What is the reason for the failure of the electric furnace wire in the high-temperature experimental electric furnace?

The failure of the electric furnace wire in the high temperature experiment is due to the slow heat dissipation of the electric furnace wire when the pitch is small, and the temperature will be higher than that of other places, and the resistivity increases with the increase of temperature, so that the heating per unit length of this place is higher than that of other places, and the temperature difference It is very large; in addition, the oxidation phenomenon here is also aggravated, and the electric furnace wire becomes thinner. Finally, the electric furnace wire breaks and fails under the action of thermal gravity generated by the fluctuation of the furnace temperature.