Low Cobalt Content Research Articles

Design and manufacturing of vacuum vessel for JT-60SA

Vacuum vessel of JT-60 Super Advanced (JT-60SA) is composed of 18 port sections with 73 ports. The vacuum vessel has a D-shaped poloidal cross-section with a double wall structure, which is filled by shielding water for neutron. The vessel is made of AISI316L with low Cobalt content of <0.05 wt.%. In order to reduce manufacturing cost, fabrication procedure was reviewed and the shell thickness and arrangement of poloidal ribs are modified from original design. Reduction of the shell thickness and poloidal ribs has large impact on manufacturing cost. Integrity of basic structure was confirmed by FEM analyses for eddy and halo current electromagnetic load. Stresses at general part of VV body are enough smaller than the design limit. Maximum stress is found near the basement of baffle plate support legs and close to design limit.

The Effect of the Processing Temperature on the Microstructures of Pr-Fe-Co-B-Nb HDDR Magnets

Pr14FebalCoxB6Nb0.1 magnets have been produced using the hidrogenation disproportionation desorption recombination (HDDR) process. The effect of the Co content (x= 0, 4, 8, 10, 12, 16) and the reaction temperature (800-900 °C) on the microstructure and magnetic properties of the HDDR material have been investigated. The processing temperature (desorption/recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880°C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840°C and 820°C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840°C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. Pr14Fe80B6Nb0.1 magnets have been processed for comparison.

Effect of liquid phase composition on the microstructure and properties of (W,Ti)C cemented carbide cutting tools

The microstructure and properties of (W,Ti)C cemented carbides with a different metal binder composition of Ni and Co fabricated by powder technology were investigated. The densifications of the prepared materials were accomplished by using vacuum sintering at 1450 °C. Nearly fully dense (W,Ti)C cemented carbides were obtained with a relative density of up to 99.7% with 30 wt% Co and 99.9% with 30 wt% Ni. The average grain size of carbides for the (W,Ti)C–Co and the (W,Ti)C–Ni was decreased with increasing the metal binder content. The hardness of the dense (W,Ti)C–15 wt%Co and (W,Ti)C–15 wt%Ni, was greater than the hardness of other different compositions of (W,Ti)C–Co and (W,Ti)C–Ni cemented carbides respectively; in addition, the (W,Ti)C–Co cemented carbides had greater hardness values than the (W,Ti)C–Ni cemented carbides. The magnetic properties, which were measured at an applied field of 0.8 T, indicate that the (W,Ti)C–Co cemented carbides have ferromagnetic properties with a higher magnetic saturation with higher cobalt content as well as higher coercivity with lower cobalt content. On the other hand, the (W,Ti)C–Ni cemented carbides are non-magnetic on account of the very low magnetic saturation and they have lower coercivity values than the (W,Ti)C–Co cemented carbides.

Effect of double exchange on thermoelectric power of CuxCoyCrzSe4

Abstract A correlation between the thermoelectric power and the double exchange and superexchange magnetic interactions in the ferromagnetically ordered Cu x Co y Cr z Se 4 p-type spinel conductors (with low Co content y up to 0.11) and in the antiferromagnetically ordered n-type semiconductor (with Co content y = 0.23) in the temperature range from 5 to 400 K is considered, respectively. The magnetic and thermopower investigations showed that a bandwidth of the 3d t 2g band due to Cr 3+ and Cr 4+ ions narrows with increasing cobalt content. For p-type conductors (with Co content y up to 0.11) all thermopower components are positive while for n-type semiconductor ( y = 0.23) the phonon drag component is positive and the diffusion and impurity components are negative. In the latter case the linear dependence between thermopower ( S ) and the normalized electrical resistivity (ln ρ / ρ 0 ) suggests a polaron conduction at high temperatures. The carrier diffusion dominates in single crystals with high cobalt content and the impurity component increases with increasing non-stoichiometry of a sample. For samples with low cobalt content y up to 0.11 the strong ferromagnetic coupling connected mainly with double-exchange mechanism makes easier the magnon excitations. Their intensities increase with increasing sample stoichiometry ( i.e. when x + y + z → 3).

Mechanical Properties of WC/Co Coatings Prepared by Cold Spraying

Microstructure, hardness and wear resistance of WC/Co coatings prepared by cold spraying and influence of powder properties, such as powder size, WC particle size and cobalt content, on those properties have been investigated in this study. Both smaller WC particle and low cobalt content are found to be effective to produce dense, hard and highly wear resistant coating. Smaller powder size is also favorable to make a coating with high mechanical properties. The cold sprayed coating using WC (0.2μm) /12% Co with powder size of -20+0μm has best mechanical properties within this study. This coating has high density compared to conventional HVOF sprayed coatings. Its abrasive wear resistance has been almost comparable to HVOF coating. Strong correlation is also seen between hardness and wear resistance.

Short communication. Use of 4-(5-Br-2 pyridylazo)-1,3-diaminobenzene (5-Br-PADAB) for the spectrometric determination of cobalt in wine

The typically low content of cobalt in wines hinders its quantification by molecular absorptiometry and atomic absorption spectrometry (AAS); difficulties arise both in the preparation of samples and cobalt detection. This work proposes a highly sensitive and selective extraction-spectrometry method that uses 4-(5-Br-2 pyridylazo)-1,3- diaminobenzene (5-Br-PADAB) for the determination of cobalt in this medium. Its accuracy and reproducibility are comparable to those of flame AAS. The molar absorptivity of the complex was 116,000 L/mol/cm. Interference from Fe (III) and Cu (II) ions was resolved by masking them with fluoride and cupron respectively.

Consolidation and Properties of Tungsten Carbide Target with Low Cobalt Content by Hot-Press Sintering

Tungsten carbide (WC) targets with low cobalt (Co) content (0.1 - 0.2 wt.%) were prepared by hot-press sintering at 1700°C for 60 minutes in argon, from element starting powders of tungsten, cobalt and carbon. Results show that the as-fabricated targets yield relatively high relative density above 99% and high HRA above 92. WC with low Co content is formed easily than pure WC. The hot-press sintering process, while element starting powders are used, is an in-situ reaction technique for accelerating the WC’s diffusion rate to obtain a dense sintered body.

Influence of cobalt and manganese content on the dehydrogenation capacity and kinetics of air-exposed LaNi 5+ x-type alloys in solid gas and electrochemical reactions

The effect of cobalt and manganese content on the dehydrogenation properties of air-exposed MmB 5+ x -type (Mm = mischmetal; B = Ni, Al, Co and Mn) alloys was investigated both in solid gas and electrochemical reactions. The cobalt and manganese content were varied separately while keeping constant the plateau pressure of the hydrides. The increase of the cobalt content leads to a decrease of the hydrogen capacity whereas the manganese content has no much effect. In solid gas reactions, the kinetics were found to be limited by the hydrogen diffusion through the surface oxidation layer. As for the electrochemistry, the kinetics are limited by a corrosion layer formed in alkaline medium. The desorption rates for both processes increase as the cobalt or manganese content decreases. This is thought to be due to an enhancement of the hydrogen diffusivity through the oxidation layer. As a result, a low cobalt or manganese content in MmB 5+ x alloys is found to be beneficial for the hydrogen desorption kinetics in both processes.

Stacking structures and electrode performances of rare earth–Mg–Ni-based alloys for advanced nickel–metal hydride battery

Rare earth–Mg–Ni-based alloys with stacking structures consisting of AB 5 unit (CaCu 5-type structure) and A 2B 4 unit (Laves structure) have received attention as negative electrode materials for advanced nickel–metal hydride (Ni–MH) battery. These alloy materials are very attractive because of high hydrogen storage capacity, low cobalt content and moderate plateau pressure, but have some difficulty to control the phase abundance and electrode performances. In this paper, relationship among composition, phase abundance, and electrochemical properties was investigated. Structural analysis was done using synchrotron X-ray diffraction patterns. In alloys such as La 0.8Mg 0.2Ni 3.4− x− y Co 0.3(MnAl) x (0 ≤ x ≤ 0.4), phase abundance was drastically changed with increasing amount of Mn and Al. In the range of 0.1 < x ≤ 0.2, hexagonal Pr 5Co 19-type (5:19H) or rhombohedral 1:4R phases were dominant. The Rietveld analysis suggested that Mg occupies La sites in A 2B 4 unit, and Al has tendency to occupy Ni sites between A 2B 4 unit and AB 5 unit or between AB 5 units in these types of phases. The developed alloys showed higher discharge capacity by 20% than the conventional one at a 0.2 C discharge rate.

Synthesis and Characterization of Mixed‐Metal Oxide Nanopowders Along the CoOx–Al2O3 Tie Line Using Liquid‐Feed Flame Spray Pyrolysis

We report here the use of liquid‐feed flame spray pyrolysis (LF‐FSP) to produce a series of nanopowders along the CoOx–Al2O3 tie line. The process is a general aerosol combustion synthesis route to a wide range of lightly agglomerated oxide nanopowders. The materials reported here were produced by aerosolizing ethanol solutions of alumatrane [Al(OCH2CH2)3N] and a cobalt precursor, made by reacting Co(NO3)2·6H2O crystals with propionic acid. The compositions of the as‐produced nanopowders were controlled by selecting the appropriate ratios of the precursors. Nine samples with compositions (CoO)y(Al2O3)1−y, y=0−1 along the CoOx–Al2O3 tie line were prepared and studied. The resulting nanopowders were characterized by X‐ray fluorescence, BET, scanning electron microscopy, high‐resolution transmission electron micrographs, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and FTIR. The powders typically consist of single‐crystal particles &lt;40 nm diameter and specific surface areas (SSAs) of 20–60 m2/g. XRD studies show a gradual change in powder patterns from δ‐Al2O3 to Co3O4. The cobalt aluminate spinel phase is observed at stoichiometries (21 and 37 mol%) not seen in published phase diagrams, likely because LF‐FSP processing involves a quench of &gt;1000°C in microseconds frequently leading to kinetic rather than thermodynamic products. Likewise, the appearance of Co3O4 rather than CoO as the end member in the tie line is thought to be a consequence of the process conditions. TGA studies combined with diffuse reflectance FTIR spectroscopic studies indicate that both physi‐ and chemi‐sorbed H2O are the principal surface species present in the as‐processed nanopowders. The only sample that differs is Co3O4, which has some carbonate species present that are detected and confirmed by a sharp mass loss event at ∼250°C. The thermal behavior of the high cobalt content samples differs greatly from the low cobalt content samples. The latter behave like most LF‐FSP‐derived nanopowders exhibiting typical 1%–4% mass losses over the 1400°C range due mostly to loss of water and some CO2. The high cobalt content samples exhibit a sharp mass loss event that can be attributed to the decomposition of Co3O4 to CoO.

Layered nickel–cobalt hydroxyacetates and hydroxycarbonates: Chimie douce synthesis and structural features

Abstract Layered nickel–cobalt hydroxyacetates Ni 1− x Co x (OH) 2− y (OAc) y · n H 2 O were first prepared by hydrolysis in polyol medium and then layered nickel–cobalt hydroxycarbonates were obtained by solid/liquid exchange reaction starting from hydroxyacetates homologues. The interlamellar distances and the characteristics of IR absorption band of anions for low cobalt content hydroxyacetates ( x ≤0.25) are different from those with a higher cobalt amount. Such a difference is not observed for carbonate compounds. Despite these different features, UV analysis shows that cobalt (II) ions are present both in octahedral and tetrahedral sites for all acetate and carbonate compounds. The amount of cobalt in T d sites, inferred from magnetization measurements, increases up to 26–27% when the total amount of cobalt increases. Two structural models closely related to the hydrozincite one are proposed for the solid solutions. These models differ by the organization of anionic species and water molecules between the layers.

Cobalt speciation in cobalt oxide-apatite materials: structure–properties relationship in catalytic oxidative dehydrogenation of ethane and butan-2-ol conversion

Impregnation of calcium hydroxyapatite by a solution of Co(II) nitrate followed by calcination at 823 K gives rise to various species, depending on the cobalt content. At low cobalt content (0.2 wt%), the cobalt species are isolated six-coordinated Co2+ ions. For Co content ≥0.4 wt%, the presence of tetrahedral Co2+ and octahedral Co3+ species is attested by UV–visible–NIR spectroscopy, magnetic measurements and XPS data. Magnetic data at low temperature suggest the formation of clustered CoxOy entities. For Co content ≥1.7 wt%, Co3O4 nanocrystals are generated, as evidenced by XRD and magnetic measurements.In the presence of oxygen, the butan-2-ol conversion produces only butan-2-one. The most active catalysts are the cobalt poorest samples which contain only isolated Co2+ ions. Oxidative dehydrogenation of ethane gives a similar trend. Upon increasing the cobalt loading above 0.9 wt%, the specific dehydrogenation activity of Co2+ ions decreases because the nature of the sites changes and the basic properties are lowered. Relationships between the nature of the sites and the catalytic performances are proposed.

The Na 0.60CoO 2 phase, a potential conductive additive for the positive electrode of Ni–MH cells

The Na 0.60CoO 2 phase, obtained by a classical solid-state reaction, is tested as a conductive additive in the nickel oxide electrode. Though the process was not optimised in terms of additive repartition, the experiments show a good efficiency of the Na 0.60CoO 2 phase even at low cobalt content, compared to usual additives like CoO. Moreover, it increases the stability of the electrode at low potential. The added Na 0.60CoO 2 phase is shown to transform, during the first cycles, into a γ-type cobalt oxyhydroxide phase that is more stable at low potential than the usual additives.

Catalytic adsorptive stripping voltammetry versus electrothermal atomic absorption spectrometry in the determination of trace cobalt and chromium in human urine

Two methods of the determination of cobalt and chromium in human urine of non-occupationally exposed populations—highly sensitive catalytic adsorptive stripping voltammetry (CAdSV) and electrothermal atomic absorption spectrometry (ET-AAS)—are evaluated and compared. The CAdSV methods are based on adsorptive accumulation of a cobalt–nioxime (1,2-cyclohexanedione dioxime) or a chromium–DTPA (diethylenetriammine- N, N, N′, N″, N″-pentaacetic acid) complexes on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of the catalytic reduction current of the adsorbed complex in the presence of sodium nitrite in case of cobalt or in the presence of sodium nitrate in case of chromium determination. In the CAdSV procedure UV-photolysis was used for the sample pre-treatment; the ET-AAS determination did not require any separate preliminary decomposition of the analyte urine samples. The accuracy of the procedures was checked by the analysis of commercially available quality control urine samples. The detection limits (3 σ) were 0.13 μg l −1 for Co and 0.18 μg l −1 for Cr in ET-AAS determination and 0.007 μg l −1 for Co and 0.002 μg l −1 for Cr in CAdSV measurements. Precision (R.S.D.) was less than 5% for both methods. The study has shown that the CAdSV is a more reliable and sensitive technique for the determination of very low cobalt and chromium contents in urine, the detection of which is not possible when using the AAS technique.

Synthesis and electrochemical characterization of gradient composite LiNi1−yCoyO2 used as cathode materials in lithium‐ion battery

AbstractGradient composites, LiNi1−yCoyO2, are synthesized from coated spherical Ni(OH)2 precursor. These composites could be applied as new cathode materials in lithium‐ion batteries because they have low cobalt content (y≤0.2) and exhibit excellent properties during high‐rate charge/discharge cycles. The initial discharge capacity of coated composite of LiNi0.95O2 is 186 mAh/g, and the decreasing rate of the capacity is 3.2% in 50 cycles at 1 C rate. It has been verified by TEM and EDX experiments that a core‐shell structure of the composite particles develops because of the cobalt enrichment near the surfaces, and the formation of the cobalt enrichment layer is sensitive to sintering tempera‐. High cobalt surface concentration may reduce the undesired reactions and stabilize the structure of the particles.

Relationship between corrosion resistance, microstructure and cobalt content in a Zn–Co alloy electroplated from alkaline electrolyte

Various protective methods may be used to improve the corrosion resistance of steel, and the application of coatings of zinc and its alloys is one of them. The efficiency of zinc in corrosion protection is due to its behaviour as a sacrificial anode. To enhance the corrosion protection, zinc has been alloyed with more noble metals such as cobalt, nickel and iron. In this work zinc-cobalt alloys were electrodeposited onto steel from an alkaline electrolyte. The investigation was carried out on electrodeposits with low and high cobalt contents. An in situ study was performed using a TEM equipped with a hot stage to relate the heat treatment with changes in structure and, consequently, corrosion behaviour. The images of the specimens as deposited and after heat treatment showed the presence of a phase that was identified as Co5Zn21. However only the diffraction pattern of the heat treated specimen fitted the strongest lines for this compound. The corrosion tests showed differences in the corrosion resistance before and after heat treatment, for alloys with low and high cobalt. The heat treated specimens displayed more active behaviour.

Development of a Bath for Electrodeposition of Zinc-Cobalt Compositionally Modulated Alloy Multilayered Coatings

The production of compositionally modulated alloy multilayers (CMAM) of Zn-Co alloys from an acid sulfate bath has been extensively studied and the electrodeposition parameters and conditions optimized to yield layers of high and low cobalt contents. It is shown that a change of deposition mechanism (from anomalous to equilibrium codeposition) occurs and is associated with the formation of ions in solution and not to the formation of an electrode film of as traditionally believed. Spectroscopic studies (UV-visible) showed that ions are formed on the anode surface due to oxidation of ions in the bath, and these trivalent ions prevent high-cobalt-containing Zn-Co alloy coatings. Using a two-compartment cell was found to be very effective in preventing the formation of trivalent cobalt ions in the catholyte portion of the bath and thus changing the codeposition mechanism from anomalous to equilibrium and consequently promoting high levels of cobalt in the deposits. This technique also increased the cathode current efficiency to 98%. By using a computer-aided pulse plating unit and designing different waveforms, various types of Zn-Co CMAM coatings of different thickness and number of layers were electrodeposited. © 2003 The Electrochemical Society. All rights reserved.

HIPERCO 15

Abstract Hiperco Alloy 15 is a development in soft magnetic alloys that combines the properties of high saturation, magnetization, high electrical resistivity, and lower cobalt content. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on forming and heat treating. Filing Code: FE-124. Producer or source: Carpenter Technology Corporation.

Structural and magnetic properties of BCC Fe/Co (0 0 1) superlattices

In thin layered Fe/Co (001), grown on MgO (001), both Fe and Co crystallize in the body-centered cubic (BCC) structure, as seen in a series of superlattices where the layer thickness of the components is varied from two to twelve atomic monolayers. These superlattices have novel magnetic properties as observed by magnetization and polarized neutron reflectivity measurements. There is a significant enhancement of the magnetic moments of both Fe and Co at the interfaces. Furthermore, the easy axis of the system changes from [100] for films of low cobalt content to [110] for a Co content exceeding 33%. No indication of a uniaxial anisotropy component is found in any of the samples. The first anisotropy constant (K1) of BCC Co is found to be negative with an estimated magnitude of 110kJ/m3 at 10K. In all cases, the magnetic moments of Fe and Co have parallel alignment.

Thin-Film Coatings Based on Zirconium and Cobalt Oxides

Thin-film coatings based on zirconium and cobalt oxides are obtained. It is demonstrated that the properties of the coatings depend on the ratio of oxides in the film, the rotational speed of the substrate, and the firing temperature. Films with a low cobalt content have the highest refractive index value and substantial adhesion.