Research On Preparation Of Glutamate-Modified Hydrotalcite And Its Corrosion Inhibition To Magnesium Alloy

Magnesium alloys have widely potential applications in clinical medicine due to their advantages such as high specific strength,low density,and good biocompatibility.However,the active chemical property of magnesium makes it extremely susceptible to corrosion in complex internal environments.Therefore,how to improve the corrosion resistance of magnesium alloys have always been a research hotspot and a problem that needs to be solved in clinical applications.In this paper,glutamic acid with good biocompatibility is combined with layered double hydroxide(LDH)with good corrosion resistance to improve the corrosion resistance and biocompatibility of magnesium alloys.Firstly,glutamic acid intercalated LDH was synthesized by co-precipitation method.The effects of pH,stirring time,and aging time on the structure,thermal stability,and adsorption performance of LDH were investigated.Secondly,the composite coating which was formed by poly-L-glutamic acid(PGA)and LDH was prepared on the surface of magnesium alloy.The effect of immersion time in PGA solution during the preparation process on corrosion resistance of coatings was investigated.The cytotoxicity of the sample was tested.Finally,the effect of the preparation method on the structure and corrosion resistance of the glutamic acid intercalated LDH coating was studied.The experimental results showed that the pH value of solution had a great effect on the glutamic acid intercalated LDH synthesised.Stirring time and aging time had an insignificant effect on the structure of glutamic acid intercalated LDH.The glutamic acid ions were monolayered and inclined between LDH structure layers.In this experiment,the best synthesis process was to stir for 12 h and age for 12 h at the initial pH value.The composite coatings after poly-L-glutamic acid(PGA)modified LDH were denser and smoother than LDH.The PGA and LDH were combined by chemical bond.The optimal immersion time in the PGA solution was 30 minutes.At this time,the sample coated with the composite coating showed the best corrosion resistance.The presence of PGA reduced the toxicity of the sample to mouse embryonic fibroblasts.It was found that a glutamic acid intercalated LDH coating was synthesized by ion exchange method duiring hydrothermal condition.Corrosion resistance of the coated sample was improved Finally,the formation mechanism and corrosion mechanism of Glu/LDH-2 coating was studied.