TY - INPR A1 - Kloiber, Jessica A1 - Anetsberger, Viktoria A1 - Schultheiss, Ulrich A1 - Hornberger, Helga T1 - Electropolishing of Magnesium Alloy Az31 with Varying Electrolyte Concentrations and Applied Potentials N2 - Magnesium alloy AZ31 is a light material with a good mechanical stability and is used in various engineering applications. Although its tendency to localized corrosion is a limiting factor in its use. Electropolishing is a widely used process for improving the surface roughness and corrosion behavior of metals. However, there is a lack of knowledge about the electropolishing of magnesium and its alloys. In this study, an optimal electropolishing process for AZ31 was developed to improve the surface properties by varying the electrolyte concentration and the applied potential. The electrolyte composition was a mixture of phosphoric acid, ethanol and deionized water. The applied potentials were selected based on measured current density potential curves. Thereby, electropolishing was performed up to an electric charge of 18 As. The experimental results indicate that the electropolishing process should be carried out at a low current density to avoid bubble evolution and surface defects. Therefore, the concentration of the electropolishing electrolyte should have an appropriate low conductivity, and the applied potential should be in the transient or passive region of the polarization curve recorded prior to electropolishing. It could be shown that an optimized electropolishing process improved the surface of AZ31 by providing a bright and mirror-like surface and a lower roughness compared to a mechanically ground surface. KW - magnesium alloy KW - AZ31 KW - electropolishing KW - electrolyte KW - surface characterization KW - polarization curve Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.4991311 PB - SSRN ER - TY - JOUR A1 - Kloiber, Jessica A1 - Schultheiß, Ulrich A1 - Sotelo, Lamborghini A1 - Sarau, George A1 - Christiansen, Silke H. A1 - Gavras, Sarkis A1 - Hort, Norbert A1 - Hornberger, Helga T1 - Corrosion behaviour of electropolished magnesium materials JF - Materials Today Communications N2 - Although magnesium and its alloys are promising candidates as biodegradable implant materials, the tendency for localized corrosion mechanism in physiological environment limit their biomedical application. Electropolishing is an attractive strategy for improving the corrosion behaviour of metals, but it is still largely unexplored in magnesium materials. In this study, the characterization of electropolished surfaces of AM50 and pure magnesium was performed, focussing on their in vitro degradation behaviour in cell medium. Corrosion rates were evaluated using potentiodynamic polarisation. The surface morphology before and after the onset of corrosion was investigated by scanning electron microscopy and confocal laser scanning microscopy. The presented electropolishing process led to improved surface performances, observable by significantly lower corrosion rates (0.08 mm·year-1 in Dulbecco's modified Eagle's medium), lower arithmetical mean height (0.05 µm), lower water contact angle (25-35°) and lower micro hardness (35-50 HV 0.1) compared to mechanically and chemically treated surfaces. MgO/Mg(OH)2 could be detected on electropolished surfaces. The localized corrosion mode could be reduced, but not entirely prevented. Electropolishing shows great potential as post-treatment of magnesium-based components, but detailed tests of the long-term corrosion behaviour are an important area of future research. KW - biomedical application KW - corrosion behaviour KW - electropolishing KW - magnesium alloy KW - pure magnesium KW - surface characterization Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-68254 N1 - Corresponding author: Helga Hornberger PB - Elsevier ET - Journal Pre-proof ER -