The Advantages of N-thermocouple:
-High temperature resistance to oxidation, the long-term stability is strong. In K-thermocouple's nickel chromium, the Cr, Si element's preferential oxidation of positive pole leads to the uneven alloy composition and the thermoelectric drift. When increasing the Cr and Si contents in N-thermocouple, nickel-chromium alloy oxidation patterns turn from internal oxidation into external oxidation, and it results in the oxidation reaction only happens on the surface.
-The stability of short-term thermal cycle in low temperature is good. And it inhibits the magnetic transition;
-Strong nuclear radiation resistance. N-thermocouple has eliminated the metamorphic elements Mn and Co in K-thermocouple, which strengthen the anti-neutron irradiation ability;
-In the range of 400~1300 ℃, the thermoelectric characteristics of N-thermocouple are better than those of K-thermocouple.
The Disadvantages of N-thermocouple
-The material of N-thermocouple is harder than K-thermocouple, so it's hard to process;
-The price of N-thermocouple is relatively high. The coefficient of thermal expansion is 15% lower than that of stainless steel, so the outer casing of N-thermocouple should be used in the alloy of NiCrSi/NiSi.
-In the range of -200~400 ℃, the non-linear error is larger.