| Zinc has a moderate corrosion rate,However,the poor mechanical properties of pure zinc are not conducive to its application in biomedical materials,so it is necessary to improve the mechanical properties of zinc.At the same time,in order to ensure the unity of mechanical properties and degradation properties of Zn,the mechanical properties and corrosion resistance of zinc alloy were improved by adding different contents of Gd,homogenization and aging treatment on the basis of ZnMgBa alloy.The mechanical properties,electrochemical properties,corrosion resistance and wear resistance of the as-cast and heat-treated aged alloys were measured and analyzed.The result of research shows that:(1)Gd can refine the microstructure of ZnMgBa alloy.With the increase of Gd content,the microhardness and abrasive wear property of ZnMgBa alloy firstly increase and then decrease.The highest microhardness value of the alloy with the addition of 0.7wt.%Gd is 223.9HV,which is 22.3%higher than that of the matrix.Under 2N and 4N external loading,the wear rates of0.7wt.%Gd alloy are 1.716g/cm2and 2.071g/cm2,respectively,which are reduced by 16.8%and14.6%compared with the matrix.However,when Gd content exceeds 0.7wt.%,the wear rate increases,but it is still better than that of the matrix alloy without Gd.(2)The corrosion products of ZnMgBa Gd alloy soaked in simulated body fluids at 37?are Zn3(PO4)2,Ca3(PO4)2,phosphate and salts containing Ca and P,which have good biocompatibility.Compared with the matrix alloy,the corrosion potential of 0.7wt.%Gd alloy is positive,the corrosion rate decreases by 25.6%,and the capacitive reactance arc is 83.5%larger than that of the matrix alloy.The results show that the corrosion resistance of the alloy decreases first and then increases with the increase of Gd content.(3)Heat treatment can not only improve the microstructure inhomogeneity of as-cast ZnMgBa Gd alloy,but also make the alloy precipitate out the strengthening phase.After150?×4h,the microstructure of the alloy is uniform and the grain size is fine.At the same time,the fine and dispersed phase is distributed in the grain,which plays a strengthening role on the properties of the alloy.With the increase of aging temperature and time,the hardness and abrasive wear properties of ZnMgBa Gd alloy increased first and then decreased.At 150?×4h,the maximum microhardness value is 278.9HV,which is 24.77%higher than that of the as-cast alloy.Under 2N and 4N external loads,the wear rates of the alloy after 150?×4h are1.505g/cm2and 1.853g/cm2,respectively,which are 12.3%and 10.5%lower than those without heat treatment,respectively.However,when the aging time exceeds 4h,the wear rate increases,which is still better than that of the alloy without heat treatment.(4)When the corrosion potential is positive at 150?×4h,the corrosion rate decreases by42.1%,and the capacitive reactance arc is 82.4%larger than that of the as-cast alloy.The corrosion products,such as Zn3(PO4)2,Ca3(PO4)2,phosphate,salts containing Ca and P,appeared on the surface of the alloy after SBF immersion at 150?×4h.There are 46 figures,11 tables and 70 references in this paper. |
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