Surface Modification of Steels and Aluminum Alloys to Control Corrosion and Hydrogen Embrittlement. Part 1. Chemical Methods.

摘要

Surface modification to control corrosion and/or hydrogen embrittlement is approached in two ways: 1) treatment of the surface by chemicals, and 2) alteration of the electroplating process. This report describes the chemical modification of surfaces. Both a ferrocene derivative and a silane are used to prepare covalently bonded thin films on steels and aluminum alloys. The ferrocene should act as an electron reservoir whereas the silane should act as a barrier. Electrochemical properties were measured using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. It was shown that the steels and an aluminum alloy which have good oxide coatings were covered more completely with the ferrocene than were carbon steels. Changes in potentiodynamic polarization scans indicated corrosion protection by the ferrocene coating on 4340 steel but not on 1018 steel. Electrochemical impedance measurements showed corrosion protection by the ferrocene coating on 7075-T6 aluminum. The electrochemical tests indicated that the silane gave corrosion protection to both 4130 and 1018 steel as well as to 7075-T6 aluminum. (sdw)