Thermal conductivity commercial metals

The high electrical and thermal conductivities and corrosion resistance of copper combined with its workabiUty give the metal its very wide range of commercial appHcations. Unlike most metals, which are alloyed with other elements to enhance properties, for example, alloy steel and aluminum, copper is primarily used in its pure, unalloyed form. 

The minerals on which the work was performed during the nineteenth century were indeed rare, and the materials isolated were of no interest outside the laboratory. By 1891, however, the Austrian chemist C. A. von Welsbach had perfected the thoria gas mantle to improve the low luminosity of the coal-gas flames then used for lighting. Woven cotton or artificial silk of the required shape was soaked in an aqueous solution of the nitrates of appropriate metals and the fibre then burned off and the nitrates converted to oxides. A mixture of 99% ThOz and 1% CeOz was used and has not since been bettered. CeOz catalyses the combustion of the gas and apparently, because of the poor thermal conductivity of the ThOz, particles of CeOz become hotter and so brighter than would otherwise be possible. The commercial success of the gas mantle was immense and produced a worldwide search for thorium. Its major ore is monazite, which rarely contains more than 12% ThOz but about 45% LnzOz. Not only did the search reveal that thorium, and hence the lanthanides, are more plentiful than had previously been thought, but the extraction of the thorium produced large amounts of lanthanides for which there was at first little use. 

The resistance thermometry is based on the temperature dependence of the electric resistance of metals, semiconductors and other resistive materials. This is the most diffused type of low-temperature thermometry sensors are usually commercial low-cost components. At very low temperatures, however, several drawbacks take place such as the low thermal conductivity in the bulk of the resistance and at the contact surface, the heating due to RF pick up and overheating (see Section 9.6.3)... 

Alloys of beryllium and of other metals with beryllium are also important. Beryllium-aluminum alloy (62%Be, 38%A1) and beryllium-copper master alloy are both available commercially The incorporation of 2% Be into copper greatly increases the hardness and strength of the metal without reducing its electrical and thermal conductance. This is the single largest use of beryllium. 

Silver — (Ag, atomic number 47) is a soft, white, lustrous metal that has the highest electrical and thermal conductivity (and the lowest contact resistance) of any metal. A solid at room temperature (melting point = 961.8 °C), Ag is commercially available in several forms, including foil, mesh, wire, rod, tube, powder, pellets, and single crystal. It is also available as an alloy with each of several metals, including Ni, Cu, Pd, Sn, Au, and Sb. 

Several commercial evidential breath alcohol measurement devices are available. The principle of measurement is either infrared absorption spectrometry (most common), dichromate-sulfuric acid oxidation-reduction (photometric), GC (flame ionization or thermal conductivity detection), electrochemical oxidation (fuel cell), or metal-oxide semiconductor sensors. A list has been published of DOT-approved breath alcohol devices.Some of these devices are approved for screening only. In this case, the second or confirmatory breath alcohol determination must be performed with an approved evidential breath alcohol analyzer. Breath alcohol devices may also be used for the medical evaluation of patients at the point of care (e.g., emergency department). A Fourier transform infrared point-of-care breath analyzer capable of measurement of... 

Conducting polymers like commercially available PEDOT PSS are the third class of printable conductors. However, their conductivity (maximum 500 S/ cm for PEDOT PSS [11]) is several orders of magnitude lower than the conductivity of metals. The advantages of PEDOT PSS are its transparency, flexibility and low-temperature post-processing the thermal treatment is only necessary to remove residual solvent, no sintering is required. 

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