单词 | chromel |
释义 | chromelchromel(ˈkrəʊmɛl)Chromelchromel[′krō‚mel]Chromelan alloy of nickel and chromium characterized by a favorable combination of thermoelectric properties and heat resistance. Chromel contains about 10 percent Cr, about 1 percent Co, and several impurities, specifically, up to 0.2 percent C and up to 0.3 percent Fe. It has a rather high and almost linear variation of thermoelectromotive force over a wide temperature range. The thermoelectromotive force of a chromel-platinum thermocouple at temperatures of 1000° and 0°C is about 33 millivolts. Chromel maintains a constant thermoelectromotive force during prolonged operation in air at temperatures ranging between 20° and 1000°C; at higher temperatures, its service reliability is reduced. Chromel is manufactured in the form of wires and is paired with alumel as a positive thermoelectrode in a chromel-alumel thermocouple, which is used for measuring temperatures. Chromel is also used as compensating wires. In the USSR, types NKh9.5 and NKh9 chromels are manufactured. |
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