Electrophoretic deposition of syntetic and naturally synthesized hydroxyapatite on az31 magnesium alloy

In this thesis, AZ31, a magnesium alloy commonly used in the biomedical field, was used as the substrate material. Due to its low density (1.74gr/cm3), high biocompatibility and biodegradability and relatively good mechanical properties, AZ31 alloy offers significant potential for many fields of study. However, its low corrosion resistance limits its use, especially in the medical and biomedical fields. For these reasons, the surfaces of AZ31 implant material were coated with bioactive materials (synthetic -sHAp) and natural Hydroxyapatite (dHAp) to increase their corrosion resistance, taking into account biocompatibility. As coating materials, sHAp and hydroxyapatite dHAp, which was obtained from waste natural resources (chicken eggshell - YK, Ostrich eggshell - DK and Mussel shell -MK) produced by calcination and chemical synthesis method, ground into powder (̴ 35 µm). Such synthesized powders were coated on AZ31 surfaces in four different groups as biocompatible coating materials by electrophoretic deposition method(EPD). At the end of the coating processes, all samples were dried overnight and sintered at 450 o C in a control atmosphere furnace. The structure formation of EPD coatings on AZ31 surfaces using synthetic -commercial (sHAp) and dHAp powders obtained from natural waste shells were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy(FTIR) and Zeta potential analysis. The adhesion strength of the coatings of the four groups of samples with the substrate was analyzed comparatively. The effect of the coatings on the corrosion protection of Mg substrate against biological media was performed in vitro by potentiodynamic polarization (PDS) and three electrode technique, and the results were given comparatively. The surface structures of the samples before and after corrosion were characterized by SEM-EDX and XRD analysis. The hydrophobic/hydrophilic properties of the coatings were demonstrated by wettability analysis. As a result of the analyzes, after EPD coating and sintering processes the presence of Hydroxyapatite peaks on the substrate surfaces, before and after corrosion were shown that the coatings were successfull. From the adhesion tests, higher adhesion strength values were obtained from DK-dHAp group specimens than sHAp group specimens. Through the wettability analysis, DK-dHAp group was observed as superhydrophilic. According to the corrosion test results, compared to the other sHAp and dHAp groups, it was determined that the corrosion resistance of the DK coated samples was found to be more corrosion resistance. At the end of the mechanical, wear and corrosion tests and analyzes, it was concluded that the DK-dHAp is found the most suitable coating group for biomedical applications .