New Method of Obtaining a Multilayer Anodized Film on 7075-T6 Al-Alloy Surface

Abstract

It is well known that the anodized thin layer formed on Al-alloys surface are
characterized with porosity of nanometric dimensions whatever acid or alkaline solutions are
used. In this study, an attempt was made for the first time to develop a new method for
obtaining anodized multilayer film by reinforcing the anodized oxide coating with
incorporating nanosized graphite in the layer structure during anodizing process by means of
anodizing Al- Alloy type 7075 T-6 in an electrolyte composed of water solution of chromic
acid and graphite . This leads to obtain a multilayer anodized film having good thickness and
high micro hardness properties. Nanosized particles of graphite have been formed into anodic
oxide layer. The influence of anodizing process parameters (voltage and current density) on
the thickness micro hardness and chemical composition of a multilayer oxide film are
determined