Influence of iron microstructure on the performance of polyacrylic acid as corrosion inhibitor in sulfuric acid solution

The corrosion inhibition behavior of bulk nanocrystalline ingot iron (BNII) fabricated from coarse polycrystalline ingot iron (CPII) by severe rolling technique by polyacrylic acid (PAA) was studied in 0.1 M H₂SO₄ using electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The results indicated that PAA inhibited the acid induced corrosion of both iron specimens, with greater effect noted for BNII. The corrosion inhibiting effect was influenced by the microstructure of the iron samples. Synergistic inhibition effect was observed on addition of iodide ions to PAA in case of CPII while for BNII inhibition efficiency marginally increased.     

Synergistic effect of iodide ion and polyacrylic acid on corrosion inhibition of iron in H2SO4 investigated by electrochemical techniques

Corrosion inhibition of iron in H₂SO₄ by polyacrylic acid (PAA) was investigated using electrochemical techniques at 30 °C. Results obtained indicate that PAA inhibited the corrosion of iron in the acid medium. Inhibition efficiency increases with increase in PAA concentration and synergistically enhanced on addition of iodide ions. Potentiodynamic polarization results suggest that PAA functions as a modest cathodic inhibitor. The adsorption of PAA onto the iron surface followed Temkin adsorption isotherm. FTIR analysis revealed that the synergistic effect due to co-adsorption of iodide ions and PAA is co-operative in nature.     

Surface nanomorphology of montmorillonite modified with polyacrylic acid

The effect of adsorption of polyacrylic acid (PAA) on the surface morphology of montmorillonite has been determined using atomic force microscopy (AFM). The analytical capabilities of this method for studying the initial stages of physicochemical transformations of the montmorillonite surface during coagulation structuring with an organic additive have been shown. It has been found that the surface structure of the original montmorillonite differs from that of the sample modified with an organic additive; the surface of the latter simultaneously contains molecular aggregates of various shapes and sizes, which depend on the suspension concentration. The surface roughness of the original and PAA-modified montmorillonite has been determined according to the derived longitudinal and transverse profiles of the samples.     

Preparation and characterization of conductor–insulator–semiconductor sandwich-structured MWCNT/double-layer polymer hybrid nanocomposites

The conductor–insulator–semiconductor sandwich-structured MWCNT/double-layer polymer hybrid nanocomposites (MWCNT-PS-PAA/PAn), multiwalled carbon nanotubes (MWCNTs) encapsulated with polystyrene (PS) inner layer and polyacrylic acid (PAA) doped polyaniline (PAn) outer layer via covalently linking, were fabricated through combining the successive surface-initiated atom transfer radical polymerization (SI-ATRP) and in situ chemical oxidative polymerization techniques. The sandwiched structure was confirmed by the XPS and TEM analysis. Due to their conductor–insulator–semiconductor sandwich structure, the electrical conductivity of the nanocomposites obtained was far less than the similar small acids doped PAn/carbon nanotubes composites. Furthermore, the dispersibility of the sandwiched hybrid nanocomposites in organic solvent obviously improved compared with the pristine carbon nanotubes.     

单宁酸复配缓蚀剂在铁质文物上的应用研究

目的通过复配的方法改善单宁酸单一缓蚀剂的缺点,以提高对铁质文物的缓蚀效果。方法采用失重实验、扫描电镜显微观察、动电位极化法等,对比和评估了单宁酸和单宁酸复配缓蚀剂对5种铁质文物模拟样品的缓蚀效果,并在铁质文物上进行了应用试验。结果在3.5%Na Cl水溶液的腐蚀体系中,单宁酸复配缓蚀剂对低硫铸铁的缓蚀效果优异,对高硫铸铁的缓蚀效果略低。用单宁酸缓蚀后的试样表面呈斑驳膜层,成膜不牢固,用单宁酸复配缓蚀剂缓蚀后的试样表面成膜均匀、稳定。添加硅酸钠、磷酸二氢锌和乙醇胺的单宁酸改进配方使试样出现钝化现象,其腐蚀电流比空白样和单宁酸的腐蚀电流均有大幅降低。在铁质文物上的实际应用结果表明,采用单宁酸复配缓蚀剂处理的铁质文物的耐腐蚀性比单宁酸处理的更好。结论单宁酸复配缓蚀剂解决了单宁酸的酸性对铁质文物造成的潜在影响,克服了单宁酸成膜不完整和不牢固,以及改变文物外观颜色的缺点,并大幅提升了缓蚀效率。     

Sorption of water by polyacrylic acid

The interaction of polyacrylic acid with water is reported. Water, which is consumed by polyacrylic acid in a wide range of humidities is found to exist in two states, i.e., statistically dissolved in the matrix (Flory-Huggins mode) and in cluster form. No retention due to the sorption on active sites according to Langmuir’s mode is detected.     

铁磁/反铁磁核壳颗粒的化学法制备

利用化学法使化合物NiCl2在室温和氩气气氛中被NaBH4溶液还原,制备出具有纳米尺度的Ni颗粒,并在其表面包覆一层锰氧化物膜,从而制备出具有核/壳结构的铁磁/反铁磁颗粒。在Ni颗粒的合成中加入了分散剂聚丙烯酸（PAA）以避免Ni颗粒团聚;应用热处理手段,对核壳颗粒进行改性。分别通过XRD、TEM、SEM测量手段,对它们进行结构分析,并对这种铁磁/反铁磁的核壳结构样品进行了磁性研究。     

聚天冬氨酸及其复配物阻垢缓蚀性能的研究

研究配制了一种高效的绿色阻垢缓蚀剂,其组成为聚天冬氨酸(PASP)、聚丙烯酸(PAA)和2-磷酸丁烷-1,2,4-三羧酸(PBTCA).通过碳酸钙沉积法对PASP及其复配物的阻垢性能进行了实验,得到其最优配方为m(PASP)∶m(PAA)∶m(PBTCA)=6∶1∶1.用旋转挂片法对复配物最优配方的缓蚀性能进行了测试.在测试条件下,该复配物阻垢率能达到91.71％,对碳钢的缓蚀率可达到92.23％,是一种性能优良的阻垢缓蚀剂.     

Amino acids as corrosion inhibitors in hydrochloric acid solutions

Inhibition of the corrosion of iron in hydrochloric acid solutions by amino acids was studied. Twenty-two different common amino acids and four related compounds were used. Potentiodynamic polarization curves were obtained for iron wire in deaerated 1 M hydrochloric acid solution. Intersection of the linear Tafel lines at the corrosion potential gave values of the corrosion current. At 10 mM concentration of the inhibitors, the best results were obtained with 3,5-diiodotyrosine, with an inhibition efficiency of 87%. The best common amino acid was tryptophan with an inhibition efficiency of 80%. Hydroxyproline, cystine, and cysteine acted as corrosion accelerators. Definite trends were observed which were related to the molecular structure. In general, amino acids with longer hydrocarbon chains showed greater inhibition. Additional amino groups or groups which increased electron density on the alpha amino group also increased the inhibition efficiency.     

改性SiC微粉复合粒子的制备与表征

针对SiC超细微粉在磨具制造过程中存在的易团聚、分散稳定性差、与结合剂相容性低等问题,本课题借助悬浮聚合工艺,采用聚丙烯酸对SiC微粉进行表面包覆改性,优化筛选出了羧甲基纤维素和CaCO3复合分散剂及其相关的较佳改性工艺条件。结果表明:反应温度65℃,反应时间30 min,搅拌速度500 r/min条件下,SiC弹性复合粒子的分散性和成球性最好;羧甲基纤维素浓度9%~11%、CaCO3用量0.5%~2%时,分散效果最好。制备出的有机物包覆的SiC微粉弹性复合粒子,显著改善了SiC超细微粉的分散流动性和其与有机结合剂的相容性。     

Fabrication of ultrahigh density ZnO-Al_2O_3 ceramic composites by slip casting

The conditions of ZnO-Al2O3 aqueous suspensions and slip casting were optimized to obtain dense green compacts and further to obtain high density ZnO-Al2O3 ceramic composites.The Zeta potential of raw powders was measured.ZnO and Al2O3 powders have lower Zeta potential than-45 mV commonly at pH 8-10.3 with polyacrylic acid(PAA)added.The influence of pH and the mass fraction of the additives on the stability and fluidity of the suspensions added with PAA and polyethylene glycol(PEG) was investigated by experiments of viscosity and sedimentation.The suspensions have the lowest viscosity and the best stability at pH 9 with 0.2%PAA(mass fraction).The maximum density of green compacts is 66.6%of theoretical density(TD)with compacting and homogeneous green particles.An ultrahigh density sintered compact(99.6%TD)could be obtained after pressureless sintering at 1 400℃for 2 h.     

Inhibitoren der Korrosion 24 (1) – Zur Vergleichbarkeit der Abhängigkeit der Korrosion und Korrosionsinhibierung von der Chloridionen- und Inhibitorkonzentration am Beispiel von DAB6-Eisen und 1405-Stahl (auch phosphatiert)

Comparability of the dependence of corrosion and corrosion inhibition on chloride ion and inhibition on chloride ion and inhibitor concentration on the example of pure iron and steel 1405 (also phosphated) The rates of uptake of O₂ under standard conditions were measured for iron powder shaken with and without added inhibitor in dependence on the amount of iron and the chloride ion concentration. The results show that the standard procedure used allows a trustworthy measure of the inhibitor efficiency to be drawn from the observed effect. The relationship between the results for DAB 6 iron powder with 1405 steel plates was confirmed by experiments performed on filings from the plates. The rate of corrosion of phosphatized 1405 steel plate is efficiently suppressed by inhibitors with phosphonic acid groups. A treatment of the unphosphatized steel plates with phosphonic acid containing inhibitors in an analogous manner to phosphatizing leads to unsatisfactory results. The conclusion was drawn that the pH value of the inhibitor at the surface layer is important for the attainment of optimal effect.     

A self-doped conducting polymer “polyanthranilic acid”: An efficient corrosion inhibitor for mild steel in acidic solution

In recent years, polyanilines have been reported as one of the efficient corrosion inhibitors for iron in acidic media. In view of the major limitation of insolubility of polyaniline, we propose the use of functionalized self-doped conducting polymer to get higher solubility and corrosion efficiency. The chemical synthesis of water soluble self-doped polyanthranilic acid using various oxidizing agents and for time intervals of polymerization is reported for the first time for the corrosion inhibition studies. The corrosion inhibition property of the polymer is demonstrated for mild steel in acidic environment using electrochemical impedance spectroscopy, Tafel polarization and weight loss methods.     

Polyacrylic acid as a corrosion inhibitor for aluminium in weakly alkaline solutions. Part I: Weight loss, polarization, impedance EFM and EDX studies

This part is devoted to study the influence of three selected polyacrylic acids (PAAs) with different molecular weights (PAA1 = 1800, PAA2 = 11,000 and PAA3 = 14,000 g mol⁻¹) on the corrosion inhibition of Al in weakly alkaline solutions (pH 8 and 10) at 30 °C. Measurements were conducted under different experimental conditions using chemical (weight loss) and electrochemical (potentiodynamic polarization and impedance) techniques, complemented with ex situ energy dispersive X-ray (EDX) examinations of the electrode surface. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented here. The results demonstrated that these polymers inhibit the alkaline corrosion of Al. The inhibition effect of these polymers is due to their adsorption on Al surface. The isoelectric point (IEP) of aluminium oxide (pH 9) seems to be an important factor controlling corrosion inhibition and adsorption of the three polymers. The three polymers inhibit the corrosion reaction of aluminium excellently at pH 8, but less effectively at pH 10. Polarization measurements showed that the three polymers act as mixed-type inhibitors. The inhibition efficiencies of these polymers increase with increasing concentration, molecular weight and immersion time. Results obtained from the chemical and electrochemical measurements are in good agreements.     

一种新颖、简单的银微米线的湿化学制备方法(英文)

提供一种新颖简单的银微米线的湿化学制备方法。在反应温度为50℃的条件下,把硫酸亚铁溶液逐渐滴加到含有柠檬酸的硝酸银溶液中,合成银微晶体。采用扫描电镜(SEM)和X射线衍射仪(XRD)对所制备的银微晶体进行表征。结果表明:所制备的银微晶体主要由大量的银微米线组成;银微晶体的形态与反应温度有很强的联系;当硝酸银浓度降低时,银微米线的长度和直径都逐渐增大,且较低的硝酸银浓度不利于生成更多的银微米线。降低硫酸亚铁浓度时也出现类似的结果。柠檬酸的用量对银微晶体的微观形态有很大的影响。根据银微米线的形成机理,推断柠檬酸在Oswald熟化形成银微米线的过程中起着非常重要的作用。     

几种氨基酸类缓蚀剂在铁表面吸附的 第一性原理研究

目的 氨基酸是一类重要的环境友好型金属有机缓蚀剂,研究缓蚀剂分子在金属表面的吸附行为,对深入理解缓蚀机理及设计新型缓蚀剂分子有重要的理论意义.方法 基于第一性原理框架下的原子轨道线性组合方法,采用Dmol3软件研究了甘氨酸、丙氨酸和亮氨酸三种分子在铁表面的吸附行为.首先对铁晶体表面的形貌学参数进行了计算,然后选取合适的晶面作为吸附表面.最后通过计算三种分子在铁表面的吸附能和分波态密度等参数分析缓蚀机制.结果 铁的三种常见晶面中,Fe(110)面为最佳吸附表面.三种氨基酸分子在Fe(110)表面呈竖直型吸附构型,甘氨酸、丙氨酸和亮氨酸的吸附能绝对值大小分别为2.233、2.254、2.472 eV,这与其实验缓蚀效率大小顺序相一致.结论 缓蚀剂分子吸附可导致金属基底的功函数减小.Hirshfeld电荷分析表明,吸附过程中存在从氨基酸分子到Fe(110)表面的电子转移现象.态密度分析表明,氨基酸分子中的活性原子与铁表面原子形成了共价键,键能的大小对缓蚀剂分子的缓蚀效率起决定性作用.     

4-amino-3-substituted-5-mercapto-1,2,4-triazolines as inhibitors for the acid corrosion of steel

Corrosion inhibition by 4-amino-3-H-5-mercapto-1,2,4-triazoline and some related compounds on the dissolution of mild steel in sulphuric acid solutions was measured using chemical and electrochemical methods. Polarization curves indicated that these compounds act as mixed-type inhibitors, that is, both the cathodic and anodic curves were affected. The effect of the structural changes in these compounds on their inhibition efficiency has been studied. Mass-loss measurements indicated that the rate of corrosion of mild steel rapidly increases with temperature over the range 25 – 60 °C both in the absence and in the presence of inhibitors, with an apparent activation energy in all instances of about 15 kcal mol^-1.     

Nicotinic acid as a nontoxic corrosion inhibitor for hot dipped Zn and Zn-Al alloy coatings on steels in diluted hydrochloric acid

The inhibition effect of nicotinic acid for corrosion of hot dipped Zn and Zn-Al alloy coatings in diluted hydrochloric acid was investigated using quantum chemistry analysis, weight loss test, electrochemical measurement, and scanning electronic microscope (SEM) analysis. Quantum chemistry calculation results showed that nicotinic acid possessed planar structure with a number of active centers, and the populations of the Mulliken charge, the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) were found mainly focused around oxygen and nitrogen atoms, and the cyclic of the benzene as well. The results of weight loss test and electrochemical measurement indicated that inhibition efficiency (IE%) increased with inhibitor concentration, and the highest inhibition efficiency was up to 96.7%. The corrosion inhibition of these coatings was discussed in terms of blocking the electrode reaction by adsorption of the molecules at the active centers on the electrode surface. It was found that the adsorption of nicotinic acid on coating surface followed Langmuir adsorption isotherm with single molecular layer, and nicotinic acid adsorbed on the coating surface probably by chemisorption. Nicotinic acid, therefore, can act as a good nontoxic corrosion inhibitor for hot dipped Zn and Zn-Al alloy coatings in diluted hydrochloric acid solution.     

Rhodanine azosulpha drugs as corrosion inhibitors for corrosion of 304 stainless steel in hydrochloric acid solution

The effect of rhodanine azosulpha drugs on the corrosion behaviour of 304 stainless steel in 1.0 M hydrochloric acid solution as corrosive medium has been investigated using weight loss and potentiostatic polarization techniques. Some corrosion parameters such as anodic and cathodic Tafel slope, corrosion potential, corrosion current, exchange current densities, surface coverage and inhibition efficiency were calculated. The polarization measurements indicated that the inhibitors are of mixed type and inhibit corrosion by parallel adsorption on the surface of steel due to the presence of more than one active centre in the inhibitor molecule. The adsorption is obeyed Langmuir adsorption isotherm. The activation energy and thermodynamic parameters were calculated at different temperature.