Corrosion Controlling Of A Surface-immobilized Amino Trimethylene Phosphonic Acid(ATMP)Coating On Biodegradable Magnesium

Magnesium and its alloys have be wildly used in temporary implantation device because of their biodegradability,good biocompatibility and excellent mechanical property.At the present,the main factor limit the application of biodegradable magnesium-base implant is its rapid corrosion rate.This will lead to accumulation of local hydrogen bubbles and increase pH value thereby hindering the healing of tissues and organs.Severe local corrosion will cause the implant device loose its mechanical properties prematurely.In order to improve the corrosion resistance of magnesium.A uniform and dense organ-phosphonate film,amino trimethylene phosphonic acid(ATMP),was deposited on alkaline pretreated magnesium through dip-coating.The ATMP molecular were covalently surface-immobilized on the alkaline pretreated Mg and then spontaneously deposited by participation in a chelating reaction with Magnesium and its alloys have be wildly used in temporary implantation device because of their biodegradability,good biocompatibility and excellent mechanical property.At the present,the main factor limit the application of biodegradable magnesium-base implant is its rapid corrosion rate.This will lead to accumulation of local hydrogen bubbles and increase pH value thereby hindering the healing of tissues and organs.Severe local corrosion will cause the implant device loose its mechanical properties.The surface morphology cross-section chemical composition and structure of ATMP coating were obtain by optical microscopy,scanning electron microscopy,Fourier transform infrared spectroscopy and X-ray electron spectroscopy.Those results showed a homogeneous and dense ATMP coating formed on alkaline pretreated Mg surface by surface-immobilizing and chelating reaction.The ATMP coating showed a strong adhesion strength with the magnesium matrix and hydrophilic properties by tape bonding test and water contact test.The result of potential dynamic polarization test showed that the ATMP coating can significantly reduce the self-corrosion current(icorr).That means the ATMP coating can improve the anticorrosion ability of magnesium by hinder the invasion of corrosion medium.The electrochemical impedance spectra(EIS)and the surface morphology after polarization testing showed the ATMP coating has a good ability to resist local corrosion.The long-term immersion test in simulation human fluid(PBS)showed that the ATMP coating can decrease the hydrogen evolution significantly.And the pH value keep a lower level than pure magnesium.After the ATMP coating modified pure magnesium corrosion resistance was significantly improved.The main reason is that a homogeneous and dense coating which has three-dimensions metal-organic frameworks has formed on magnesium by surface immobilized and chelation reaction...