Developments in anticorrosive organic coatings modulated by nano/microcontainers with porous matrices.

The durability and functionality of many metallic structures are seriously threatened by corrosion, which makes the development of anticorrosive coatings imperative. This state-of-the-art survey explores the recent developments in the field of anticorrosive organic coatings modulated by innovations involving nano/microcontainers with porous matrices. The integration of these cutting-edge delivery systems seeks to improve the protective properties of coatings by enabling controlled release, extended durability, targeted application of corrosion inhibitors, and can be co-constructed to achieve defect filling by polymeric materials. The major highlight of this review is an in-depth analysis of the functionalities provided by porous nano/microcontainers in the active protection and self-healing of anticorrosive coatings, including their performance evaluation. In one case, after 20 days of immersion in 0.1 M NaCl, a scratched coating containing mesoporous silica nanoparticles loaded with an inhibitor benzotriazole and shelled with polydopamine (MSNs-BTA@PDA) exhibited coating restoration indicated by a sustained corrosion resistance rise over an extended period monitored by impedance values at 0.01 Hz frequency, rising from 8.3 × 104 to 7.0 × 105 Ω cm2, a trend assigned to active protection by the release of inhibitors and self-healing capabilities. Additionally, some functions related to anti-fouling and heat preservation by nano/microcontainers are highlighted. Based on the literature survey, some desirable properties, current challenges, and prospects of anticorrosive coatings doped with nano/microcontainers have been summarized. The knowledge gained from this survey will shape future research directions and applications in a variety of industrial areas, in addition to advancing smart corrosion prevention technology.

Recent Advances on Development of Hydroxyapatite Coating on Biodegradable Magnesium Alloys: A Review.

The wide application of magnesium alloys as biodegradable implant materials is limited because of their fast degradation rate. Hydroxyapatite (HA) coating can reduce the degradation rate of Mg alloys and improve the biological activity of Mg alloys, and has the ability of bone induction and bone conduction. The preparation of HA coating on the surface of degradable Mg alloys can improve the existing problems, to a certain extent. This paper reviewed different preparation methods of HA coatings on biodegradable Mg alloys, and their effects on magnesium alloys' degradation, biocompatibility, and osteogenic properties. However, no coating prepared can meet the above requirements. There was a lack of systematic research on the degradation of coating samples in vivo, and the osteogenic performance. Therefore, future research can focus on combining existing coating preparation technology and complementary advantages to develop new coating preparation techniques, to obtain more balanced coatings. Second, further study on the metabolic mechanism of HA-coated Mg alloys in vivo can help to predict its degradation behavior, and finally achieve controllable degradation, and further promote the study of the osteogenic effect of HA-coated Mg alloys in vivo.

The mechanical property and corrosion resistance of Mg-Zn-Nd alloy fine wires in vitro and in vivo.

Titanium and its alloy are commonly used as surgical staples in the reconstruction of intestinal tract and stomach, however they cannot be absorbed in human body, which may cause a series of complications to influence further diagnosis. Magnesium and its alloy have great potential as surgical staples, because they can be degraded in human body and have good mechanical properties and biocompatibility. In this study, Mg-2Zn-0.5Nd (ZN20) alloy fine wires showed great potential as surgical staples. The ultimate tensile strength and elongation of ZN20 alloy fine wires were 248 MPa and 13%, respectively, which could be benefit for the deformation of the surgical staples from U-shape to B-shape. The bursting pressure of the wire was about 40 kPa, implying that it can supply sufficient mechanical support after anastomosis. Biochemical test and histological analysis illustrated good biocompatibility and biological safety of ZN20 alloy fine wire. The residual tensile stress formed on the outside of ZN20 fine wire during drawing would accelerate the corrosion. The second phase had a negative influence on corrosion property due to galvanic corrosion. The corrosion rate in vitro was faster than that in vivo due to the capsule formed on the surface of ZN20 alloy fine wire.

Influence of stamping on the biodegradation behavior of Mg-2Zn-0.5Nd (ZN20) sheet.

Stamping processing is commonly used to form medical devices and implant. However, for biodegradable Mg alloy, the stamping will influence the degradation behavior because of the change in microstructure after stamping. So in this study, the As-rolled Mg-2Zn-0.5Nd alloy (ZN20) was processed by stamping. The microstructure, crystallographic orientation and corrosion performance of this processing method was investigated to reveal the influence of the stamping process on the degradation rate of Rolled Mg-2Zn-Nd (ZN20). The degradation rate was measured by immersion of the Mg-2Zn-0.5Nd alloy in simulated body fluid using Electrochemical Impedance Spectroscopy, Potentiodynamic polarization and mass loss. The in vitro degradation result shows that the degradation rate of the Rolled Mg-2Zn-0.5Nd increased from 0.2 mm/year to 0.5 mm/year after stamping processing. The result reveals that the activation of the { 10 1 ‾ 2 } tension twin during stamping can remarkably weaken the { 0001} basal texture and have a significant influence on the corrosion rate of Stamped Mg-2Zn-0.5Nd sheet. After removing the deformation by annealing, the degradation rate was reduced to 0.15 mm/year. This work is expected to prompt better microstructural design of biomedical Mg in order to control its degradation behavior for biomedical application.

In vitro degradation and antibacterial property of a copper-containing micro-arc oxidation coating on Mg-2Zn-1Gd-0.5Zr alloy.

Copper (Cu) has a good antibacterial effect and micro-arc oxidation (MAO) coating has good corrosion resistance for magnesium (Mg) alloys. If they are combined together, the coated Mg alloy is expected to have both good corrosion resistance and antibacterial effect. In this work, the degradation, antibacterial property and cytotoxicity of a Cu-containing MAO coating on an extruded Mg-2Zn-1Gd-0.5Zr alloy were systematically studied. The results revealed that the addition of Cu could further improve the degradation resistance of MAO coated alloy. After two weeks immersion, the corrosion rate of Cu + MAO coated alloy was 0.16 mm/y, lower than those of both MAO coated and uncoated alloy. The release of Cu2+ from Cu + MAO coated alloy inhibited the bacterial proliferation. After 12 h co-culture, the antibacterial rate reached 96%. Cytotoxicity test (MG63 cell) showed that Cu + MAO coated alloy had good biocompatibility. The Cu + MAO coating has great potential for application on Mg alloys due to its good corrosion resistance, antibacterial property and good biocompatibility.

Mechanical properties of magnesium alloys for medical application: A review.

Magnesium alloys as a class of biodegradable metals have great potential to be used as implant materials, which attract much attention. In this review, the mechanical properties of magnesium alloys for medical applications are summarized. The methods to improve the mechanical properties of biodegradable magnesium alloys and the mechanical behaviors of Mg alloys in biomedical application are illustrated. Finally the challenges and future development of biodegradable magnesium alloys are presented.