生物医用AZ31B镁合金表面氧化锰转化涂层制备及性能研究

采用转化处理的方式,在AZ31B镁合金表面成功制备一层氧化锰转化涂层,以提高合金表面耐蚀性能。SEM研究表明,氧化锰转化涂层均匀分布在AZ31B镁合金表面,涂层中无规分布着微裂纹,涂层厚度为10~12μm。XRD研究表明,氧化锰转化涂层的主要成分包括MgO、MnO和Mn2O3。电化学和腐蚀浸泡实验结果表明,氧化锰转化涂层能够有效改善AZ31B镁合金的体外耐蚀性能。     

电化学沉积法制备镁基Ca-P生物陶瓷涂层的研究

利用电化学沉积法在AZ31镁合金表面制备了Ca-P基生物涂层,使用扫描电子显微镜观察了经不同沉积时间处理后的涂层形貌,采用X射线衍射和能谱分析了涂层的结构和成分,通过电化学测试技术研究了在Hank’s仿生溶液中AZ31镁合金及其Ca-P涂层的腐蚀行为。结果表明,镁合金表面在Ca(NO3)2和NH4H2PO4电解液中电化学沉积形成Ca-P涂层由DCPD(CaHPO4·2H2O)片状晶体组成。且涂层形貌随时间发生变化。AZ31镁合金表面的钙磷涂层提高了镁合金的自腐蚀电位,显著地减小了镁合金的腐蚀电流密度。这表明经钙磷涂层处理的AZ31镁合金耐蚀性能得到明显的提高。钙磷涂层的形貌和结晶程度影响AZ31镁合金的耐蚀性。     

AZ31镁合金的生物降解行为研究

研究了AZ31镁合金作为生物医用材料的体内外生物降解行为.初步分析了其作为可降解生物医用材料的可行性.体外浸泡实验结果表明,AZ31镁合金的降解行为与其所处环境有关,在Hank's溶液中的降解速度较在0.9%NaCl溶液中低;经过热处理后的AZ31镁合金较铸态和锻态降低了点蚀发生倾向,降解速度更慢.体内植入实验结果表明,AZ31镁合金与动物不同组织接触,其降解速度不同,在骨髓腔内的降解速度更快.植入5周时,镁合金已发生降解,20周降解更为明显.降解过程中镁合金表面有Ca-P物质沉积,表面具有优异的生物活性,其降解产物主要通过尿液进行排泄.在表面制备Ca-P涂层可降低镁合金的降解速度.AZ31镁合金是一种具有良好应用前景的新型生物可降解医用植入材料.     

表面改性后AZ31B镁合金在不同模拟体液中的降解性能研究

采用化学沉积法在AZ31B镁合金表面制备了钙磷陶瓷涂层,通过浸泡试验和电化学试验研究了其在3种不同模拟体液(生理盐水、PBS、Hank′s)中的降解性能。结果表明,沉积处理改变了AZ31B镁合金在模拟体液中的降解性能,明显抑制了其降解速度;浸泡后溶液的pH值变化结果和电化学实验结果均表明,在3种不同模拟体液中,表面处理后AZ31B镁合金显示出不同的降解速度,顺序依次为:生理盐水>PBS溶液>Hank′s溶液。     

自蔓延高温合成反应热喷涂Al2O3基复相陶瓷涂层的性能

为了改善AZ31B镁合金的耐磨性,以Al2O3-13%TiO2为陶瓷骨料,在其中加入Al/CuO铝热荆,采用普通氧乙炔火焰自蔓延高温合成反应热喷涂技术在镁合金表面制备Al2O3基复相陶瓷涂层.通过X射线衍射分析了陶瓷涂层的组成.结果表明,所得复相陶瓷涂层具有良好的抗热震性,涂层内有Cu4MgO5,CuAlO2等新的物相产生.磨粒磨损试验、黏着干磨损试验和黏着油磨损试验表明:自蔓延反应热喷涂陶瓷涂层的耐磨性是AZ31B基体的6.48,3.32,6.04倍,普通热喷涂层的耐磨性是AZ31B基体的3.60,1.76,1.67倍,自蔓延反应热喷涂陶瓷涂层的耐磨性比普通热喷涂层有较大提高.     

AZ31和Ti6Al4V表面Nb2O5涂层的微观结构与性能研究

采用射频溅射技术在AZ31镁合金和Ti6Al4V钛合金表面分别沉积Nb2O5陶瓷涂层,对比研究其微观结构、残余应力、附着力和耐腐蚀性能。研究结果表明：两种涂层试样表面组织致密,颗粒大小均匀,无明显的裂纹和孔洞等缺陷。当Nb2O5涂层的厚度为1.98 μm时,Ti6Al4V涂层试样的残余应力（27.1 MPa）比AZ31涂层试样的小65.1%,附着力（9.24 N）比AZ31涂层试样的大13.2倍。Nb2O5陶瓷涂层能明显提高Ti6Al4V和AZ31的耐腐蚀性能,但在腐蚀电流密度的降低幅度、极化电阻的增大程度和保护效率方面,镁合金涂层试样优于钛合金涂层试样。     

高锰酸盐转化处理对医用AZ31B镁合金体外耐蚀性能的影响

现有的医用镁及镁合金在植入人体后耐蚀性能较差。采用高锰酸盐在医用AZ31B镁合金表面制备氧化锰转化膜,并采用SEM、XRD、电化学测试及浸泡试验研究其性能,对膜的形貌、组分、电化学性能和耐体液腐蚀性能进行了探讨。结果表明:氧化锰转化膜均匀分布在AZ31B镁合金表面,无规则分布有微裂纹,膜厚约52~165μm;转化膜的主要成分包括MgO,MnO,MnO2,Mn2O3和Mn3O4;转化膜能够有效改善AZ31B镁合金的体外耐蚀性能。     

AZ31B镁合金表面锌系磷化膜制备工艺及性能研究

采用极化曲线分析方法(Tafel)及扫描电子显微镜(SEM)对AZ31B镁合金在不同磷化时间及不同磷化温度条件下所形成的锌系磷化膜的防腐性能及表面微观形貌进行了研究,并应用X射线衍射仪(XRD)、能谱仪(EDS)对最佳工艺条件下所形成的磷化膜的相组成以及磷化膜的成分进行了研究.结果表明:磷化时间及磷化温度对AZ31B镁合金磷化膜的防腐性能有较大影响,其最佳磷化时间为5min,最佳磷化温度为50℃;磷化膜的成分为Zn3(PO4)2·4H2O,Zn2Mg(PO4)2以及少量的单质Zn;在锌系磷化液中AZ31B镁合金中的Mg在微阳极发生溶解而Al没有溶解.此外还探讨了AZ31B镁合金表面的磷化反应机理.     

多道次弯曲对AZ31B镁合金板材织构与性能的影响

提出了一种改善镁合金板材织构与冲压性能的新方法,即单向多道次弯曲工艺.研究了该工艺对AZ31B镁合金板材织构以及成形性能的影响,分析了单向多道次弯曲前后各种状态板材的显微组织、力学性能以及杯凸值.结果表明,多道次弯曲改善了冷轧态AZ31B镁合金板材中不利于对后续塑性加工的(0002)基面织构,能够较好地改善AZ31B镁合金板材的力学性能和冲压性能.     

可降解镁合金表面载药涂层的制备和性能

在可降解AZ31B镁合金心血管支架表面成功制备了携带雷帕霉素的聚乳酸-聚三亚甲基碳酸酯(PLA-PTMC)共聚物涂层,评价了涂层的表面形貌、降解性能、血液相容性和药物释放性能.结果表明,PLA-PTMC共聚物作为载药涂层具有良好的柔韧性,表面均匀、光滑,降解周期超过1个月,血液相容性良好.涂层具有缓释雷帕霉素的功能,释药周期超过1个月,可在内膜增生期内有效抑制支架植入后再狭窄的发生,满足冠脉支架表面载药层的使用要求.     

Fluoride Conversion Coating on Biodegradable AZ31B Magnesium Alloy

A fluoride conversion coating was successfully prepared on AZ31B magnesium alloy by chemical reaction in hydrofluoric acid. Morphologies, composition, bonding strength, corrosion properties, in vitro cytotoxicity and antibacterial properties of the coating were investigated, respectively. The scanning electron microscopy observations revealed a dense coating with some irregular pores. The thin-film X-ray diffraction analysis indicated that the coating was mainly composed of MgO and MgF2. The electrochemical impedance spectroscopy results showed that the fluoride conversion coating significantly improved the corrosion resistance of AZ31B. The hydroxyapatite formed on the surface of the fluoride coated AZ31 B after being immersed in the simulated blood plasma indicated the good bioactivity of the material. The in vitro cytotoxicity test showed that the fluoride coated AZ31B alloy was not toxic to BMMSCs （human bone marrow-derived mesenchymal stem cells）. It was also found that the fluoride coated AZ31 B alloy had antibacterial capability.     

Fluoride treatment and in vitro corrosion behavior of an AZ31B magnesium alloy

As a new class of biodegradable material, magnesium alloys have attracted much attention in recent years. In order to improve the corrosion resistance, a fluoride coating was prepared on the surface of AZ31B magnesium alloy. The surface characterization analysis showed a dense coating with some irregular pores was formed. The TF-XRD analysis indicated that the coating was mainly composed of MgO and MgF₂. Electrochemical and immersion tests proved that the fluoride conversion coating significantly improved the corrosion resistance of AZ31B. Three-point bending test revealed that the degradation behavior of the fluoride treated AZ31B could meet the requirement as a biodegradable material.     

Biodegradable poly(lactide-co-glycolide) coatings on magnesium alloys for orthopedic applications

Polymeric film coatings were applied by dip coating on two magnesium alloy systems, AZ31 and Mg4Y, in an attempt to slow the degradation of these alloys under in vitro conditions. Poly(lactic-co-glycolic acid) polymer in solution was explored at various concentrations, yielding coatings of varying thicknesses on the alloy substrates. Electrochemical corrosion studies indicate that the coatings initially provide some corrosion protection. Degradation studies showed reduced degradation over 3 days, but beyond this time point however, do not maintain a reduction in corrosion rate. Scanning electron microscopy indicates inhomogeneous coating durability, with gas pocket formation in the polymer coating, resulting in eventual detachment from the alloy surface. In vitro studies of cell viability utilizing mouse osteoblast cells showed improved biocompatibility of polymer coated substrates over the bare AZ31 and Mg4Y substrates. Results demonstrate that while challenges remain for long term degradation control, the developed polymeric coatings nevertheless provide short term corrosion protection and improved biocompatibility of magnesium alloys for possible use in orthopedic applications.     

Cytocompatibility and Hemolysis of AZ31B Magnesium Alloy with Si-containing Coating

In the present study,a Si-containing coating was fabricated on AZ31 B Mg alloy.Cytocompatibility of the coated alloy was evaluated by both indirect and direct contact methods,respectively.Effects of a number of incubation variables on the sensitivity and reproducibility of the hemolysis test were also examined by using positively and negatively responding biomaterials.Cytocompatibility testing results indicated that cell condition,cell adherence,cell proliferation and extracellular matrix secretion of the coated alloy were improved compared with those of the uncoated alloy for different extraction and co-culture time.The hemolysis test suggested that hemolysis testing conditions were critical to determine the hemolysis of the alloy.It was also found that 1 day in vitro degradation of the uncoated AZ31 B alloy had no destructive effect on erythrocyte.As for the coated AZ31 B alloy at any time point,the hemolysis rate was much lower than 5%,the safe value for biomaterials.These in vitro experimental results indicate that the Si-containing coating is effective to improve the cytocompatibility and hemolysis behaviors of AZ31 B alloy during its degradation.     

Growth and corrosion of aluminum PVD-coating on AZ31 magnesium alloy

Magnetron sputtering was applied to prepare aluminum coating on a mechanically polished AZ31 magnesium alloy. A loose oxide film was spontaneously formed on the surface of AZ31 magnesium alloy during polishing process. The aluminum coating, which was subsequently deposited on this oxide layer, presented a developed columnar microstructure. Attributed to the barrier effect of Al coating, the Al coated AZ31 showed a higher corrosion resistance than bare AZ31 in corrosion tests. Generally, Al coating is cathodically protected by magnesium alloy substrate. But it is interesting in this study that Al coating still suffered from severe corrosion due to the occurrence of the alkalization effect.     

Fabrication of Al and Al/Ti coatings on magnesium alloy by sputtering

Multi-magnetron sputtering was applied to prepare aluminum coating and aluminum/titanium multilayer coating on AZ31 magnesium alloy. FESEM, AFM and XRD were used to investigate the morphology and phase structure of these obtained coatings. Aluminum coating presented a (111) preferred texture and this texture was strongly strengthened with the Ti(002) plane as template in Al/Ti multilayer coating. The top surface of Al/Ti-coated sample took on a round roof-like morphology compared to the pyramid-like morphology of Al-coated sample. The result of polarization tests showed that both Al coating and Al/Ti multilayer coating could improve the corrosion resistance of AZ31 magnesium alloy in 3.5 wt.% NaCl solution.     

退火处理对AZ31镁合金表面Ni-Mo-P镀层组织与耐腐蚀性能的影响

为了进一步提高镁合金表面Ni-Mo-P镀层的耐蚀性,采用0M、XRD和浸泡试验等方法,研究了退火处理对AZ31镁合金表面Ni-Mo-P镀层组织与腐蚀性能的影响。结果表明:AZ31镁合金阳极氧化-化学镀Ni-Mo-P镀层表面为“胞状”组织,随着退火温度的升高或退火时间的延长,AZ31镁合金阳极氧化-化学镀Ni-Mo-P镀层的胞状组织逐渐细化,但镀层厚度降低,同时,非晶态Ni-Mo-P镀层组织逐渐向晶态转变,350℃退火1.0h具有较高的非晶化程度,退火处理后的Ni-Mo-P镀层由Mg、MgO、Mg2SiO4、Ni和Ni3P组成;退火使AZ31镁合金阳极氧化-化学镀Ni-Mo-P镀层耐蚀性降低,350℃退火1.0 h镀层具有相对较好的耐蚀性,这与镀层的厚度和非晶化程度有关。     

镁合金磷化处理对化学镀镍层性能的影响

为了有利于环保,采用磷化工艺对AZ31B镁合金进行化学镀镍前处理.采用直观法、扫描电子显微镜和阴极极化曲线法对磷化膜及其化学镀镍层进行了分析.结果表明:AZ31B镁合金表面经磷化处理后得到了良好的化学镀镍层;AZ31B镁合金化学镀镍层的耐蚀性随磷化时间的延长先增加后减小,当磷化时间为75 s时,化学镀镍层的腐蚀电势比直...