Research On Mechanical,Damping Performance Balance And Surface Treatment Of Mg-Zn-Y-Ce-Zr Alloy

In the context of large population and aging society for our country,rehabilitation mobile assistive devices have huge market demand and prospects.Lightweight,cheap,comfortable and durable are the core indicators of rehabilitation mobility aids.At present,commonly used materials such as steel and titanium alloys on t he market cannot meet the needs of lightweight and cheap.Magnesium alloy possess low density and high damping performance,and it has great potential to be developed as a new generation of rehabilitation mobility aid materials.However,the strength of ma gnesium alloy is low,and it is difficult to meet the mechanical performance requirements of structural materials;the chemical properties are active and easy to be corroded,and its application is greatly restricted.Based on the above problems,this paper adopts the Mg-Zn-Y-Ce-Zr alloy obtained by adding a small amount of Y and Ce elements on the basis of ZK60,and adjusts the mechanical and damping properties through extrusion and heat treatment to obtain excellent mechanical and damping properties.Comprehensive performance.In order to improve the corrosion resistance and have a beneficial effect on the damping performance,a micro-arc oxidation coating with a certain porosity and a high-damping polytetrafluoroethylene are selected for the composite surface treatment of the Mg-Zn-Y-Ce-Zr alloy.The prepared coating effectively improves the corrosion resistance of the material.First,the as-cast Mg-Zn-Y-Ce-Zr alloy is extruded.After extrusion,the degree of recrystallization is high,the grains are refined,the mechanical properties are greatly improved,and the tensile strength is 361 MPa.According to the G-L linear fitting of the original data,the damping of the extruded alloy can be explained by the dislocation mechanism.When?=1×10^-3,the damping Q^-1=0.016(>0.01),which is still a high-damping material.The grain size of the extruded alloy grows up after solution treatment at 420?,and part of the second phase is dissolved.Through G-L linear fitting analysis,the damping of the alloy can still be explained by the dislocation mechanism,when?=1×10^-3,Q^-1=0.0192(SDC=12%),the damping increased by 20%,which is related to the decrease in the number of strong pinning points of the alloy after solution treatment;the tensile strength is 317 MPa(>300 MPa),420?solid solution The alloy has good comprehensive properties of mechanical damping.Compared with the ZK60 and Mg-Zn-Y-Zr alloys reported in the literature,the Mg-Zn-Y-Ce-Zr alloy in this paper has better comprehensive mechanical and damping properties after being processed by a suitable process.The Mg-Zn-Y-Ce-Zr alloy is subjected to micro-arc oxidation surface treatment.The key process parameters of C₃H₈O₃ concentration,Na₂B₄O₇ concentration and oxidation time affect the deposition of the coat ing by changing the energy of the micro-arc discharge or the discharge rate.The optimal process parameters C ₃H₈O₃6ml/L,Na₂B₄O₇ 2g/L,oxidation time 10 min.PTFE filled MAO coating holes further improve the corrosion resistance of the coating.The MAO/PTFE-1 composite coating prepared by the optimal sealing process has a self-corrosion current density 4 orders of magnitude lower than that of the bare alloy in 3.5%Na C l solution.After immersing in 5%NaCl solution for 14 days,the MAO/PTFE-1 coating was not significantly damaged,and the corrosion products were small in size and quantity.In addition,the surface of the MAO/PTFE-1 composite coating has high hydrophobicity,good adhesion,and can improve the damping of low strain and high strain.