NICROSIL-NISIL: A NEW HIGH STABILITY THERMOCOUPLE FOR THE INDUSTRIAL USER.

Thermocouples based on alloys of nickel, with various concentrations of chromium ( plus ve arm), and aluminum ( minus ve arm), plus other ingredients in small quantities, have been used since the early twentieth century to measure and monitor temperatures up to about 1200 degree C. The advantages of this type of thermocouple, officially known as type K (BS 4937, part 4), or 'chromel-alumel' or 'T1/T2' are pointed out, along with its disadvantages. The development of some new nickel-based thermocouple alloys which came to be known as 'nicrosil' and 'nisil' is reported, including their properties. Nicrosil, the positive arm, is made up of nickel, 14. 2% silicon, and the negative arm, nisil, is made up of nickel, 4. 4% silicon, 0. 1% magnesium.