Effect of Calcium Lactate Additions on the Structure and Properties of ZK60 Magnesium Alloy Microarc Oxidation Coatings

This study examines the impact of C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub>H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub>CaO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> addition on the microstructure and corrosion resistance of micro-arc oxidation (MAO) coatings on ZK60 magnesium alloy. Various C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub>H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub>CaO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> concentrations were incorporated into the electrolyte, with coatings evaluated via scanning electron microscope (SEM), X-ray diffraction, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM). The results indicate that 3 g/L C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub>H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub>CaO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> optimizes coating performance, achieving maximum hardness (286.3 HV) and thickness (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$47.7~\mu $</tex-math> </inline-formula>m) while minimizing porosity and roughness. EIS analysis showed enhanced impedance, implying improved charge transfer resistance, while SECM confirmed reduced electrochemical activity. Excessive concentrations, however, introduced structural defects, diminishing corrosion protection. Thus, 3 g/L C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub>H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub>CaO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> emerges as the optimal concentration, significantly enhancing MAO coating integrity and corrosion resistance on ZK60, suitable for biomedical applications.