氟化处理对植入材料Mg-Ca二元合金腐蚀行为的影响(英文)

在室温下,将Mg-0.5Ca合金在不同浓度的氢氧化钠和HF溶液浸渍不同的时间,研究HF处理对合金腐蚀行为的影响。采用原子力显微镜、X射线衍射、场发射扫描电子显微镜表征样品的微观组织变化。通过动电位极化和Kokubo溶液浸泡试验测试样品的耐腐蚀性。结果表明,与35%HF处理的样品相比,经40%HF溶液处理的Mg-0.5Ca合金具有更均匀、更致密、更薄的涂层(12.6μm)。电化学测试表明,在Kokubo溶液中,经氟化物处理的Mg-0.5Ca合金样品的耐腐蚀性比未处理样品的高35倍;前者的体外降解速率远远低于后者的。在40%HF溶液处理过的样品表面只出现了一些腐蚀点,而未经处理的样品完全被腐蚀产物覆盖且出现了分层现象。40%HF处理的Mg-0.5Ca合金,具有低的降解速率和良好的生物相容性,是一种有潜力的植入材料。     

Microstructure and corrosion behavior of Mg-Sn-Ca alloys after extrusion

Mg-Sn-Ca alloys promise a reasonable corrosion resistance in combination with good creep resistance, likely due to the presence of Ca2-xMgxSn and other phases. The selected alloys with 3% Sn and Ca in the range of 1%-2% have been extruded in order to achieve more homogeneous microstructure compared with the as-cast alloys. Optical microscopy(OM) and X-ray diffraction(XRD) techniques were used to study the microstructure and phases of these alloys. The corrosion behavior of these alloys was investigated by means of salt spray test and potentio-dynamic measurements. The results obtained on the alloys Mg-3Sn (T3), Mg-3Sn-1Ca (TX31), and Mg-3Sn-2Ca (TX32) indicate the presence of the same phases in as-cast and after extrusion, namely Mg2Sn, Ca2-xMgxSn, and Ca2-xMgxSn/Mg2Ca, respectively. However, due to the occurrence of extensive recrystallization in the extrusion process, the grain size has significantly reduced after extrusion. The reduction leads to the improvement of the corrosion resistance after extrusion which is then comparable with the commercial alloy AZ91D.     

Porous TiO2 film prepared by micro-arc oxidation and its electrochemical behaviors in Hank's solution

Porous titanium oxide film was prepared by micro-arc oxidation (MAO) method on the surface of titanium alloy in electrolyte containing Ca and P. Surface characterizations of the film were carried out using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) before and after immersion in Hank's solution. Electrochemical behaviors and corrosion resistance were studied by electrochemical techniques. The film was mainly composed of titania, α-tricalcium phosphate (α-TCP) and amorphous Ca-P compounds. α-TCP and amorphous compounds could transformed into hydroxyapatite (HA) when immersed in Hank's solution. MAO film showed higher corrosion potential and lower corrosion current than the titanium alloy and its chemical stability was slightly changed after formation of HA. Fitted electrochemical impedance spectroscopy (EIS) data indicated that after immersion for 2 weeks the MAO film kept good corrosion resistance. Porous TiO₂ film on titanium alloy by MAO method showed good chemical stability in Hank's solution and the transformation of Ca-P compounds into HA indicated that MAO was an effective method for preparing titanium alloys as bioactive artificial bone substitute even when Ca and P in the tissue environment were not abundant.     

Sb对Mg-4Zn-Y合金耐腐蚀性能的影响

研究了Mg-4Zn-Y-xSb(x=0,0.5,1,2)合金在3.5%NaCl溶液中的腐蚀行为,利用金相显微镜、电化学极化曲线和电化学阻抗测试研究了Sb对Mg-4Zn-Y合金耐蚀性能的影响.结果表明,在试验范围内Mg-4Zn-Y-xSb(x=0,0.5,1,2)合金的耐蚀性能随着Sb含量的增加而降低.Mg-4Zn-Y-2Sb合金的腐蚀速率比Mg-4Zn-Y合金上升了一个数量级,合金的腐蚀电流达到2.254E-4A.     

Effects of ECAP Extrusion on the Microstructure,Mechanical Properties and Biodegradability of Mg-2Zn-xGd-O.5Zr Alloys

Effects of equal channel angular pressing (ECAP) extrusion on the microstructure,mechanical properties and biodegradability of Mg-2Zn-xGd-0.5Zr (x =0,0.5,1,2 wt％) alloys were studied in this work.Microstructure analysis,tensile test at ambient temperature,immersion test and electrochemical test in Hank's solution were carried out.The results showed that Gd could further enhance the grain refinement during the ECAP extrusion.Both Gd addition and ECAP extrusion could improve the mechanical properties of the alloys,and the extrusion played the dominant role.Minor addition of Gd (0.5-1 wt％) could obviously enhance the corrosion resistance of the alloys.To some extent,ECAP extrusion improved the corrosion resistance of the alloys due to the change of second phases distribution and the refinement of grains.Further increase in extrusion pass was detrimental to the improvement of the corrosion resistance as a result of increment of the grain boundaries.     

Zn对均匀化态Mg-3Sn-Ca镁合金腐蚀性能的影响

研究了Zn元素对均匀化态Mg-3Sn-Ca合金耐腐蚀性能的影响。通过XRD、金相、SEM、失重、析氢、电化学极化曲线和阻抗谱分析了Mg-3Sn-Ca(TX31)和Mg-3Sn-Ca-Zn(TXZ311)2种合金的耐蚀性能。结果表明,Mg-3Sn-Ca合金中主要由CaMgSn及Mg₂Sn相组成,加入Zn元素后晶粒得到显著细化,第二相体积分数增加并呈弥散分布,并有Mg₂Ca相析出。而Zn的添加可显著提高Mg-3Sn-Ca合金的耐蚀性能,这主要归因于TXZ311合金具有更细小的晶粒尺寸以及均匀密集分布的CaMgSn相,使合金在腐蚀过程中形成的钝化膜更加均匀。因此,TXZ311合金的耐蚀性远高于TX31合金。     

Hg和Ga元素对Mg阳极材料组织和电化学腐蚀性能的影响(英文)

采用动电位极化、恒电流和交流阻抗测试方法研究了Hg和Ga元素对Mg2%Hg,Mg2%Ga和Mg2%Hg2%Ga合金电化学腐蚀性能的影响,并用扫描电镜、X射线衍射和能谱分析了上述合金的显微组织和腐蚀表面形貌。结果表明:Mg2%Ga合金是固溶体,Mg-2%Hg和Mg-2%Hg2%Ga合金的晶界有白色第二相。Mg-2%Ga合金的平均电位为1.48V,腐蚀电流密度为0.15mA/cm2,电化学活性差,耐腐蚀性能好。Mg-2%Hg-2%Ga合金的平均电位1.848V,腐蚀电流密度为2.136mA/cm2,电化学活性好,耐腐蚀性能差。MgHgGa合金的活化机制是Hg和Ga原子的溶解沉积。     

镁锂合金表面高锰酸盐转化膜的研究

采用化学转化法在镁锂合金表面制得了结构致密、耐蚀性能较好的高锰酸盐转化膜,研究了转化液中高锰酸盐溶液浓度对成膜效果的影响.实验采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱(XPS)对所制得转化膜的表面形貌、结构和组成进行了测试.同时,使用动电位极化曲线、电化学交流阻抗谱和腐蚀失重3种方法对镁锂合金及其转化膜的耐腐蚀性能进行了深入研究.结果表明:高锰酸盐转化膜较均匀、平整,间隙较小,转化膜主要由锰的氧化物组成.提高了镁锂合金的耐腐蚀性能,当高锰酸盐溶液浓度为4.0 g/L时,转化膜的腐蚀电流密度小、容抗弧大、腐蚀速率低,耐腐蚀性能佳.     

Zr含量对Mg-3Zn-1Y合金显微组织和腐蚀行为的影响

采用传统重力铸造法制备了Mg-3Zn-1Y-xZr (x=0,0.2,0.4,0.6)合金,并通过光学显微镜(OM)、扫描电镜(SEM)、失重和电化学实验研究了Zr含量对Mg-3Zn-1Y显微组织和腐蚀行为的影响.结果 表明:Mg-3Zn-1Y主要由α-Mg基质和Mg3YZr6(Ⅰ)相组成,Zr的加入没有改变第二相的类...     

新型镁合金在生理体液环境下腐蚀行为评价

研究了2种新型医用植入镁合金材料(Mg-6%Zn和Mg-6%Zn-2%Y合金)在生理盐水和林格试液(人体模拟体液)中的腐蚀行为,来评价其作为医用植入材料的服役情况.实验结果表明:在中性介质环境下,镁合金很快被腐蚀.随着介质溶液pH值的提高,镁合金表面能够形成厚的Mg(OH)2沉淀膜,阻止腐蚀的深入.镁合金在林格试液中的...     

AZ91D镁合金微弧氧化膜在不同浓度NaCl溶液中的腐蚀行为(英文)

采用微弧氧化技术(MAO)在镁合金 AZ91D 表面制备微弧氧化陶瓷膜。利用电化学技术和浸泡实验研究该镁合金试样在不同浓度(0.1%,0.5%,1.0%,3.5%和 5.0%,质量分数) NaCl 溶液中的腐蚀行为。结果表明,试样的腐蚀速率随着氯离子浓度的升高而增大。在较高浓度(1.0%,3.5%和 5.0%)的 NaCl 溶液中的主要腐蚀形式是点蚀,而在较低浓度(0.1%和 0.5%)中是全面腐蚀。腐蚀过程可以分为两个阶段:亚稳态蚀点的出现和蚀点的生长。根据腐蚀过程中阻抗谱的特点,对镁合金微弧氧化膜试样在不同浓度 NaCl 溶液中浸泡 120 h 提出了不同的等效电路来模拟其腐蚀行为。     

等通道转角挤压对生物Mg-Zn-Ca合金显微组织与腐蚀行为的影响

旨在探讨等通道转角挤压(equal-channel-angular-pressed,ECAP)对生物医用Mg-3Zn-0.2Ca合金的显微组织以及腐蚀行为的影响。对铸态Mg-3Zn-0.2Ca合金进行了1,2,4道次的剪切挤压变形。采用光学显微组织观察、X射线反射法、电化学等手段研究了挤压道次对镁合金显微组织、织构以及腐蚀行为的影响,也特别关注了ECAP对试样的不同截面方向的显微组织演变以及模拟体液(simulatedbodyfluid,SBF)电化学腐蚀行为的影响。结果表明:ECAP变形后铸态Mg-3Zn-0.2Ca镁合金晶粒逐渐细化,变形后镁合金呈现出与挤压方向呈一定角度的002面剪切织构;随着挤压道次增加,合金的耐蚀性先增加后降低。等通道转角挤压对合金耐蚀性的影响是晶粒尺寸、晶体缺陷和织构变化的综合效果;ECAP变形后合金不同截面方向呈现不同的耐蚀性,垂直于挤压方向截面的耐蚀性优于另2个方向截面的耐蚀性。     

Effect of ageing treatment on microstructures,mechanical properties and corrosion behavior of Mg-Zn-RE-Zr alloy micro-alloyed with Ca and Sr

Effects of ageing treatment on the microstructures, mechanical properties and corrosion behavior of the Mg-4.2Zn-1.7RE-0.8Zr-xCa-ySr [x=0, 0.2 (wt.%), y=0, 0.1, 0.2, 0.4 (wt.%)] alloys were investigated. Results showed that Ca or/and Sr additions promoted the precipitation hardening behavior of Mg-4.2Zn-1.7RE-0.8Zr alloy and shortened the time to reaching peak hardness from 13 h to 12 h. The maximum hardness of 77.1±0.6 HV for the peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy was obtained. The microstructures of peak-aged alloys mainly consist of α-Mg phase, Mg₅₁Zn₂₀ phase and ternary T-phase. The Zn-Zr phase is formed within the α-Mg matrix, and the Mg₂Ca phase is formed near T-phase due to the enrichment of Ca in front of the solid-liquid interface. Furthermore, fine short rod-shaped β′₁ phase is precipitated within the α-Mg matrix in the peak-aged condition. The peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy exhibits optimal mechanical properties with an ultimate tensile strength of 208 MPa, yield strength of 150 MPa and elongation of 3.5%, which is mainly attributed to precipitation strengthening. In addition, corrosion properties of experimental alloys in the 3.5wt.% NaCl solution were studied by the electrochemical tests, weight loss, hydrogen evolution measurement and corrosion morphology observation. The results suggest that peak-aged alloys show reduced corrosion rates compared with the as-cast alloys, and minor additions of Ca and/or Sr improve the corrosion resistance of the Mg-4.2Zn-1.7RE-0.8Zr alloy. The peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy possesses the best corrosion resistance, which is mainly due to the continuous and compact barrier wall constructed by the homogeneous and continuous second phases.

     

Sb对Mg-5Al-2Sr合金耐腐蚀性能的影响

采用失重法、极化曲线、电化学阻抗谱和腐蚀形貌等方法研究了微量Sb对Mg-5Al-2Sr合金在3.5 mass% NaCl中性水溶液中耐腐蚀性能的影响。结果表明,Mg-5Al-2Sr-xSb(x=0,0.3,0.6,1.0)合金在3.5 mass% NaCl中性水溶液中初期的腐蚀类型为点蚀,点蚀源于块状三元τ相和颗粒状SbSr₂相。这些相的数量越多,尺寸越大,合金的腐蚀愈严重。网状分布的Al_4Sr相能够成为合金腐蚀的有效障碍。Mg-5Al-2Sr合金中加入0.3% Sb不仅能够有效地细化α-Mg基体组织,同时促进了Al₄Sr相的形成,使该相的分布更趋网状化,该合金的自腐蚀电位明显正移,腐蚀电流密度减小,腐蚀速率降低,合金的耐蚀性能提高。     

Microstructure and Corrosion Properties of Duplex-Structured Extruded Mg-6Li-4Zn-xMn Alloys

The extruded Mg-6Li-4Zn-xMn (x = 0, 0.4, 0.8, 1.2 wt%) alloys were prepared, and the microstructure of the test alloys was investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The corrosion properties were determined by electrochemical measurements and immersion measurements in 3.5% NaCl solution. The results indicate that the extruded Mg-6Li-4Zn-xMn alloys are mainly composed of α-Mg phase, β-Li phase, Mn precipitates and some intermetallic compounds (MgLi₂Zn). With the addition of Mn, stable corrosion products were formed on the surface of the test alloy, which can effectively inhibit further corrosion progress and improve the corrosion resistance. Mg-6Li-4Zn-1.2Mn alloy exhibits the best corrosion resistance, attributed to grain refinement, the improvement of the stability of corrosion product film and uniform distribution of fine second phases.     

Ca、Mn元素对Mg-Zn系合金在磷酸盐缓冲液中腐蚀行为的影响

采用XRD、SEM、EDS、三维轮廓仪和失重法等手段研究了Mg-6Zn、Mg-6Zn-1Ca和Mg-6Zn-1Mn合金在磷酸盐缓冲盐溶液(PBS)中的腐蚀行为,并探讨了3种合金的腐蚀机理。结果表明,添加相同含量的Ca和Mn均能使合金的失重率(W_r)降低,但添加Mn元素后(浸泡10d时W_r=3.91%)比添加Ca元素后(W_r=6.78%)合金的失重率更低,说明Mn元素更有抗PBS腐蚀能力,这与Mn的加入在合金表面形成致密的氧化膜有关;同时,Mg-6Zn-1Mn合金在浸泡过程中表面存在点蚀现象,经分析是由第二相与基体构成原电池导致。在420℃不同保温时间(2～20 h)固溶处理后,合金表面的点腐蚀现象随着保温时间的增加而减弱,表明长时间的固溶处理可以减少第二相与镁基体之间的微电偶腐蚀,增加了合金均匀腐蚀的倾向。     

Mg-4.0Zn-2.0Sr-0.4Ca合金复合涂层的耐腐蚀性能

通过环保型阳极氧化工艺及聚合沉积技术在生物材料Mg-4.0Zn-2.0Sr-0.4Ca合金表面逐层制备阳极氧化膜、SiO₂溶胶凝胶、聚多巴胺(PDA)和壳聚糖(CS)复合涂层。采用扫描电镜(SEM)、X射线衍射仪(XRD)观察涂层形貌并确定相组成,采用电化学测试、SBF浸泡试验比较涂层对合金耐蚀性能的影响。结果表明,制备的复合涂层致密完整无缺陷。在SBF溶液中,复合涂层随腐蚀时间的延长逐渐产生裂纹并破碎,产生较小的腐蚀坑,腐蚀在一定程度上被控制在表面,而无涂层Mg-4.0Zn-2.0Sr-0.4Ca合金在SBF溶液中的腐蚀以点蚀和局部腐蚀为主,且腐蚀程度随腐蚀时间的延长而加剧。复合涂层在SBF溶液中的腐蚀电流密度、腐蚀电位和平均腐蚀速率分别为5.7039 μA/cm²、-1.4203 V(vs SCE)和0.163 g/(m²·h),均优于无涂层镁合金,且平均腐蚀速率降幅达50%以上,说明制备的复合涂层可显著提高Mg-4.0Zn-2.0Sr-0.4Ca合金的耐腐蚀性能。     

合金元素Ga和In对Mg阳极组织和电化学性能的影响

采用动电位极化和恒电流曲线测试合金元素Ga和In对Mg阳极材料电化学性能的影响。采用扫描电镜法分析Mg?In?Ga合金的显微组织和腐蚀表面,并用X射线衍射法检测Mg?0.8%In合金和Mg?0.8%Ga?0.3%In 合金的腐蚀产物。结果表明：Mg?xIn (x=0?0.8%)合金中没有第二相出现,Mg?0.8%In?xGa (x=0?0.8%)合金中存在富含Ga和In元素的晶间化合物。合金元素In和0.05%?0.5%Ga的添加提高了镁阳极的耐腐蚀性能,Ga元素的添加更促进了Mg?In合金的电化学活性。Mg?0.8%In?0.8%Ga合金的平均电位最负,为?1.682 V,此电位比AZ91D合金的?1.406 V更负。Mg?In?Ga合金的腐蚀类型是全面腐蚀,其腐蚀产物是Mg(OH)2。     

Microstructure and Corrosion Behavior of the As-Extruded Mg-4Zn-2Gd-0.5Ca Alloy

In order to study the corrosion resistance of extruded magnesium alloys,the Mg-4 Zn-2 Gd-0.5 Ca alloy was extruded at the speed of 0.01-0.1 mm/s with the temperature of 280-360℃in present study.Hot extrusion results show that the volume fraction of precipitates(V_(pre)),V_(DRX)(the dynamic recrystallization rate) and the average size of DRXed grain(d_(DRX)) decrease with the decrease in extrusion speed,and the corrosion rate of the alloy also shows a downward trend.On the contrary,the values of V_(pre),V_(DRX) and d_(DRX) increase with the increase in extrusion temperature,and the corrosion resistance of Mg-4 Zn-2 Gd-0.5 Ca alloy decreases.When the extrusion speed is 0.01 mm/s and the extrusion temperature is 280℃,the alloy has the best corrosion resistance.The corrosion of extruded Mg-4 Zn-2 Gd-0.5 Ca alloy occurs preferentially on the magnesium matrix around W and I phases in the DRXed zone.With the further corrosion,the corrosion continues to spread along the phase,and the corrosion area gradually increases.Galvanic corrosion plays a leading role in the corrosion process.Moreover,there are a large number of basal plane textures in the unDRXed region,which is conducive to improving the corrosion resistance of magnesium alloys.In addition,the decrease in grain size also makes the corrosion of magnesium alloy more uniform.     

Mn添加对挤压态Mg-Zn-Y-Nd合金微观组织和腐蚀行为的影响

通过光学显微镜,配备能量色散光谱仪的扫描电子显微镜,X射线衍射仪,浸泡法和电化学测试的方法研究了Mn的添加对挤压Mg-Zn-Y-Nd合金在3.5wt.％NaCl溶液中的微观组织和腐蚀行为的影响。结果表明,在研究的Mg-Zn-Y-Nd合金中添加Mn可以诱导Mg3Y2Zn3（I相）沉淀,可以抑制热挤压过程中动态再结晶（DRX）晶粒的粗化。同时,添加了Mn也可以提高合金的耐腐蚀性。不含Mn的Mg-5.6Zn-1Y-0.4Nd合金与含锰1.0 wt.％的Mg-5.6Zn-1Y-0.4Nd合金腐蚀速率分别为18.78 mm·y-1和9.89mm·y-1。而耐腐蚀性的提高主要归因于腐蚀产物层保护性的增强。