激光熔凝对生物可降解Zn-1Mg-0.2Fe合金组织和性能的影响

通过激光熔凝技术,在可降解Zn-1Mg-0.2Fe合金表面制备了一层熔凝层,并采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、高速往复摩擦实验机、显微硬度计、电化学工作站和浸泡实验系统评估了熔凝层的微观组织、摩擦磨损性能、硬度和腐蚀行为。结果表明:铸态和激光熔凝试样均主要由α-Zn基体相、Mg2Zn11和FeZn13相组成。激光熔凝层组织较锌合金基体致密且FeZn13第二相趋于圆整和细化。在Hank’s溶液中的摩擦磨损实验表明,激光熔凝试样的摩擦系数为0.821、磨损损失为1.7 mg,相对于铸态试样具有更低的摩擦系数和磨损失重量。腐蚀磨损机理主要为犁削和轻微的磨粒磨损;激光熔凝试样在Hank’s溶液中的腐蚀电位为-1.030 V vs.SCE、腐蚀电流密度为37.4μA/cm2、腐蚀速率为498.0μm/a,相对于铸态试样具有更正的腐蚀电位、更低的腐蚀电流密度和腐蚀速率。激光熔凝试样在Hank’s溶液中浸泡30和90 d后的降解速率分别为39.2和28.7μm/a,较铸态试样分别降低了9.4%和3.7%,表现出更优异的耐腐蚀性能。

Effect of Laser Melting on Microstructure and Properties of Biodegradable Zn-1Mg-0.2Fe Alloy

A remelted layer on the surface of a degradable Zn-1Mg-0.2Fe alloy is prepared via laser remelted technology,and their microstructure,friction and wear performance,hardness,and corrosion behavior of the remelted layer are evaluated systematically by OM,SEM,XRD,high-speed reciprocating friction tester,micro-hardness tester,electrochemical workstation and immersion test.The results show that both the as-cast and laser remelted samples are mainly composed ofα-Zn matrix phase,Mg2Zn11,and FeZn13.The laser remelted layer is denser than the substrate of Zn alloy,and the second phase of FeZn13 also tends to be round and thin.The friction and wear tests in Hank’s solution revealed that the laser remelted sample shows a lower friction coefficient and wear loss than those of the as-cast sample,with coefficient of friction of 0.821 and wear loss of 1.7 mg.The corrosion-wear mechanism consists mainly of plowing and slight abrasive wear.The average micro-hardness value of the laser remelted sample is 104.3 kg/mm2,which is increase of 15.2%as compared to that of the as-cast sample.Laser remelted sample exhibits more positive corrosion potential,lower values of corrosion current density and corrosion rate than their as-cast alloy counterparts in Hank’s solution,with corrosion potential of-1.030 V vs.SCE,corrosion current density of 37.4μA/cm2,and corrosion rate of 498.0μm/a.The degradation rates of the laser remelted sample after immersing into Hank’s solution are 39.2μm/a for 30 days and 28.7μm/a for 90 days,which are 9.4%and 3.7%lower than those of the as-cast sample,respectively,exhibiting better corrosion resistance.