1.Antioxidant property of elements

The element start to being oxidized when heat to 800 ℃ in air ;and a SiO2 protect filn will be generated on the surface of hot zone when temperature get to 1000—1300℃; cristobalite will be crystallized at 1300℃;the protect film get to a certain thickness when the temperature get to 1500 ℃ ,which make the oxidation speed being very slowly to stable, If continue to heat to over 1627℃,the protect film will be damaged and oxidation speed will be more rapid evidently and make the element damaged earlier.

Though the element will be oxidized very slowly in course of application,it also will make the resistance increased following long time application, this phenomenon calls aging. In order to lower the aging speed,we use special technology to coat a protect film on the surface of hot zone in the course of production,which enhance the Antioxidant property of element evidently and lengthen the service life.

2.The effects of alkali and alkaline metal oxide to elements

The alkali & alkaline metal oxide will react with SiC at about 1300℃ and generate silicate, which calls alkali-chemical corrosion ,and can influence the glowing of element evidenty.

3.The effects to elements from melting metal

Some metals, such as cobalt, nickel ,chrome and so on,can corrade the element in high temperature melting state and affect the service life of element.