镁合金表面非晶涂层的构筑及其腐蚀行为

目的提高镁合金的耐腐蚀性能。方法采用超音速火焰喷涂技术,在AZ61镁合金表面引入Ni Cr Al作为中间层,最终在镁合金表面构筑一层铁基非晶涂层。通过扫描电子显微镜、X射线衍射仪、差热分析仪、显微硬度测试仪、开路电位测试仪、动电位极化测试仪、X射线光电子能谱仪和接触角测量仪,分别评价了镁合金基体和铁基非晶涂层的形貌特征、微观结构、热稳定性、力学性能、腐蚀行为和表面性质。结果在AZ61镁合金表面成功构筑了一层厚度约200～240μm的铁基非晶涂层,该涂层在XRD有效分辨率内呈单一非晶结构。热分析结果表明,该非晶涂层的起始晶化温度可达657℃,具有极高的热稳定性。铁基非晶涂层和AZ61镁合金的显微硬度分别为892HV和71HV,合金表面显微硬度提高了10倍以上。在模拟海水中,AZ61镁合金和铁基非晶防护涂层的稳态开路电位分别为-0.59V和-1.58V,自腐蚀电流密度分别为80μA/cm~2和4μA/cm~2;在酸雨介质中,镁合金和非晶涂层的稳态开路电位分别为-0.45 V和-1.51 V,自腐蚀电流密度分别为7.27μA/cm~2和1.64μA/cm~2。去离子水在AZ61镁合金的表面润湿角为(59.8±1.5)°,而铁基非晶涂层的接触角为(74.4±0.6)°。结论在镁合金表面构筑铁基非晶涂层,可以显著提高镁合金的耐蚀性,同时非晶涂层高的热稳定性和显微硬度,意味着良好的耐热和耐磨性能。     

CA-P/AZ31B镁合金的生物相溶性研究

将具有磷酸钙(CA-P)表面涂层的AZ31B镁合金植入家兔的骨髂和肌肉组织间,观察了体内CA-P/AZ31B合金周围骨骼、肌肉组织的炎性反应,以及CA-P/AZ31B合金的微观结构,评价了CA-P/AZ31B合金的细胞毒性作用及溶血性.结果表明,CA-P涂层可有效地延缓AZ31B镁合金降解产物的释放速度,增加合金的表面粗糙度,减轻合金在体内诱导的组织炎性反应,显著降低合金的溶血率.CA-P/AZ31B合金具有良好的生物相容性,有望成为新一代可降解生物医学材料.     

5083铝合金表面钛铝基耐蚀涂层与TA2钛合金接触腐蚀

针对5083铝合金与TA2钛合金接触腐蚀问题,采用超音速微粒沉积技术在5083铝合金表面制备Ti-45Al-7Nb-4Cr耐蚀涂层,采用扫描电子显微镜(SEM)和能谱仪(EDS)对涂层截面和与基体界面进行测试,分析涂层孔隙率和与5083铝合金基体的结合机制;采用电化学工作站测试5083铝合金、TA2钛合金、TiAl合金铸锭和涂层的极化曲线,并对比研究5083铝合金、TiAl合金铸锭和涂层与TA2钛合金接触腐蚀敏感性。结果表明:涂层孔隙率为1.4%,涂层与基体结合机制为机械结合,通过在5083铝合金表面制备Ti-45Al-7Nb-4Cr合金防护涂层后,可使材料电极电位由-913.90mV升高到-572.47mV,与TA2钛合金的接触腐蚀电流密度由16.2μA/cm2降为0.21μA/cm2,接触腐蚀敏感性由E级降到A级,解决了铝合金与钛合金的接触腐蚀防护问题。     

磷酸盐后处理对Mg-Gd-Y合金微弧氧化涂层耐蚀性能的影响

目的 为进一步提高镁稀土合金微弧氧化涂层的耐蚀性能.方法 首先在镁稀土合金表面制备了微弧氧化涂层,随后用磷酸盐后处理溶液,对Mg-Gd-Y合金硅酸盐微弧氧化涂层进行了封孔后处理,并在此过程中添加了缓蚀剂.利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对涂层表面形貌和成分进行分析,利用极化曲线和电化学阻抗(EIS)测试了涂层的耐蚀性能.结果 后处理能够在微弧氧化涂层表面形成MgHPO4沉积层,沉积层的产生有效地封闭了微弧氧化涂层表面的微孔、裂纹等缺陷.缓蚀剂的添加显著增加了沉积物的量,使涂层的磷元素原子数分数由5.37％增加至14.90％,沉积效果显著.极化实验证明,封孔后处理涂层的腐蚀电流密度由1.51×10–7 A/cm2降至4.91×10–8 A/cm2,负载缓蚀剂后,涂层的腐蚀电流密度进一步降低至5.76×10–9 A/cm2,表明其耐蚀性能显著提高.微弧氧化涂层在3.5％NaCl溶液中浸泡384 h后,含缓蚀剂的涂层的总阻抗值可达7825.3?·cm2,明显高于未封孔处理的微弧氧化涂层(403?·cm2),这证明,后处理可有效提高微弧氧化涂层的耐蚀性能.结论 磷酸盐后处理能够在微弧氧化涂层表面生成MgHPO4沉积层,有效地对微弧氧化涂层表面的微孔和微裂纹进行了封闭.缓蚀剂的添加能够显著增强磷酸盐的沉积效果,使涂层的耐蚀性能在后处理的基础上进一步提高.     

热处理对静液挤压AZ80镁合金管材腐蚀行为的影响

采用浸泡腐蚀、失重腐蚀以及电化学腐蚀中的动电位极化曲线、电化学阻抗谱等方法研究静液挤压AZ80镁合金经350℃退火热处理1、2和4 h后,在p H 6.1的0.1 mol/L Na2SO4溶液中的腐蚀行为。结果表明:退火热处理使得挤压后的AZ80镁合金晶粒发生再结晶,改变AZ80镁合金的组织和成分分布,可有效提高镁合金的腐蚀性能;但是热处理时间也会对合金的耐蚀性产生影响,其中经(350℃,1 h)退火热处理后,合金自腐蚀电位为-1.4501 V,腐蚀电流密度为0.02323 m A/cm2,耐腐蚀能力显著提高,表现出较好的综合性能。     

AZ31B镁合金表面喷熔Al涂层的组织和性能

目的提高AZ31B镁合金的耐蚀性。方法采用氧乙炔在AZ31B镁合金表面喷熔Al涂层,对喷熔的Al涂层进行扫描电镜(SEM)分析,采用能谱仪(EDS)对涂层进行面扫描检测涂层元素的分布情况。利用电化学分析法、浸泡试验检测喷熔涂层的耐蚀性,用维氏硬度计测试喷熔涂层的硬度。结果喷熔的Al涂层与AZ31B镁合金基体结合良好,呈现冶金结合。喷涂过程中,喷熔的Al涂层呈等轴晶生长。通过面扫描结果可知,喷熔涂层中发现Mg元素,说明基体中的Mg元素发生了扩散。通过电化学测试可知,喷熔Al涂层的自腐蚀电压为-1.45 V,比AZ31B镁合金的自腐蚀电压(-1.5 V)降低了0.05 V;喷熔Al涂层的自腐蚀电流密度为1.58×10~(-4) A/cm~2,约为AZ31B镁合金自腐蚀电流密度(8.66×10-4 A/cm2)的1/5。由浸泡实验可知,喷熔Al涂层的平均腐蚀速率约为AZ31B镁合金的1/5倍。喷熔Al涂层的显微硬度是AZ31B镁合金基体硬度的2.9倍。结论喷熔Al涂层的组织较好,性能比镁合金基体有所提高。     

镁合金表面谷氨酸、丙氨酸、天冬氨酸诱导Ca–P涂层耐蚀性能比较

目的 细化Ca-P涂层晶粒,提高其致密性、耐蚀性,得到氨基酸等电点(Isoelectric point,pI)的作用及生物矿化机制。方法 选取谷氨酸、丙氨酸、天冬氨酸,通过60℃水浴,在AZ31镁合金表面制备无氨基酸和3种氨基酸Ca-P涂层,即丙氨酸Ca-P涂层(Ca-P_Ala)、谷氨酸Ca-P涂层(Ca-P_Glu)、天冬氨酸Ca-P涂层(Ca-P_Asp)。采用高分辨扫描电子显微镜(SEM)、X射线衍射仪(XRD)和傅里叶红外光谱仪(FTIR)对涂层的微观形貌及成分进行表征分析;通过电化学极化、交流阻抗(EIS)及析氢实验探究涂层在Hank’s人体模拟体液中的耐蚀性能。结果 Ca-P、Ca-P_Ala、Ca-P_Glu、Ca-P_Asp涂层的厚度分别为(8.46±0.43)、(14.39±0.96)、(8.48±0.16)、(10.07±0.94)μm。涂层的主要组成物相为透钙磷灰石(Ca HPO₄·2H₂O,DCPD...     

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。     

磷酸钙表面改性镁合金的生物腐蚀性能及细胞相容性(英文)

在镁合金表面制备磷酸钙涂层,利用X射线衍射仪确定涂层的相组成。用扫描电镜观察涂层的微观形貌。结果表明,涂层由板条状的CaHPO4·2H2O晶体组成。采用电化学测试和浸泡实验研究磷酸钙改性镁合金的生物腐蚀性能,并与未改性合金进行对比。通过观察L929细胞在材料表面的粘附生长状况来评价材料的生物相容性。电化学测试结果表明,磷酸钙改性镁合金比未改性合金显示出更好的耐腐蚀性能。浸泡实验表明,磷酸钙涂层可以减缓合金的腐蚀,且在浸泡过程中磷酸钙涂层发生了向羟基磷灰石(HA)的转变。与未改性合金相比,L929细胞在磷酸钙改性镁合金表面显示出良好的粘附、生长和分化特征,表明磷酸钙改性能明显提高基体合金的细胞相容性。     

AZ31B镁合金表面Al-80Mg_3Sb_2涂层的腐蚀磨损性能

采用热喷涂技术,在AZ31B表面制备Al-80Mg_3Sb_2复相涂层。采用XRD、SEM、电化学工作站和电化学腐蚀磨损试验仪对涂层进行物相、微观组织、极化曲线和腐蚀磨损性能的测试。结果表明,涂层主要物相为Mg_3Sb_2和Al,组织均匀,自腐蚀电位为-0.98V,自腐蚀电流密度为0.048×10~(-3 )A/cm~2;磨损腐蚀时,AZ31B的开路电位始终为一条直线;而涂层开路电位则是加载后下降,卸载后上升;在往复磨损的一个周期内(约0.008s),AZ31B和涂层的开路电位都呈微"W"形;涂层的平均摩擦因数(0.10)小于AZ31B的(0.14)。     

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.     

Influence of potassium pyrophosphate in electrolyte on coated layer of AZ91 Mg alloy formed by plasma electrolytic oxidation

The effect of potassium pyrophosphate in the electrolyte on plasma electrolytic oxidation (PEO) process for AZ91 Mg alloy was investigated. The morphologies and chemical compositions of the coating layer on the AZ91 Mg alloy were evaluated and corrosion resistance was also estimated by potentiodynamic polarization analysis. The coating layer on AZ91 Mg alloy coated from the Bath 2 containing 0.03 mol/L of potassium pyrophosphate for 360 s exhibited considerably dense structure and contained 11%–18% (mass fraction) of phosphorous. The higher content of phosphorous of coating layer coated from Bath 2 could be detected at the bottom of oxide layer, which strongly implied that the phosphorous ion might be concentrated at the barrier layer. Corrosion potential of coating layer of AZ91 Mg alloy increased and corrosion current density decreased with increasing the concentration of potassium pyrophosphate. The polarization resistance (R_p) of coating layer of AZ91 Mg alloy coated from Bath 2 was 4.65×10⁷ Ω/cm², which was higher than that (R_p=3.56×10⁴ Ω/cm²) of the sample coated from electrolyte without potassium pyrophosphate. The coating layer coated from Bath 2 containing 0.03 mol/L potassium pyrophosphate exhibited the best corrosion resistance.     

Corrosion and wear resistance of AZ31 Mg alloy treated by duplex process of magnetron sputtering and plasma electrolytic oxidation

In order to improve the wear and corrosion resistance of AZ31 magnesium alloy, a magnetron-sputtered Al layer with a thickness of 11 μm was firstly applied on the alloy, and then treated by plasma electrolytic oxidation (PEO) in an aluminate and silicate electrolytes, respectively. The performance of PEO coatings was investigated by dry sliding wear and electrochemical corrosion tests. The aluminate coating exhibits excellent wear resistance under both 10 and 20 N loads. The silicate coating only shows low wear rate under 10 N, but it was destroyed under 20 N. Corrosion tests show that the Al layer after magnetron sputtering treatment alone cannot afford good protection to the Mg substrate. However, the duplex layer of PEO/Al can significantly improve the corrosion resistance of AZ31 alloy. Electrochemical tests show that the aluminate and silicate coatings have corrosion current densities of ∼1.6×10⁻⁶ and ∼1.1×10⁻⁶ A/cm², respectively, which are two orders lower than that of the un-coated AZ31 alloy. However, immersion tests and electrochemical impedance spectroscopy (EIS) show that the aluminate coating exhibits better long-term corrosion protection than silicate coating.     

Wear and corrosion resistance of AZ91 magnesium alloy coated by pulsed current electrodeposited Ni–Al2O3 nanocomposite

In this work, Ni and Ni–Al₂O₃ nanocomposite coatings were applied on AZ91 magnesium alloy using a pulse plating process and the corrosion resistance of coated samples was evaluated by means of the potentiodynamic polarisation method in 3.5?wt-% NaCl solution. Field emission scanning electron microscopy was employed to identify microstructure and morphology of the coatings. Vickers microhardness and pin-on-disc wear tests were also used to investigate mechanical properties of the coatings. The polarisation test revealed that the pure Ni coating on AZ91 along with the presence of nanoparticles were key factors leading to a reduction in the corrosion current density and the improvement of corrosion resistance so that the corrosion current density of 210.45?µA?cm^?2 for the substrate (AZ91) decreases to 31.92 and 1.54?µA?cm^?2 by applying pure Ni and Ni–Al₂O₃ nanocomposite coatings, respectively. Furthermore, Ni–Al₂O₃ nanocomposite coating increased the microhardness and wear resistance compared to the substrate up to 435 and 340%, respectively.     

电流密度对ZK60镁合金表面超疏水涂层的制备及耐腐蚀性的影响

为了提高镁合金的耐腐蚀性能,基于层状双氢氧化物（LDHs）膜在ZK60镁合金表面制备了超疏水（SH）涂层。涂层制备过程中引入电场辅助,研究了工作电流密度对涂层性能的影响。结果表明,工作电流密度显著影响LDHs膜的微观结构,这对SH涂层的疏水性具有重要影响。当工作电流密度为25 mA/cm²时,SH涂层表面呈现均匀的微纳米结构,并表现出超疏水性。超疏水涂层的腐蚀电流密度（I_corr=9×10^-7 A·cm^-2）比ZK60基体的腐蚀电流密度（I_corr=3×10^-5 A·cm^-2）低了2个数量级,表现出优异的耐腐蚀性。     

Enhanced corrosion behavior and mechanical properties of AZ91 magnesium alloy developed by ultrasonic-assisted friction stir processing

In this study, ultrasonic-assisted friction stir processing (UaFSP) and friction stir processing (FSP) were conducted on AZ91 magnesium alloy sheets, and their microstructure, corrosion behavior, and mechanical properties were comparatively investigated. Scanning electron microscopy, open-circuit potential, and potentiodynamic polarization were used to study the corrosion behavior of the material. Electrochemical measurements reveal that employing UaFSP, the corrosion rate of the AZ91 magnesium alloy was significantly reduced where lower corrosion current density for UaFSP specimens was obtained (2.09 µA/cm²) compared with 3.42 µA/cm² for the FSP and 6.82 µA/cm² for the base metal. This is mainly attributed to the alteration of morphology and better distribution of the β-Mg₁₇Al₁₂ phase during UaFSP. By using ultrasonic vibration in FSP, a finer grain structure was obtained, which improved the tensile strength and hardness of the AZ91 Mg alloy.     

TC4钛合金表面沉积CrSiN/SiN纳米多层膜在3.5%NaCl溶液中的腐蚀磨损性能

为了研究纳米多层膜的耐腐蚀性能以及腐蚀磨损机理,采用离子源辅助磁控溅射在TC4钛合金表面制备不同调制周期的CrSiN/SiN纳米多层膜。使用扫描电子显微电镜、能谱仪表征涂层的微观结构、腐蚀形貌以及元素分布;使用划痕仪、纳米压痕仪、维氏硬度计测量涂层的膜基结合力、硬度、弹性模量及断裂韧性,采用电化学工作站以及销盘磨损仪测量涂层耐腐蚀性和腐蚀磨损性。结果表明:调制周期为90 nm与360 nm时涂层耐腐蚀性能较好,腐蚀电流密度分别为1.31×10~(-8)A·cm~(-2)和1.20×10~(-8)A·cm~(-2)。此外,调制周期为45nm时,涂层硬度及弹性模量最大,分别为(22.5±0.6)GPa和(226.4±6.3)GPa,且腐蚀磨损率最低,为9.67×10~(-7)mm~3·N~(-1)·m~(-1)。多层膜结构显著改善了TC4钛合金的耐腐蚀及腐蚀磨损性能。     

An Investigation into the Corrosion Behavior of MgO/ZrO<Subscript>2</Subscript> Nanocomposite Coatings Prepared by Plasma Electrolytic Oxidation on the AZ91 Magnesium Alloy

Plasma electrolytic oxidation (PEO) of AZ91 Mg alloys was performed in ZrO₂ nanoparticles containing Na₂SiO₃-based electrolytes. The phase composition and the microstructure of PEO coatings were analyzed by x-ray diffraction and scanning electron microscopy followed by energy dispersive spectroscopy. Pitting corrosion properties of the coatings were investigated using cyclic polarization and electrochemical impedance spectroscopy tests in a Ringer solution. The results showed the better pitting corrosion resistance of the composite coating, as compared to the oxide one, due to the thickened inner layer and the decrease in the surface defects of the composite coating. Also, the PEO process decreased the corrosion current density from 25.06 µA/cm² in the Mg alloy to 2.7 µA/cm² in the oxide coating and 0.47 µA/cm² in the composite coating.     

AZ31B镁合金表面火焰喷涂Al-Mg_2Si涂层的耐腐蚀性能

为提高AZ31B镁合金表面的耐腐蚀性能,用火焰喷涂方法在镁合金表面制备Al-Mg_2Si复合涂层。采用XRD、SEM和EDS分析涂层的物相组成、微观组织及元素分布;通过电化学试验测试样品在3.5%NaCl溶液中的腐蚀电位、腐蚀电流密度;通过3.5%NaCl溶液浸泡试验测试样品的腐蚀速率;并测试涂层的显微硬度。结果表明:涂层中的主要物相有Mg_2Si、Al,组织比较致密,元素分布均匀。Tafel极化曲线测试表明,Al-Mg_2Si涂层样品与AZ31B镁合金样品相比腐蚀电位从-1.489 V正移到-1.366 V,腐蚀电流密度从2.817×10~(-3) A/cm~2降低到1.198×10~(-3) A/cm~2。浸泡试验结果表明,喷涂Al-Mg_2Si的镁合金的腐蚀速率明显低于没有喷涂的镁合金。显微硬度测试表明,涂层的显微硬度集中分布在259~308 HV0.05之间,镁合金为50~60 HV0.05。因此在AZ31B镁合金表面火焰喷涂Al-Mg_2Si涂层可以提高其耐腐蚀性能,表面硬度显著提高。     

Corrosion performance and tribological behavior of diamond-like carbon based coating applied on Ni−Al−bronze alloy

The effect of diamond-like carbon (DLC) coating (fabricated by cathodic arc deposition) on mechanical properties, tribological behavior and corrosion performance of the Ni?Al?bronze (NAB) alloy was investigated. Nano-hardness and pin-on-plate test showed that DLC coating had a greater hardness compared with NAB alloy. Besides, the decrease in friction coefficient from 0.2 for NAB substrate to 0.13 for the DLC-coated sample was observed. Potentiodynamic polarization and EIS results showed that the corrosion current density decreased from 2.5 μA/cm² for bare NAB alloy to 0.14 μA/cm² for DLC-coated sample in 3.5 wt.% NaCl solution. Moreover, the charge transfer resistance at the substrate–electrolyte interface increased from 3.3 kΩ·cm² for NAB alloy to 120.8 kΩ·cm² for DLC-coated alloy, which indicated an increase in corrosion resistance due to the DLC coating.