The Study On The Biodegradable KA/Mg-Zn-Zr Composites

Magnesium has the closest comprehensive mechanical properties with the natural bonecompared with other implanting materials, and also has the excellent biological corrosioncharacteristics, presents high chemical and electrochemical activity in the physicalenvironment, for this reasons, Mg is considered as promising biodegradable bone fixation.The commercial magnesium alloys which had already been put into used were widespreaddegradation overheated, so it is necessary to developed the new biomedical magnesium alloyswhich have better corrosion resistance and comprehensive mechanical properties.The Mg-3wt%Zn-0.5wt%Zr-xwt%HA (x=0, 0.5, 1, 1.5) and Mg-3wt%Zn-1wt%HAcomposites were smelted in this work. And chosen the 400℃and 450℃extrusiontemperature pressed the ingots to bars. The effects of trace elements Zr, nano HA particles anddifferent extrusion temperature on the microstructure and properties of HA/Mg compositeswere investigated by microstructure observation, mechanical testing and in-vitro corrosionevaluations. The results are as follows:1. The addition of trace Zr could significantly refine the grains of HA/Mg-Zn composites,and also can improve the tensile strength, plastic and the in-vitro corrosion resistance.2. The grain size of Mg-3wt%Zn-0.5wt%Zr-1.5wt%HA composites got by 400℃extrusiontemperature are much smaller than the 450℃extrusion temperature, the tensile strength,plastic and in-vitro degradation rate before aging are 288 MPa, 18.5% and 6.18 mm/yr,respectively, are all better than the specimens extruded by 450℃.3. With the increase of HA content, the strength, plastic and in-vitro corrosion resistance ofMg-3wt%Zn-0.5wt%Zr-xwt%HA(x=0.5, 1, 1.5) composites are all improved distinctlycompared with the Mg-3wt%Zn-0.5wt%Zr alloy. The tensile strength, plastic and in-vitrodegradation rate of Mg-3wt%Zn-0.5wt%Zr-1.5wt%HA composites are 297 MPa, 20.9%and 6.45 mm/yr, respectively.