lie below the temperatures of the liquidus curve of the polymer of the considered system.     

Miscibility diagrams of random copolymer blend systems

The miscibility of copolymers A_xB_1?x and A_yB_1?y, derived from the same monomer pair (A, B) but differing in composition, was studied. The systems (A, B) were (S, MMA), (BMA, MMA), (S, BMA), and (CIS, BMA) (S: styrene, CIS: p-chlorostyrene, MMA: methylmethacrylate, BMA: n-butylmethacrylate). Miscibility diagrams were recorded, at low and high temperatures, using cast films and dry films. All blend systems feature hightemperature miscibility gaps. Unusual effects of the compositions x and y on miscibility in blends A_xB_1?x/A_yB_1?y were observed. The classical prediction that miscibility should depend only on the composition difference |x – y| usually is too simple. It appears necessary to consider dyad interactions.     

β-Modification of polypropylene and its two-component systems

β-modification and multi-component systems ofβ-polypropylene were prepared both under laboratory and processing conditions. Characteristic features of crystallization, melting, and annealing ofβ-PP are summarized. The very distinct memory effect in the melting and annealing ofβ-PP is also presented. The existence of a lower and an upper limit temperature ofβ-PP formation is demonstrated. The structural stability and the orientation-inducedβα-recrystallization ofβ-PP are analyzed. Preparation and properties of polymer blends and filled composites fromβ-PP are introduced, too.     

Solubility diagrams of the systems nickel sulfamate-water and cobalt sulfamate-water

Solubility diagrams of nickel and cobalt sulfamates in water in the temperature range from ?40 to 145°C are presented.     

Solubility diagrams of the potassium iodide-water-ethanol and iodine-water-ethanol ternary systems

The solubility of potassium iodide and iodine in water-methanol mixed solvents was studied by the method of sections at 25°C and atmospheric pressure. The solubility of potassium iodide was found to decrease as the content of ethanol in aqueous-alcoholic solutions increased. The solubility of crystalline iodine had a complex dependence on mixed solvent composition; it was maximum in mixtures containing 90 wt % alcohol. The compositions of the solid phases that crystallized in the KI-H₂O-C₂H₅OH and I₂-H₂O-C₂H₅OH systems were substantiated by X-ray measurements.     

Complete solution of the problem of one-dimensional non-covalent non-cooperative self-assembly in two-component systems

Equations for the mass conservation law and the molecular parameters observed in spectroscopic experiments have been derived for non-covalent, non-cooperative, one-dimensional self-assembly in systems containing two types of interacting molecules (hetero-association), taking into account "reflected" complexes and "edge effects."     

Forward and reverse excitation energy transport in concentrated two-component systems

The experimental and numerical study of the forward and reverse energy transport in concentrated two-component solutions is presented. Experimental results are compared with those of diagrammatic and hopping theories. It is shown that the effect of direct acceptor excitation by the light beam is important in the presence of the reverse transfer and it must be taken into account to describe correctly the experimental results within the framework of any theoretical model. This effect leads in particular to the decrease in the donor emission anisotropy and to the increase in its quantum yield. Our analysis indicates the advantage of the diagrammatic model over the hopping approach.     

Topology of the liquidus hypersurface of the phase diagrams of quaternary systems

Consideration was made of structural features of the liquidus and solidus hypersurfaces of the isobaric melting diagrams of quaternary systems with a single liquid phase and solid phases of constant compositions which undergo neither phase transitions nor decomposition into other phases while cooling. An intimate relationship between the topologies of such hypersurfaces was noted. The oriented graph of the liquidus hypersurface can be obtained from the graph of the solidus hypersurface by drawing arrows on its edges in the direction of decreasing temperature along the corresponding monovariant lines or by labeling its vertices with symbols of types of invariant reactions. An example was given for constructing different variants of the melting diagram of a system that correspond to the same topology of the solidus hypersurface.     

Trialing of the topological types of phase diagrams for unary systems

The topological isomorphism of polyhedra with tervalent vertices and phase diagrams of unary systems allows us to reduce the problem of constructing the full set of topological types of diagrams with tailored parameters to the problem of generating labeled graphs. Each of them is the Schlegel projection of some polyhedron onto one of its faces. This work concerns the problem of listing possible topological types of phase diagrams of unary systems. A great variety of the types of these diagrams is demonstrated.     

Diffusion and fast reactions in two-component systems discussed in the framework of the lattice-gas model

The interdependence of diffusion and chmemical reactions in two-component systems is discussed. It is shown that the diffusion coefficient of the components may be substantially influenced by the reactions taking place in the system.     

UV-curable epoxy systems containing hyperbranched polymers: Kinetics investigation by photo-DSC and real-time FT-IR experiments

The effect of the presence of a hyperbranched OH-functionalized polymer (HBP) on the kinetics of cationic photopolymerization of an epoxy system was investigated employing two complementary techniques, photo-DSC and real-time FT-IR spectroscopy.Lower rates of cross-linking reactions and higher conversion degrees were obtained in photo-DSC experiments with respect to real-time FT-IR spectroscopy. A limited amount (10% wt) of HBP influenced to a certain extent the cure kinetics of the epoxy resin followed by RT-IR; a final conversion of epoxy groups equal to 100% was achieved by increasing the content up to 20% wt The addition of 10% wt of HBP leaves the cure kinetics of the CE resin studied by p-DSC almost unchanged. By increasing the HBP content, a slightly lower reaction rate is observed at lower reaction times. The presence of the HBP produced a continuous decrease of the T_g of the UV-cured epoxy resin but only modest reductions in its thermo-oxidative stability.