Hydrothermal Preparation Of LDH Coatings On Magnesium Alloy Surface And Their Structure And Properties

Magnesium（Mg）alloys have the advantages of high specific strength,good toughness,and biodegradability,which are often used as orthopedic implant materials.However,Mg has active chemical properties and is prone to electrochemical corrosion,that is the main reason for the poor corrosion resistance of Mg alloys.In practical application of Mg alloys as metal implants,they are susceptible to bacterial infection,and the regulation of osteogenesis is not significant,resulting in implant failure,which seriously hinders its development.In order to solve the above problems,two layered double hydroxide（LDH）coatings were prepared on the surface of AZ91D alloy by hydrothermal method.The biological properties of Mg alloys in antibacterial and osteogenic differentiation were investigated.The main conclusions are as follows:（1）Mg（Cu）-Al-LDH coatings with regular hexagonal morphology and uniform distribution were prepared on the surface of AZ91D by hydrothermal method under the conditions of molar ratio n(Mg²⁺:Cu²⁺)=3:1,pH=10.0,T=100℃,to obtain Mg（Cu）-Al-LDH/AZ91D（Mg（Cu）-LDH/AZ91D）samples.The corrosion resistance of the Mg alloy modified by the Mg（Cu）-LDH coating has been effectively improved,the corrosion inhibition efficiency of AZ91D reaches 92.26%;the results of the hydrogen evolution experiment show that the Mg（Cu）-LDH coating has a long-term protective effect on the AZ91D.After 14 days,the total hydrogen evolution of Mg（Cu）-LDH/AZ91D was only 38.44%,and the corrosion rate accounted for 41.52%of which of AZ91D.Because the coating contains Cu²⁺with bactericidal function,it has strong antibacterial properties against Escherichia coli and Staphylococcus aureus,and the antibacterial rate is over 85%.（2）Uniformly dispersed and dense Mg-Fe-LDH（Fe-LDH）coatings were synthesized under the conditions of molar ratio n(Mg²⁺:Fe³⁺)=2:1,pH=10.0,T=100℃and obtained Mg-Fe-LDH/AZ91D（Fe-LDH/AZ91D）samples.The Fe-LDH modified Mg matrix also showed good corrosion resistance,and the corrosion resistance efficiency to the Mg matrix was as high as 96.04%;after long-term immersion,there was only a little degradation on the surface of Fe-LDH/AZ91D,while AZ91D is fully corroded.Different Fe-LDH/AZ91D extract concentrations（30%,60%,90%）had good cell viability,and slightly promoted the osteogenic differentiation of human osteosarcoma（Sa OS-2）cells,but did not show significant difference.The results of this paper provide a theoretical basis and practical guidance for the research and development of LDH as a surface modification coating of Mg-based metal implants in antibacterial and bone functionalization.42 Figures,6 Tables and 156 References...