Analysis of electrodeposition processes to obtain calcium phosphate layer on AZ31 alloy

Magnesium alloys have become promising materials in the medical field, particularly in tissue engineering applications. To solve the lack of durability, the production of calcium phosphate coatings onto the magnesium alloys is under research worldwide. Specifically, the electrodeposition processes using the magnesium alloy as electrode material, are among the most interesting production methods found on the recently published research. The electrodeposition methods present many parameters that influence the quality of the final product and due to it the published literature presents a large scatter of results obtained with the same method. In this article four commonly used electrodeposition methods, i.e. the constant potential method, the pulsed potential method, the constant current method and the current pulsed method, have been evaluated to optimize the electrical parameters that are essential to achieve smooth uniform coatings with high reproducibility and simplicity of operation. Scanning Electron Microscopy (SEM) and X-ray diffraction have been used to characterise the obtained coating material. Using the constant current and the current pulsed methods, smooth uniform coatings have been obtained onto AZ31 alloy when a current density in a specific range is used (0.1-0.3 mA·mm− 2). These deposits are formed by plate-form particles of brushite. Using the current pulsed method plate growth of particles is observed when low frequencies (50 Hz) and high frequencies (1000 Hz) are used. The employment of various steps in that deposition method, applying the same current density range, confirms an increase of the layer thickness.