A simple single-step permanganate surface treatment for rare-earth containing magnesium alloys

Abstract

This paper is a part from a running project aiming at optimizing the permanganate coating treat ment for rare earth (RE) containing magnesium alloys. Alloying of Mg alloys with RE elements enhances the galvanic corrosion and decreases the overall resistance. The objective of this paper is to optimize the perman ganate treatment time that can provide the highest protection, so that permanganate coating can be engi neered for Mg alloys. Electrochemical characteristics, morphology, and microstructure examination were investigated as a function of permanganate treatment time. EIS and polarization testing correlated to macro and microscopic surface examinations and visual inspection. Taking into account the industrial applicability and the economic aspects, the optimum treatment time was determined to be 10 min and this value is critical where increasing or decreasing it has a detrimental effect on the overall performance. Accordingly, processes active during permanganate treatment are kinetically dependent and strongly influenced by the treatment time.