超声处理制备的生物可降解Zn-1Mg-0.5Ca合金的微观组织与腐蚀行为

Microstructure and Corrosion Behavior of Biodegradable Zn-1Mg-0.5Ca Alloy Prepared by Ultrasonic Treatment

锌合金不仅具有良好的生物相容性,而且还有较好的降解行为,成为近些年来国内外研究者关注的热点。但是,不管在力学性能上,还是在腐蚀性能上,铸态锌合金皆不具备人体植入金属材料的条件。所以,为了提升与优化锌合金的力学性能,同时符合植入人体后的腐蚀速率需求,本实验研究了不同超声功率(300 W,600 W,900 W)处理对的Zn-1Mg-0.5Ca合金微观组织及腐蚀性能的影响。研究结果表明:随着超声功率的增加,Zn-1Mg-0.5Ca的初生α-Zn树枝晶,片层的共晶Mg2Zn11相以及块状的CaZn13相被有效细化,初生α-Zn相由粗大的树枝晶转变为细小的等轴枝晶。粗大的多边形状CaZn13相被细化为细小的粒状,平均尺寸从34μm减小到5μm,片层的共晶Mg2Zn11相转变成细小的棒状和粒状。电化学测试表明:未经超声处理的Zn-1Mg-0.5Ca合金的腐蚀速率最低,为0.190 mm·a-1。随着超声功率的增加,合金的腐蚀速率逐渐增加,当超声功率达到900 W时,合金的腐蚀速率达到了0.490 mm·a-1。将样品浸泡15 d后的实验发现,未经超声处理的Zn-1Mg-0.5Ca合金的腐蚀速率低于超声处理合金的腐蚀速率,且随着超声功率的增加,合金腐蚀速率从0.144 mm·a-1增加到0.263 mm·a-1。

Zinc alloys have acceptable biocompatibility and ideal physiological degradation behavior,which has become a hot spot for researchers in recent years.However,no matter in mechanical properties or corrosion properties,cast zinc alloy is not suitable for human implantation of metal materials.Therefore,in order to improve the mechanical properties of zinc alloys and meet the requirements of corrosion rate after implantation in human body,the effects of different ultrasonic power(300 W,600 W,900 W)treatment on the microstructure and corrosion properties of Zn-1Mg-0.5Ca alloys were studied.The results show that with the increase of ultrasonic power,the primaryα-Zn dendrites of Zn-1Mg-0.5Ca,the eutectic Mg2Zn11 phase of lamellae and the bulk CaZn13 phase are effectively refined.The primaryα-Zn phase changes from coarse dendrites to fine isometric grains.The coarse multi-sided CaZn13 phase is refined to fine granular shapes,with the average size decreasing from 34μm to 5μm.The eutectic Mg2Zn11 phase of the lamellar is transformed into fine rods and granular shapes.The electrochemical test shows that the corrosion rate of the Zn-1Mg-0.5Ca alloy without ultrasonic treatment is the lowest,which is 0.190 mm·a-1.With the increase of ultrasonic power,the corrosion rate of the alloy increases gradually.When the ultrasonic power reaches 900W,the corrosion rate of the alloy is 0.49 mm·a-1.After soaking the samples for 15 days,it is found that the corrosion rate of the Zn-1Mg-0.5Ca alloy without ultrasonic treatment is lower than that with the ultrasonic treatment,and the corrosion rate increases from 0.144 mm·a-1 to 0.263 mm·a-1 with the increase of ultrasonic power.