Chromel is a nickel-chromium alloy with an excellent combination of thermoelectric properties and heat resistance. The alloy is based on Nickel (Ni) with a mass fraction of 89 - 91%. Depending on the brand, Chromel contains up to 10% Chromium (Cr), about 1% Cobalt (Co), as well as difficult-to-remove impurities (up to 0.2% Carbon (C) and up to 0.3% Iron (Fe)).
Chromel is characterized by a wide and almost linear change in thermal electromotive force (TEMF) over a wide temperature range. TEMF of chromel - platinum thermocouples at junction temperatures from zero to one thousand degrees Celsius about 33 μV /K.
Chromel has a constant TEMF value during long-term operation in air at temperatures up to a thousand degrees Celsius. In principle, the alloy can continue to work at higher temperatures, but in this case its operational reliability is reduced.
Usually, chromel can be purchased in the form of a wire, which is used in tandem with an alumel wire as a positive thermoelectrode of a chromel-alumel thermocouple, which is used for temperature measurement. Chromel is also used as compensation wires.
composition of chromel alloy depending on grade
