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Surface analysis of nitride layers formed on Fe‐based alloys through plasma nitride process
Author(s) -
Sato Shigeo,
Omori Koji,
Araki Sawa,
Takahashi Yohei,
Wagatsuma Kazuaki
Publication year - 2009
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.3053
Subject(s) - nitriding , nitride , oxide , x ray photoelectron spectroscopy , layer (electronics) , glow discharge , materials science , nitrogen , alloy , metal , analytical chemistry (journal) , substrate (aquarium) , sputtering , metallurgy , plasma , inorganic chemistry , chemical engineering , chemistry , thin film , composite material , nanotechnology , environmental chemistry , physics , oceanography , organic chemistry , quantum mechanics , engineering , geology
Abstract Nitriding phenomena that occur on the surfaces of pure Fe and FeCr alloy (16 wt% Cr) samples were investigated. An Ar + N 2 mixture‐gas glow‐discharge plasma was used so that surface nitriding could occur on a clean surface etched by Ar + ion sputtering. In addition, the metal substrates were kept at a low temperature to suppress the diffusion of nitrogen. These plasma‐nitriding conditions enabled us to characterize the surface reaction between nitrogen radicals and the metal substrates. The emission characteristics of the band heads of the nitrogen molecule ion (N 2 + ) and nitrogen molecule from the glow‐discharge plasma suggest that the active nitrogen molecule is probably the major nitriding reactant. AES and angle‐resolved XPS were used to characterize the thickness of the nitride layer and the concentration of elements and chemical species in the nitride layer. The thickness of the nitride layer did not depend on the metal substrate type. An oxide layer with a thickness of a few nanometers was formed on the top of the nitride layer during the nitriding process. The oxide layer consisted of several species of N x ‐Fe y ‐O, NO + , and NO 2 − . In the FeCr alloy sample, these oxide species could be reduced because chromium is preferentially nitrided. Copyright © 2009 John Wiley & Sons, Ltd.