Nickel-uranium oxides

Table 13.6 Activity of nickel-uranium oxide catalysts for steam reforming of naphtha [72],...

Carbide-based cermets have particles of carbides of tungsten, chromium, and titanium. Tungsten carbide in a cobalt matrix is used in machine parts requiring very high hardness such as wire-drawing dies, valves, etc. Chromium carbide in a cobalt matrix has high corrosion and abrasion resistance it also has a coefficient of thermal expansion close to that of steel, so is well-suited for use in valves. Titanium carbide in either a nickel or a cobalt matrix is often used in high-temperature applications such as turbine parts. Cermets are also used as nuclear reactor fuel elements and control rods. Fuel elements can be uranium oxide particles in stainless steel ceramic, whereas boron carbide in stainless steel is used for control rods. 

The force constants of the Ni—P bond in P " nickel carbonyl complexes increase in the order MeaP < PHg < P(OMe)a < PFs. This order is different from that of the donor-acceptor character, as estimated from uco-The lengthening of the P—O bond of triphenylphosphine oxide upon complexation with uranium oxide has been estimated by i.r. spectroscopy. However, A -ray diffraction shows little difference in the P-O bond lengths (see Section 7). Some SCF-MO calculations on the donor-acceptor properties of McaPO and H3PO have been reported. 

SRM 979), Ni (nickel metal isotopic standard NIST SRM 986), Rb (rubidium chloride isotopic standard NIST SRM 984) and Sr (strontium carbonate isotopic standard NIST SRM 987). In addition, isotope reference materials are available for heavy elements such as T1 (thallium metal isotopic standard NIST SRM 997), Pb (NIST lead standard reference materials SRM 981-983) or U (uranium oxide NIST isotope standard U 005, U020, U350, U500 or U930) and others. The most important isotope standard reference materials applied in inorganic mass spectrometry are summarized in the table in Appendix V.17... 

Nicklin, with others, filed several early patents describing the use of uranium oxides as steam reforming catalysts [69], U3O8 was used along with nickel oxide as the basis of a steam reforming catalyst, and it was modified with potassium species (potassium hydroxide, potassium oxide and/or potassium carbonate), all supported on either alumina or a mix of alumina and magnesium oxide. The uranium and nickel catalysts proved to be extremely efficient for steam reforming. 

More and more minerals are being found amenable to bacteriological leaching. The copper sulfide minerals, such as chalcopyrite (B31-B33, D22, D24), chalcocite (B35), and tetrahedrite (B32, D21) are among the best studied. The iron sulfide (pyrite) (B31, B33, C22, L4) and sulfur (B33, B34, C22, L4) oxidation processes are the best understood. Investigations on the leaching of nickel sulfides (D21, D24, T17), lead sulfide (E4), molybdenum sulfide (molybdenite) (B17, B31, D24), cobalt sulfide (D9), zinc sulfide (D24), and uranium oxide (D24, F2, H13, H14, Ml) have been reported in the literature. 

T1 ecent investigations have shown that chromium, manganese, cobalt, nickel, copper, and zinc oxides react with uranium oxides at elevated temperatures to form double oxides with the formulas MUO4 and MU3O10. Table I lists eight compounds for which some structural and thermal stability information has been reported. 

Among the transition metals from chromium through zinc, iron remains the only element for which no double oxide formation with uranium oxide has been reported. Both the l.T and 1 3 compounds of mainganese, cobalt, and copper have been prepared, while only the 1 1 compound of chromium, and the 1 3 compound of nickel and zinc are known. 

Davyds interest in minerals went back to his Penzance days. In a paper in i8i8 he says of the Wherry Mine, a mile from Penzance and with its workings entirely under the sea I have seen in the refuse heaps, blende, oxide of uranium, oxide of titanium and of iron pechblende [pitchblende], nickel, and arsenical pyrites and in a single piece of the vein of a few inches square many of these substances might be found imbedded in quartz or chlorite. ... 

NBS Steel NBS Nickel Alloy NBS Aluminium Molybdenum Tantalum Gallium Uranium Oxide... 

Cermet fuel is one of the advanced concepts that has been considered in the case of thorium. It envisages kernels of uranium oxide coated with nickel and chromium dispersed in a matrix of thorium metal. A certain level of success has been achieved in coating uranium oxide micro spheres with nickel. 

Bunsenite [1313-99-1] [Named after the German chemist and spectroscopist Robert Wilhelm Bunsen(1811-1899)] (ICSD 9866 and PDF 4-835) NiO M = 74.6928 78.58 wt.%Ni 21.42 wt.% 0 (Oxides and hydroxides) Coordinence Ni(6) Cubic a = 417.69 pm Bl,cF8 (Z=4) S.G. Fm3m P.G. 432 Rock salt type Periclase group Isotropic = 2.37 5.5 6898 (6806) Habit octahedral crystals. Color dark pistachio green. Luster vitreous. Diaphaneity transparent. Streak brownie black Clivage unknown. Fracture unevea Chemical soluble with difficulty in strong mineral acids. Occurrence found in the oxidized zone of hydrothermal nickel-uranium veins along with nickel and cobalt arsenates. 

The nuclear fuel must be clad with a corrosion-resistant material to prevent the release of radioactive gases and fission products to the primary water. The fuel itself is usually uranium oxide, which is quite resistant to the primary water. The fuel is clad with austenitic stainless steel or Zircaloy-2 (R60802) or the extra-low nickel Zircaloy-4 (R60804). 

From such a concentrated aqueous solution of the metal, the recovery of the metal is achieved in a variety of the ways. The metal may be precipitated as a hydroxide, an oxide, or calcined as an oxide or recovered as a metal via electrowinning (e.g., Cu, Co, Ni), etc. Illustrations of process flowsheets for the recovery of a variety of metals, e.g. copper, zinc, nickel, uranium, chromium, beryllium, etc., are available in Ritcey and Ashbrook (1984b). Benedict et al. (1981) also provide process flowsheets and descriptions of metals relevant to the nuclear power industry. 

Any canning metal had to be compatible not only with the uranium oxide fuel but with carbon dioxide. A form of stainless steel (containing 20% chromium and 25% nickel together with niobium) was found to be satisfactory at temperatures up to about 850°C. It had a melting point of almost 1,500°C. The maximum can surface temperature selected was 650°C (this meant the system could produce steam at the same temperature as conventional power stations), which allowed for local hot spots. One drawback to stainless steel was that it had a relatively high cross-section area for thermal neutrons, which meant using enriched fuel, of the order of 2.5% enrichment. 

Catalysts used for preparing amines from alcohols iaclude cobalt promoted with tirconium, lanthanum, cerium, or uranium (52) the metals and oxides of nickel, cobalt, and/or copper (53,54,56,60,61) metal oxides of antimony, tin, and manganese on alumina support (55) copper, nickel, and a metal belonging to the platinum group 8—10 (57) copper formate (58) nickel promoted with chromium and/or iron on alumina support (53,59) and cobalt, copper, and either iron, 2iac, or zirconium (62). 

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