钢中Si、Mn的电子探针定量分析与标样

采用特制的Fe-Si、Fe-Mn合金系列标样，用电子探针测定了钢或铁基合金中低含量的Si和Mn元素、与用纯元素作标样、经ZAF修正的结果相比较，提高了分析准确度．     

Corrosion Behavior in Alkaline Media of Steel with Various Conversion Coatings in Concrete

The corrosion behavior in alkaline media of St.3 steel with various conversion coatings in concrete was studied.     

Study of electropolishing inhibition of steel using natural products as a green inhibitor in ortho-phosphoric acid

ABSTRACT

Anodic inhibition of steel in 8?mol?L^?1 H₃PO₄ was investigated in the absence and presence of different concentrations of extracts of Lawsonia inermis. An experimental measurement, including galvanostatic polarization studies, was done. The anodic corrosion rate and the inhibition efficiencies of the extract were calculated. The results obtained show that the inhibition was found to increase with increasing concentration of Lawsonia inermis extract. The inhibition actions of extracts are discussed on the basis of adsorption of Lawsonia inermis at the steel surface. Theoretical fitting of different isotherms were tested to clarify the nature of adsorption. Polarization curves revealed that Lawsonia inermis inhibitor acts as a corrosion inhibitor. The activation energy (E_a) as well as other thermodynamic parameters (ΔH*, ΔS*, ΔG*) for the inhibition process were calculated. These thermodynamic parameters show strong interaction between the inhibitor and the steel surface. The scanning electron microscope analysis study confirmed the adsorption of inhibitor molecules on the steel surface. The social organization and morphology of the extract were characterized by Fourier transform infrared spectroscopy.     

Allylacetylenes and their derivatives as inhibitors of steel corrosion in sulfuric acid

New functionalized derivatives of allylacetylenes were prepared, and their ability to inhibit corrosion of St.3 low-carbon steel in 5 N sulfuric acid was studied. The effectiveness of inhibition of steel corrosion was studied in relation to the structure of acetylene derivatives, their concentration, and temperature of acidic medium.     

Inhibitory Action of Funtumia elastica Extracts on the Corrosion of Q235 Mild Steel in Hydrochloric Acid Medium: Experimental and Theoretical Studies

The inhibiting effect of aqueous extracts of Funtumia elastica (FE) on mild steel corrosion in 1 M HCl solution was investigated using electrochemical and surface characterization techniques. The results revealed that FE effectively inhibited the corrosion reaction. Polarization data reveal that the extract functioned as a mixed-type inhibitor, while impedance results show that the extract organic matter gets adsorbed on the metal/solution interface. Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy results confirmed the formation of a protective layer of extract adsorbed on the mild steel surface. Adsorption of some organic constituents of FE on mild steel was theoretically described by quantum chemical computations and molecular dynamics simulations, in the framework of the density functional theory.     

Offline combination of pressurized fluid extraction and electron paramagnetic resonance spectroscopy for antioxidant activity of grape skin extracts assessment

A comprehensive characterization of grape skin methanolic and ethanolic extracts prepared by pressurized fluid extraction (PFE) at various temperatures within 40 to 120 °C from two wine grape varieties, St. Laurent and Alibernet was performed. For the first time, an offline combination of PFE and electron paramagnetic resonance (EPR) spectroscopy together with other experimental methods was employed to assess the effect of extraction conditions on numerous extract characteristics including antioxidant or radical-scavenging ability, HPLC profile of anthocyanins, total phenolic compounds content (TPC), tristimulus color values (CIE Lab), and pH values. The properties of extracts depend on the solvent used, the mass of grape skins as well as on the extraction conditions among which the temperature plays a crucial role. In spite of wide interval of extraction temperatures, all extracts still retain their antioxidant and/or radical-scavenging properties, indicating that the extracts prepared by PFE can serve as potential source of functional food supplements or color enhancers.     

Effect of amino acids on corrosion of copper and steel in acid medium

Efficiency of four amino acids (glycine, threonine, phenylalanine, and glutamic acid) in inhibition of corrosion of M3 copper and St.3 low-carbon steel in a 0.5 M HCl solution was evaluated.     

Influence of aminodiester on steel hydrogenation in a hydrosulfuric medium

The influence of N-(2-carboethoxyethene)-N-(2-carbobuthoxyethyl)methylamine on the process of hydrogen penetration in steel (St.3) in a hydrosulfuric medium was studied.     

Effect of External Polarization on Hydrogen Diffusion across Steel Membrane in Dilute HCl Solutions Containing a Number of Aromatic Amines

The effect of a number of aromatic amines on the hydrogen diffusion flux across a steel (St.3 brand) membrane under conditions of anodic and cathodic polarization in weakly acidic solutions, including media containing hydrogen sulfide, was studied. The experimentally observed dependences are interpreted in terms of the Horiuti approach.     

Protection of carbon steel with superhydrophobic coating against corrosion in NaCl solution

Corrosion and kinetics of partial electrode reactions on carbon steel St3 with superhydrophobic coatings of three types were studied in 0.5 M NaCl and 50 g/L NaCl +400 mg/L H₂S solutions. The investigations were carried out on electrodes made of carbon steel St3 with a chemical composition, wt. %: C – 0.20; Mn – 0.50; Si – 0.15; P – 0.04; S – 0.05; Cr – 0.30; Ni – 0.20; Cu – 0.20, and Fe – 98.36. To obtain the type I coating, the metal surface was textured by an IR laser radiation of nanosecond duration followed by chemisorption of fluorobutylsilane out of a solution in n-decane. To obtain a coating of type II, a nanoscale composite layer consisting of aggregates of aerosil nanoparticles was applied additionally to the outcome of type I method. To obtain a coating of type III, the metal surface after being textured by the infrared (IR) laser radiation of nanosecond duration was followed by chemisorption of fluoroxy silane. The influence of duration τ of the medium corrosive impact on protective effect of the superhydrophobic coating is considered. It was shown that upon reaching a steady state (after 72 h), the corrosion rate of steel with a superhydrophobic coating of I and II types in a 0.5 M NaCl solution is reduced by 23 ± 3 times compared with unprotected samples. Approximately the same picture is characteristic of electrodes with a coating of type III in a solution of 50 g/L NaCl +400 mg/L H₂S.     

Inhibition of Corrosion and Hydrogenation of Carbon Steel with a Number of Inhibitors in Weakly Acid Media Containing H<Subscript>2</Subscript>S and CO<Subscript>2</Subscript>

The inhibitive power of AMDOR IK-7 formulation, homologous mixture of alkyl ammonium acetates C₁₀–C₁₄ in a specific solvent, and PKU-6 toward corrosion of St. 3 steel in weakly acid media containing 5.8 g l^?1 NaCl, H₂S, and CO₂ was studied. The influence exerted by the inhibitors on the kinetics of partial electrode reactions and on the hydrogenation of steel was examined. Impedance spectra were recorded and analyzed.     

Fabrication and Characterization of Sulfonate‐containing Polystyrene/CaCO3 Core‐shell Nanoparticles

Polystyrene (PSt) seed latex was first prepared via soap‐free emulsion polymerization in the presence of a small amount of methacrylic acid using ammonium persulfate as initiator, and then seeded emulsion polymerization of sodium 4‐styrenesulfonate (NaSS) and St was carried out to synthesize P(St‐NaSS) core latex using 2,2′‐azobisisobutyronitrile as initiator. After that, P(St‐NaSS)/CaCO₃ core‐shell nanoparticles were fabricated by sequentially introducing Ca(OH)₂ aqueous solution and CO₂ gas into the core latex. The morphology of the core and core‐shell nanoparticles was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and the state of CaCO₃ shell was confirmed with high‐resolution scanning transmission electron microscope (HR‐STEM) and selected area electron diffraction (SAED). Results showed that PNaSS chains were successfully grafted onto the PSt seed surface, and length of the PNaSS "hairs" could be modulated by adjusting NaSS amount. Sulfonic groups of the PNaSS hairs served as additives in the formation and stabilization of amorphous CaCO₃(ACC) and prevented ACC from sequent transformation into crystalline states. The amount of the anchored CaCO₃ increased with the growth of PNaSS hair length, and reached 51 wt% (by thermalgravimetric analysis) under the optimal encapsulating temperature of 45°C. Moreover, the forming mechanism of P(St‐NaSS)/CaCO₃ core‐shell nanoparticles was proposed.     

Synthesis of co-oligomers of 2-propenylphenol with maleic anhydride and study of products of their transformations with amines as steel corrosion inhibitors

Modification with diethylamine and diethanolamine of co-oligomers of 2-propenylphenol with maleic anhydride yielded water-soluble nitrogen-containing derivatives inhibiting the corrosion of St.3 steel in watersalt solutions.     

Characterization of ear piercing studs and their corrosion products by neutron activation analysis

Neutron activation analysis has been applied to analyse ear piercing studs manufactured with three different types of metallic materials and also in the analyses of cell culture media in which these studs were immersed. Results obtained in these analyses indicated the release of metal from the studs to the culture media. Zn and Fe were found, respectively, in the extracts of gold coated copper-zinc alloy and stainless steel. These findings were correlated with the results already obtained for studs surface analysis by scanning electron microscopy and for the cytotoxicity tests of culture extracts.     

Synergism of Saccharum officinarum and Ananas comosus extract additives on the quality of electroplated zinc on mild steel

Synergism of Saccharum officinarum (sugarcane) and Ananas comosus (pineapple) extract additives on the quality of electroplated zinc on mild steel in acid chloride solution was investigated experimentally at ambient temperature (~28 °C). The experiments were performed at different plating times (15 and 18 min), additive concentrations (2, 2.5, 3 ml/50 ml of acid chloride solution), pH 5, temperature (27–30 °C), current (0.08 A), and voltage (13 V DC) conditions. Zinc electroplating on mild steel was performed using a DC-supply. The surface of the plated steel was examined with scanning electron microscopy, and energy dispersive spectroscopy for surface elemental composition analysis. Different surface characteristics were obtained depending upon the concentration of the additive and the plating time. The corrosion resistance of the plated surface was determined by a gravimetric method. Microstructural morphology of the plated surface indicated a good quality electroplating that was better than either the sugarcane or pineapple extracts alone. The electroplating process was sensitive to changes in additive concentration and plating time. Any variation in the plating parameter produced an entirely new and different surface crystal morphology.     

Cathodic Dehalogenation with Dimerization. Dimerization in the Course of Reduction of Butyl Iodide

Electrochemical reduction of butyl iodide in methanol with a sodium methylate supporting electrolyte was studied. The yield of the dimeric product, octane, largely depends on the cathode material, with copper and iron (St.3 steel) being the most active. At a current density of 0.03-0.10 A cm^{- 2}, 0°C, and 0.005 M CH₃ONa, the yield of octane, based on butyl iodide, is as high as 83-84%.     

Pseudohypericin and hypericin in St. John's wort extracts. Breakdown of pseudohypericin

Photodiode array detector-coupled HPLC analysis of extracts of St. John's wort (Hypericum perforatum) reveals two main compounds: pseudohypericin (PH) and hypericin (H) (peaks A and B respectively). When the pH of the extracts is raised, peak A irreversibly disappears whereas peak B does not change. This instability at high pH means that alkaline conditions should be avoided during extraction and raises a question concerning the bioavailability of pseudohypericin from St. John's wort extract-containing medicinal products designed for oral administration.     

Extraction and determination of biologically active components of St. John’s wort and its pharmaceutical preparations

A procedure is developed for the determination of biologically active substances (BAS) of common St. John’s wort (Hypericum perforatum L.) by HPLC using two columns, Luna C18, 100 Å (for the determination of phenolcarboxylic acids and flavonoids), and Onyx Monolithic C18 (for the determination of phloroglucinols and naphthodianthrones), in the gradient elution mode with diode array detection. The detection limits for analytes are 0.05–0.20 μg/mL. To optimize the conditions, we studied the extraction of biologically active substances from St. John’s wort by a water–ethanol solution at different temperatures and pressures and under the effect of microwave radiation and ultrasound. The maximum amounts of substances were extracted in a dynamic mode under heat and pressure. The procedure was applied to the St. John’s wort samples of different brands and some pharmaceutical products based on it. The components of extracts were identified by retention times, UV spectra, and mass spectra. It was shown that the content of biologically active substances in pharmaceutical samples of St. John’s wort depends on the herb habitat. It was shown that hyperforin decomposed in pharmaceutical formulations based on St. John’s wort during storage.     

多单体接枝聚丙烯对PBT/PP共混体系的形态结构及力学性能影响研究

研究了甲基丙烯酸缩水甘油酯 (GMA)和苯乙烯 (St)多单体熔融接枝聚丙烯 (PP g (GMA co St) )对聚对苯二甲酸丁二酯 (PBT) 聚丙烯 (PP)共混物的形态结构和力学性能的影响 .利用双螺杆挤出机对PBT PP合金进行共混挤出 ,使用DSC、FT IR和SEM、TEM等手段对共混物进行了分析和相形态观察 ,并测试了力学性能 .实验证明 ,熔融共混过程中PP g (GMA co St)的环氧基团可以与PBT的端羧基发生化学反应 ,就地生成了PBT g PP共聚物 ,该共聚物可对PBT PP合金起到良好的增容剂作用 ,使共混物的相区尺寸显著减小 ,共混物的拉伸强度和冲击强度等力学性能同时得到明显改善 ,达到了弹性体系或小分子增容所难以达到的力学性能平衡的效果 .此外 ,TEM的研究还在PBT PP g (GMA co St)共混物中发现了特殊的微相分离结构     

乳液聚合法制备P(St/BA)-KAl(OH)2CO3纳米复合物

利用乳液聚合法制备了一种含KAl(OH)2CO3纳米粒子的聚苯乙烯／丙烯酸丁酯复合物．Zeta电位、粒径分布、扫描电镜(SEM)和透射电镜(TEM)等分析表明KAl(OH)2CO3粒子能够稳定地分散于苯丙乳液的乳胶粒中,形成核一壳结构．热失重(TG)分析表明KAl(OH)2CO3粒子的加入能提高复合物的热稳定性,使其在阻燃涂料领域有着潜在的应用前景．