电解液体系对镁合金微弧氧化涂层的影响

采用3种电解液体系对AZ91镁合金进行微弧氧化（MAO）处理。通过扫描电子显微镜和能量色散光谱观察涂层的表面形貌和元素组成,利用X射线衍射仪对涂层物相进行分析。同时,通过比较不同电解液体系微弧氧化涂层的粗糙度、润湿角和结合力来评估其特性,并利用极化曲线评价其耐蚀性能。此外,还使用模拟体液（SBF）浸泡实验来评估涂层的生物降解性能。结果显示：微弧氧化涂层具有良好的结合力;不同电解液体系处理得到的涂层在表面形貌和物相上存在差异,其中磷酸盐体系和硅酸盐体系具有较高粗糙度,而铝酸盐体系则具有较低粗糙度;此外,在各个系统中,磷酸盐体系呈现最小的润湿角值,而铝酸盐体系呈现最大值;这些差异导致了磷酸盐体系涂层耐蚀性最强,硅酸盐体系涂层次之,铝酸盐体系涂层耐蚀性最差;模拟体液浸泡21 d后的涂层表面产生了开裂,但耐蚀性得到了提高,这归因于浸泡过程中腐蚀产物和钙磷盐沉积物对于涂层的覆盖作用。     

Corrosion mechanism of micro-arc oxidation treated biocompatible AZ31 magnesium alloy in simulated body fluid

The rapid degradation of magnesium(Mg) based alloys has prevented their further use in orthopedic trauma fixation and vascular intervention,and therefore it is essential to investigate the corrosion mechanism for improving the corrosion resistance of these alloys. In this work, the effect of applied voltage on the surface morphology and the corrosion behavior of micro-arc oxidation(MAO) with different voltages were carried out to obtain biocompatible ceramic coatings on AZ31 Mg alloy. The effects of applied voltage on the surface morphology and the corrosion behavior of MAO samples in the simulated body fluid(SBF) were studied systematically. Scanning electron microscope(SEM) and X-ray diffractometer(XRD)were employed to characterize the morphologies and phase compositions of coating before and after corrosion. The results showed that corrosion resistance of the MAO coating obtained at 250 V was better than the others in SBF. The dense layer of MAO coating and the corrosion precipitation were the key factors for corrosion behavior. The corrosion of precipitation Mg(OH)2and the calcium phosphate(Ca–P) minerals on the surface of MAO coatings could enhance their corrosion resistance effectively. In addition, the mechanism of MAO coated Mg alloys was proposed.     

Hydrothermal synthesis of hydroxyapatite coating on the surface of medical magnesium alloy and its corrosion resistance

The early corrosion control of biomedical magnesium alloy is an important measure to determine its good performance during implantation into human body. The deposition of calcium phosphate biological coating is the most effective solution at present. In this paper, hydroxyapatite (HAP) coating was hydrothermal synthesized on the surface of AZ31B magnesium alloy, and the influence mechanism of hydrothermal synthesis temperature, time and solution concentration was investigated. The synthesis conditions and deposition mechanism of hydroxyapatite coating without DCPA (CaHPO₄) were proposed. The surface morphology of the coating was observed by field emission electron scanning microscope (FESEM). The types and contents of microelements in the material were analyzed by energy disperse spectroscopy (EDS). Fourier transform infrared spectroscopy (FTIR) was used to analyze the functional group information of the coating surface. The corrosion resistance of different experimental groups was studied by electrochemical test. The results showed that when the calcium phosphate solution concentration was 0.1 ?mol/L and the calcium/phosphorus ratio was 1.67, the coating had better morphology structure and corrosion resistance, and the calcium/phosphorus ratio of HAP crystals reached 1.58, the epit of the prepared AZ31B-HAP coating by bare metal increased from ?1.51 ?V to ?1.18 ?V, the impedance value reached 1.0 ?× ?10⁵ ?Ω?cm², and the early corrosion of magnesium alloy substrate was effectively delayed.     

水性硅酸盐富锌涂层的SEM/EDS研究

利用自制的不同模数(SiO2/K2O摩尔比)硅酸钾溶液与锌粉复配制备成系列模数硅酸盐富锌涂料.采用场发射电子显微镜(SEM)研究了碳钢上水性硅酸钾富锌涂层在质量分数为3.5%NaCl溶液中腐蚀形貌的变化,分析了水性硅酸钾溶液的模数对涂层结构及其防腐蚀性能的影响.采用能谱仪(EDS)测定了涂层在浸泡前及不同浸泡时期表面组成的变化,并据此分析了腐蚀产物对涂层结构和涂层防腐蚀性能的影响.结合腐蚀产物的X-ray衍射图谱(XRD)分析了腐蚀产物的组成.研究结果表明:水性硅酸钾溶液模数的增加有利于提高Zn粉颗粒间的粘接形成致密的富锌涂层.使用过程中该涂层的腐蚀产物能够增强涂层对腐蚀介质渗透的屏蔽效应,并与涂层中Zn粉对基材的阴极保护产生协同作用.     

镁合金微弧氧化-涂装体系的研究

提出了一种镁合金/微弧氧化膜/有机涂层的镁合金防护体系.在以硅酸钠为主的复合溶液中,利用双向对称脉冲电压在阴、阳极镁合金表面同时微弧电沉积陶瓷膜.利用盐雾实验比较了以镁合金微弧氧化膜为基底并涂覆环氧底漆和聚胺脂丙烯酸面漆的试样与镁合金/微弧氧化膜/有机硅、镁合金/微弧氧化膜/溶胶凝胶涂装试样的耐蚀性,并利用盐雾实验与交流阻抗谱相结合跟踪对比分析了镁合金/有机涂层、镁合金/铬酸盐转化膜/有机涂层、镁合金/微弧氧化膜/有机涂层的屏蔽性能.结果表明:采用溶胶凝胶、有机硅和有机涂层对微弧氧化膜进行涂装的方法均可进一步提高镁合金的耐蚀性,其中镁合金/微弧氧化膜/有机涂层试样可承受480h以上的中性盐雾实验,且其介质屏蔽性能优于镁合金/有机涂层和传统的镁合金/铬酸盐转化膜/有机涂层防护体系.     

硅酸根电迁移反应法处理砂浆的耐久性

为提升砂浆的耐久性,用硅酸根电迁移反应法处理砂浆。通过对比试验,研究了基准砂浆、去除表面涂层的被处理砂浆、带有表面涂层的被处理砂浆试件的抗碳化、抗硫酸盐侵蚀、抗氯离子扩散和抗钢筋氯离子腐蚀的耐久性能。应用扫描电子显微镜(SEM)与压汞仪(MIP)研究了硅酸根电迁移反应法影响砂浆耐久性的微观作用机制。结果表明:砂浆试件的抗碳化、抗硫酸盐侵蚀、抗氯离子扩散与抗钢筋氯离子腐蚀的耐久性能由小到大的顺序为:基准砂浆、去除表面涂层的被处理砂浆试件、带有表面涂层的被处理砂浆试件;硅酸根电迁移反应法对耐久性的提升作用缘于它能致密化砂浆并生成表面涂层的双重效果;由于生成的表面涂层较薄,且含有众多微米级孔隙,使表面涂层对砂浆耐久性影响减弱,砂浆致密化在耐久性的提升中起主要作用。     

NaCI溶液中Fe—W非晶镀层磷化膜的耐蚀机理

将Fe-W非晶镀层在锌系磷化液中进行磷化处理,表面形成致密的磷化膜,显著提高了镀层在NaCI溶液中的耐蚀性能;采用AES和XPS测定Fe-W磷化膜的成分和化学价态,并对膜层进行了深度剖析。实验结果表明,磷化膜主要由ZeZn2(PO4)2、Zn3(PO4)2及少量Fe2O3、WO3和钼酸盐组成,厚度约为210nm。此外,还探讨了磷化膜的耐蚀机理。     

微波加热硬化水玻璃砂表面涂层的抗湿性研究

针对微波加热硬化水玻璃砂吸湿性强的特点,以PbO-ZnO系低温玻璃粉作为主要的涂层材料,研究测试了涂层的抗湿性．结果表明：表面涂层后的水玻璃砂样抗吸湿性明显高于普通水玻璃砂样,4h存放强度提高了2．33倍,4h吸水率降低了45．9％．通过SEM和XRD等测试方法,对表面涂层砂样和普通砂样的物相和成分进行了分析：SEM分析表明,表面涂层砂样的表层有涂层材料渗入形成防湿层,防湿层内砂粒表面的粘结桥有许多细小颗粒状物质分布．表面xRD扫描表明：涂层表面出现了3种新的物相,即Al2TiO3,NaAlO2和PbTiO3,它们是表面涂层提高砂样抗湿性的主要原因．     

化学镀Ni-P基体的磷含量对亚硫酸盐镀金体系置换镀金层表面形貌的影响

以亚硫酸-硫代硫酸盐镀金体系作为置换镀金液,在化学镀Ni-P镀层上制备了置换镀金层,并采用原子力显微镜分析了磷含量及置换镀金时间对镀金层微观表面形貌的影响.结果表明,磷含量越高,Ni-P基体耐腐蚀性能越好,镀金层表面越好,表面粗糙度越小;置换镀金时间为600s时,所得镀金层最为平整光滑,镀金时间越长,Ni-P基体受到腐蚀越大,所得镀金层表面粗糙度变大.     

铝合金表面电镀镍的耐腐蚀性能

在铝合金表面电镀镍,考察镀液温度、电流密度和镀液pH值等因素对镀层耐蚀性能的影响,获得最佳电镀条件下的镍镀层.选择3.50%NaCl溶液作为腐蚀介质,采用稳态阳极极化曲线法研究镀层的耐蚀性能.用SEM和XRD研究镍镀层在腐蚀前后的微观结构和表观形貌的变化.结果表明镀镍的最佳工艺条件为温度50℃、电流密度30mA/cm2、镀液pH值3.82.XRD测试表明镍镀层的结构为立方晶系,晶面择优取向为(111),腐蚀前后晶面择优取向不变,但(111)晶面的织构系数由35.35%增至61.73%,说明低指数晶面(111)具有较好的耐蚀性能.SEM测试表明最佳条件下制备的半光亮镍镀层均匀致密,具有较好的耐腐蚀性能.     

Epitaxial growth of single-crystalline Ni46Co4Mn37In13 thin filmand investigation of its magnetoresistance

Single-crystalline thin film of Ni46Co4Mn37In13alloy grown on MgO(0 0 1) was prepared by Pulsed Laser Deposition(PLD) method. The epitaxial growth process was monitored by in situ Reflection High Energy Electron Diffraction(RHEED). Structure measurements reveal that the single-crystalline Ni46Co4Mn37In13film could be stabilized on MgO(0 0 1) as a face-centered-cubic(fcc) structure. From the evolution of RHEED,it can be deduced from the patterns that Volmer-Weber growth mechanism(3-D) dominates at the initial stage. Then,it becomes layerby-layer growth mechanism(2-D) with the increase of the film thickness. Lastly,growth mechanism converts back to 3-D when the film is thick enough. Both electrical resistance and magnetoresistance(MR) were measured at various temperatures using Physical Property Measurement System(PPMS). The electrical resistance measurement indicates that the film sample does not have martensitic transformation in the measurement temperature range. However,with the temperature increasing,the film sample exhibits a transition from metallic to semiconductorlike properties. Moreover,a small negative magnetoresistance was observed at different temperature,which can be explained by the spindependent scattering of the conduction electrons.     

超重力法制备的LDH涂层对镁合金耐蚀性的提升作用

采用超重力法在旋转填充床（RPB）中制备富马酸根与柠檬酸根复配插层的层状双氢氧化物（LDH）浆液,然后进行水热处理,在AZ31镁合金表面生长出富马酸根与柠檬酸根插层的LDH涂层。利用X射线衍射仪（XRD）、傅里叶变换红外光谱仪（FT-IR）对LDH粉末进行表征,利用X射线光电子能谱仪（XPS）对AZ31镁合金表面的LDH涂层进行表征,结果证明成功制备出富马酸根与柠檬酸根插层的LDH涂层。使用场发射扫描电子显微镜（FESEM）观察LDH涂层的外观形貌,通过电化学试验测试了生长LDH涂层的AZ31镁合金的耐腐蚀性能,结果表明,采用超重力法制备的含有富马酸根与柠檬酸根插层的LDH涂层表面生成完整、致密的覆盖层,几乎看不到簇立状的LDH片。与共沉淀法相比,使用超重力法制备的LDH涂层,其动电位极化曲线拟合出的腐蚀电位更大,腐蚀电流密度更小。在3.5% NaCl溶液中浸泡96 h后,采用超重力法制备的含有富马酸根与柠檬酸根插层的LDH涂层的阻抗值R_ct为56.69kΩ·cm²,大于仅浸泡1 h的采用共沉淀法制备的不含富马酸根与柠檬酸根插层的LDH涂层（R_ct为49.45kΩ·cm²）,表明超重力法制备的LDH涂层表现出更好的耐腐蚀性。     

Preparing Ca-P coating on biodegradable magnesium alloy by hydrothermal method: In vitro degradation behavior

Magnesium alloys are potentially attractive biodegradable materials.However,their rapid corrosion rate limits their biomedical application.To slow down the rate of biodegradation,a protective calcium-phosphate coating was formed on a magnesium alloy substrate by a hydrothermal method.Scanning electron microscope results showed that the coating consisted of two layers with different crystalline characteristics.The loose outer layer showed a prism-like crystal structure,while the compact inner layer is a dense ultra-fine regular di-pyramid-like structure with an average grain dimension of ～200 nm.The compositions of the inner layer and outer layer were calcium-deficient hydroxyapatite (Ca-def HA) and dicalcium phosphate (DCPa),respectively.The coating adhered well to the substrate with a thickness of about 15 m.Immersion in Hank’s solution indicated that the coating could significantly improve the degradation properties of magnesium alloy.The pH of the solution containing the coated samples increased much more slowly than the untreated control.After 8 d immersion,the uncoated sample had corroded seriously while the coated sample was much less corroded.The Ca/P atom ratio in both the layers of the coating increased and the coating was still protecting the substrate.The two layers of the coating corroded differently because of differences in solubility.The outer layer was more severely attacked and many holes were formed on the surface,the inner layer suffered less attack.In addition,a growth of precipitate on the inner layer was observed,indicating that surface bioactivity was improved by the coating.Thus,magnesium alloys coated with a Ca-P coating prepared by a hydrothermal method are promising candidate biodegradable biomaterials,and further investigation of in vivo degradation behavior is suggested.     

纳米TiO2改性环氧富锌涂料的防腐性能

将纳米TiO2以机械搅拌的方式加入到环氧富锌涂料中,制备纳米TiO2改性环氧富锌涂料。采用喷涂法将纳米TiO2改性环氧富锌涂料和未改性的环氧富锌涂料分别涂覆到耐候钢电极表面上,在NaCl电解质溶液中测量电化学极化曲线,并通过金相显微镜观察样品湿热试验后的表面形貌。实验结果表明,纳米TiO2的光电转换作用提高了环氧富锌涂层防腐性能,耐候钢表面涂覆纳米TiO2改性环氧富锌涂料后,其自腐蚀电流减小,表面腐蚀程度减轻。     

微弧氧化法制备镁基羟基磷灰石/碳纳米管复合生物涂层及其性能研究

 通过化学沉淀法制备了羟基磷灰石/碳纳米管纳米(HA/CNTs)复合粉体,并作为电解液的添加剂,采用微弧氧化方法(MAO)制备了镁合金表面MAO/HA/CNTs 复合活性涂层。分别采用扫描电子显微镜(SEM)、X 射线衍射分析(XRD)、傅里叶红外光谱(FTIR)和电化学工作站,研究所制备的复合粉体的形貌和物相组成、复合粉体对微弧氧化涂层表面形貌和在模拟体液(SBF)中耐腐蚀性能和生物活性的影响。结果表明,所制备的HA/CNTs 复合粉体结晶良好,无其他杂质相;复合粉体在微弧氧化过程中沉积在样品表面,对微弧氧化涂层起到封孔作用。MAO/HA/CNTs 样品的腐蚀电位为-1.50 V,经过30 天的SBF 浸泡后,表面沉积了大量的亚微米级别的颗粒沉积物,相比于镁基体和MAO 样品具有更好的生物活性和耐腐蚀性。     

热浸Zn-Ti合金镀层的显微组织与耐蚀性能

为了抑制热镀锌过程中因含硅活性钢引起的镀层超厚生长,本文采用在纯锌浴中加Ti的方法,研究了0.09%Si钢在含低于0.1%Ti的几种锌浴中热浸镀获得的组织,并采用盐雾腐蚀,电化学极化以及X射线光电子能谱等方法,研究了Zn和Zn-Ti镀层的耐蚀性能。结果表明,随着锌浴中Ti含量的增加,Ti对ζ相生长的抑制作用增强,合金层厚度逐渐减薄,Ti能有效地抑制含硅活性钢镀层的超厚生长。当Ti含量大于0.05%时,镀层中出现Γ2粒子。Zn-Ti合金镀层在5%NaCl溶液中发生自发腐蚀的倾向小于Zn镀层,其极化电阻增大,腐蚀电流密度减小,耐蚀性能提高。Zn-Ti镀层表面形成的氧化膜由ZnO 和TiO2组成。锌钛合金镀层的耐腐蚀性能优于纯锌镀层是由于在镀层表面形成了更加稳定的TiO2膜。     

Anti-corrosion performance of waterborne Zn-rich coating with modified silicon-based vehicle and lamellar Zn (Al) pigments

In order to develop the eco-friendly Zn-rich coatings with higher corrosion resistance and lower pigment contents, several series of coatings were designed and manufactured employing lamellar Zn (Al) pigments mixed with silicone-acrylate emulsion modified inorganic silicate vehicle, and then were evaluated by conventional methods and the electrochemical method. The results indicated that the pigment contents reduced to approximate 25 mass% with lamellar Zn or (Zn and Al) pigments as substitute for spherical Zn pigments, and pigment mixtures were homogeneously dispersed due to silicone-acrylate emulsion moistening modification. Furthermore, the optimal coating had good coating properties (adhesion grade: one), acid resistance (lower mass losses) and anti-corrosive performance (improved corrosion potential and anodic passivation). The experimental results indicated that the modified lamellar Zn (Al) coating was suitable for large-scale spread and application on protecting steel structures in the hostile environment.     

含氯离子环境下锌铝伪合金涂层的耐蚀性及电化学特性

采用盐雾试验和电化学阻抗谱测试技术研究了纯锌和锌铝伪合金涂层在含氯离子环境中的腐蚀行为和电化学特性,通过扫描电镜、X射线物相分析等手段研究了原始涂层及腐蚀后的表面形貌和腐蚀产物的相结构,并对两种涂层的腐蚀机理进行了初步的探讨.随着盐雾时间的增加,纯锌涂层表面逐渐生成疏松多孔的胞状腐蚀产物层,主要腐蚀产物为Zn5(OH)8-Cl2H2O、ZnO和Zn5(CO3)2(OH)6,盐雾试验达到768 h后腐蚀产物层局部区域发生龟裂.锌铝伪合金涂层表面生成致密的腐蚀产物层,主要为Zn5(OH)8Cl2H2O、Zn0.71Al0.29(OH)2(CO3)0.145.xH2O及ZnAl2O4.电化学阻抗谱测试结果表明:随着盐雾时间的延长,两种涂层的电荷转移电阻均逐渐增大,但锌铝伪合金涂层的阻抗要明显大于纯锌涂层,表现出了更好的耐蚀性.     

镍基合金镀层在北方老工业城市冬季降水中的腐蚀行为

为研究镍基合金镀层在北方老工业城市冬季降水中的腐蚀行为,采用电沉积技术制备了Ni--P、Ni--Fe合金镀层,对其结构与耐蚀性能进行检测.结果表明:不同镍基合金镀层在冬季降水中耐蚀性能不同,其中Ni--Fe合金镀层由于Fe掺杂增加了镍基合金与氧的亲和力,可以快速在Ni--Fe合金镀层表面形成一层连续的氧化膜,对基体起到很好的防护作用,电位最正,自腐蚀电流密度值最小,耐蚀性较好,年腐蚀速率约为20号钢的1/2;而Ni--P合金镀层表面形成氧化膜的速率较缓慢,阻抗值较低,不适合在北方老工业城市的室外装饰与防护中应用.     

Investigation of the Ce-Mn conversion coating on 6063 aluminium alloy

In this paper, the sustainable Ce-Mn chemical conversion coating was fabricated on 6063 aluminium alloy by means of Ce(NO₃)₃ and KMnO4 as the inhibitors and NaF as the accelerator. The morphologies, composition and valence state of the coating were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The results indicated that the Ce-Mn conversion coating was formed. The anticorrosion of the coating was evaluated in 3.5 wt.% NaCl aqueous solution at room temperature by using polarization curve and electrochemical impedance spectroscopy (EIS). It indicated that the treated surface presented better anticorrosion behavior in chloride media than on the original material surface. The corrosion resistance of Ce-Mn conversion coating was about equal to the trivalent chromium conversion coating.