After being electrified and heated, the temperature of silicon carbide rods rises rapidly. Generally, in the air, when the rod temperature reaches 800 degrees Celsius, an oxidation reaction begins on the surface. As the temperature continues to rise to 1,000–1,300 degrees Celsius, the heating part of the silicon carbide rod reacts with the air, producing carbon dioxide and silicon dioxide. The silicon dioxide condenses on the surface of the rod, forming a dense protective film.

When the rod temperature continues to rise to around 1,550 degrees Celsius, the thickness of the protective layer increases due to the continuous production of silicon dioxide, effectively isolating the rod from the air and providing effective protection. This begins to slow down the oxidation rate of the silicon carbide rod.

However, the silicon dioxide protective layer also has a certain melting point. If the rod temperature continues to rise above 1,600 degrees Celsius, the silicon dioxide protective film may be damaged due to reactions such as peeling caused by excessive temperature, leading to a renewed increase in the oxidation rate of the silicon carbide rod. This situation should be avoided as much as possible during use. Proper design of the resistance furnace or industrial electric furnace structure, along with careful attention to the positioning of the rods during installation, can help prevent localized overheating or other electrical faults that may cause excessive temperatures in the silicon carbide rods, thereby significantly reducing their service life.