220 research outputs found

    The Electrochemical and Corrosion Behavior of Biocompatible Magnesium Alloy in simulated body fluid

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    poster abstractMagnesium alloys are newly promising biomaterials for human bone replacement or repair. However, magnesium alloy need more resistant to corrosion when it is implant in human body. In this investigation, protective microarc oxidation (MAO) coatings were generated on AZ31 Mg alloys in sodium phosphate electrolyte. The coating were produced under various applied voltage. The corrosion behavior of MAO was analyzed in this study. Optimization of the MAO controlling parameters would provide a higher corrosion resistance on AZ31 magnesium alloy. A seven-day-immersion test was applied on both uncoated Mg alloy and MAO-coated Mg alloy. To evaluate the corrosion properties, the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) experiments were used in this research. The degrading rate of the MAO-coated AZ31 alloy is reduced because MAO coating and the corroding product layer protected the substrate and declined the reflecting rate. The corrosion process and mechanism of MAO-coated AZ31 alloys in SBF were modeled according to the electrochemical corrosion results and surface analysis. Under optimized controlling parameters, it is to be sure that the MAO-coated AZ31Mg alloy is superior on material which are implanted in human body for biomedical applications

    Electrochemical Behavior of Micro-arc Oxidation Coated Magnesium Alloy in Cell Culture Medium

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    poster abstractThe electrochemical behaviors of MAO (micro-arc oxidation) coated AZ31 magnesium alloys immersed in cell culture medium are reported. Four different MAO processing times (1 minute, 5 minutes, 15 minutes and 20 minutes) were used to produce the MAO coatings on AZ31 magnesium alloy sample surface. After cell culture medium immersion tests, all samples demonstrate similar electrochemical behaviors regardless of MAO processing time, which is in contrast with immersion in simulated body fluids. The corrosion rates in cell culture medium are much lower than in simulated body fluid. This can be explained by the organic molecules in the cell culture medium and a dense passive layer formed on the samples surface, which prevent aggressive ions, such as chloride ions, from corroding the alloy substrate

    Micro power management of active 802.11 network interfaces

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    Micro power management (muPM), a standard-compliant MAC level solution to save power for active 802.11 interfaces is developed. muPM enables an 802.11 interface to enter unreachable power-saving modes even between MAC frames, without noticeable impact on the traffic flow. To control data loss, muPM leverages the retransmission mechanism in 802.11 and controls frame delay to adapt to demanded network throughput with minimal cooperation from the access point. Extensive simulation has been conducted to systematically investigate an effective and efficient implementation of muPM. A prototype muPM on an open-access wireless hardware platform has been presented. Measurements show that more than 30% power reduction for the wireless transceiver can be achieved with muPM for various applications without perceptible quality degradation

    A Natural Wind Defrosting, Nano-coated Antibacterial Self-cleaning Energy-saving Health Air-cooled Refrigerator

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    The air-cooled frost-free household refrigerator is popular in the market because of its large size and frost-free size. However, the evaporator defrost process consumes a large amount of electrical energy to limit the wide spread of this refrigerator, at the same time because of its structural problems, resulting in its evaporator, air duct can not be artificially cleaned, leading to the growth of bacteria, pollution of food storage. This research has developed a self-cleaning energy-saving health refrigerator that uses indoor natural wind defrosting, ultra-hydrophilic nano-titanium dioxide coating photocatalytic sterilization and sterilization. After experimental comparison, under the same operating time of the same operating conditions, the refrigeration mode saves 1.5%, the defrost process saves 95%, reduces the amount of frosting by 23%, the temperature changes of the freezer is less than 7 ℃ , and the desterilization rate of nano-coated reaches 80%

    Effect of microarc oxidation time on electrochemical behaviors of coated bio-compatible magnesium alloy

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    Magnesium alloys are newly promising biomaterials with potential application of human bone replacement. However, there is a drawback due to their high corrosion rates. In this study, AZ31 magnesium alloys were coated using microarc oxidation (MAO) process. Two oxidation durations, 1 minute and 5 minutes, were used. The samples were immersed in the simulated body fluid (SBF) for up to seven days. Then the electrochemical behaviors of the two samples were comparatively investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) experiments were used. The results show that the 5-minute MAO coated sample had a better corrosion resistance than the 1-minute MAO coated sample. The study shows processing parameters, e.g., oxidation time, can be used to design an optimized MAO-coated magnesium alloy with controlled corrosion rates