Showing papers on "Nickel published in 2000"

Synthesis of Nickel Nanoparticles in Water-in-Oil Microemulsions

Abstract: The synthesis of nickel nanoparticles by the reduction of nickel chloride with hydrazine in the cationic water-in-oil microemulsions of water/CTAB (cetyltrimethylammonium bromide)/n-hexanol at 73 °C has been studied. By the analyses of electron diffraction pattern and X-ray diffraction, the resultant particles were characterized to be the pure nickel crystalline with a face-centered cubic (fcc) structure. The investigation on the composition of microemulsion solution indicated that the average diameter of nickel nanoparticles was affected mainly by the ratio of CTAB to n-hexanol instead of the size of microemulsion droplets. Smaller particles could be obtained at higher ratios of CTAB to n-hexanol. At a constant nickel chloride concentration, the average diameter of nickel nanoparticles decreased with the increase of hydrazine concentration and then approached to a constant value when the concentration ratio of hydrazine to nickel chloride was above 10. At a sufficient high hydrazine concentration, the av...

Layered Hydroxide Metal Acetates (Metal = Zinc, Cobalt, and Nickel): Elaboration via Hydrolysis in Polyol Medium and Comparative Study

Abstract: Layered hydroxide metal acetates (metal = zinc, cobalt, and nickel) have been prepared by a new route belonging to the chimie douce method. This novel method involves the hydrolysis, in polyol medium, of in situ-formed complexes supposed to be alkoxyacetates. These layered hydroxide metal acetates present poorly ordered character, and their X-ray patterns have features typical of lamellar compounds with turbostratic disorder. Their chemical formula was established to be M(OH)2-x(CH3COO)x·nH2O with (x, n) = (0.42, 0.31), (0.38, 0.53), and (0.40, 0.63) for Zn, Co, and Ni, respectively. The layered hydroxide nickel acetate has a classical brucite structure with a random substitution of some hydroxyl groups by acetate groups. The layered hydroxide zinc and cobalt acetates are isomorphous with the hydrozincite structure, in which cations are located in both octahedral and tetrahedral sites. The acetate anion behaves as a unidentate ligand in LHS−Ni and LHS−Co, where LHS indicates layered hydroxide salt, and is...

High-temperature part and method for producing the same

Abstract: The present invention relates to a high-temperature part (1) made of a nickel super-alloy having the following composition in wt %: 11-13 % of Cr; 3-5 % of W; 0.5-2.5 % of Mo; 3-5 % of Al; 3-5 % of Ti; 3-7 % of Ta; 1-5 % of Re; the balance consisting of nickel. This invention also relates to a corresponding part (1) made of an alloy having a composition essentially similar to the above-mentioned one and in which the rhenium proportion is replaced with 0.1-5 wt % of ruthenium.

Method for producing semiconductor device

Abstract: In producing a thin film transistor, after an amorphous silicon film is formed on a substrate, a nickel silicide layer is formed by spin coating with a solution (nickel acetate solution) containing nickel as the metal element which accelerates (promotes) the crystallization of silicon and by heat treating. The nickel silicide layer is selectively patterned to form island-like nickel silicide layer. The amorphous silicon film is patterned. A laser light is irradiated while moving the laser, so that crystal growth occurs from the region in which the nickel silicide layer is formed and a region equivalent to a single crystal (a monodomain region) is obtained.

Preparation and characterization of ZnO clusters inside mesoporous silica

Abstract: Wide band-gap semiconductor-zinc oxide nanoclusters have been prepared in the channels of MCM-41 materials by functionalizing the MCM-41 with ethylenediamine groups, absorbing zinc cations, and calcinating at high temperatures. The products have been characterized by XRD, TEM, EDS, nitrogen adsorption and desorption, and UV-vis and PL spectroscopies. ZnO clusters were mostly confined and dispersed in the pores of mesoporous hosts. No large ZnO particles on the external surfaces have been detected. A massive blue-shift in UV-vis absorption spectra has been observed and large band increase can be expected. The nature of the PL spectrum has been attributed to the defects related to oxygen vacancies. In addition, the assembly of cobalt, nickel, and copper oxides inside MCM-41 materials has also been tried by this scheme, but at the moment, only the cobalt oxide can be prepared with good results. Unfortunately, noble metals have usually grown into large particles on the outside surface of MCM-41 by this scheme, e.g., a lot of silver particles with sizes much larger than the pore diameter of MCM-41 host have been obtained. However, the explanation is not yet clear.

Nickel, cobalt, and their alloys

Abstract: This book is a comprehensive guide to the compositions, properties, processing, performance and applications of nickel, cobalt, and their alloys. It includes all of the essential information contained in the 20-volume ASM Handbook series. Includes new or updated coverage in the following areas: Expanded corrosion coverage including guidelines for selecting the best alloy for specific environments or applications Data sheets covering the compositions, specifications, applications and properties for dozens of the most commercially important heat, corrosion and wear-resistant nickel and cobalt alloys Recent advances in superalloy development, including coatings to extend high-temperature service life Unique characteristics of nickel and cobalt which allow them to be used in special-purpose applications, e.g., magnets, controlled-expansion devices, electronics, and implants for the human body Engineering applications for nickel and cobalt coatings produced by electroplating, electroforming, electroless coating, thermal spraying, and weld surfacing. Contents include: Nickel and Its Alloys: The Nickel Industry, occurrence, recovery and consumption Uses of nickel Wrought and Cast Corrosion-Resistant Alloys Cast Heat-Resistant Ni-Cr and Ni-Cr-Fe alloys Superalloys Special-Purpose Alloys Nickel Coatings Corrosion Behavior, including performance in specific environments, Stress-Corrosion Cracking and Hydrogen Embrittlement, and High-Temperature Corrosion Fabrication and Finishing, including forming, forging, powder metallurgy, heat treating, machining, welding and brazing, cleaning and finishing, and high-temperature coatings for superalloys Metallography, Microstructures, and Phase Diagrams Cobalt and Its Alloys: The Cobalt Industry, occurrence, recovery and consumption Uses of cobalt Cobalt-base alloys Wear behavior Corrosion Behavior Fabrication Characteristics Metallography, Microstructures and Phase Diagrams.

Nickel-Catalyzed Cyclizations, Couplings, and Cycloadditions Involving Three Reactive Components

Abstract: Transition-metal-catalyzed processes that allow the efficient coupling of three reactive components in a chemoselective and stereoselective fashion are particularly useful in the synthesis of complex organic molecules from simple, readily available substrates. This account outlines work primarily from the author's laboratory on the development of nickel-catalyzed multicomponent coupling processes. An overview of new synthetic methods, a discussion of potential mechanisms, and a description of applications in complex-molecule synthesis are provided.

Effective catalysts for direct cracking of methane to produce hydrogen and filamentous carbon: Part I. Nickel catalysts

Abstract: Data obtained by studying model catalytic systems were used to develop high-loaded nickel catalysts for direct cracking of methane into hydrogen and catalytic filamentous carbon (CFC). The approach to the synthesis of these catalysts can be the basis for development of catalytic nickel systems for commercial processing of natural gas. The catalysts were synthesized by fusing nickel nitrate with zirconium nitrate, or nickel nitrate with copper-doped aluminium nitrate followed by decomposition of the mixture at 300–450°C and its additional stabilization by silica. The silica textural promoter was formed by thermal decomposition of polyethoxysilane introduced into pores of the oxide matrix. The catalysts reduced by hydrogen comprised nickel in the amount of 85–90%. Unlike preparation of co-precipitated systems, synthesis of the catalysts mentioned does not include stages of filtration and wastewater treatment. Principal characteristic of the catalysts’ effectiveness for the reaction of decomposition of methane, i.e. carbon yield per gram of nickel, of the suggested systems was close or superior to that achieved before using the best nickel or nickel–copper catalysts prepared by co-precipitation.

Surface Spectroscopic Study of the Stabilization Mechanism for Shape-Selectively Synthesized Nanostructured Transition Metal Colloids

Abstract: Nanoscale palladium and nickel colloids prepared in the presence of certain tetra-n-octylammonium carboxylates contain a high proportion of nonequilibrium trigonal cross section particles. Specifically, those carboxylates which bear a hydroxy function at the α-position, e.g., tetra-n-octylammonium glycolate, exert a strong influence on the shape of the metal colloids. It is shown by an in situ FTIR study of the preparation of colloidal nickel from bis(cyclooctadiene)nickel in the presence of tetra-n-octylammonium glycolate that the interaction of the α-hydroxy carboxylate with the surface of the colloidal metal particle is likely to be the morphology-determining factor in the shape-selective preparation of these metal particles.

Microstructural study of the theta-alpha transformation in alumina scales formed on nickel-aluminides

Abstract: Luminescence spectroscopy and scanning electron microscopy have been used to study the transformation from theta-Al2O3 to alpha-Al2O3 on the surface of platinum-modified nickel aluminide, (Ni,Pt)Al, bond coats on superalloys during initial stages of oxidation at 1,000-1,200°C. The transformation can proceed in a number of ways, depending on the surface roughness, leading to different microstructures of the stable alpha-alumina scale. The use of the luminescence method makes it possible to correlate microstructural features of the oxide with the local stress through piezospectroscopic shifts of both alpha- and theta-alumina optical spectra.

Desulfurization and novel sorbents for same

Abstract: Particulate sorbent compositions which are suitable for the removal of sulfur from streams of cracked-gasoline or diesel fuel are provided which have increased porosity, improved resistance to deactivation through the addition of a calcium compound selected from the group consisting of calcium sulfate, calcium silicate, calcium phosphate or calcium aluminate to the support system comprised of zinc oxide, silica and alumina having thereon a promotor wherein the promotor is metal, metal oxide or metal oxide precursor with the metal being selected from the group consisting of cobalt, nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin and vanadium or mixtures thereof and wherein the valence of such promotor has been substantially reduced to 2 or less. Process for the preparation of such sorbent systems as well as the use of same for the desulfurization of cracked-gasolines and diesel fuels are also provided.

Pressure Acid Leaching of Nickel Laterites: A Review

Abstract: A review of the literature over the past 30 years on the processing of nickel laterites by high temperature acid leaching has been carried out to provide a better understanding of the mineralogy, leaching process chemistry and effect of operating conditions on nickel recovery, residue properties and scaling. Particular attention is paid to the leaching experience of the commercial Moa Bay plant and to the recently reported testwork and flowsheets associated with the three Western Australia lalerite plants that will be operating in 1999. It is shown that laterites can vary significantly in their mineralogy according to location, climate and depth, and that the main host minerals for nickel and cobalt can be either goethite (iron oxide) or nontronite (clay) or manganese oxides. The mechanism of leaching involves acid dissolution of the host mineral lattice followed by hydrolysis and precipitation (transformation) of a variety of insoluble oxides and sulphates of iron, aluminium and silica under the...

Effect of surface treatment and sterilization processes on the corrosion behavior of NiTi shape memory alloy

Abstract: Nickel-titanium (NiTi) alloy derives its biocompatibility and good corrosion resistance from a homogeneous oxide layer mainly composed of TiO(2), with a very low concentration of nickel. In this article, we described the corrosion behavior of NiTi alloys after mechanical polishing, electropolishing, and sterilization processes using cyclic polarization and atomic absorption. As a preparative surface treatment, electropolishing decreased the amount of nickel on the surface and remarkably improved the corrosion behavior of the alloy by increasing the mean breakdown potential value and the reproducibility of the results (0.99 +/- 0.05 V/SCE vs. 0.53 +/- 0. 42). Ethylene oxide and Sterrad(R) sterilization techniques did not modify the corrosion resistance of electropolished NiTi, whereas a steam autoclave and, to a lesser extent, peracetic acid sterilization produced scattered breakdown potential. In comparing the corrosion resistance of common biomaterials, NiTi ranked between 316L stainless steel and Ti6A14V even after sterilization. Electropolished NiTi and 316L stainless-steel alloys released similar amounts of nickel after a few days of immersion in Hank's solution. Measurements by atomic absorption have shown that the amount of released nickel from passive dissolution was below the expected toxic level in the human body. Auger electron spectroscopy analyses indicated surface contamination by Ca and P on NiTi during immersion, but no significant modification in oxide thickness was observed.

Red and blue luminescent metallo-supramolecular coordination polymers assembled through π–π interactions

Abstract: The use of π-stacking interactions to control the aggregation of photo-active metal centres is explored through the design of bis(2,2′;6′,2′′-terpyridyl) metal complexes functionalised with biphenyl ‘tails’. Aryl–aryl interactions control the aggregation of the metal complexes into polymetallic arrays in the solid state. Cobalt(II), ruthenium(II), nickel(II), copper(II), zinc(II) and cadmium(II) bis-ligand complexes and a mixed ligand ruthenium(II) complex have been structurally characterised. The solid-state structures are dependent on which units dominate the π-stacking. For cobalt, ruthenium, nickel and copper, biphenylene–biphenylene interactions lead to linear rod-like arrays, while for the group 12 d10 ions zinc and cadmium, biphenylene–pyridyl interactions lead to two-dimensional sheets. The addition of the biphenylene tail has favourable effects on the photophysical-properties of the complexes which exhibit room temperature red (ruthenium) or blue (zinc and cadmium) luminescence, both in solution and the solid state.

Mechanical properties and non-homogeneous deformation of open-cell nickel foams: application of the mechanics of cellular solids and of porous materials

Abstract: The mechanical properties of open-cell nickel foams are investigated for the range of densities used in industrial applications for energy storage. The obtained Young’s modulus, compression yield stress and tensile fracture stress are compared to the predictions of models based on periodic, Penrose and Voronoi beam networks. It is found that Gibson and Ashby’s model [L.J. Gibson, M.F. Ashby, Cellular Solids, Cambridge University Press, Cambridge, 1998] provides the proper scaling laws with respect to relative density for almost all investigated properties. The strong anisotropy of the observed overall responses can also be accounted for. The two-dimensional strain field during the tension of a nickel foam strip has been measured using a photomechanical technique. Non-homogeneous deformation patterns are shown to arise. The same technique is used to obtain the strain field around a circular hole in a nickel foam strip. The observed deformation fields are compared to the results of a finite element analysis using anisotropic compressible continuum plasticity.

Simultaneous Production of Hydrogen and Nanocarbon from Decomposition of Methane on a Nickel-Based Catalyst

Abstract: From the decomposition of methane, hydrogen without carbon oxides can be produced with a high energy-efficiency, which is attractive for its suitability of utilization in the fuel cells. At a same time nanocarbon materials with attractive texture and structure can be produced in a large amount. Toward a simultaneous bulk production of hydrogen and nanocarbon, catalysts based on nanometer-scale nickel particles prepared from a hydrotalcite-like anionic clay precursor have been designed and tested to fit the process goals. For hydrogen production, as the equilibrium methane conversion of the reaction increases with the increase of the reaction temperature, the process is commercially more attractive if it can be operated at a temperature higher than 1073 K. However, a nickel catalyst has a maximum activity for nanocarbon production at 923 K. Modification of the catalyst with doping of copper increased the activation temperature and leads to a production of nanocarbon with an attractive structure. The feasib...

Gas-phase hydrogenation/hydrogenolysis of phenol over supported nickel catalysts

Abstract: The gas-phase hydrogenation/hydrogenolysis of alcoholic solutions of phenol between 423 and 573 K has been studied using a Y zeolite-supported nickel catalyst (2.2% w/w Ni) and Ni/SiO2 catalysts (1.5−20.3% w/w Ni). This is a viable means of treating concentrated phenol streams to generate recyclable raw material. Phenol hydrogenation proceeded in a stepwise fashion with cyclohexanone as a reactive intermediate while a combination of hydrogenolysis and hydrogenation yielded cyclohexane. Hydrogenolysis to benzene is favored by high nickel loadings and elevated temperatures. A catalytic hydrogen treatment of cyclohexanone and cyclohexanol helped to establish the overall reaction network/mechanism. The possible role of thermodynamic limitations is considered and structure sensitivity is addressed; reaction data are subjected to a pseudo-first-order kinetic treatment. Hydrogen temperature-programmed desorption (H2-TPD) has revealed the existence of different forms of surface hydrogen. Selectivity is interprete...

Highly active and stable Ni/ZrO2 catalyst for syngas production by CO2 reforming of methane

Abstract: CO2 reforming of CH4 was studied at 1030 K over Ni/ZrO2 catalysts with different preparations. It was shown that catalytic stability depends greatly on the preparation method of the support precursor. The catalyst prepared by impregnation of ultra-fine Zr(OH)4 (6 nm) particles with nickel nitrate showed high and extremely stable activity for syngas production. In contrast, the nickel catalyst prepared using bigger Zr(OH)4 particles deactivated rapidly. Also, the nickel catalyst made from co-precipitation of ultra-fine nickel–zirconium hydroxide (7 nm) was not resistant to coke deposition during the reaction.

Adsorption of nickel(II), zinc(II) and cadmium(II) by new chitosan derivatives

Abstract: Chitosan beads were cross-linked with a dialdehyde or a tetracarboxylic acid in order to obtain sorbents that are insoluble in aqueous acidic solutions. Further chemical modifications improved the metal ion capacities and selectivities of the products. The capacities for nickel(II), zinc(II) and cadmium(II) ions were measured in aqueous nitrate, chloride and sulphate solutions at pH 6. The selectivities were determined in mixtures of nickel(II), zinc(II), cadmium(II), magnesium(II) and calcium(II) and were recorded as a function of the pH value and the counter-ion. Four of six chitosan derivatives show higher metal uptake rates in sulphate solution than in solutions of nitrate or chloride. They possess, however, poor metal ion selectivities, except in chloride solutions where cadmium(II) is preferentially bonded. In contrast, the other two chitosan derivatives are highly selective for nickel(II) and cadmium(II), respectively. This selective behaviour exists over the pH range 3–6 and is independent of the counter-ion. These products have relatively high capacities even at pH 3. Yet the bonded metal ions are completely released at pH 0.5.

Nickel-based amorphous alloy compositions

Abstract: Disclosed are nickel-based amorphous alloy compositions, and particularly quaternary nickel-based amorphous alloy compositions containing nickel, zirconium and titanium as main constituent elements and additive Si or P, the quaternary nickel-zirconium-titanium-silicon alloy compositions comprising nickel in the range of 45 to 63 atomic %, zirconium plus titanium in the range of 32 to 48 atomic % and silicon in the range of 1 to 11 atomic %, and being represented by the general formula: Ni a (Zr 1−x Ti x ) b Si c . Also, at least one kind of element selected from the group consisting of V, Cr, Mn, Cu, Co, W, Sn, Mo, Y, C, B, P, Al can be added to the alloy compositions in the range of content of 2 to 15 atomic %. The quaternary nickel-zirconium-titanium-phosphorus alloy compositions comprising nickel in the range of 50 to 62 atomic %, zirconium plus titanium in the range of 33 to 46 atomic % and phosphorus in the range of 3 to 8 atomic %, and being represented by the general formula: Ni d (Zr 1−y Ti y ) e P f . The nickel-based amorphous alloy compositions have a superior amorphous phase-forming ability to produce the bulk amorphous alloy having a thickness of 1 mm by general casting methods.

Self-Assembling Solid Oxide Fuel Cell Materials: Mesoporous Yttria-Zirconia and Metal-Yttria-Zirconia Solid Solutions

Abstract: A new class of mesoporous (nickel/platinum)-yttria-zirconia materials, denoted meso-(Ni/Pt)YZ, which may have utility as electrode material in solid oxide fuel cells (SOFCs), have been synthesized by aqueous co-assembly of glycometalates and metal complexes with a surfactant template. These materials form as solid solutions with compositions that can be tuned over the range 12−56 atom % yttrium and 10−30 atom % nickel or 1−10 wt % platinum. The microstructure of the channel wall is nanocrystalline yttria-zirconia (YZ) and nickel/platinum is incorporated as metal oxide/metal clusters with diameters comparable to the size of the pores depending on the degree of loading of the metal precursor. Calcination in air of as-synthesized meso-(Ni/Pt)YZ materials causes the channel walls to crystallize and thicken as the imbibed organics are lost. It is the relatively thick, YZ nanocrystalline walls which are believed to be responsible for the impressive 800 °C thermal stability of meso-(Ni/Pt)YZ. This new class of b...