APPLICATION OF MATERIAL SPECIFIC TESTING ON MAGNESIUM ALLOYS USING ELECTROCHEMICAL NOISE

摘要

The corrosion behaviour of magnesium alloys is not substantially comparable to other light metal alloys, it is more similar to that of steels. Voluminous reaction products, formed in neutral electrolytes, leads to a diffusion controlled dissolution on the surface of the underlying magnesium alloy. Therefore, influences from structure and alloying are suppressed very strongly. In alkaline environments, passivation occurs as a result of the formation of a hydroxide layer on the magnesium surface. Therefore, differences in the corrosion behaviour between the alloys are hardly detectable. Measurable effects can only be detected using very "aggressive" corrosion conditions. Presently used methods do not adequately take into account the specific character of the corrosion of magnesium alloys. The application of electrochemical noise offers the possibility of a simple and sensitive assessment of the corrosion susceptibility of magnesium alloys. Due to the high sensitivity of this measurement procedure it is also possible to carry out examinations under more practical conditions.