Evaluation of Corrosion Protection Methods for Aluminum Metal Matrix Composites(Final Report)

摘要

Corrosion protection of Aluminum Metal Matrix Composites (MMC) using anodizing,chromate conversion coating and polymer coatings was investigated. Electrochemical Impedance Spectroscopy, DC polarization measurements, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) were used. The materials studied included 606 1/SiC, A356/SiC, 2009/SiC, 2014/Al203 and 6061/Al203 in various reinforcement concentrations. The electrochemical behavior of the MMCs without protection was also investigated. MMCs were found to have similar corrosion and pitting potentials as the matrix alloy. The cathodic current density were found to be higher for MMCs with the current density increasing with reinforcement concentration. The increased current density is attributed to the interface between the matrix and the reinforcement particles which increases the corrosion rate. Anodizing was performed on both Al alloys and MMCS. A new model is proposed for Al alloys. Anodizing and hot water sealing on MMCs was less effective than on Al. Improved results were noted for dichromate sealing.