전해액 중 Sodium silicate의 농도에 따라 양극 산화된 AZ31B 마그네슘 합금 양극 피막의 특성 평가

• Published in: Biuletyn Uniejowski Vol. 42; no. 3; pp. 109 - 115
• Main Authors: 이동길(Dong-Kil Lee), 김용환(Yong-Hwan Kim), 박현(Hyun Park), 정우창(Uoo-Chang Jung), 정원섭(Won-Sub Chung)
• Format: Journal Article
• Language: Korean
• Published: 한국표면공학회 2009
• Subjects: 기계공학; Sodium silicate; AZ31B Mg alloy; Anodic film; Hardness; Anodizing
• ISSN: 1225-8024; 2299-8403; 2288-8403

Magnesium is one of the lightest metals, and magnesium alloys have excellent physical and mechanical properties such as high stiffness/weight ratios, good castability, good vibration and shock absorption. However their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To improve these defects, many techniques are developed. Micro arc oxidation(MAO) is a one of the surface treatments under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy. In this study, the characteristics of anodic film were examined after coating the AZ31B magnesium alloy through the MAO process. MAO was carried out in potassium hydroxide, potassium fluoride, and various concentration of sodium silicate in electrolyte. The morphology and chemical composition of the coating layer were characterized by SEM, XRD, EPMA and EDS. The hardness of anodic films was measured by micro-vickers hardness tester. As a result, the morphology and composition of anodic film were changed by concentration of sodium silicate. Thickness and Si composition of anodic film was increased with increasing concentration of sodium silicate in electrolyte. The hardness of anodic film was highly increased when the concentration of sodium silicate was above 40 g/l in electrolyte.