HA and HA/Col were prepared by a solution treatment on AZ31 magnesium alloy. The microstructure and composition of coatings were studied by SEM, XRD. In vitro study was performed by immersion the sample In Hank’s solution for 7 days. The H2 evolution of the HA/col coating was as low as 0.24 ml/cm2 which can insignificant increase the corrosion resistance of AZ31.
Magnesium-substituted hydroxyapatite coatings have been deposited on magnesium alloy for biomedical applications by sol–gel technology. The Ca(10−x)Mgx(PO4)6(OH)2 coatings obtained, with magnesium contents up to x = 1.5, show dense and compact and with visible cracks. The results of Hydrogen (H2) evolution testing in Hank’s solution show that magnesium-substituted hydroxyapatite coatings can improve the corrosion resistance of magnesium alloy.
HA and HA+Y2O3 films were prepared by pulsed laser deposition. The microstructure and composition of films were studied by EPMA, XRD, AFM and SEM. In vitro study was performed by immersing the sample in simulate body fluid (SBF) in different days. There are more droplets on films prepared by HA+Y2O3 target than that of HA. And addition of Y2O3 can decrease the size of crystal grains. The XRD results show that the peaks corresponding to HA slightly shift to lower angel which indicates the HA lattice distorting due to addition of Y2O3. The critical load of the films increases from 10.3N to 13N when Y2O3 added. The film prepared by target HA+Y2O3 shows a higher resistance to dissolution and the precipitated grain size is small. New precipitated phases have similar functional groups with the original films.
Y, Zn and Ca were selected to develop a Magnesium alloy, Mg-Y-Ca-Zn for biomedical application due to the good biocompatibility of Zn and Ca elements. Microstructure, mechanical properties and corrosion properties of the Mg-Y-Ca-Zn alloy have been investigated using both optical and scanning electron microscope. In the as-cast condition, primary α-Mg matrix and second phase are mainly distributed along grain boundary. After solution treatment, the distribution of second phase decreased and after aging, there are many second phases precipitated along the grain boundary and inside the grains. The hardness of as-cast samples was low and increased after solution treatment and aging. An aged sample had more corrosion resistance than as-cast and solution treatment alloys.
A dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD) coating is prepared to reduce the biodegradation rate of Mg–Ca–Zn alloy. The substrate is immersed into a solution with Ca(NO3)2·4 H2O 0.1 mol/L and Na3PO4 0.1 mol/L to obtain calcium phosphate coating. Surface morphology is observed by scanning electron microscopy (SEM). Chemical composition is determined by X-ray diffraction (XRD) and EDX. The biodegradable behavior is investigated by immersion tests. The results show that calcium phosphate coating consists of many flake particles and with immersion time increasing, the coating thickness increased and became more uniform and smooth. The coating can reduce the biodegradation rate of Mg alloys in Hank’s.
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