Influence of AlN Formation on Corrosion Behavior and High-Temperature Oxidation Resistance Using Tungsten Inert Gas Process

Influence of AlN Formation on Corrosion behavior and High-Temperature Oxidation Resistance using Tungsten Inert Gas Process

M.Ghazizadeh , M Heydarzadeh Sohi, H.Zebardast  

_Abstract

Surface alloyed layer based on aluminum nitride has been produced on wrought aluminum 5052 using tungsten inert gas technique. Process control parameters such as heat input and nitrogen gas flow have been studied. The structural analysis by X-ray diffraction indicates that the crystalline AlN phase was formed by surface melting in nitrogen atmosphere. Studies of XRD, OM and SEM showed that surface alloying in nitrogen atmosphere resulted in AlN layers with a hardness of 1400 HV. The AlN layer on the sample surface prevented oxygen from penetrating into the sample matrix, suggesting the enhancement of oxidation resistance and improvement of corrosion behavior by formation of alloyed layer (AlN). The remarkable of oxidation resistance was ascribed to the production of AlN layer with no microscopic defect such as pinhole.