Azeotropic phase equilibrium diagrams: a survey

An analysis of the structural properties of vapor-liquid equilibrium (VLE) diagrams provides a fundamental understanding of the thermodynamic behavior of azeotropic mixtures upon distillation.In addition to a review of well-known fundamental work on the analysis of VLE diagrams, this survey comprises less-known published results, especially from the Russian literature. Some new results are also presented for the first time.     

高能球磨高温固相法制备尖晶石型铜铬黑颜料

以Cr2O3与CuO为原料,采用高能球磨高温固相法制备尖晶石型铜铬黑颜料;利用XRD、SEM和激光粒度仪等方法对制备颜料的结构、形貌及粒度进行了表征。系统研究了前体混料方式、球磨时间、煅烧温度、煅烧时间等条件对铜铬黑颜料晶型、粒度的影响;探讨了掺杂对铜铬黑颜料着色力的影响。研究表明,通过高能球磨可有效地控制颗粒大小及均匀性,NiO与CoO的掺入可显著提高其着色力。高能球磨10 min,煅烧温度900 ℃,保温时间3 h下制备出了粒径分布均匀着色力较好的铜铬黑颜料。     

Using phase diagrams to deal with moisture expansion

Consensus has it that the post-fabrication moisture expansion of fired clay-based materials is governed by the presence of amorphous and/or vitreous phases. In this work, very simple calculations using the lever rule and the phase diagram of the Al₂O₃–SiO₂–K₂O (A–S–K) system, were used to show that the experimentally observed dependencies between moisture expansion and the A/S and K/A weight ratios in clay-based compositions can be correlated with the amount of liquid phase formed during the initial melting of the composition, which remains in the fired body as a vitreous phase. This correlation might, if judiciously used, help ceramists in the choice of additives and/or processing conditions, while avoiding changes in the firing temperatures. Also, the results obtained throw a sharper light in the dual and, in this respect, antagonistic role played by the liquid phase during firing.     

从相图解析干式捣打料

根据有关二元系与三元系相图解析了硅质、刚玉质、镁钙质、方镁石-镁铝尖晶石质以及刚玉-镁铝尖晶石质干式捣打料的化学组成、合适的烧结剂及其加入量。     

Ternary phase diagrams for gasoline-water-alcohol mixtures

The ternary phase diagrams for gasoline-water-alcohol (where the alcohol is methanol, ethanol, 1-propanol, 1-butanol or a ‘SASOL alcohol substitute’) mixtures have been determined over the whole composition range at temperatures between 2 °C and 40 °C. The result shows that the miscibility of water in these blends is strongly dependent on the type of alcohol present. Furthermore the tie-line results show the composition of the separated water-rich phase are also strongly dependent on the type of alcohol. It is believed that these results have a bearing on the carburettor corrosion problems experienced when using gasoline-SASOL alcohol substitute blends.     

Liquid-liquid phase separation in multicomponent polymer systems. XIII quasi-binary phase diagrams with three-liquid-phase separation

Using the Gibbs free energy of mixing relation of Flory and Huggins with a concentration-dependent interaction parameter one can calculate quasi-binary phase diagrams for solvent-polymer systems. If the polymer has a very asymmetric molecular weight distribution, separation into three-liquid-phases occurs which may result in a cloud-point curve without stable critical point. In the latter case the spinodal does not touch the stable branches of the cloud-point curve and the coexistence curves show marked bends and kinks. These phenomena could be qualitatively verified by experiments on the system cyclohexane-polystyrene. The phase-volume ratio method for the determination of consolute states itself clearly indicates when situations prevail precluding its applicability.     

Simulation of coating phase structure formation in solid phase synthesis assisted by electron-beam treatment

The model of coating synthesis on an iron substrate under heating by a moving energy source typical for electron-beam treatment has been proposed and analyzed. The problem has been solved numerically. The time and spatial distributions of the temperature and the concentrations of the elements and compounds have been found. The regimes of coating formation from the initial material may proceed in a stationary or non-stationary, self-sustaining or forced regime, depending on the energy parameters that characterize the external source and chemical reactions, as well as on the initial concentrations of the elements and phases.     

Range of solid solutions of silica in spinel type phase

Abstract

Al₂O₃–SiO₂ mixed gel of varying compositions has been synthesised by using aluminium nitrate nonahydrate (AR) and tetraethyl orthosilicate (BDH) by coprecipitation technique. Phase evolution studies of these gels have been made by X-ray diffraction technique and ²⁹Si MAS NMR analysis. The lattice parameter of intermediate Al–Si spinel phase has been measured. The calculated data indicate that the composition of spinel phase does not alter irrespective of the composition of mixed gels chosen. Results demonstrate that slightly <28 wt-%SiO₂ is likely to be present as solid solution with γ-Al₂O₃ in Al–Si spinel structure. Mullitisation reactions of mixed gels of compositions on two sides of mullite stoichiometry are described.     

Synthesis of a new modification of aluminum oxide with the spinel structure under shock-wave action on gibbsite

A new modification of aluminum oxideγ ₁-Al₂O₃ with the spinel structure was produced under shock-wave impact on gibbsite. The parameter of the face-centered latticea=7.935(1) Å. The x-ray pattern and the indexing results are presented. The methods of synthesis are described.     

Euler characteristic as a structural invariant of the phase diagrams of multicomponent multiphase systems

A new approach to analysis of the phase diagrams of splitting systems is suggested. The approach is based on a graph theoretical examination of the topological structure of phase separation diagrams. The possible quaternary splitting systems have been analyzed using the new approach.     

Combined shock-wave synthesis of noble spinel and laves cubic phase

The paper described the shock-wave synthesis of high-pressure high-temperature mineral MgAl₂O₄ with the parameter a = 8.085(3) Å and the Laves phase MgCu₂ with a = 7.076(2) Å from a mixture of MgO and aluminum powder placed into a copper insert inside a steel conservation ampoule. Spinel MgAl₂O₄ with a smaller lattice parameter a = 8.0798 Å has been formed in an aluminum insert cup. __________ Translated from Steklo i Keramika, No. 6, pp. 21–22, June, 2006.     

How to calculate phase diagrams for microemulsions — a simple rule

For nonionic microemulsions a simple rule is given to achieve a semiquantitative prediction of phase boundaries. In particular, we consider the phase boundaries between a single-phase microemulsion and a 2Φ-microemulsion (i.e. a microemulsion coexisting with a water- or an oilrich phase), as well as between a 2Φ-microemulsion and a 3Φ-microemulsion (i.e. a microemulsion coexisting with a water- and an oilrich phase). Our method treats weak and strong surfactants within a unified approach.     

Visualization of high-dimensional phase diagrams of molecular and ionic mixtures

A general method for visualizing high-dimensional phase diagrams of systems containing a mixture of molecular and ionic species is presented. Based on geometric modeling with homogeneous coordinates, canonical coordinates are developed to represent cuts and projections, which, being reaction-invariant, do not depend on the degree of ionization. Examples are provided to illustrate the application of this method for identifying useful transforms with potential applications in separation system synthesis.     

Mixtures of polymeric and low-molecular-mass mesogens: Theoretical phase diagrams

Behavior of the solution of a polymer capable of nematic ordering in a nematic solvent is considered. The systematic effect of the characteristics of individual components on the behavior of mixtures is investigated, and the main features of phase diagrams are studied.     

Electromagnetic wave absorption by an organic resin solution based on ferrite particles with a spinel crystal structure

We have investigated an organic resin solution designed for EM wave absorption based on a magnetic filler, composed of phases within the Mn_0.66Zn_0.27Fe_2.07O₄ system, embedded in an absorber composite with concentration ratios of 50:50, 75:25 and 90:10 by weight. The formation of the manganese zinc ferrite particles, as the principal magnetic phases, was achieved via the conventional ceramic method. The electromagnetic parameters of the composites were measured with a vector network analyser at 100 MHz to 10 GHz. The subject of the paper was a study of the electromagnetic absorber properties and the rheological properties of the resin composite based on ferrite particles with respect to using the materials in architectural coatings.     

Inversion domain network stabilization and spinel phase suppression in ZnO

The development of inversion domain networks consisting of basal‐plane and pyramidal‐plane inversion domain boundary (b‐IDB and p‐IDB) interfaces within grains in Sn‐Al dual‐doped ZnO (Zn_0.98Sn_0.01Al_0.01O) polycrystalline ceramics has been confirmed using transmission electron microscopy. The atomic structure of the b‐IDB and p‐IDB interfaces has been analyzed using atomic‐resolution scanning transmission electron microscopy. The localization of Sn and Al at the respective sites of the b‐IDBs and p‐IDBs was confirmed by energy‐dispersive X‐ray spectroscopy. In contrast to Sn or Al single‐dopant addition to ZnO, which results in the formation of spinel phase precipitates without the development of inversion domain networks, Sn‐Al dual‐doping caused the suppression of spinel phase formation and the formation of monophasic inversion domain networks composed of RMO₃(ZnO)_n homologous phase compound members, where R and M represent dopants substituting at the b‐IDB and p‐IDB sites, with a general formula of SnAlO₃(ZnO)_n. The results of this study demonstrate that the formation of inversion domain networks in ZnO‐based ceramics can be stabilized via multiple‐dopant addition. This finding has potential implications for the modification of the bulk or nanoscale properties based on the choice of the specific dopants, R and M, the control of the ratio R:M and the value of n in the RMO₃(ZnO)_n homologous phase compound members constituting the inversion domain networks.