The electrochemical synthesis of poly(o-phenylenediamine) on stainless steel and its corrosion protection ability in 3.5 % NaCl solution

In this study, electrochemical synthesis of poly(o-phenylenediamine) (PoPDA) on 316L stainless steel and its corrosion inhibition effect were studied. Electropolymerization of o-phenylenediamine (oPDA) was carried out by a potentiodynamic method using 0.5 M H₂SO₄ solution containing 0.05 M oPDA monomer. The corrosion protection ability of the PoPDA in 3.5 % NaCl was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, and change of open circuit potential with immersion time (E_OCP ? t). The results showed that PoPDA acted as a protective layer on stainless steel against corrosion in 3.5 % NaCl solution.     

Electrochemical behavior of Ni-Al-Fe alloys in simulated human body solution

An investigation about the corrosion resistance of Ni-Al-Fe intermetallic alloys in simulated human body fluid environments has been carried out using electrochemical techniques. Tested alloys included 57 (wt%) Ni-(20 to 30) Al-(12 to 23) Fe using the Hank's solution because the high corrosion resistance provided by protective Al₂O₃ external layer. For comparison, AISI 316L type stainless steel has also been used. Electrochemical techniques included potentiodynamic polarization curves, electrochemical impedance spectroscopy, and electrochemical noise measurements. The different techniques have shown that these alloys showed a similar or higher corrosion resistance than conventional AISI 316L type stainless steel, and this corrosion resistance decreased as the Al content in the alloy increased. The alloys were susceptible to pitting type of corrosion on the interdendritic Ni-rich phases.     

磁场对316L不锈钢微生物腐蚀行为的影响

采用循环极化、微生物分析法、扫描电镜及表面能谱分析等方法,研究了磁场对316L不锈钢在含硫酸盐还原菌(SRB)的土壤模拟溶液中的腐蚀行为。结果表明,磁场可以抑制SRB的生长;未外加磁场时316L不锈钢表面膜层以局部堆积为主,加有磁场时,局部堆积明显减小,膜层均匀致密的排列于基体表面;无论有或没有外加磁场,316L不锈钢表面均发生钝化膜破裂型点蚀,未外加磁场时的点蚀电位低于加有磁场时的。在相同的浸泡时间,未外加磁场时循环极化滞后环面积明显比加有磁场时的大,说明磁场可以有效抑制316L不锈钢点蚀的形成与发展,降低316L不锈钢的点蚀诱发能力。     

溶胶-凝胶法制备改性TiO2纳米薄膜及其防腐蚀性能

应用溶胶-凝胶法和浸渍提拉技术在316L不锈钢表面分别制备TiO2纳米膜和 B-Fe-Ce改性的TiO2纳米膜. 采用场发射扫描电子显微镜(FE-SEM)、原子力显微镜(AFM)、拉曼光谱法和能量分散谱(EDS)对薄膜进行表征,通过电化学阻抗谱(EIS)和动电位阳极极化曲线的测试考察薄膜的耐蚀性及对不锈钢的保护性能. 结果表明:两种纳米薄膜均含锐钛矿型的TiO2纳米颗粒,纯TiO2纳米膜与改性后的纳米膜中颗粒直径分别约为15和10 nm. TiO2/316L不锈钢和 B-Fe-Ce-TiO2/316L不锈钢膜电极浸泡在0.5 mo.lL-1 NaCl溶液后,后者的电化学反应电阻较大,动电位阳极极化曲线的稳定钝化区较宽,击穿电位更高,说明改性的纳米膜的耐蚀性及其保护性能更好.     

Superior corrosion protection and in vitro biocompatibility of Na-HAp/CS composite coating on PoPD-coated 316L SS

The synthesis and development of sodium (Na)-substituted hydroxyapatite (HAp)/chitosan (CS) composite using poly (O-phenylenediamine) (PoPD) coating on 316L SS substrate for improving bioactivity and corrosion protection was studied. The surface of Na-HAp/CS/PoPD bilayer coatings on 316L SS substrate was characterized by diverse analytical techniques. The open circuit potential (OCP) measurement, potentiodynamic polarization, and impedance test revealed that the bilayer coating provides excellent protection to the substrate against the corrosion in the simulated body fluid (SBF) solution. This interior layer of the coating acts as a barrier against the release of metal ions from the substrate, which was confirmed by inductively coupled plasma-atomic emission spectroscopy. Besides, the mechanical properties of the coatings were analyzed. From the obtained results, the bilayer coating exhibited greater mechanical strength than the individual coating. An in vitro bioactivity of the coatings was assessed by immersion in the SBF solution at 7–28 days. The apatite formation of bilayer coatings on 316L SS substrate is found to be more bioactive compared with the Na-HAp, PoPD, and Na-HAp/CS. The in vitro biocompatibility test showed no adverse effects, which was proved by the enhanced biocompatibility of the bilayer coating on 316L SS.     

不锈钢表面Schiff碱自组装分子膜的制备及性能

以乙二胺和乙酰丙酮为原料,在盐酸催化下合成了新的Schiff 碱化合物,其收率为73.2%。 采用红外光谱和核磁共振谱对化合物的结构进行了表征。 并将其自组装在不锈钢基体表面,利用极化曲线、电化学阻抗谱和自腐蚀电位 时间曲线进行电化学分析。 结果表明,在1 mol/L HCl中,不锈钢表面自组装分子膜能快速有效的抑制异相电子的转移,促进不锈钢表面发生钝化,减少了不锈钢基体的腐蚀。 总结了Schiff碱自组装分子膜对金属防护的效用和价值。     

海洋微生物对316不锈钢的电化学腐蚀行为

采用自腐蚀电位、电化学极化曲线、电化学阻抗谱技术研究了316不锈钢在无菌培养基介质和海水微生物接种培养有菌培养基介质中不同周期的腐蚀行为．结果表明,316不锈钢电极在有菌介质中比在无菌介质中的腐蚀电流密度大,腐蚀电位负移,微生物加速了不锈钢的腐蚀速度．随着浸泡时间的增加,有菌介质中的不锈钢电极极化电阻值逐渐减小,表明了海洋微生物的附着和繁殖加速了316不锈钢的腐蚀速率,降低了其在海洋环境中的耐蚀性．     

Synthesis and Assessment of Two Malonyl Dihydrazide Derivatives as Corrosion Inhibitors for Carbon Steel in Acidic Media: Experimental and Theoretical Studies

Despite the extensive use of carbon steel in all industrial sectors, particularly in the petroleum industry, its low corrosion resistance is an ongoing problem for these industries. In the current work, two malonyl dihydrazide derivatives, namely 2,2’-malonylbis (N-phenylhydrazine-1-carbothiamide (MBC) and N’1, N’3-bis(-2-hydroxybenzylidene) malonohydrazide (HBM), were examined as inhibitors for the carbon steel corrosion in 1.0 M HCl. Both MBC and HBM were characterised using thin-layer chromatography, elemental analysis, infrared spectroscopy, and nuclear magnetic resonance techniques. The corrosion tests were performed using mass loss measurements, polarisation curves, and electrochemical impedance spectroscopy. It is obtained from the mass loss studies that the optimal concentration for both inhibitors is 2.0 × 10⁻⁵ mol/L, and the inhibition efficiencies reached up to 90.7% and 84.5% for MBC and HBM, respectively. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) indicate an increased impedance in the presence of both MBC and HBM and mixed-type inhibitors, respectively. Both inhibitors can mitigate corrosion in the range of 298–328 K. Values of free energy changes obtained from the Langmuir model suggest that the inhibitors suppress the corrosion process principally by chemisorption. The computational investigations were conducted to identify the factors connected with the anti-corrosive properties of the examined inhibitors.     

A zirconia-polyester glycol coating on differently pretreated AISI 316L stainless steel: corrosion behavior in chloride solution

The effect of zirconia and zirconia-polyester glycol hybrid coatings on the corrosion resistance of mechanically polished or anodized AISI 316 stainless steel (316L), was studied by potentiodynamic polarization and electrochemical impedance spectroscopy in 0.1 M NaCl and scanning electron microscope and atomic force microscopy examinations. The deposition of zirconia coatings was achieved by the sol–gel technique by immersing the samples in either the inorganic polymer or the organic–inorganic polymer mixture. From potentiodynamic and impedance measurements, the grade of protection is reduced with the exposure time to the electrolyte, which is mainly associated with lost of film adhesion and, consequently, detachment from the metal substrate. However, the uncoated anodized sample revealed an unexpected corrosion behavior; the anodic film formed during anodizing readily increased the corrosion resistance of the 316L stainless steel in 0.1 M NaCl, revealing a considerable reduction in the corrosion current density and an increase in the pitting potential.     

Some Corrosion Inhibitors Based on Schiff Base Surfactants for Mild Steel Equipments

Two series of Schiff base amphiphiles were prepared throughout condensation of benzaldehyde or anisaldehyde and three different fatty amines with various alkyl chain length; namely: dodecyl, hexadecyl and octadecyl amine. The chemical structures of the prepared Schiff bases were confirmed using elemental analysis, FTIR, and ¹H-NMR spectra. The data of structural analysis for these compounds were confirmed the chemical structures and the purity of the synthesized amphiphiles. The synthesized Schiff base amphiphiles were evaluated as corrosion inhibitors for low carbon steel (mild steel) in various acidic media (HCl and H₂SO₄) using weight loss technique. The corrosion inhibition measurements of these inhibitors showed high protection of the low carbon steel alloys against corrosion process in the tested acidic media at different periods as well as they have good biocidel effectagainest SRB. The discussion was correlated the efficient corrosion inhibition of these inhibitors to their chemical structures.     

Anticorrosive and Microbial Inhibition Performance of a Coating Loaded with Andrographis paniculata on Stainless Steel in Seawater

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.     

表面改性SUS316L不锈钢的电化学行为研究

分别以表面镀Rh,表面离子束增强沉积Ta2O5膜及溶胶凝胶法沉积TiO2膜对冠状动脉支架用材料SUS316L不锈钢进行表面改性.采用电化学方法研究了该表面改性试样在Tyrode's模拟人工体液中的电化学行为.结果表明,上述3种表面改性方法均可提高SUS316L不锈钢在模拟人工体液中的阳极极化性能.其中对于采用离子束增强法沉积的Ta2O5膜和溶胶凝胶法沉积的TiO2膜,因Ta和Ti上的d轨道空位已被氧的电子占据,不利于氢吸附,从而抑制了阴极的析氢过程.X射线衍射分析发现,3种改性方法在SUS316L不锈钢表面依次形成均匀而致密的Rh金属层,Ta2O5的无序膜层和TiO2晶态膜层,阻止了合金元素的溶解,改善不锈钢的电化学性能.     

An experimental and theoretical investigation on adsorption properties of some diphenolic Schiff bases as corrosion inhibitors at acidic solution/mild steel interface

The effect of novel synthesized three Schiff bases, namely, 1,3-bis[2-(2-hydroxy benzylidenamino) phenoxy] propane (P1), 1,3-bis[2-(5-chloro-2-hydroxybenzylidenamino) phenoxy] propane (P2), and 1,3-bis[2-(5-bromo-2-hydroxybenzylidenamino) phenoxy] propane (P3), on the corrosion of mild steel in 0.1 M HCl was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy methods. Polarization measurements suggest that P1 acts as mixed type inhibitor while P2 and P3 behave as mainly cathodic inhibitors for acidic corrosion of steel. All electrochemical measurements show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on steel surface. Adsorption of these inhibitors follows Temkin adsorption isotherm. The correlation between the adsorption ability of inhibitors and their molecular structures has been investigated using quantum chemical parameters obtained by MNDO semi-empirical method. Calculated quantum chemical parameters indicate that Schiff bases adsorbed on steel surface by chemical mechanism.     

Electrochemical and XPS studies on corrosion behaviours of AISI 304 and AISI 316 stainless steels under plastic deformation in sulphuric acid solution

The corrosion behaviours of austenitic stainless steels were investigated by electrochemical methods under plastic deformation with constant strain in the naturally aerated 0.5 M H₂SO₄ + 0.2 M KCl solution at room temperature. The work addresses the influence of plastic deformation and molybdenum element on the corrosion resistance of austenitic stainless steels in the test solution. Electrochemical impedance spectroscopy presents the decreasing charge transfer resistance (R_t) and polarization resistance (R_p) values with the immersion time for AISI 304 stainless steel under constant strain deformation, and the increasing R_t and R_p values with the immersion time for AISI 316 stainless steel. The analysis of the chemical composition of the corrosion products was carried out by XPS. Molybdenum addition in AISI 316 stainless steel affects significantly the corrosion resistance because of its high ability to form Mo (VI) and MoCl₅ insoluble compounds in acid medium. Copyright © 2011 John Wiley & Sons, Ltd.     

Corrosion inhibition studies on mild steel in HCl by a newly synthesized benzil monohydrazone based Schiff base

The corrosion inhibition effect of newly formulated Schiff base 2-((E)-((E)-2-hydrazone-1, 2-diphenylethylidene) amino phenol) (HDAP) ligand L derived from Benzil monohydrazone and 2-Aminophenol on mild steel in 1 ​M HCl was examined. Electrochemical (Tafel and EIS) and mass loss techniques were employed to evaluate its corrosion protection efficiency. The inhibition efficiency (η %) was elevated with raise in concentration of compound L.Maximum inhibition efficiency of 94.18% was obtained at 0.01 ​M concentration of HDAP from Tafel polarisation curve. From electrochemical impedance (EIS) studies, it was confirmed that increase in concentration of HDAP led to enhancement of the charge transfer resistance. Both physical and chemical types of adsorptions were observed for the Schiff base via π-bonding electrons which obey Langmuir adsorption isotherm. The SEM picture revealed development of a thin layer on metallic surface. Quantum chemical evaluations were conducted to find out the mechanism of corrosion retardation power of HDAP.     

Corrosion and biological behavior of nanostructured 316L stainless steel processed by severe plastic deformation

Nanostructured metals have different mechanical, chemical, and physical behaviors in comparison with the microstructured ones. Numerous research studies demonstrated that the biological behavior of nanostructured metallic implants was improved significantly. Concerning the nanostructured metals, decreasing the corrosion rate and the releasing of hazardous ions from metallic implants, and thus increasing the biocompatibility of implants are due to improving the native oxide layer. In the present study, nanostructured 316L stainless steel (biomedical grade) was manufactured via equal channel angular pressing (ECAP) method. To do so, the 316L stainless steel (SS) was exposed to the ECAP operation for eight passes. The impact of the ECAP process on corrosion behavior of SS samples was evaluated through performing the electrochemical polarization corrosion tests in Ringer's solution. Scanning electron microscopy was employed to study the surface morphology of common SS and ECAPed SS sample after the electrochemical polarization tests. Moreover, the biological behavior of the samples was evaluated via cell culture using fibroblast cells. The corrosion test results revealed a substantial decrease of corrosion rate from 3.12 (coarse‐grained sample) to 0.42 μA cm^?2 (for nanostructured). Furthermore, the cell proliferation in the interface of nanostructured sample and cell culture medium enhanced dramatically compared with the coarse‐grained one. The much better biological behavior of nanostructured SS sample in comparison with the coarse‐grained one is mostly due to the significant decrease of corrosion rate on the surface of SS samples, and the presence of much more chrome oxide on the surface of SS sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Corrosion inhibition of mild steel by highly stable polydentate schiff base derived from 1,3- propanediamine in aqueous acidic solution

Recently, the hydrolysis of Schiff bases under experimental conditions gives suspicion for their corrosion inhibition performance. The current study employs a stable Schiff base namely, 2,2′-{propane-1,3-diylbis[azanylylidene (E) methanylylidene]}bis(6-methoxyphenol) (LPD) as corrosion inhibitor for mild steel (MS) in 1 M HCl solution. The presence of the characteristic peak of the imine group in UV-visible spectra was taken as an indicator for LPD stability in acidic media. The inhibition action was examined using electrochemical techniques including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) besides gravimetric measurement. The inhibition efficiency reached 95.93 % for 0.75 mM LPD after 24 h of immersion at 25 °C. This high efficiency is owing to the presence of the characteristic imine group and other heteroatoms and π- electrons of the aromatic benzene rings. The mechanism of inhibition depends on adsorption phenomena on mild steel surface which obeys Langmuir isotherm model. The calculated values of adsorption equilibrium constant (K_ads), adsorption free energy ΔG_ads, adsorption enthalpy ΔH_ads and adsorption entropy ΔS_ads indicated spontaneous exothermic adsorption process of both physical and chemical nature. By rising temperature, the inhibition efficiency of LPD was decreased. The calculated activation energy was increased as the concentration of LPD increased. LPD was considered as a mixed-type inhibitor as indicated from PDP measurements. The obtained surface morphology and composition analysis using SEM/EDS, AFM and FTIR techniques ensures the high efficiency of LPD as corrosion inhibitor.     

微纳米多孔不锈钢表面高效吸附活性生物大分子

不锈钢(AISI 316L)是目前在医药器械中应用最为广泛的商业化材料. 下一代的不锈钢智能材料将特殊功能的生物活性分子(或纳米粒子)修饰在金属表面以模拟组织功能、提高生物/细胞相容性, 这是目前材料科学研究的热点领域之一. 本文研究了具有微纳米多孔表面结构的316L 不锈钢对抗体和生物酶分子的吸附作用,并与这些生物分子在光滑表面以及镀金表面的吸附进行了比较. 研究发现不锈钢可通过简单的电化学腐蚀方法在表面产生微纳米多孔结构. 微纳米孔不锈钢表面可稳定地吸附抗体或辣根过氧化物酶分子, 其吸附量与喷镀金表面相当或更好. 用表面活性剂(10%牛血清白蛋白(BSA)或0.2% Tween-20)洗涤不能除去吸附的蛋白.用5% Tween-20 预处理金属表面, 则可减少一半的抗体吸附量; 但表面活性剂预处理对辣根过氧化物酶的吸附没有影响. 吸附蛋白质后的金属表面湿润度大大增加; 蛋白质修饰的微纳米孔不锈钢表面表现出了很好的亲水性(水接触角小于50°), 指示了很好的生物相容性. 而金属表面的湿润度则主要取决于蛋白质物种, 并与蛋白质的吸附量正相关. 吸附于不锈钢微纳米孔表面的抗体仍保持了良好的生物活性; 用此种方式制备的抗CD34抗体修饰的不锈钢血管支架可以高密度并高选择性地吸附其目标细胞(如KG-1细胞). 本文工作为未来制备新型的无高聚物涂层的不锈钢智能医学生物材料提供了基础.     

A study on the electrochemical polymerization, characterization, and corrosion protection of o-toluidine on steel

Poly(o-toluidine) (POT) coatings were electrochemically synthesized on 304 stainless steel using cyclic voltammetric method. These coatings were characterized by Fourier transform infrared spectroscopy, UV–vis absorption spectroscopy, and cyclic voltammetry. The corrosion performance of POT coating in aqueous 3 wt% sodium chloride was assessed by the electrochemical techniques such as open circuit potential measurements, potentiodynamic polarization technique, cyclic potentiodynamic polarization measurements, and electrochemical impedance spectroscopy. The results reveal that POT coating on 304 stainless steel prevents general and localized corrosion, and reduces the exchange current density almost by a factor of 45 than bare 304 stainless steel.     

TiO_2/316L不锈钢薄膜电极在NaCl溶液中的耐腐蚀性能

应用sol gel法和提拉技术于 316L不锈钢表面构筑纳米TiO2薄膜,再经水热后处理以消除膜中的细小龟裂.SEM和XRD技术表征膜的形貌和厚度,线性极化法分别考察膜厚度、pH、和Cl浓度对纳米膜电极耐腐蚀性能影响.电化学交流阻抗检测纳米TiO2膜在 0. 5mol/LNaCl溶液中的阻抗随浸泡时间的变化,光电子能谱技术测定了经浸泡 1008h后的纳米膜中各元素相对百分含量和价态.结果表明:在中性或碱性条件下,厚度为 375~464nm的纳米膜其耐腐蚀性随浸泡时间的延长呈现初期增加而后稳定,浸泡 48h后腐蚀电流较之浸泡初期降低 2个数量级,耐腐蚀电阻增加 2个数量级,在浸泡 1 008h内没有发现腐蚀的产物,Fe是以原子态扩散到膜中.