Type K is the most common thermocouple conductor(≥500℃), it has a good resistance against oxidation and can be recommended for oxidizing and inert atmospheres.It can not be used in sulphurous and vacuum atmospheres directly at a high temperature,as this will have a significant impact on the EMF values. The composition of positive(KP) is Ni90Cr10, negative(KN) is Ni97Si3.