The Preparation Of Magnesium Alloy Materials Modified With Mechanical And Chemical Methods And Investigation Of Degradation Properties

Magnesium alloys have better biocompatibility and biodegradability than conventional biomedical metal materials,but the corrosion resistance is so poor that the implant loses its mechanical integrity before the damaged tissue completely recovers.The widespread use of magnesium alloys is restricted,so improved corrosion resistance is crucial for its application.This article chooses ZEK100 magnesium alloy as the research object,studies the basic mechanical properties of the material,and studies the corrosion behavior and corrosion mechanism through in vitro immersion experiments.The results show that mechanical parameters including average stress,stress amplitude,and loading history have a great influence on the uniaxial ratcheting behavior.In addition,pre-corrosion can significantly deteriorate the material's resistance to ratcheting.The ZEK100 magnesium alloy is pre-deformed with a high-pressure torsion process.A large number of cumulative shear strains are introduced during the treatment process.A series of mechanical properties and corrosion performance tests are performed on the treated material,and the microstructure evolution of the material is analyzed using microscopic methods.Corrosion mechanism.The results show that after high-pressure torsion treatment,many twins appear within the grain of the material,and the grain size is significantly refined.The refinement mechanism is mainly the twinning.The hydrogen evolution rate and hydrogen evolution volume of the ZEK100 magnesium alloy sample are significantly reduced.Electrochemical test results show that the self-corrosion potential of the material increases,the self-corrosion current decreases,and the corrosion resistance of the material significantly improves.In addition,the corrosion morphology and corrosion pattern of the material are greatly changed.The original sample corrosion pattern is pitting corrosion.The corrosion morphology is very uneven and the corrosion product layer does not protect the substrate well.After high-pressure torsion treatment,the corrosion morphology is uniform and regular,and the formed corrosion product layer is dense and uniform,which has a good protection effect on the substrate,and ultimately improves the corrosion resistance of the magnesium alloy.The change in the corrosion mechanism is closely related to the grain boundary density and the second phase distribution of the material.The surface modification of ZEK100 magnesium alloy with hydroxyapatite coating significantly improves the corrosion resistance of the material.In the synthesis process,nano-magnesium hydroxide micro-particles are added to optimize the synthesis process and further improve the coating performance.The results showed that after adding nano-magnesium hydroxide micro-particles,the prepared hydroxyapatite particles changed from acicular to network structure,the coating was more dense,and the corrosion resistance of the coating was further improved.