Corrosion Behavior of Magnesium with Hydroxyapatite Coatings Formed by Hydrothermal Treatment

Abstract

Corrosion resistance of magnesium alloys must be improved for their applications to orthopaedic bioabsorbable devices. Since hydroxyapatite (HAp) is chemically stable in the body and is the main component of bones, HAp coatings have been well studied to improve the corrosion resistance and osteoconductivity of magnesium alloys. In this study, highly crystallized HAp coatings were formed on pure magnesium with a single-step hydrothermal treatment using a C 10 H 12 CaN 2 Na 2 O 8 solution with various pH values. Morphology of the HAp coating varied depending on the pH value. Corrosion behavior of the HAp-coated magnesium was investigated by anodic polarization, impedance and immersion tests in a simulated body fluid. It was revealed that the corrosion resistance of pure magnesium was improved more than 10 times with the HAp coatings. Stable localized corrosion was prevented with the HAp coatings although the occurrence and moderation of unstable localized corrosion appeared to take place at the defects of the HAp coatings. The initial protectiveness of the HAp coating depended on the treatment condition. During 4-day immersion, the precipitated HAp sealed the defects of the HAp coatings, resulting in the negligible release of magnesium ions regardless of the treatment conditions.

In vitro degradation behavior and cytocompatibility of biodegradable AZ31 alloy with PEO/HT composite coating

“…The HA coated magnesium substrate showed enhanced corrosion resistance in simulated body fluid [21]. Moreover, the HA coated magnesium samples showed enhanced cytocompatibility and mitigated the in vivo biodegradation of magnesium implant, particularly over the first 6 weeks of implantation, which considerably promoted bone growth at the interface between the implant and bone [22].…”

“…Recently, a hydrothermal treatment (HT) in solutions containing ethylenediaminetetraacetic acid calcium disodium salt hydrate (Ca-EDTA) and potassium dihydrogenphosphate (KH 2 PO 4 ) has been applied to fabricate hydroxyapatite (HA) coating on magnesium [20,21]. The HA coated magnesium substrate showed enhanced corrosion resistance in simulated body fluid [21].…”

Self-healing property of hydroxyapatite and octacalcium phosphate coatings on pure magnesium and magnesium alloy

“…Magnesium and its alloys are suitable for use as orthopaedic implant materials because they are bioabsorbable/biodegradable and therefore do not require surgical removal. They also have high specific strength and low Young's modulus (41)(42)(43)(44)(45) GPa) similar to that of bone (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) [1][2][3][4][5].…”

Direct and Rapid Quantification of Calcium Phosphate Precipitate on Titanium by X-Ray Fluorescence Analysis Using Fundamental Parameter Method

“…Hiromoto et al reported that experimental conditions such as the pH of the soaking solution could affect the nature of the precipitated hydroxyapatite. 38,39) Hence, control of the solution for precipitating CP might change the density of the resultant-precipitate layer. Therefore, our suggested method using XRF can be recommended as a simple and reliable tool to obtain the density of the CP-precipitate layer.…”