Abstract
The microstructure of type AZ63 magnesium alloy anode for catholic protection and the dissolution behavior of the anode in tap-water were analyzed with an electron probe micro analyzer, a scanning electron microscope with energy dispersive X-ray spectrometer and a microscope. Crystal grain of this alloy anode was composed of Mg solid solution with very slight content of Al, and the grain boundary of this alloy anode was composed of Al-Mg mixture phase and Al-Zn-Mg mixture phase. When this anode dissolved sacrificially into the electrolyte, Mg dissolved more preferentially than Al and Zn. The local cell was formed within the anode. The grain boundary or impurities acted as cathode of the local cell, and the Mg solid solution as anode. Gray coarse particles fell from the surface of the anode. The cause of this phenomenon was that the dissolution of the anode was not uniform. Those particles contained un-dissolved anode in metallic form.
