Nickel 7 phase

Fig. 20.45 (a) Iron-rich end of the iron-nickel phase diagram and (ft) iron-rich end of the iron-... 

Zatka VJ. 1990. Chemical speciation of nickel phases in industrial dusts Method 90-05-03. Sheridan Park, Mississauga, Ontario, Canada Inco, Ltd., J. Roy Gordon Research Laboratory,... 

The active sites for the oxygen adsorption, which are found on the surface of NiO (250) but not of NiO (200), are to be identified with anionic vacancies because this high heat of adsorption is not caused by the sorption of oxygen on the nickel phase (13). The decrease in the capacity for adsorption of oxygen at 30°C. when the temperature of oxide preparation is increased from 200° to 250°C. is explained by the reduction of surface nickel ions, sites for the adsorption only of oxygen, and the formation of nickel crystallites whose surface atoms may be active towards the adsorption of oxygen at 30°C. Recession of nickel ions below the surface for NiO (250) may also contribute to this decrease. 

Pan Y.Y., Nash P., La-Ni (Lanthanum-Nickel) , Phase Diagrams of Binary Nickel Alloys, P. Nash, Ed., ASM International, Materials Park, OH. - 1991. -P. 183-188. 

The necessity of a larger ensemble for the dissolution of carbon into nickel than for activating methane corresponds to observations in surface physics. Adsorbed carbon atoms result in a distortion of the metal atom geometry whereas the bonding of adsorbed methane may require only 3-4 free nickel atoms. In simple terms, the two-dimensional surface sulfide prevents a distortion of the surface being necessary for the diffusion of surface carbon atoms into the bulk nickel phase. 

The anodes contain nickel both as metal and as sulfide. During nickel metal anode refining, the nickel phase dissolves selectively, leaving sulfides undissolved. The increase in sulfur content decreases the anode overvoltage but increases the quantity of anode slime [42]. 

A period of particularly rapid accumulation of carbon from CH4 was observed during the initial 5 min at 873 K. This effect (Fig. 2d) is favored by higher CH4 pressure. This phenomenon is not observed at 973 K or 1073 K. Buoyancy is observed as a weight loss at the moment when CH4 enters the reactor and is thus excluded as a potential explanation for the rapid weight increase. Calculations show that the Ni/C ratio is very close to 1 at the end of this initial period (at 4.5 bar) indicating that a rapid saturation of the nickel phase could possibly be of importance. 

After calcination (air at 300 °C for 2 h) and reduction (H2 at 400 °C for 2 h) the carbon nanotubes decorated with nickel metal were obtained. The concentration of nickel measured by ICP-MS was 20 wt.%. The TEM micrograph of the sample reduced under flowing hydrogen at 400°C unambiguously proved that the nickel phase was exclusively located on the outer walls of the carbon nanotubes with a particle mean diameter of about 40-50 nm [12]. It should be noted that despite the low reactivity of the exposed basal planes of the carbon nanotubes the nickel particles were well dispersed without formation of aggregates. 

The carbon nanofibers formed were extremely homogeneous with a mean diameter of about 50 nm and lengths up to several hundred micrometers (Fig. 1). From statistical SEM observation, it seemed that their diameter did not depend on the synthesis temperature but only on the initial diameters of the nickel catalyst particles [12], This observation was attributed to the absence of significant sintering of the supported nickel phase when the reaction temperature increased from 550 °C up to 650 °C. 

The stress-strain curves of Zr02-Ni system in three-point bending test are presented in Figure 2. It can be found that the Zr02-Ni system shows quite different deformation and fracture behavior with the change of constitution. The nickel-rich material displays typically elasto-plastic deformation behavior, which is controlled by the continuous matrix nickel phase and similar to metallic material. During bending test, the specimen can be bowed to V shape... 

The energy diagram for the nickel-sulfur system is shown in Figure 3.4. Sulfur segregates to the surface of the metal because of the stronger surface bonds it forms as compared to its bond energies at grain boundaries or in the bulk nickel phase (the heat of solution). 

The high surface concentration of these centers at which the growth of the nickel phase occurs ( 103 per square micron) guarantees the high resolution of the resulting metal pattern. Since nickel deposition occurs at the exposed areas, the resulting pattern is the negative one. 

G. Platz, C. Thunig, J. Policke. W, Kirchhoff, D. Nickel, Phase behavior of alkyl-poly g I ucos ides in combination with fatty alcohols and alky (sulfates. Colloids Surfaces A 88 113-122. 1994. 

Zijlstra and Westendorp (1969) of the Philips Research Laboratories, Eindhoven, The Netherlands, were the first to note that the RM5 (R = rare earth, M = iron, cobalt or nickel) phases readily absorb reasonable amounts of hydrogen at room temperature, in particular SmCoj absorbed 2.5 moles. Their co-workers. Van Vucht et al. (1970), were the first to report on the excellent hydrogen absorption properties of LaNij. 

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