After a period of use, the temperature sensor (thermometer) in high-temperature furnaces is severely damaged on the outer layers that are directly exposed to heat.
Nickel alloys become weak in the furnace environment due to sulphideisation, thus requiring stronger alloy coatings such as WC or similar.
An effective solution is to coat the surface with heat-resistant alloys using methods such as Laser Cladding or Plasma Transfer Arc (PTA), the new coating will significantly extend the life of the device.