Cobalt characteristics

Density is a particularly important characteristic of alloys used in rotating machinery, because centrifugal stresses increase with density. Densities of the various metals in Table 1 range from 6.1 to 19.3 g/cm. Those of iron, nickel, and cobalt-base superaHoys fall in the range 7-8.5 g/cm. Those alloys which contain the heavier elements, ie, molybdenum, tantalum, or tungsten, have correspondingly high densities. 

Many competitive programs to perfect a metallic anode for chlorine arose. In one, Dow Chemical concentrated on a coating based on cobalt oxide rather than precious metal oxides. This technology was patented (9,10) and developed to the semicommercial state, but the operating characteristics of the cobalt oxide coatings proved inferior to those of the platinum-group metal oxide. 

Toluhydroquinone and methyl / fX butyUiydroquinone provide improved resin color retention 2,5-di-/-butyIhydroquinone also moderates the cure rate of the resin. Quaternary ammonium compounds, such as benzyl trimethyl ammonium hydroxide, are effective stabilizers in combination with hydroquinones and also produce beneficial improvements in color when promoted with cobalt octoate. Copper naphthenate is an active stabilizer at levels of 10 ppm at higher levels (150 ppm) it infiuences the cure rate. Tertiary butylcatechol (TBC) is a popular stabilizer used by fabricators to adjust room temperature gelation characteristics. 

Approximately 25—30% of a reactor s fuel is removed and replaced during plaimed refueling outages, which normally occur every 12 to 18 months. Spent fuel is highly radioactive because it contains by-products from nuclear fission created during reactor operation. A characteristic of these radioactive materials is that they gradually decay, losing their radioactive properties at a set rate. Each radioactive component has a different rate of decay known as its half-life, which is the time it takes for a material to lose half of its radioactivity. The radioactive components in spent nuclear fuel include cobalt-60 (5-yr half-Hfe), cesium-137 (30-yr half-Hfe), and plutonium-239 (24,400-yr half-Hfe). 

The hardness on the basal plane of the cobalt depends on the orientation and extends between 70 and 250 HK. Cobalt is used in high temperature alloys of the superaHoy type because of its resistance to loss of properties when heated to faidy high temperatures. Cobalt also has good work-hardening characteristics, which contribute to the interest in its use in wear alloys. 

Silver-palladium-manganese brazes possess excellent creep characteristics and have been developed for high-temperature applications involving the use of cobalt or nickel-based alloys, heat-resistant steels, molybdenum and tungsten. Their liquidus temperatures lie in the range 1 100-1 250°C. 

Numerous proprietary electrolytes have been developed for the production of harder and brighter deposits. These include acid, neutral and alkaline solutions and cyanide-free formulations and the coatings produced may be essentially pure, where maximum electrical conductivity is required, or alloyed with various amounts of other precious or base metals, e.g. silver, copper, nickel, cobalt, indium, to develop special physical characteristics. 

Figure 16 shows the charge-discharge cycle characteristics of alloys in which part of the nickel component was replaced with cobalt. Misch metal (Mm), which is a mixture of rare earth elements such as lanthanum, cerium, praseodymium, and neodymium, was used in place of lanthanum. It was found that the partial replacement of nickel with cobalt and the substi-... 

Thickness gaging, of steel strip, 69-71 use of cobalt-60 for, 291 Thick-target x-ray spectra, 6, 7, 99-101 Thin films, thickness determined by characteristic line intensity, 153 Thin samples, analysis by x-ray emission spectrography, 167... 

Hofer et al. [671] observed that the decompositions of Ni3C and Co2C (the iron compounds melt) obeyed the zero-order equation for 0.3 < a < 0.9 (596-628 K and E = 255 kJ mole-1) and 0.2 < a < 0.75 (573-623 K and E = 227 kJ mole-1), respectively. The magnitudes of the rate coefficients for the two reactions were closely similar but the nickel compound exhibited a long induction period and an acceleratory process which was not characteristic of the reaction of the cobalt compound. Decomposition mechanisms were not discussed. 

The present research showed a dependence of various ratios of rutile anatase in titania as a catalyst support for Co/Ti02 on characteristics, especially the reduction behaviors of this catalyst. The study revealed that the presence of 19% rutile phase in titania for CoATi02 (C0/RI9) exhibited the highest number of reduced Co metal surface atoms which is related the number of active sites present. It appeared that the increase in the number of active sites was due to two reasons i) the presence of ratile phase in titania can fadlitrate the reduction process of cobalt oxide species into reduced cobalt metal, and ii) the presence of rutile phase resulted in a larger number of reduced cobalt metal surface atoms. No phase transformation of the supports further occurred during calcination of catalyst samples. However, if the ratios of rutile anatase were over 19%, the number of active sites dramatically decreased. 

Bond length differences between HS and LS isomers have been determined for a number of iron(II), iron(III) and cobalt(II) complexes on the basis of multiple temperature X-ray diffraction structure studies [6]. The available results have been collected in Table 17. Average values for the bond length changes characteristic for a particular transition-metal ion have been extracted from these data and are obtained as AR 0.17 A for iron(II) complexes, AR 0.13 A for iron(III) complexes, and AR = 0.06 A for cobalt(II) complexes. These values may be compared with the differences of ionic radii between the HS and LS forms of iron(II), iron(III) and cobalt(II) which were estimated some time ago [184] as 0.16, 0.095, and 0.085 A, respectively. 

---