Nisil is an austenitic nickel-silicon alloy (NiSi alloy) used for the negative leg of thermocouples type N. It offers higher thermoelectric stability in air above 1000°C (1830°F) and better oxidation resistance than type E, J and K thermocouples.
Nisil alloy can not be exposed to sulphur-containing gases. This thermocouple alloy is the most recent one among the different types covered by the international standards.
Chemical composition
| Ni % | Si % | Mg % | |
|---|---|---|---|
| Nominal composition | Bal. | 4.3 | 0.1 |
Mechanical properties
| Wire size | Yield strength | Tensile strength | Elongation |
|---|---|---|---|
| Ø | Rp0.2 | Rm | A |
| mm | MPa | MPa | % |
| 2.00 | 300 | 680 | 33 |
Physical properties
| Density g/cm3 | 8.585 |
|---|---|
| Electrical resistivity at 20°C Ω mm2/m | 0.365 |
|
Temperature coefficient of resistance between 20°C and 100°C x 10-6/K |
680 |
| Temperature °C | Thermal Expansion x 10-6/K |
|---|---|
| 20 - 100 | 17 |
| Temperature °C | 100 |
|---|---|
| W m-1 K-1 | 27 |
| Melting point °C | 1420 |
|---|---|
| Magnetic properties | The material is non-magnetic |
| Wire size Ø | 3.26 | 1.63 | 1.00 | 0.50 | 0.25 |
|---|---|---|---|---|---|
| Bare wire °C | 1100 | 1010 | 960 | 890 | 800 |
| Protected wire °C | 1250 | 1180 | 1110 | 1000 | 910 |
Note that the indicated temperatures should be considered as guide values
Thermoelectric properties
| Temp °C | mV | |
|---|---|---|
| 100 | 2.774 | |
| 200 | 5.913 | |
| 300 | 9.341 | |
| 400 | 12.974 | |
| 500 | 16.748 | |
| 600 | 20.613 | |
| 700 | 24.527 | |
| 800 | 28.455 | |
| 900 | 32.371 | |
| 1000 | 36.256 | |
| 1100 | 40.087 | |
| 1200 | 43.846 | |
| 1300 | 47.513 |
ITS90- Reference junction 0°C
