Influence of yttrium element on the corrosion behaviors of Mg-Y binary magnesium alloy

The influence of yttrium on the corrosion behavior of Mg–Y alloys has been investigated by electrochemical measurements,scanning electron microscope(SEM)observation,X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS)analysis in NaCl solution.The corrosion resistance decreased with increasing Y content due to increasing Y-rich zone.The solid-dissolved Y improved the chemical activity of the substrate which promoted the corrosion reaction by forming Y2O3.The corrosion resistance was improved by increasing the Y concentration of matrix and proper net Y-rich structure.The sample has the best corrosion resistance when all the Y element was dissolved into the matrix of Mg–5Y in 0.1 M NaCl.

In vitro corrosion of Mg-Ca alloy- The influence of glucose content

Influence of glucose on corrosion of biomedical Mg-1.35Ca alloy was made using hydrogen evolution, pH and electrochemical polarization in isotonic saline solution. The corrosion morphologies, compositions and structures were probed by virtue of SEM, EDS, FTIR, XRD and XPS. Results indicate that the glucose accelerated the corrosion of the alloy. The elemental Ca has no visible effect on the corrosion mechanism of glucose for the Mg-1.35Ca alloy in comparison with pure Mg. In addition, the presence of CO2 has beneficial effect against corrosion due to the formation of a layer of carbonate- containing products.

In vitro corrosion of Mg-6Zn-IMn-4Sn-1.5Nd/0.5Y alloys

The microstructure evaluation, surface morphology, chemical compositions and phase analysis of the biomedical Mg-6Zn-IMn-4Sn-1.5Nd/0.5Y （ZMT614- 1.5Nd/0.5Y） alloys were investigated by means of optical microscopy, EPMA, X-ray EDS, XRD and FTIR. The corrosion behavior was evaluated using weight-loss measurement, hydrogen evolution, electrochemical and pH measurements, The results demonstrate that the microstructure for both ZMT614-1,5Nd alloy and ZMT614-0.5Y alloy is characterized by α-Mg and intermetallic compounds, most of which are distributed along the grain boundaries. These second phases contain Mg2Zn, Mg2Zn11, Mg2Sn and single metal Mn, together with Mg12Nd phase for the ZMT614-1.5Nd alloy, and with Mg24Y5 phase for the ZMT614-0.5Y alloy. Honeycomb-like corrosion product layers form. The corrosion resistance of the ZMT614-0.5Y alloy is higher than that of the ZMT614-1.5Nd alloy, which is ascribed to the addition of the element Y into the alloy delaying the corrosion initiation in comparison to that of Nd element in the alloy.

Effect of Cl- Concentration on the SCC Behavior of 13Cr Stainless Steel in High-Pressure CO2 Environment

An effect of Cl-concentration on the stress corrosion cracking(SCC)behavior of 13 Cr stainless steel was investigated by employing electrochemical measurements and the slow strain rate tensile tests.These tests were conducted in various solutions with different concentrations of NaCl at 90℃ under 3 MPa CO2 with 3 MPa N2.The results indicate that the passive film of the specimen formed in the 10% NaCl solution has the best protective effect on the matrix.The SCC susceptibility does not increase with increasing the chloride ion concentration,the lowest SCC susceptibility occurs when the NaCl concentration is 10%,and the specimens show higher SCC susceptibility in the 5% NaCl and 20% NaCl solutions.

In vitro degradation of MAO/PLA coating on Mg-1.21Li-1.12Ca-1.0Y alloy

Magnesium and its alloys are promising biomaterials due to their biocompatibility and osteoinduction. The plasticity and corrosion resistance of commercial magnesium alloys cannot meet the requirements for degradable biomaterials completely at present. Particularly, the alkalinity in the microenvironment surrounding the degradation, implants, resulting from the arises a major concern. Micro arc oxidation （MAO） and poly（lactic acid） （PLA） composite （MAO/PLA）coating on biomedical Mg- 1.21Li-1.12Ca-1.0Y alloy was prepared to manipulate pH variation in an appropriate range. Surface morphologies were discerned using SEM EMPA. AM corrosion resistance was evaluated via electrochemical Polarization and impedance and hydrogen volumetric method. The results demonstrated that the MAO coating predomlnantly consisted of MgO, Mg2SiO4 and YzO3. The composite coating markedly improved the corrosion resistance of the alloy. The rise in solution pH for the MAO/PLA coating was tailored to a favorable range of 7.5-7.8 The neutrallzation caused by the alkalinity of MAO and Mg substrate and acidification of PLA was probed. The reSult designates that MAOI PLA composite coating on Mg-1.21Li-1.12Ca-1.0Y alloys may be a promising biomedical coating.