Cobalt electrical resistivity

Nonferrous alloys account for only about 2 wt % of the total chromium used ia the United States. Nonetheless, some of these appHcations are unique and constitute a vital role for chromium. Eor example, ia high temperature materials, chromium ia amounts of 15—30 wt % confers corrosion and oxidation resistance on the nickel-base and cobalt-base superaHoys used ia jet engines the familiar electrical resistance heating elements are made of Ni-Cr alloy and a variety of Ee-Ni and Ni-based alloys used ia a diverse array of appHcations, especially for nuclear reactors, depend on chromium for oxidation and corrosion resistance. Evaporated, amorphous, thin-film resistors based on Ni-Cr with A1 additions have the advantageous property of a near-2ero temperature coefficient of resistance (58). 

The data indicate that the properties of the lower glass transition temperature metal ion modified polyimides are altered more than the properties of the higher glass transition temperature metal ion modified polyimides. Extraction removes both cobalt and chlorine from the films and slightly increases bulk thermal stability and both surface resistivity and bulk electrical resistivity. Details pertaining to the structure, analysis and properties of these novel gradient composites are discussed. 

Figure A. Comparison of air-side electrical resistivity of a cobalt chloride modified BDSDA-ODA polyimide film before and after soaking in distilled water.

The specific electric resistance of cobalt wires of great purity is 89-64 X 10 7 ohms per cm. cube, but this value increases enormously by the addition of small quantities of impurities. 

Then a mixture of diamond and cobalt powders was placed into the cell and subjected to pressure and temperature. Liquid cobalt that wetts diamond is pulled out of the compact if the volume occupied by cobalt somewhat exceeds the total volume of pores which remained after shrinkage of diamond powder. When liquid metal is in contact with a graphite heater, the current flow at first increases due to a total drop of the system electric resistance and then decreases because of diamond formation in the heater. In this case, the shrinkage value corresponds to the volume of cobalt in the powder. 

A bolometer has a conducting element whose electrical resistance changes as a function of temperature. Bolometers are fabricated from thin strips of metals, such as nickel or platinum, or from semiconductors consisting of oxides of nickel or cobalt the latter are called thermistors. 

Another type of resistance thermometer uses metal oxides, instead of metals it is frequently referred to as a thermistor. Electrical resistance of these metal oxides changes rapidly with even rather small temperature changes. Hence, thermistors are often emplyed to measure small temperature changes such as 1°C to 5 °C. The thermistor proper tends to have low purchase prices. Metal oxides, which are semiconductors, include mixtures of the following oxides nickel, manganese, copper, cobalt, tin, germanium, etc. [1]. 

SnO containing films the bulk materials and cast-side surfaces were characterized as dielectric in nature with loss and conduction. The air-side charging characteristics, on the other hand, were markedly different from the volume mode charging characteristics. No short term polarization occurred in the samples implying little or no direct contribution from the polymer matrix to the air-side electrical properties. Also, the air-side electrical resistivity of BTDA-ODA polyimide films at room temperature was reduced substantially for both cobalt chloride modified and tin chloride dihydrate modified samples (i.e. six orders of magnitude and eleven orders of magnitude, respectively). 

FIGURE 1 Change of the normalized electrical resistance (GMR effect) as a function of the magnetic field for a granular thin film of silver/cobalt prepared by molecular beam epitaxy. SOURCE Alof, 2000. 

This paper presents the methods used to calculate the electrical resistances and the results for a number of different widely accepted ICCB designs currently used in electrowinning plants. The paper also makes comparisons between the systems on other key parameters for ICCB performance in nickel and cobalt tankhouses. 

As of file early 1990s the hislnrieal importance of coball ill alloys for reducing wear resistance was markedly diminished by the development of Norem alloys, which were derived from stainless steel, particularly the Armco Nitronic 60. admittedly one of the few stainless steels that has excellent wear resistance. This is an outgrowth of research conducted by EPRI (Electric Power Research Institute) in an effort to lower equipment costs. Initial uses of the new cobalt-frec alloys will he power plant valves and turbines. Also. In nuclear reactor applications, the Nnrem alloys will not become activated [Co does), reducing worker-protection and maintenance costs. Tests have confirmed that the new cobalt-free alloys retain their wear-resistant properties when produced as rods and powders, the most common forms used by welders. 

Staff Nonferrous Metals-Nickel, Cobalt, Lead, Tin, Zinc, Cadmium, Precious, Reactive. Refractory Metals and Alloys Materials for Thermostats, Electrical Heating and Resistance Contacts, and Connectors, American Society for Testing Materials. West Conshohockcn, PA, 2004. 

Pure nickel was first isolated in 1751. Like cobalt, nickel was used to color glass, though nickel compounds turn glass and other substances green rather than blue. Because nickel is resistant to corrosion, it is often combined with other metals to form alloys that resist oxidation. A process known as electroplating uses nickel to coat the surface of metals that are vulnerable to corrosion, like iron or steel. Stainless steel is an example of a product made from nickel almost half the nickel that is mined each year is used to manufacture it. Also composed of chromium, stainless steel is extremely resistant to corrosion. Another nickel alloy is monel, which is made with copper. Monel is hard and resistant to corrosion, making it ideal for commercial marine applications such as the manufacture of boat propellers. The heating parts in toasters and electric ovens are made from an alloy called nichrome, which is another metal, made from chromium and nickel. 

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