Abstract
This study examines the critical but often overlooked role of surface roughness in gaseous nitriding processes. While nitriding technology fundamentally relies on gas-solid interactions through multiple stages—including ammonia diffusion to the metal surface, dissociation reactions, nitrogen transfer, and bulk diffusion—the authors highlight how surface conditions significantly impact treatment outcomes, particularly at the relatively low processing temperatures (380-590°C) where surface reactions become rate-limiting. The research investigates how surface roughness affects the gas-metal contact area and consequently influences nitrogen uptake kinetics, challenging the traditional assumption that nitriding produces negligible changes in surface morphology. Working with commercial furnaces that use nitriding potential as the primary process control parameter, the researchers correlate various surface finishes with nitrogen absorption rates, ammonia dissociation, and atmosphere activity. The ultimate goal is to incorporate surface roughness—a specification widely used in metalworking industries—as a formal parameter in control systems, thereby enhancing process predictability and meeting increasingly stringent industrial standards for surface quality in nitrided components.
