Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM...Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM60B magnesium alloy in order to provide sufficient protection against the corrosion.The first composite(Ti-Zr/hybrid)was obtained via combination o f a hybrid sol-gel film(synthesized by mixing tetraethoxysilane(TEOS),and 3-glycidyloxypropyl-trimethoxysilane(GPTMS))as outer layer and Ti-Zr conversion coating as primer.Also,the second composite(Ti-Zr/PTMS)was applied in a similar manner by combination o f phenyl-trimethoxysilane(PTMS)so lgel film with the Ti-Zr conversion coating.The morphology and elemental composition of the Ti-Zr conversion film were assessed by the Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS),respectively.A cracky conversion film was applied on the alloy surface after immersion in the Ti-Zr conversion coating bath which was mainly composed of MgO,T i02,Zr02,and MgF2 compounds.Uniform,but not-adherent PTMS and hybrid sol-gel films(pure sol-gel films)with obvious defects were directly deposited onto the magnesium alloy without the Ti-Zr pretreatment which were morphologically characterized by the SEM.However,formation o f relatively uniform and completely defect-free Ti-Zr/hybrid and Ti-Zr/PTMS composites after using the Ti-Zr conversion coating as pretreatment was revealed by the SEM observations.In addition,the defects of the Ti-Zr conversion coating were completely filled by the sol-gel layers.The Ti-Zr/PTMS and Ti-Zr/hybrid composite coatings were provided much better corrosion protection capacity than the pure PTMS and hybrid sol-gel films,respectively which was confirmed by the Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)examinations in 0.05 M NaCl solution.展开更多
Sol-gel coatings containing various amounts of hydroxylated nanodiamond(HND)particles were applied on the magnesium alloy for corrosion protection.The micrometric defects in the sol-gel coating completely disappeared ...Sol-gel coatings containing various amounts of hydroxylated nanodiamond(HND)particles were applied on the magnesium alloy for corrosion protection.The micrometric defects in the sol-gel coating completely disappeared after adding 0.01,0.02 and 0.05 wt.%of the HND nanoparticles.The AFM analyses showed that average roughness of the sol-gel film is about 6.7 nm which increases to 16.1 and 20.2 nm after incorporating 0.005 and 0.02 wt.%of the HNDs,respectively.The corrosion resistance of the coatings was tested in Harrison’s solution by means of EIS technique after 15,30,60 and 120 min immersion.The corrosion resistance of the sol-gel coating was remarkably enhanced by incorporating different contents of the HNDs and the best result was obtained for 0.01 wt.%.The results of the EIS experiments were confirmed by the potentiodynamic polarization tests.The corrosion resistance enhancement was attributed to the film compactness(due to the chemical interaction with the HNDs),formation of tortuous pathways for diffusion of the corrosive solution,and filling of the defects by the nanoparticles.However,the beneficial effect of the HNDs on the corrosion resistance gradually diminished as the content of nanoparticle was increased.Finally,the micromorphology of the sol-gel nanocomposites was studied after the corrosion tests.展开更多
Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectr...Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.展开更多
Objective： Since appropriate and time- table methods in trauma care have an important impact on patients＇ outcome, we evaluated the effect of Advanced Trauma Life Support （ATLS） program on medical interns＇ perfor...Objective： Since appropriate and time- table methods in trauma care have an important impact on patients＇ outcome, we evaluated the effect of Advanced Trauma Life Support （ATLS） program on medical interns＇ performance in simulated trauma patient management. Methods： A descriptive and analytical study before and after the training was conducted on 24 randomly se- lected undergraduate medical interns from Imam Reza Hospital in Mashhad, Iran. On the first day, we assessed in- terns＇ clinical knowledge and their practical skill performance in confronting simulated trauma patients. After 2 days of ATLS training, we performed the same study and evaluated their score again on the fourth day. The two findings, pre- and post- ATLS periods, were compared through SPSS version 15.0 software. P values less than 0.05 were considered statistically significant. Results： Our findings showed that interns＇ ability in all the three tasks improved after the training course. On the fourth day after training, there was a statistically significant increase in interns＇ clinical knowledge of ATLS procedures, the sequence of procedures and skill performance in trauma situations （P〈0.001, P=0.016 and P=0.01 respectively）. Conclusion： ATLS course has an important role in increasing clinical knowledge and practical skill performance of trauma care in medical interns.展开更多
文摘Application o f defect-free,adherent,and corrosion protective sol-gel film on the magnesium alloys is generally difficult.In this study,two novel sol-gel/conversion coating composites were successfully deposited on AM60B magnesium alloy in order to provide sufficient protection against the corrosion.The first composite(Ti-Zr/hybrid)was obtained via combination o f a hybrid sol-gel film(synthesized by mixing tetraethoxysilane(TEOS),and 3-glycidyloxypropyl-trimethoxysilane(GPTMS))as outer layer and Ti-Zr conversion coating as primer.Also,the second composite(Ti-Zr/PTMS)was applied in a similar manner by combination o f phenyl-trimethoxysilane(PTMS)so lgel film with the Ti-Zr conversion coating.The morphology and elemental composition of the Ti-Zr conversion film were assessed by the Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS),respectively.A cracky conversion film was applied on the alloy surface after immersion in the Ti-Zr conversion coating bath which was mainly composed of MgO,T i02,Zr02,and MgF2 compounds.Uniform,but not-adherent PTMS and hybrid sol-gel films(pure sol-gel films)with obvious defects were directly deposited onto the magnesium alloy without the Ti-Zr pretreatment which were morphologically characterized by the SEM.However,formation o f relatively uniform and completely defect-free Ti-Zr/hybrid and Ti-Zr/PTMS composites after using the Ti-Zr conversion coating as pretreatment was revealed by the SEM observations.In addition,the defects of the Ti-Zr conversion coating were completely filled by the sol-gel layers.The Ti-Zr/PTMS and Ti-Zr/hybrid composite coatings were provided much better corrosion protection capacity than the pure PTMS and hybrid sol-gel films,respectively which was confirmed by the Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)examinations in 0.05 M NaCl solution.
文摘Sol-gel coatings containing various amounts of hydroxylated nanodiamond(HND)particles were applied on the magnesium alloy for corrosion protection.The micrometric defects in the sol-gel coating completely disappeared after adding 0.01,0.02 and 0.05 wt.%of the HND nanoparticles.The AFM analyses showed that average roughness of the sol-gel film is about 6.7 nm which increases to 16.1 and 20.2 nm after incorporating 0.005 and 0.02 wt.%of the HNDs,respectively.The corrosion resistance of the coatings was tested in Harrison’s solution by means of EIS technique after 15,30,60 and 120 min immersion.The corrosion resistance of the sol-gel coating was remarkably enhanced by incorporating different contents of the HNDs and the best result was obtained for 0.01 wt.%.The results of the EIS experiments were confirmed by the potentiodynamic polarization tests.The corrosion resistance enhancement was attributed to the film compactness(due to the chemical interaction with the HNDs),formation of tortuous pathways for diffusion of the corrosive solution,and filling of the defects by the nanoparticles.However,the beneficial effect of the HNDs on the corrosion resistance gradually diminished as the content of nanoparticle was increased.Finally,the micromorphology of the sol-gel nanocomposites was studied after the corrosion tests.
文摘Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.
文摘Objective： Since appropriate and time- table methods in trauma care have an important impact on patients＇ outcome, we evaluated the effect of Advanced Trauma Life Support （ATLS） program on medical interns＇ performance in simulated trauma patient management. Methods： A descriptive and analytical study before and after the training was conducted on 24 randomly se- lected undergraduate medical interns from Imam Reza Hospital in Mashhad, Iran. On the first day, we assessed in- terns＇ clinical knowledge and their practical skill performance in confronting simulated trauma patients. After 2 days of ATLS training, we performed the same study and evaluated their score again on the fourth day. The two findings, pre- and post- ATLS periods, were compared through SPSS version 15.0 software. P values less than 0.05 were considered statistically significant. Results： Our findings showed that interns＇ ability in all the three tasks improved after the training course. On the fourth day after training, there was a statistically significant increase in interns＇ clinical knowledge of ATLS procedures, the sequence of procedures and skill performance in trauma situations （P〈0.001, P=0.016 and P=0.01 respectively）. Conclusion： ATLS course has an important role in increasing clinical knowledge and practical skill performance of trauma care in medical interns.
