Corrosive Atmosphere Protection: High-Temper"&"ature Treatment Solutions for Fluorine and Chlorine-Containing Materials
Two years ago, in the autumn, a customer's equipment, which produced fluorine-containing precursor materials, developed extensive corrosion on the surface of its induction c"&"oil within six months, and the sealing rings aged and cracked. The cause was the generation of hydrogen fluoride gas in the process, which conventional graphitization furnaces could not withstand.
Corrosion Principle
Hydrogen fluoride and hydrogen chloride are highly corrosive media at high temperatures, directly attacking metallic materials and causing pitting corrosion, intergranular corrosion, and even stress corrosion cracking.
Once the surface of the in"&"duction coil is corroded, its resistance increases, its heating efficiency decreases, and in severe cases, localized overheating may cause it to burn out. **Four-Layer Protection Design** **1?? Induction Coil Coating Protection** **The coil surface is "&"treated with a Teflon coating or a ceramic coating to form a dense protective film, completely isolating corrosive gases from the metal coil.** The coating thickness should be uniform, without bubbles or cracks. The service life is generally 1-2 years, af"&"ter which recoating is required. **2?? Furnace Shell Inner Wall Corrosion Protection** **A high-temperature resistant anti-corrosion coating is added to the inner wall of the furnace shell.** During construction, surface treatment must be done properly—"&"rust removal, degreasing, and polishing are all essential steps.**
3?? Sealing System Upgrade
Conventional fluororubber cannot withstand hydrogen fluoride for long. Upgrade to **perfluoroelastomer (FFKM)** materia"&"l, one of the best chemically resistant sealing materials currently available. Use metal spiral wound gaskets or flexible graphite gaskets at pipe connections.
4?? Exhaust System Enhancement
Add a **condensation tr"&"ap** and a **scrubber** to the exhaust pipe to ensure corrosive gases are fully condensed and neutralized before discharge. Simultaneously, increase the diameter of the exhaust pipe to prevent liquid accumulation or blockage.
Key points of process operation: After each process, continuously purge with inert gas for at least two hours during the cooling process to completely remove any residual corro"&"sive gases. Before opening the furnace door, use a portable gas detector to confirm safety.
