Pure Cobalt Metal Research Articles

XPS excitation dependence of measured cobalt 2 p[formula omitted] peak intensity due to auger peak interference

Quantitative X-ray photoelectron spectroscopy (XPS) analysis of cobalt-nickel (80:20) alloy material has revealed that the observed Co/Ni ratio using Al Kα excitation is about 20% higher than that observed with Mg Kα excitation. The ratio observed with Mg Kα is correct to within experimental error. Analysis of pure cobalt metal shows that the apparent increase in the alloy ratio with Al Kα excitation is primarily due to interference in the Co 2 p 3 2 spectral region by the cobalt L 3 M 23 M 45 Auger peak, which causes the Co 2 p 3 2 integrated intensity to be overestimated by about 15%. Analysis of fully oxidized cobalt shows that the Auger peak no longer significantly affects the measured Co 2 p 3 2 intensity, due to a chemical shift in the XPS peak and a change in structure of the Auger peak. Thus the contribution of the Auger peak to the measured Co 2 p 3 2 intensity varies with the degree of oxidation, and this should affect the interpretation of data in analyses of mixed oxide-metal systems, such as sputter profiling from oxidized to metallic cobalt. When Mg Kα excitation is used the same Auger peak interferes with the oxygen 1s photoelectron peak.

X ray chemical shifts and atomic charges

The LIII X-ray absorption discontinuity of rare earths (Tb, Dy, Ho, Er, Tm) in their pure metallic forms and in the compounds TbCo5, DyCo5, HoCo5, ErCo5, TmCo5 and the K absorption discontinuity of cobalt in TmCo5 have been recorded using a 40 cm Cauchois-type bent crystal spectrograph. It is observed that the LIII absorption discontinuity in the compounds shifts to the higher energy side with respect to that of the pure rare earth metals and that the cobalt K absorption discontinuity shifts towards the lower energy side as compared to that of pure cobalt metal. The observed rare earth LIII chemical shifts and the cobalt K shifts (with our previous data on K discontinuity of cobalt) have been correlated with the atomic charges on the rare earth and cobalt atoms. An attempt has been made to explain the observed correlations.

Cobalt Metal Inhalation Studies on Miniature Swine

Cobalt is considered to be the chief component in the tungsten carbide mixture responsible for hard-metal disease. An animal inhalation study was undertaken simulating conditions under which these workers in the tungsten carbide industry are exposed to cobalt. In this semichronic study, miniature swine were exposed to an inhalation of pure cobalt metal powder at concentrations of 0.1% mg/m3 (present TLV) and 1.0 m/m3. At peroidic intervals, the following studies were performed: pulmonary function tests, electrocardiograms, x-ray examinations, blood and urine tests, electron microscopy, and light microscopic pathology. Early detection of pulmonary disease is apparent from the pulmonary function tests showing a mark decrease in lung compliance, and from electron microscopy showing an increase in the amount of septal collagen. This study demonstrates that the present TLV of 0.1 mg/3 for cobalt seems to be too high, even at this relatively brief duration of exposure.

Internal friction recoverl of cemented carbides

Previous lork has sholn that internal friction measurements can provide a verl sensitive means to studl plastic deformation of cemented carbides lhich in general possess onll a limited ductilitl. In this paper, in order to throl light on recoverl of the cemented carbides, measurements of internal friction, loung′s modulus and some other properties of several prestrained cemented carbides have been carried out as a function of isochronal annealing temperature betleen 25–1000°C. Internal friction of the deformed cemented carbides starts to fall at temperatures in excess of 300~ 400°C and at 950~1000°C it recovers to the value corresponding to the undeformed state. loung′s modulus largell exhibits a corresponding variation. Anallsis of the internal friction recoverl in terms of Granato and Lücke theorl reveals that it reflects the process of a reduction of the dislocation densitl in the binder phase. Characteristic features in comparison lith the case of recoverl of a pure cobalt metal are broadening of the recoverl spectrum and shift of the center position to higher temperature side. This suggests that dense distribution of the carbide particles retards recoverl of the cemented carbides by acting as effective barriers against annihilation of dislocations. A small peak corresponding to the precipitation of Co 3l appears at 800°C on the recoverl curves of amplitude independent component of internal friction for the cemented carbides of comparativell lol carbon concentration. Mechanisms of the precipitation have been discussed in some detail.

Magnetic Resonance Studies in Dilute Ferromagnetic Alloys

The nuclear magnetic resonance of iron group element alloyed with Palladium has been studied with special emphasis on dilute ferromagnetism and the giant moment problem. This paper reports on the NMR of Co 59 in dilute ferromagnetic Co-Pd alloys and gives a simple interpretation of these results, The resonance frequency of Co 59 in these alloys was about 216 Mc at liquid helium temperature, nearly the same as that in pure fcc cobalt, 217.2 Mc at 0°K 1) . This suggests that the magnetic moment on Co atom is roughly equal to that in pure cobalt metal. By use of these results the range of the magnetic interaction of Co atoms in these alloys is roughly estimated using simple probability arguments. The giant moment is constructed from the sum of the moment of the Co atom and the moments of Pd atoms within an interaction “distance” from the Co atom.

Oxidation of cobalt in CO-CO 2 mixtures in the temperature range 920°C–1200°C

The oxidation of cobalt has been studied in CO-CO 2 mixtures in the temperature range 920°C–1200°C. The kinetics of oxidation were determined by using an automatic recording vacuum balance. The mechanism of oxidation was studied through the analysis of kinetics and by marker studies, X-ray analysis and metallographic examination of oxidized specimens. In the temperature range from 1000°C–1200°C and for oxide films up to 7 × 10 −5 cm thick, the rate-determining step has been found to be the dissociation of CO 2 into CO and adsorbed oxygen atoms or ions. For large oxide thicknesses, the diffusion of cobalt ions through the oxide layer eventually became the rate-controlling step. Pure cobalt metal has been found to oxidize by movement of cobalt ions and electron holes through the oxide layer. Moreover small amounts of manganese have been found to alter the mechanism of oxidation of cobalt.