No abstract

Magnesium and its alloys are potential biodegradable materials due to their outstanding biological performance, but their poor corrosion resistance greatly limits their applications as bone implants. This paper investigates the influence of in situ magnesium oxide coating on corrosion resistance of pure magnesium in normal saline. It was discovered by SEM that rough and porous oxide coatings were obtained on the surface of the pure magnesium after heat-treated at 400~500°C and the samples were severely corroded after immersion in 0.9 wt.% NaCl solution for 3 days. It also showed that the weight loss rates of the treated pure magnesium (TPM) samples were about 5~6 times higher than that of the untreated pure magnesium (UPM) sample. Electrochemical measurements showed that the corrosion current density (icorr) of the TPM samples was one order of magnitude higher than that of the UPM sample.

Novel K2Ti6O13 nanowires were successfully synthesized by a new method， that is sol-gel/ hydrothermal combined method. The crystal structure and morphology of the products were characterized by a series of methods including XRD, SEM, EDX and TEM. The results indicate that the products synthesized are K2Ti6O13 nanowires. The diameter is about 5nm, and its length is in the range of from a few micrometers to hundreds of micrometers. The TiO2 nanoparticles synthesized via a sol-gel method, as hydrothermal reaction precursors, play an important decisive role on the diameter of K2Ti6O13 nanowires and the hydrothermal reaction rate. Photocatalytic degradation of MB in presence of the K2Ti6O13 nanowires was compared with that in presence of the TiO2 nanoparticles. The results show that the nanowires have better photocatalytic activity.

The TiO2 nanotube array film was synthesized on the surface of Ti-Nb-Zr-Mo βTitanium alloy via anodic oxidation in single electrolytic solution only containing HF. The diameter of TiO2 nanotubes was 30-50nm, and the length was 240nm. Compared with the processing parameters (including anodizing voltage, reaction time, concentration and kinds of electrolytic solution) used for pure Titanium or Ti-6Al-4V alloy, the parameters was further optimized. The surface morphology and element compositions Ti-Nb-Zr-Mo alloy before and after anodic oxidation were observed and analyzed by a scanning electron microscope (SEM) and an energy dispersive X-ray (EDX) spectrometer. The antibacterial property of TiO2 nanotube array film prepared with optimal conditions was evaluated by coculture in vitro between Actinomyces viscosus and materials tested. The results indicated that the TiO2 nanotube array film had very good antibacterial activity to resist Actinomyces viscosus. TiO2 nanotube array film/Ti-Nb-Zr-Mo βTi alloy biocomposite will be an more excellent dental implant owning good biomechanical adaptability, biocompatibility and antibacterial property.

A binary Mg-4Zn alloy was fabricated as a potential degradable biomaterial. To improve the corrosion resistance of Mg-4Zn alloy, an amorphous micro-arc oxidation (MAO) coating was prepared on the Mg-4Zn substrate. Electrochemical measurements and immersion tests were employed to evaluate the corrosion resistance of the specimen in simulated body fluid (SBF). Electrochemical measurements show that the Mg-4Zn alloy covered with a MAO coating has a much lower corrosion current density and a much greater polarization resistance. Immersion tests suggest that the degradation of Mg-4Zn substrate is relatively serious during the initial 8 h of immersion although it has been protected by a MAO coating. When most micro-pores within the MAO coating have been filled with precipitates resulted from the corrosion of the metal substrate, the degradation of the Mg-4Zn substrate is significantly delayed.