Service life extension for belts and muffles with protective atmospheres

Continuous furnaces running with N2/H2 atmospheres in particular can be prone to high maintenance costs due to premature wear of muffles and furnace belts. The resulting increase in reject rates and plant downtime can push costs up further. The reason for this wear is often a type of high-temperature corrosive degradation in furnace atmospheres caused by entrained carbon-containing residue, referred to as metal dusting. This article first describes the underlying mechanisms that cause this high-temperature corrosion process and the relevant parameters that influence atmosphere carburization. It concludes with recommendations for action to optimize the atmosphere composition.