Design And Properties Of Novel Degradable Zinc Alloys

Zinc alloy has great potential as biodegradable materials for biomedical applications due to its suitable degradation rate and good biocompatibility.However,the poor mechanical properties of pure zinc,such as low strength and poor plasticity,limit its clinical application.A large number of studies have shown that mechanical properties of zinc-based alloys can be effectively improved by selecting appropriate alloying and preparation processes.In this paper,new Zn-0.8Li-x Ca(x=0,0.05,0.1wt.%)-0.2Ag and Zn-0.8Li-0.05Ca-x Ag(x=0,0.5,1wt.%)quaternary zinc base alloys were designed and prepared,and their microstructures,mechanical and mechanical properties,corrosion and degradation properties were characterized and analyzed.The effects of different Ca and Ag contents and processing technology on the microstructure and properties of zinc-based alloy were investigated.The results showed that:The microstructure of Zn-Li-Ca-Ag alloy is mainly composed of Zn matrix and CaZn13 phase.When a small amount of Ca is added to the alloy,angular CaZn13 phase begins to appear in the microstructure of the alloy.With the increase of Ca content,CaZn13 phase gradually increased and its size increased.The hardness and strength of Zn-Li-Ca-Ag alloys increase with the increase of Ca content.The as-cast Zn-0.8Li-0.05Ca-0.2Ag alloy has the best comprehensive mechanical properties,and its tensile strength,elongation and microhardness are 151 MPa,4.6% and 66.28 HV,respectively.After the same diameter Angle extrusion,the coarse dendrites in the alloy microstructure change into banded structure,the CaZn13 phase is broken and evenly distributed,and the hardness of the alloy is significantly increased.The compressive yield strength of Zn-LiCa-Ag alloys increases gradually with the increase of Ca and Ag contents,and the compressive yield strength of Zn-0.8Li-0.1Ca-0.2Ag alloys in ECAP state is the highest,reaching 362 MPa.The in vitro degradation behavior of Zn-Li-Ca-Ag alloy was studied by immersion test and electrochemical test.The results of in vitro immersion test and electrochemical experiment show that the addition of Ca improves the corrosion resistance of the alloy,and the addition of Ag reduces the corrosion resistance of the alloy.The corrosion rate of the alloy firstly decreases and then increases with the increase of Ca content,and firstly increases and then decreases with the increase of Ag content.The results of immersion test and electrochemical test tend to be consistent,and the corrosion rate of the alloy decreases with the extension of time.The surface corrosion morphology of the alloy shows that with the increase of soaking time,the corrosion of the alloy is gradually deepened,the corrosion pit scope is gradually expanded,and the corrosion is relatively more uniform.The corrosion resistance of ECAP Zn-0.8Li-0.05 Ca alloy is the best,and the corrosion rate is 0.0046mm/y.