[en] A process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 600⁰C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at a temperature of at least about 800⁰C for a period sufficient to convert substantially all of the vanadium to the soluble form, leaching the calcine with a suitable dilute mineral acid or water at a pH of neutral to about 2 to recover vanadium values, precipitating vanadium values as iron vanadate from the leach solution with a soluble iron compound at a pH from neutral to about 1, and recovering ferrovanadium from the iron vanadate by a reduction vacuum smelting operation. The conversion of vanadium in the ore to the soluble form by the oxidizing roast is accomplished without the addition of an alkaline salt during calcining

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[en] A high-temperature metallography setup is presented. In this setup the observation of processes such as that of copper recrystallization was made possible, and the structure of metals such as uranium could be revealed. A brief historical review of part of the research works that have been done with the help of high temperature metallographical observation technique since the beginning of this century is included. Detailed description of metallographical specimen preparation technique and theoretical criteria based on the rate of evaporation of materials present on the polished surface of the specimens are given

[en] The high-temperature enthalpies of plutonium monocarbide and plutonium sesquicarbide have been determined with a copper-block calorimeter of the isoperibol type. The experimental enthalpy data, which was measured relative to 298 K, covered the temperature range from 400 to 1500 K. The calculation of the temperature rise of the calorimeter takes into account the added heat evolution from the radioactive decay of the plutonium samples. These enthalpy results, combined with the heat capacity and entropy of the respective carbide at 298 K available from the literature, has made it possible to generate tables of thermodynamic functions for the plutonium carbides. The behavior of the heat capacity of both of the plutonium carbides, i.e., a relatively steep increase in the heat capacity as the temperature increases, may be attributed to a premelting effect with the formation of vacancies within the crystal lattice although a theoretical treatment of this phenomenon is not given

[en] The elastic modulus of hot-pressed boron carbide with 1 to 15% porosity was measured at room temperature. K/sub IC/ values were determined for the same porosity range at 500⁰C by the double torsion technique. The critical stress intensity factor of boron carbide with 8% porosity was evaluated from 25 to 1200⁰C

[en] Our recommendation for the thermal conductivity of fully dense, solid UO₂ between 773 and 3120 K is κ=(0.0375+2.165x10^-4T)^-1+4.715x10⁹/T^-2 exp[-16361/T], where κ is the thermal conductivity (W m^-1 K^-1) and T the temperature (K). The first term, due to the contribution from phonons, decreases monotonically with increasing temperature right up to the melting point because the corresponding phonon mean free path, being always greater than the inter-ionic spacing, also falls in like manner. Numerical values in the second term, which is due to the small polaron contribution, are derived from the results of measurements of other physical properties. The recommendation is in good agreement with the available experimental data. (orig.)

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No abstract available

[en] The vapour pressures of barium and strontium have been measured by continuous monitoring of the weight loss of Knudsen cells in the temperature range 700-1200 K. The results for strontium agree with those reported in the literature, but the vapour pressure of barium has been found to be considerably lower than the generally accepted value. The experimentally determined pressures are in good agreement with theoretical values obtained using the Gibbs-Bogoliubov first-order variational method. (orig.)

[en] A system was designed to provide a perfect seal at the back of the container during the drawing operation so that the lubricant is used to best advantage. With this device it is possible, without serious modification, to use a conventional press for hydrostatic drawing at high temperatures and pressures up to 13 kilobars