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Register a new userAnticorrosion and biocompatibility of a functionalized layer formed on ZK60 Mg alloy via hydroxyl ion implantation
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Magnesium and its alloys have aroused tremendous interests because of their promising mechanical properties and biocompatibility. However, their excessively fast corrosion rate hinders the development of Mg alloys in the biomedical fields. Inspired by conventional ion implantation, a less-toxic functional group (hydroxyl) is used as the ion source to bombard the ZK60 Mg alloy surface to form a functionalized oxide layer. This functionalized oxide layer significantly facilitates the corrosion resistance of the ZK60 Mg alloy substrate and the proliferation of MC3T3-E1 cells, which is confirmed by electrochemical, immersion, and in vitro cytocompatibility tests. In comparison with results of ZK60 alloy implanted with carboxyl ions in our previous work, it is concluded that hydroxyl-treated alloys exhibit slightly higher corrosion rate while better biocompatibility. In summary, less-toxic functional ion implantation can be an effective strategy for inhibiting corrosion of Mg alloy implants and promoting their biocompatibility.
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Magnesium alloys have been considered to be potential biocompatible metallic materials. Further improvement on the anti-corrosion is expected to make this type of materials more suitable for biomedical applications in the fields of orthopedics, cardiovascular surgery and others. In this paper, we introduce a method of carboxyl ion (COOH+) implantation to reduce the degradation of ZK60 Mg alloy and improve its functionality in physiological environment. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) experiments show the formation of a smooth layer containing carbaxylic group, carbonate, metal oxides and hydroxides on the ion implanted alloy surface. Corrosion experiments and in vitro cytotoxicity tests demonstrate that the ion implantation treatment can both reduce the corrosion rate and improve the biocompatibility of the alloy. The promising results indicate that organic functional group ion implantation may be a practical method of improving the biological and corrosion properties of magnesium alloys.
Magnesium alloys have been considered to be favorable biodegradable metallic materials used in orthopedic and cardiovascular applications. We introduce NH+2 to the AZ31 Mg alloy surface by ion implantation at the energy of 50 KeV with doses ranging from 1e16 ions/cm2 to 1e17 ions/cm2 to improve its corrosion resistance and biocompatibility. Surface morphology, mechanical properties, corrosion behavior and biocompatibility are studied in the experiments. The analysis confirms that the modified surface with smoothness and hydrophobicity significantly improves the corrosion resistance and biocompatibility while maintaining the mechanical property of the alloy.
Ge-Sn alloys with a sufficiently high concentration of Sn is a direct bandgap group IV material. Recently, ion implantation followed by pulsed laser melting has been shown to be a promising method to realize this material due to its high reproducibility and precursor-free process. A Ge-Sn alloy with ~9 at.% Sn was shown to be feasible by this technique. However, the compressive strain, inherently occurring in heterogeneous epitaxy of the film, evidently delays the material from the direct bandgap transition. In this report, an attempt to synthesize a highly-relaxed Ge-Sn alloy will be presented. The idea is to produce a significantly thicker film with a higher implant energy and doses. X-ray reciprocal space mapping confirms that the material is largely-relaxed. The peak Sn concentration of the highest dose sample is 6 at.% as determined by Rutherford backscattering spectrometry. Cross-sectional transmission electron microscopy shows unconventional defects in the film as the mechanism for the strain relaxation. Finally, a photoluminescence (PL) study of the strain-relaxed alloys shows photon emission at a wavelength of 2045 nm, suggesting an active incorporation of Sn concentration of ~6 at.%. The results of this study pave way to produce high quality relaxed GeSn alloy using an industrially scalable method.
Increasing pressure on the power industry to reduce carbon emissions has led to increased research into the use of biomass feedstocks. This work investigates the effects of HCl and KCl, key species influencing biomass boiler corrosion, on a laser clad coating of the FeCrAl alloy Kanthal APMT. In-Situ SEM exposure of the coating at 450 oC for 1 h was performed to investigate the initial effects of KCl on the corrosion process. The same coatings were exposed to 250 h exposures in both an air environment and a HCl rich environment. The influence of KCl was investigated in both. Evidence of a slow growing aluminium oxide was observed. It was found that HCl allowed chlorine based corrosion to occur suggesting it can interact from the gas phase. It was also observed that the presence of both HCl and KCl reduced the mass gain compared to KCl in an air environment.
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