Publications

Determination of solubility of chlorides of d-elements in chloroaluminate melts

Solubility of several transition metal chlorides (NiCl2, CrCl2, MoCl3, FeCl2) was measured in KCl-AlCl3 based melts. It was found that the solubility of studied metal chlorides depends on K : Al mole ratio. MoCl3 solubility decreases with increasing AlCl3 content. Solubility of CrCl2 and FeCl2 reaches maximum at K : Al ratio of 1 and decreases when this ratio either de-creases or increases. The dependence of NiCl2 solubility on K : Al mole ratio is V-shaped with the maximum near 0.9-0.95. The effect of temperature on solubility of transition metal chlorides in KCl-AlCl3 melts was also investigated. Increasing temperature does not alter the character of «solubility – K : Al mole ratio» dependences.

Cathodic Processes in Uranium Containing Molybdate Melts

Cathodic processes in Li 2 MoO 4 –K 2 MoO 4 –MoO 3 and K 2 MoO 4 –MoO 3 melts containing added UO 2 MoO 4 were investigated at 550–800 °C using cyclic voltammetry, cathodic polarization and bulk electrolysis. Cathodic reduction of molybdate melts (not containing uranium) resulted in formation of molybdenum dioxide. Products of the cathodic reactions in the melts containing uranium molybdate predominantly consisted of crystalline uranium oxides (mostly UO 2 and U 4 O 9 ) and MoO 2 . Minor products formed included other uranium oxides (U 3 O 8 , U 13 O 34 ), mixed uranium-molybdenum oxides (U 1.5 Mo 10 O 32 , Mo 2 UO 8 ) and molybdates (provisionally attributed to K 2 U(MoO 4 ) 3 ). Effect of temperature, cathodic current density 0.05–1 A cm −2 ), excess MoO 3 concentration (30–50 mol%) on the composition of the cathodic reaction products were analyzed. Oxygen-to-uranium atomic ratio (oxygen coefficient) for primary uranium oxide phases was determined and varied from 1.963 to 2.161 for UO 2±x and from 2.209 to 2.287 for U 4 O 9±y . The effect of the electrolysis regime on the composition of the cathodic product was also considered. Constant-current and constant-potential electrolysis, as well pulsed-current, pulsed-potential and pulsed-reversed-current electrolysis were investigated with varying the parameters of alternating pulses (duration, current density or potential). Chemical and phase composition of the products produced by bulk electrolysis was fully characterized.

Spectroelectrochemical study of neptunium in molten LiCl-KCl eutectic

Neptunium behaviour in an LiCl-KCl eutectic melt at 723 K was studied using spectroelectrochemistry. Cathodic reduction of neptunium(IV)-containing melts led to the formation of Np(III) ions and then Np metal. Electronic absorption spectra of Np(IV) and Np(III) chloro species in LiCl-KCl melt were recorded and resolved into inidividual Gaussian bands. The nature of neptunium complex ions in the melt is discussed.

CSD 2004524: Experimental Crystal Structure Determination

СПЕКТРОЭЛЕКТРОХИМИЧЕСКОЕ ИССЛЕДОВАНИЕ ПРОЦЕССОВ КОРРОЗИИ НЕРЖАВЕЮЩИХ СТАЛЕЙ В РАСПЛАВЕ ЭКВИМОЛЬНОЙ СМЕСИ NACL-КCL

No abstract is provided for this article.

A Method of Producing Al–REE Master Alloys Using Exchange Reduction Reaction

Modern aerospace engineering relies on Al-based alloys with enhanced high-temperature strength properties and oxidation resistance. These requirements can be fulfilled by modifying alloys’ structure employing rare earths metal doping. Direct addition of metallic rare earths to aluminium is complicated due to high chemical activity of molten rare-earth metals and significant vapor pressure of aluminium at elevated temperatures. To overcome these drawbacks, lanthanide-containing master alloys with relatively low REE content can be employed instead of pure scandium. Currently there are three methods for preparing aluminium-based alloys containing rare earths, i.e. direct fusing, molten salt electrolysis and exchange or metallothermic reduction reactions. In the last case, Al–Gd and Al–Sc master alloy can be prepared by aluminothermic reduction of GdF 3 or ScF 3 in a molten binary NaF–KCl salt mixture at 800–1050 °С. In the present work we suggest the modification of the above mentioned method for aluminium–cerium and aluminium–neodymium master alloy production with a lanthanide concentration of 1 to 7 wt. %. Based on thermodynamic calculations we proposed that the high-temperature exchange reaction between metallic aluminum and corresponding fluoride containing salt electrolyte should be carried out at temperatures from 740 to 780 ° C to provide the higher recovery of REE. The influence of the time of the exchange reaction and «aluminium–salt» ratio on the process to obtain ligatures of various compositions is analyzed. The yield higher than 85 % is achieved. The microstructure of the alloys represents a metal matrix of aluminum in which intermetallic compounds of Ln 3 Al 11 compositions are distributed In the case of an exchange reaction between aluminum and cerium fluoride, the formation of a new phase, presumably related to the Al 4 Ce intermetallic compound, is found.

Interaction of Tellurium with Molybdenum in Molten Halides

Abstract—Molybdenum and molybdenum-containing alloys are used as structural materials in various high-temperature processes, including the operation

The Effect of the Second Coordination Sphere on Vanadium Speciation in Molten Chlorides

Vanadium speciation in a variety of alkali chloride based melts was studied in situ using high temperature electronic absorption spectroscopy. The experimental spectra were resolved into constituent Gaussian bands. Octahedral VCl 6 3– complex ions is the only soluble species of V(III). Oxidation of VCl 6 3– complexes or chlorination of V 2 O 5 , V 2 O 4 or V 2 O 3 by hydrogen chloride produces soluble vanadyl-based complexes. The results obtained indicate that the coordination environment of vanadyl-species in NaCl–2CsCl melts is different from the melts containing smaller cations. Anodic dissolution of metallic vanadium in chloride melts produces vanadium(II) ions. Increasing temperature and the mean radius of the salt-solvent cation resulted in changes of the electronic spectra as a result of shifting VCl 6 4– ↔VCl 4 2– equilibrium towards the tetrahedral complexes.

Corrosion of ceramic materials in molten KCl-LiCl-UCl3

Corrosion resistance of such ceramic materials as BN, Si3N4, YSZ (yttria stabilized zirconia) was studied in fused KCl–LiCl mixtures containing 8 wt. % UCl3. The rate and the mechanism of the corrosion of the materials studied were determined. The processes taking place during the interaction between perspective materials and the melt were investigated.

Коррозионная стойкость сплавов типа Inconel в хлоралюминатных расплавах

CSD 2062818: Experimental Crystal Structure Determination

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Коррозионная стойкость сплавов типа Inconel в хлоралюминатных расплавах

No abstract is provided for this article.

Electrochemical and Spectroscopic Properties of Tellurium in Fused Alkali Chlorides

not Available.

Investigation of structure and heat treatment of various grades of corrosion-resistant alloy VDM® alloy C-4

The phase stability of nickel-based solid solution VDM® Alloy C-4 was studied, and time-temperature-precipitation diagram was built. The processes of heat treatment of sheets and tubes made of VDM® Alloy C-4 were investigated. The following regime of heat treatment was chosen – annealing at 1100 °C for 10 min/mm thickness with further rapid cooling in air. It was also shown that the cooling rate should be higher than 0.1 °С/s to prevent sigma-phase formation along the grain boundaries.

Uranium Oligomerization in Chloride-Based High Temperature Melts: <i>In Situ</i> XAS Studies

In situ EXAFS spectroscopic studies of uranium compounds in high temperature alkali chloride melts indicate the presence of oligomeric species. An investigation into UCl(3) and UCl(4) dissolved in LiCl reveals long range ordering of uranium atoms in the molten state which is not maintained on quenching. Studies of uranium dioxide dissolved in LiCl-KCl eutectic with HCl exhibit long range ordering in both molten and quenched states, and the EXAFS data can be modeled using multiple coordination shells.

Erratum to: Corrosion of Various Types of Stainless Steel in Chloroaluminate Melts

Processing of Vanadium and Niobium Electrodeposited from Alkali Chloride Melts

not Available.

Distribution of Impurities during Vanadium Electrorefining and Determination of Optimal Conditions of the Process

The process of vanadium electrolytic refining in NaCl-KCl melt was performed in the specially designed semi-industrial scale electrolyser. The method of experiments mathematic planning was used to determine the electrolysis optimal conditions. In a special series of industrial experiments distribution of metallic and non-metallic impurities during vanadium electrorefining was investigated. The optimal parameters of the electrolysis for producing 99.5% pure vanadium were determined and the requirements for purity of crude materials formulated.