Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403

공학

한국표면공학회지 (43권2호 73-79)

Characteristics Evaluation of Conversion Coating of Acid Pickling AZ31 Magnesium Alloy by a Chromium-Free Phosphate-Permanganate Solution

비크롬계 인산-과망간산 용액을 이용한 AZ31 마그네슘 합금의 산처리에 따른 화성 피막의 특성 평가

김명환;곽삼탁;문명준;
Kim, Myung-Hwan;Kwag, Sam-Tag;Moon, Myung-Jun;

부경대학교 화학공학과;부경대학교 공업화학과;
Department of Chemical Engineering, Pukyong National University;Department of Industrial Chemistry, Pukyong National University;

DOI : 10.5695/JKISE.2010.43.2.073

Abstract

A chromium-free conversion coating for AZ31 magnesium alloy has been obtained by using a permanganatephosphate solution, which has been developed with acid pickling. Examination have been carried out on the conversion coatings for morphology, composition and corrosion resistance. The morphology of the conversion-coated layer was observed using optical microscope and SEM. It was shown that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to 2.7 ${mu}m$. The chemical composition of conversion coating was mainly consisted of Mg, O, P, K, Al and Mn by EDS analysis. It was found that the corrosion resistance of the AZ31 magnesium alloy has been improved by the permanganate-phosphate conversion treatment from electrochemical polarization.

Keywords

AZ31;Magnesium alloy;Conversion coating;Chromium-free;Acid pickling;