Thermocouple Alloys for Type N Thermocouple and Extension Wires. Nicrosil + & Nisil
Material can be ordered to all National or International emf standards as well as customer’s own specifications.
Scott Precision Wire Nicrosil and Nisil alloys are available in solid wire, strip or tape and flexible bunch or strand constructions.
Physical and Mechanical Properties
| | Units | Nicrosil + | Nisil - | |
|---|---|---|---|---|
| Nominal composition | % | Ni 84.4 | Ni 95.6 | |
| Si 1.4 | Si 4.4 | |||
| Cr 14.2 | ||||
| Density at 20°C | g/cm³ | 8.5 | 8.6 | |
| Resistivity at 20°C | µΩcm | 99 | 35 | |
| Temperature Coefficient of resistance. | 20 – 100°C | 1/K | 0.00009 | 0.00068 |
| Coefficient of thermal expansion, | 20 – 100°C | 1/K | 16 x 10^6 | 16 x 10^6 |
| Thermal conductivity at | 20°C | W/mK | 14 | 28 |
| Melting point (approx.) | °C | 1415 | 1380 | |
| Magnetic properties at 20°C | Non-Magnetic | Slight | ||
| Tensile strength Rm | N/mm² | 760 | 620 | |
| (0.5mm annealed wire) | ||||
The combination is not immune to corrosion and the following environments can cause detrimental effects: Type N thermocouple wire has greater emf stability and corrosion resistance than Type K, however the combination develops a lower emf output and cannot, therefore, be directly substituted.
The removal of Chromium from the alloy is accompanied by a significant emf drop and embrittlement.'Green rot' can develop on the Nicrosil+ due to the preferential oxidation of Chromium occurring in a reducing or mildly oxidising atmosphere where the partial pressure of oxygen is low.
Sulphur reacts corrosively with the Nisil- at higher temperatures.
The figures given in these tables represent nominal or typical values.
Information contained within this technical data sheet is based upon the general experience of Scott Precision Wire Ltd and is believed to be correct at the time of issue.
No warranty is given or is to be implied from the details above.
Customers are advised to carry out independent tests in order to determine the suitability of any Scott Precision Wire Ltd product for an application.