一步电沉积Ca-P/CTS复合涂层的制备及其耐蚀性

通过一步电沉积法在AZ31镁合金基体表面上沉积钙磷/壳聚糖(Ca-P/CTS)复合涂层,通过共聚焦显微镜(CLSM)、扫描电镜(SEM)和红外光谱分析仪(FT-IR)对Ca-P/CTS复合涂层的形貌、结构以及成分进行分析,采用电化学测试研究了其耐蚀性。结果表明:Ca-P/CTS复合涂层能够有效提高AZ31镁合金基体的耐蚀性,当壳聚糖的质量浓度为0.2g/L时,复合涂层的耐蚀性最好。     

氟处理对AZ31B镁合金生物耐蚀降解行为的影响

采用低温化学方法在AZ31B镁合金表面制备出氟涂层,并研究了涂层的表面特征,氟处理后AZ31B镁合金在模拟体液中的腐蚀行为。结果表明,氟涂层均匀致密,与基体结合良好。经氟处理后的AZ31B镁合金的耐蚀性能有较大提高,其在模拟体液中的降解缓慢,合金浸泡后溶液的pH值保持在7.5~8.8之间,有效降低了合金降解而引起的碱性增强趋势。氟涂层在模拟体液中会逐渐转化为Ca3(PO4)2,新生成的表面膜会继续起到保护合金基体的作用。     

Fabrication of Cr coating on AZ31 magnesium alloy by magnetron sputtering

Chromium-plating is considered an effective method to improve surface properties of metal materials.Magnetron sputtering was applied to prepare Cr coating on AZ31 magnesium alloy and the influence of bias voltage on properties of Cr coating was investigated.The obtained coatings present an(110) preferred texture and have a developed columnar structure.With increasing bias voltage,the surface structure of Cr coating becomes denser.All of the Cr-coated AZ31 have much higher surface microhardness than bare ...     

镁合金表面层层组装PSS/PAH膜诱导钙磷涂层

目的镁合金具有良好的生物相容性和可降解性,作为生物医用材料具有广泛的应用前景。有效地提高镁合金的耐蚀性能,对镁合金作为医用材料具有重要意义。方法利用浸泡法在AZ31镁合金基体表面层层组装制备聚苯乙烯磺酸钠(PSS)、聚丙烯胺盐酸盐(PAH)多层膜,并将获得的样品采用水热法在Ca(NO)_3、NaH_2PO_4、Na_2CO_3溶液中诱导钙磷涂层(羟基磷灰石)的形成。利用高分辨扫描电子显微镜、傅里叶红外光谱、X射线光电子能谱对Ca-P/(PAH/PSS)5/Mg复合膜层的表面形貌、化学成分进行了表征,通过析氢和电化学实验(包括极化曲线及阻抗谱)研究了Ca-P/(PAH/PSS)5/Mg涂层的耐腐蚀性能。结果Ca-P/(PAH/PSS)5/Mg膜层厚度约为7.67μm,表现为立体叶草状,在镁合金表面紧密排列。Ca-P/(PAH/PSS)5/Mg涂层耐蚀性提高一个数量级,其腐蚀电流密度从镁合金AZ31的3.69×10–5 A/cm2降低到1.61×10–6 A/cm~2,同时析氢速率降低。结论该涂层可以有效地提高镁合金的耐蚀性能,其成因则主要归功于组装的两种聚电解质的类生物矿化作用。这种诱导所得钙磷膜层对镁合金在生物医用领域的应用提供了新的思路。     

沉积时间对镁合金表面Ca-P生物涂层耐蚀性能的影响

目的：镁合金在生物医学领域具有很好的应用前景,为消除其在人体环境中降解速度过快的不足,需在镁合金表面制备一层能够降低其腐蚀速度且具有很好生物相容性的防护涂层。方法采用电沉积法在AZ91D镁合金表面制备Ca-P生物涂层,沉积条件为：在Ca(NO3)2和NH4H2PO4浓度分别为0.1 mol/L和0.06 mol/L的电解液中,pH值4.5,沉积电压2 V,沉积时间分别为1、2、3和4 h。采用XRD、SEM/EDS分析Ca-P涂层的相结构、微观形貌和化学成分,测试Ca-P涂层在Hank,s模拟体液中的极化曲线。结果镁基体表面均获得物相为 DCPD(二水合磷酸氢钙)的生物涂层,但涂层表面形貌随沉积时间的不同变化明显,当沉积时间为3 h时,涂层颗粒尺寸均匀、细小,涂层钙磷比为1.324。极化曲线结果表明,沉积1 h时涂层对基体已有一定的防护作用,随着沉积时间的加长,涂层的腐蚀电压也呈增大趋势。相对镁基体,沉积3 h的涂层腐蚀电位升高了180 mV,腐蚀电流密度降低了3个数量级。结论当沉积时间为3 h时,涂层的耐蚀性最好。     

镁合金表面高频感应熔涂铝涂层显微组织分析

采用感应熔涂技术在镁合金表面熔涂一层金属铝。运用SEM、EDS、XRD等手段研究了涂层的显微组织，通过测定动电位极化曲线研究了涂层的电化学腐蚀行为。结果表明，涂层与基体形成了扩散白亮带．实现了较好的冶金结合；涂层具有亚共晶组织的特点；大量的Mg17Al12相存在于涂层表面是耐腐蚀性能提高的主要原因。     

微弧表面处理对AZ31B镁合金耐腐蚀及耐腐蚀疲劳性能的影响

采用微弧表面处理技术(微弧氧化MAO和微弧复合MCC)在AZ31B镁合金基体上制备出不同断面结构的防护涂层。通过电化学腐蚀及腐蚀疲劳测试方法,研究了MAO、MCC涂层的电化学腐蚀及腐蚀疲劳性能。结果表明,生长10 min的MAO涂层具有较好的耐电化学腐蚀性能。MAO涂层表面存在微孔和微裂纹,在应力条件下微孔和微裂纹作为疲劳断裂的裂纹萌生点,可加速裂纹的萌生与扩展,使其腐蚀疲劳寿命相较AZ31B合金基体降低了55%。而具有MCC涂层的AZ31B合金试样腐蚀疲劳极限为(64.0±5.4) MPa,比AZ31B合金基体提高了59%。在低应力载荷下(＜80 MPa),微弧复合涂层试样的腐蚀疲劳强度得到明显提高。     

铝稀土合金(Al-Nd)高能微弧火花合金化的研究

用高能微弧火花合金化设备将铝稀土(Al-Nd)电极合金熔化到AZ31镁合金上以提高其耐蚀性,用极化曲线测试和浸泡试验表征合金的耐蚀性,用金相显微镜和扫描电镜观察合金化层的显微结构,用X射线衍射进行物相分析.结果表明,使用高能微弧火花Al-Nd合金化后,由于晶粒细化、快速凝固和合金化层中富含Al和Nd,可显著提高AZ31镁合金的耐蚀性.     

AZ31镁基高速火焰喷涂WC涂层的研究

材料的轻量化已经越来越成为一种趋势.镁合金因为更高的比强而作为铝合金的替代材料,在机械、电子和航空等工业有着广泛的应用前景.然而镁合金因硬度低,抗腐蚀性差而使应用受限制,因此需要进行表面处理以提高材料的使用寿命和拓宽应用领域.采用High-Velocity-Air-Fuel(高速火焰喷涂)技术在AZ31镁合金基体上制备了WC-CoCr涂层,采用XRD、SEM分别对涂层的相和显微结构进行了分析,同时研究了拉伸对偶件的弹性模量对涂层结合强度测试的影响,重点阐述了涂层的结合机理.此外,还研究了镁基高速火焰喷涂WC涂层的抗中性盐雾腐蚀性能.结果表明,采用HVAF技术,可在AZ31镁合金基体上获得致密,结合强度较高且具有良好抗腐蚀性能的WC-CoCr涂层.     

Statistical Process Control

Abstract

In order to improve the corrosion resistance provided by a micro-arc oxidation (MAO) coating on AZ31 magnesium alloy, a polypropylene film was prepared on its surface. Scanning electron microscopy, energy dispersive X-ray analysis and Fourier transform infrared spectroscopy were used to characterise the surfaces of the coatings. The corrosion protective performance of the coatings was evaluated by potentiodynamic polarisation curves, electrochemical impedance spectroscopy and immersion testing. The results show that the microdefects of the MAO coating can be filled by PP and the corrosion resistance of the AZ31 magnesium alloy is improved greatly.     

磁控溅射和等离子体电解氧化双重工艺处理AZ31镁合金的耐蚀和耐磨性能

为了提高AZ31镁合金的耐磨和耐腐蚀性能,通过磁控溅射法在合金表面涂覆约11μm的纯铝层,然后分别在铝酸盐和硅酸盐电解液中通过等离子电解氧化(PEO)进行表面处理.涂层的性能通过干滑动摩擦试验和电化学腐蚀试验进行研究.铝酸盐涂层在10和20 N的负载下均表现出良好的耐磨性能;硅酸盐涂层只在较低的载荷下(10 N)表现出...     

前处理工艺对镁合金化学镀Ni-P质量的影响

采用扫描电镜和性能检测的方法,分析了表调、活化和浸锌等前处理工艺对镁合金化学镀Ni-P质量的影响.结果表明,表调可使晶界凸出于α-Mg基体,降低镁合金的表面粗糙度,提高化学镀层的结合强度.活化及浸锌后,促进了化学镀的进行.按表调、活化、一次浸锌、退镀、二次浸锌的工艺进行前处理后实施化学镀,得到的Ni-P镀层致密、平整,与基体结合力强,有效提高了镁合金表面耐蚀性及显微硬度.     

镁合金表面等离子喷涂Al2O3-TiO2陶瓷涂层的耐腐蚀性研究

采用等离子喷涂技术在AZ31镁合金表面制备Al2O3-13％TiO2陶瓷复合涂层,对涂层的微观组织进行了观察分析,测试了涂层的表面硬度.通过极化曲线和浸泡腐蚀试验,对比研究了镁合金基材及喷涂陶瓷涂层的试样在5％ NaCl溶液中的耐腐蚀性能.结果表明:涂层镁合金试样的硬度和耐腐蚀性优于基体镁合金,但当腐蚀液透过涂层孔隙时...     

Enhanced corrosion resistance of micro-arc oxidation coated magnesium alloy by superhydrophobic Mg−Al layered double hydroxide coating

To further enhance the corrosion resistance of the porous micro-arc oxidation (MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg−Al layered double hydroxide (LDH) coating was fabricated on MAO-coated AZ31 alloy by using in-situ growth method followed by surface modification with stearic acid. The characteristics of different coatings were investigated by XRD, SEM and EDS. The effect of the hydrothermal treatment time on the formation of the LDH coatings was studied. The results demonstrated that the micro-pores and cracks of MAO coating were gradually sealed via in-situ growing LDH with prolonging hydrothermal treating time. Electrochemical measurement displayed that the lowest corrosion current density, the most positive corrosion potential and the highest impedance modulus were observed for superhydrophobic LDH/MAO coating compared with those of MAO coating and LDH/MAO coating. Immersion experiment proved that the superhydrophobic LDH/MAO coating with the active anti-corrosion capability significantly enhanced the long-term corrosion protection for MAO coated alloy.     

硅烷增强镁合金防腐有机涂层的研究

为了提高镁合金的耐腐蚀性能,结合硅烷处理和胶粘涂层技术在AZ31镁合金表面制备了环氧防腐涂层。通过扫描电镜对涂层表面形貌进行观察,采用划格法、浸泡法及盐雾试验等分析镁合金表面硅烷处理对有机涂层的附着力及耐蚀性的影响。研究结果表明：采用KH-550型硅烷进行处理后,镁合金基体与有机涂层之间形成化学键,涂层与基体结合牢固,附着力为1级,耐饱和盐水23d不起泡。硅烷处理明显提高了有机涂层对基体的附着力和耐蚀性,因此,硅烷＋胶粘涂层的方法可用于镁舍金的表面防腐。     

AZ31B镁合金钒/硅烷复合转化膜的制备与表征

目的 改善钒酸盐转化膜表面形貌,提高单一钒酸盐转化膜的耐蚀性能。方法 使用偏钒酸盐和硅烷通过两步法在镁合金表面制备钒/硅烷复合转化膜,比较不同硅烷制备的复合膜的耐蚀性能,从而确定使用硅烷的种类,采用扫描电子显微镜(SEM)、X射线能谱(EDS)、X射线光电子能谱(XPS)和傅里叶红外光谱(FT-IR)观察转化膜的微观形貌并分析转化膜的组成和结构,通过交流阻抗测试(EIS)、Tafel极化曲线测试和全浸腐蚀实验评价转化膜的耐蚀性能,并采用划格实验和接触角测试评价转化膜的结合力和疏水性。结果 确定使用BTEPST(双-[3-(三乙氧基硅)丙基]-四硫化物)作为成膜组分,使用偏钒酸钠和BTESPT在镁合金表面成功制备钒/BTESPT复合膜,复合膜表面均匀平整,致密无裂纹,与基体结合力好,具有疏水性,该复合膜的组成元素为Mg、V、C、O、Si和S,且元素分布较均匀,膜层是包含Si—O—S、Si—O—Mg、Si—O—V等共价键的交联结构。交流阻抗测试结果显示,钒/BTESPT复合转化膜的膜层电阻为1.17×10⁵?·cm²,电荷转移电阻为1.076×1...     

镁合金等离子喷涂Al/Al_2O_3涂层的耐腐蚀性能

采用等离子喷涂技术在AZ31镁合金表面制备Al/Al_2O_3复合涂层,测试了镁合金及表面喷涂有Al/Al_2O_3复合涂层的镁合金试样的极化曲线,研究了没有涂层、经封孔处理和未经封孔处理的喷涂有复合涂层的镁合金三种试样在浸泡腐蚀和5%NaCl盐雾腐蚀情况下的耐腐蚀性能及其腐蚀行为.结果表明,经封孔处理的Al/Al_2O_3复合涂层镁合金试样在上述腐蚀条件下的耐腐蚀性均优于镁合金和涂层未封孔处理的试样,在浸泡试验中未封孔处理的涂层试样比镁合金腐蚀更加严重,在盐雾试验中却优于镁合金.     

Improving wear resistance and corrosion resistance of AZ31 magnesium alloy by DLC/AlN/Al coating

A novel protective coating, consisting of three layers (top: diamond-like carbon, middle: aluminum nitride, bottom: aluminum), was deposited on the surface of AZ31 magnesium alloy layer by layer. Nano-indenter, electrochemical system and tribological tester were performed to investigate the hardness, wear resistance and corrosion resistance of the coated AZ31 magnesium alloy, respectively. The DLC/AlN/Al coating improved the magnesium alloy's surface hardness and reduced its friction coefficient, which consequently induced a great improvement of the magnesium alloy's wear resistance. Furthermore, the corrosion resistance of the AZ31 magnesium alloy with the DLC/AlN/Al coating was also enhanced with the corrosion current density decreasing from 2.25 × 10⁻⁵ A/cm² to 1.28 × 10⁻⁶ A/cm² in a 3.5 wt.% NaCl solution.     

Study on microstructure and properties of laser surface melted layer of AZ31B magnesium alloy

An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO_2 laser as a heat generating source. X-ray diffraction (XRD) was used to identify the phases. Microstructure and properties of laser melted layer of AZ31B magnesium alloy were observed or tested by means of optical microscope (OM), scanning electron microscope (SEM), micro-hardness equipment and electrochemical corrosion equipment etc. The results show that the microstructure of laser melted layer becomes finer significantly and uniform. Compared with the substrate, the content of β-Mg_(17)Al_(12) phase of melted layer decreases comparatively. Microhardness of the laser melted layer is improved to 50-95HV_(0.05) as compared to 40-45HV_(0.05) of the AZ31B Mg alloy substrate. The results of electrochemical corrosion show that the corrosion resistance of laser surface melted layer has been improved.     

AZ31B镁合金表面微弧电泳复合膜层微观结构及耐蚀性表征

采用微弧氧化技术在AZ31B镁合金表面制备陶瓷层,利用其表面多孔结构借助电泳技术沉积有机膜层,对比研究陶瓷层和复合膜层表面粗糙度、表面及截面形貌、电化学性能及划伤腐蚀特性。结果表明:陶瓷层表面放电微孔被电泳层完全填充并形成均匀膜层,复合膜层表面粗糙度明显降低;微弧电泳复合膜层腐蚀电流密度与陶瓷层和基体相比分别降低2个和4个数量级,极化电阻分别增大2个和4个数量级,腐蚀倾向降低;微弧电泳复合膜层电化学阻值与陶瓷层相比增加4个数量级,同时电容值降低4个数量级,耐蚀性显著提高;由于陶瓷层与电泳层的机械嵌合作用,复合膜层划伤腐蚀过程表现为基体腐蚀及陶瓷层与基体界面的破坏,复合膜层界面处结合完好。