Liquid zirconium

Molten zirconium reacts with B4C to form ZrB2 and ZrC. Concurrently, boron and carbon can dissolve into the liquid zirconium and graphite may precipitate at the interface with the B4C. 

Bonell [72BON] used levitation calorimetry to measure the heat content of liquid zirconium in the temperature range 2233 to 3048 K, referring to a reference temperature of 2128 K (the melting point of zirconium see Section V. 1.1.1). The data obtained were linear with respect to temperature (Figure V-6) indicating that the heat capacity of the liquid phase is a constant. The value of the heat capacity determined for liquid zirconium from the data of [72BON] is ... 

Figure V-6 Comparison of the calculated enthalpy change for liquid zirconium (line) with the data of [72BON].

Studies of the enthalpy of sublimation of both solid and liquid zirconium tetrachloride to gaseous ZrCU have been reviewed by van der Vis et al. [97VIS/COR]. Their third law evaluations of data from the studies of the sublimation reaction ... 

In this study, the thermal properties of a number of metals were determined in their liquid state using levitation calorimetry. Liquid zirconium was studied from 2233 to 3048 K, with a reference temperature of 2128 K (the melting point of zirconium). The change in the enthalpy increment over this temperature range was found to be linear indicating that the heat capacity was constant and equal to (40.7 0.7) J-K -mof. From the measurements, the heat of fusion was found to be (14.7 0.3) kJ-mof. These values are accepted by this review. 

Comparison of the calculated enthalpy change for liquid zirconium with... 

Mazdiyasni [22,23] reported the direct pyrolysis of the metal alkoxides, which form very fine ceramic powders. The overall thermal decomposition of a liquid zirconium tertiary butoxide to Zr02 is as follows ... 

Introduction.— The half-life of Hf has been determined as 1.9 0.3 years. The electronic spectrum of Zr has been re-analysed and the ionization potential of this ion estimated as 95.8 0.6 eV. The vapour pressures of solid and liquid zirconium and hafnium have been determined and used to calculate the enthalpies of sublimation at 298.15 K as 621 and 600 kJ mol, respectively. ... 

Zirconium and hafnium have very similar chemical properties, exhibit the same valences, and have similar ionic radii, ie, 0.074 mm for, 0.075 mm for (see Hafniumand hafnium compounds). Because of these similarities, their separation was difficult (37—40). Today, the separation of zirconium and hafnium by multistage counter-current Hquid—Hquid extraction is routine (41) (see Extraction, liquid—liquid). 

A number of attempts to produce tire refractory metals, such as titanium and zirconium, by molten chloride electrolysis have not met widr success with two exceptions. The electrolysis of caesium salts such as Cs2ZrCl6 and CsTaCle, and of the fluorides Na2ZrF6 and NaTaFg have produced satisfactoty products on the laboratory scale (Flengas and Pint, 1969) but other systems have produced merely metallic dusts aird dendritic deposits. These observations suggest tlrat, as in tire case of metal deposition from aqueous electrolytes, e.g. Ag from Ag(CN)/ instead of from AgNOj, tire formation of stable metal complexes in tire liquid electrolyte is the key to success. 

Thus, a novel chiral zirconium complex for asymmetric aza Diels-Alder reactions has been developed by efficient catalyst optimization using both solid-phase and liquid-phase approaches. High yields, high selectivity, and low loading of the catalyst have been achieved, and the effectiveness of chiral catalyst optimization using a combination of solid-phase and liquid-phase methods has been demonstrated. 

In the chemical process industry molybdenum has found use as washers and bolts to patch glass-lined vessels used in sulphuric acid and acid environments where nascent hydrogen is produced. Molybdenum thermocouples and valves have also been used in sulphuric acid applications, and molybdenum alloys have been used as reactor linings in plant used for the production of n-butyl chloride by reactions involving hydrochloric and sulphuric acids at temperatures in excess of 170°C. Miscellaneous applications where molybdenum has been used include the liquid phase Zircex hydrochlorination process, the Van Arkel Iodide process for zirconium production and the Metal Hydrides process for the production of super-pure thorium from thorium iodide. 

It is in its behaviour to caustic alkalis that zirconium shows itself to be superior to those other elements of Groups IV and V whose resistance to corrosion results primarily from an ability to form surface films. Thus, in contrast to tantalum, niobium and titanium, zirconium is virtually completely resistant to concentrated caustic solutions at high temperatures, and it is only slightly attacked in fused alkalis. Resistance to liquid sodium is good. Zirconium is thus an excellent material of construction for sections of chemical plant demanding alternate contact with hot strong acids and hot strong alkalis—a unique and valuable attribute. 

The liquid-liquid extraction (solvent extraction) process was developed about 50 years ago and has found wide application in the hydrometallurgy of rare refractory and rare earth metals. Liquid-liquid extraction is used successfully for the separation of problematic pairs of metals such as niobium and tantalum, zirconium and hafnium, cobalt and nickel etc. Moreover, liquid-liquid extraction is the only method available for the separation of rare earth group elements to obtain individual metals. 

The extraction of metals by liquid amines has been widely investigated and depends on the formation of anionic complexes of the metals in aqueous solution. Such applications are illustrated by the use of Amberlite LA.l for extraction of zirconium and hafnium from hydrochloric acid solutions, and the use of liquid amines for extraction of uranium from sulphuric acid solutions.42,43... 

Estruga, M., Domingo, C., Domenech, X., and Ayllon, J.A. (2010) Zirconium-doped and silicon-doped Ti02 photocatalysts synthesis from ionic-liquid-like precursors. Journal of Colloid and Interface Science, 344 (2), 327-333. 

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