Exploring the relationship between sputter-deposition conditions and electrochemical response of ZrO2 films on biodegradable MgZnCa alloy.

In this work, we investigated the enhancement of corrosion resistance in a biodegradable Mg-0.7Zn-0.6Ca (wt. %) alloy (MgZnCa) by applying ZrO₂ thin films deposited via reactive magnetron sputtering. We employed a fractional factorial experimental design to systematically examine the influence of the deposition power, deposition time, and O₂ fraction on the effectiveness of the ZrO₂ thin film in preventing corrosion of the Mg alloy. Our analysis revealed that the ZrO₂ thin films exhibited a monoclinic crystal phase and maintained stoichiometry across various O₂ fractions. Interestingly, we observed a 78% roughness reduction when using the lowest O₂ fraction, while roughness increased with the deposition power and time. The corrosion response of bare and ZrO₂-coated MgZnCa alloy was assessed by electrochemical techniques and detection of H₂ production during the Mg corrosion via gas chromatography. The optimal set of deposition conditions, essential for enhancing the short-term corrosion resistance of magnetron-sputtered ZrO₂ coatings, involves maximizing thickness through high power (400 W) and extended deposition time (90 min). It is crucial to balance these factors while maintaining an appropriate O₂ fraction (20%) to ensure the formation of a stoichiometric film. Avoiding excess oxygen is imperative, as it can lead to undesirable intergranular porosity and surface roughness. This optimization resulted in a 46% reduction in the evolution of H₂ gas compared to the bare MgZnCa alloy. Overall, this work sheds light on the potential of ZrO₂ thin films as effective corrosion-resistant coatings for MgZnCa alloys, emphasizing the critical role of deposition parameters in achieving superior protection against corrosion. [ABSTRACT FROM AUTHOR]