S. Kaabi Falahieh Asl, S. Nemeth, and M. J. Tan, "Hydrothermal Deposition of Bio-resorbable Calcium-Phosphate Coating on AZ31 Magnesium for Implant Application", International Conference on Metallurgical Coatings and Thin Films (ICMCTF). 28-Apr-2014 to 02-May-2014, San Diego, USA
Abstract:
Interest in biodegradable magnesium (Mg) implants has increased dramatically in the last decade due to their desirable mechanical properties that are close to that of human bone, thus avoiding stress shielding effect. In addition, Mg is resorbed in the body and surgery to remove the implant after healing is not needed. However, the high corrosion rate of magnesium and its alloys severely limit their practical applications as implants. To control the corrosion rate of magnesium, biocompatible and bioresorbable Ca-P (calcium phosphate) coatings were deposited in this study using AZ31 magnesium substrate and hydrothermal deposition process. Coatings obtained at various temperatures were found to mainly consist of a mixture of monetite [CaHPO4] and tricalcium phosphate [Ca2.86Mg0.14(PO4)2] with partially magnesium substituted tricalcium phosphate structure as determined by XRD (X-ray diffraction) and FTIR (Fourier transform infrared) spectroscopy methods. Coating morphology was examined with scanning electron microscopy (SEM) and the results showed
that coatings became denser with increasing temperature. Coating adhesion was examined by pull-out
adhesion test indicating only coating cohesive failure at 5.2-5.8 MPa. It was clearly observed that significant
portion of the coating still remained on the substrate after adhesion test. Potentiodynamic polarization
conducted in SBF (simulated body fluid) solution confirmed that coating significantly enhanced the corrosion performance of Mg substrate. The corrosion current density of Mg substrate decreased approximately
10,000-fold in the presence of coating. The mass loss for the coated samples was only around 1/3
of that observed for bare substrate, and the amount of Mg ions released from the coated samples was significantly lower than in case of bare substrate after immersion in SBF solution. The described hydrothermal
method provided crystalline and compact coatings with excellent adhesion strength and significantly
improved corrosion resistance with good prospects for biomedical application.
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Funding Info:
This research was supported by A*STAR, under its Singapore International Graduate Award (SINGA) scheme; by Singapore Institute of Manufacturing Technology, A*STAR; and Nanyang Technological University. Grant number is not applicable.
Description:
The provided article is a description of the research presented at the conference.