Influence of Furnace Atmosphere

At high temperatures, silicon carbide (the main component of silicon carbide rods) can react with many media, meaning these media can cause varying degrees of corrosion to the silicon carbide rods. Here, we discuss the effects of oxygen (air), water vapor, and boron trioxide in the context of the glass industry.

(1) Influence of Oxygen.

At high temperatures, silicon carbide slowly oxidizes, forming silicon dioxide and carbon dioxide, causing the rod's resistance to gradually increase, i.e., aging. Generally, silicon dioxide forms a protective layer on the rod's surface, preventing further oxygen penetration and continued oxidation. However, in the feeder channel, glass volatiles can damage this protective layer, allowing the rod to continue oxidizing. Therefore, the rod must maintain a certain safe distance from the glass melt surface.

(2) Influence of Water Vapor.

At high temperatures, even trace amounts of water vapor can cause significant oxidation of silicon carbide rods. The reaction equation is as follows:

SiC + 4H₂O → SiO₂ + CO₂ + 4H.

The hydrogen gas produced can also erode the silicon carbide rods, and in severe cases, cause the rod heating element to crack and become porous, shortening the rod's lifespan. Therefore, furnaces that produce water vapor should have exhaust vents, and special attention must be paid during the kiln drying of new furnaces.