Nicrosil NPX strip is an austenitic nickel-chromium-silicon alloy (NiCrSi alloy) used for the positive leg of thermocouple type N. It offers a better oxidation resistance in air than type E, J and K thermocouples.
Nicrosil NPX strip alloy cannot be exposed to reducing or alternatively oxidizing and reducing atmospheres or to vacuum. This thermocouple is the most recent one among the different types covered by the international standards.