Affiliation:
1. Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
Abstract
Surface engineering of chromium-oxide-passivated alloys (e.g., stainless steels) by low-temperature infusion of interstitial solutes (carbon, nitrogen) from a gas phase requires “surface activation” by removing or perforating the passivating oxide film. We demonstrate a new approach for surface activation based on pyrolysis of a reagent powder, introduce advanced methodology to study its microstructure, and compare it to an established activation method. Rather than a bare alloy surface, stripped of its oxide, we find that an “activated” surface involves a reaction layer containing high concentrations of Cl, carbon, or nitrogen. We propose a model for the microscopic mechanism of surface activation that will enable future systematic development toward more effective process schemes.
Subject
General Materials Science,Metals and Alloys