Green Approach to Corrosion Inhibition of Mild Steel by Lignin Sulfonate in Acidic Media

The inhibition effect of lignin sulfonate against corrosion for mild steel in acidic solution has been examined by means of FTIR(fourier transform infrared spectroscopy),FAA(flame atomic absorption)spectroscopy,SEM(scanning electron microscope),EDS(energy dispersive X-ray spectroscopy),and mass loss techniques.The results revealed that lignin is a beneficial inhibitor for mild steel corrosion in acidic medium.It has been further found that Langmuir adsorption isotherm is obeyed by the tested lignin′s adsorption over the surface of mild steel.The range of inhibition efficiency(IE)in 2mol·L~(-1) HCl was found to be 75.88%-87.88%for Reax 88 A,40.72%-60.32%for Reax 88 B,and 54.32%-63.03%for Reax 100 M,after immersed at 298 Kfor 24htime.     

Alkylimidazolium Bromides as Corrosion Inhibitors for Mild Steel in Acidic Medium

Inhibition of mild steel corrosion in 1 M HCl solution by 1-alkyl-3-methylimidazolium bromides was investigated using electrochemical and weight loss methods. The studied ionic liquids showed appreciable inhibition efficiencies. Polarization measurements proved that the studied compounds were mixed-type inhibitors with predominantly anodic inhibition. The inhibition efficiency increased with the ionic liquid concentration and with the length of the alkyl chain. The values obtained from the polarization curves and weight loss measurements were in good agreement. The highest inhibition efficiency reached for the 1-octyl-3-methylimidazolium bromide was 94%. The Gibbs energy of adsorption was calculated by means of the Langmuir and Flory–Huggins isotherm and El-Awady thermodynamic-kinetic model.     

Corrosion Inhibitive Evaluation of an Environmentally Friendly Water-Base Acrylic Terpolymer on Mild Steel in Hydrochloric Acid Media

The corrosion inhibitive performance of an environmentally friendly water-base acrylic terpolymer [methyl methacrylate/Butyl Acrylate/Acrylic acid (ATP)] on mild steel in 1 M HCl was investigated by alternating current and direct current electrochemical techniques and the quantum chemical method. An efficiency of more than 97 pct was obtained with 0.8 mmol/L ATP. The increase in inhibitor concentration and immersion time has a positive effect, while the temperature influence is negligible on the inhibitor efficiency. The present terpolymer obeys the Langmuir isotherm, and thermodynamic calculation reveals a chemisorption type on the surface. Density functional calculations showed that the lone pairs of electrons of oxygen in the structure of three monomers are suitable sites to adsorb onto the metal surface. Finally, in the presence of ATP, a decrease in surface roughness and corrosion attacks was demonstrated by atomic force microscopy and optical microscopy examinations, respectively.     

Effect of Heat Treatment on Corrosion Activity of Nonmetallic Inclusions and Steel Corrosion Resistance in Aqueous Media

Metallurgist - Results of the studying the effect of heat treatment on the corrosion activity of non-metallic inclusions in contemporary steels, and correspondingly on corrosion resistance of the...     

淫羊藿有效成分抗氧化活性研究

对不同溶剂提取的淫羊藿有效成分进行抗氧化活性的测定,并与TBHQ抗氧化剂进行对比.结果证明,乙酸乙酯和氟仿提取物抗氧化活性最高,且当浓度达到0.3mg/ml时,淫羊藿提取物的抗氧化活性与TBHQ相当,当浓度达到0.5 mg/ml时, 淫羊藿提取物的抗氧化活性强于TBHQ.     

Decomposition Products of s-Triazine Herbicides by Electron-Transfer in Acidic Aqueous Media

The reduction of atrazine and terbutylazine was preceded by protonation equilibrium. Three protonation sites of the s-triazine molecule determined the structure of the final reduction product. Protonation was investigated by the change of UV-Vis spectra. Two slightly different pKs corresponding to protonation on N5 and N1 heteroatoms were evaluated. The principal reduction pathway involved the cleavage of a chlorine atom. A small quantity of desethylatrazine was detected in the most acidic media.     

酸雨对低碳钢腐蚀行为的影响

利用金相显微镜(OM)、扫描电镜(SEM)、X射线衍射(XRD)等分析手段及电化学方法研究了低碳钢在模拟酸雨环境中的腐蚀行为.研究结果表明:碳钢在酸雨环境中腐蚀是一个局部腐蚀和均匀腐蚀并存的过程,溶液中的SO24-和Cl-离子的存在加速了碳钢表面腐蚀坑的形成和生长,腐蚀坑优先出现在铁素体上.腐蚀产物主要有Υ-FeOOH...     

Caustic Stress Corrosion Cracking of Mild Steel

The stress corrosion cracking (SCC) behavior of cold worked mild steel in hot, aqueous, 33 pct NaOH solutions was studied with prefatigue cracked double cantilever beam specimens. SCC kinetics were studied under freely corroding potentials (E _corr ≈ −1.00 V_SHE) and potentiostatic potentials of −0.76 V_SHE near the active-passive transition. The pH of the liquid within the crack was determined and fractography was studied by scanning electron microscopy. Cracking was transgranular atE _corr, intergranular at −0.76 V_SHE, and produced no detectable change in crack liquid pH from that of the bulk solution. Crack rates were dependent upon temperature, potential, and stress intensity (K ₁). The apparent activation energy in Region II, where crack growth rate was independent ofK, was ∼ 24kJ/mol for both cracking modes. This was considered to be due to mixed rate control involving activation polarization and mass transport processes. The mechanism of cracking was entirely consistent with metal dissolution at –0.76 V_SHE and may involve hydrogen embrittlement and/or dissolution effects atE _corr. DOUGLAS SINGBEIL, formerly Research Student, University of British Columbia, is Research Scientist, Pulp and Paper Research Institute of Canada, 570-Blvd. St. Jean, Pointe Claire, Quebec, Canada H9R 3J9.     

Separation of Europium from Cobalt Using Antimony Silicates in Sulfate Acidic Media

The ores of rare earth elements (REEs) are usually digested in concentrated sulfuric acid media, which dissolve the REEs as main product with heavy metals as byproduct. In the present work, inorganic ion exchangers based on silico-antimonates (SiSb) were synthesized and characterized. SiSb mixed with metal oxides were prepared in molar ratio 2:1 with different aging time. In batch experiments, radionuclides Eu-152 and Co-57 were taken to represent the lanthanides and heavy metals, respectively. The sorption behavior was examined and distribution coefficients were evaluated for different effective conditions such as sulfuric acid concentration, pH, shaking time, metal ion concentration, and aging time. The new inorganic SiSb materials are characterized by rapid kinetics for Eu(III) and high adsorption selectivity for Co(II). The results showed that the SiSb are acidic in character and that their cation-exchange properties are better in low acidic media. Sorption efficiency is highly correlated with the structural framework, which depends on exchangeable water content. Various chelating agents were tested for desorption of the retained Eu(III) and Co(II). Maximum separation factors were obtained with SiSb materials after 2 or 3 days aging, providing efficient exchangers for the separation of economically valuable REEs from heavy metals.     

Inhibition Effects of Chloroquinolines on Corrosion of Mild Steel in Hydrochloric Acid Solution

The corrosion inhibition efficiencies of four compounds namely N-[(1E)-(2-chloroquinolin-3-yl)methylene]-N-phenylamine(CQMA),N-(1E)-(2-chloroquinolin-3-yl)methylene]-N-(4-fluorophenyl)amine(CQMFA),N-(4-chloro phenyl)-N-[(1E)-(2-chloroquinolin-3-yl)methylene]amine(CQMCA),and N-(4-bromo phenyl)-N-[(1E)-(2-chloroquinolin-3-yl)methylene]amine(CQMBA)on mild steel corrosion in hydrochloric acid media were investigated using mass loss,potentiodynamic polarization and electrochemical impedance spectroscopy.For all the studied inhibitors the inhibition efficiency values were found to increase with increasing concentration up to 5.00×10-4 mol·dm-3.Scanning electron microscopic technique showed the formation of a thick film on the steel surface in the presence of inhibitors.     

酵母提取物对浸铀混合菌群活性的影响

考察了不同浓度的酵母提取物对浸铀混合菌群生长和氧化活性的影响。结果表明,随着酵母提取物浓度的增大,有机物对浸铀混合菌生长、氧化活性有较强的抑制作用;酵母提取物浓度小于1g/L时,对混合菌的氧化活性和生长周期影响较小,微量的酵母提取物反而能促进浸铀混合菌群的细胞分裂,提高铁氧化速率。     

晶粒细化对Cu-40Ni合金在酸性含Cl-介质中耐蚀性能的影响

采用电弧熔炼（CA）和机械合金化（MA）通过热压烧结工艺制备了晶粒尺寸差别较大的Cu-40Ni合金，借助于PARM273A和M5210电化学综合测量仪，利用动电位扫描法和交流阻抗技术对比研究了上述合金在酸性含Cl^-介质中的腐蚀电化学性能以及腐蚀机制。结果表明：两种合金的腐蚀电位随时间逐渐稳定，在中性Na2SO4溶液中加入H2SO4和NaCl后，两种合金的自腐蚀电位负移；晶粒细化后，两种合金的自腐蚀电位则正移。两种合金在中性及酸性含Cl^-介质中均存在钝化现象，但在酸性含Cl^-介质中钝化区间很短，钝化能力较弱。两种合金的交流阻抗谱均由单容抗弧组成，反应由电化学过程控制。晶粒细化后，合金中存在大量晶界，参与腐蚀反应的活性原子数增加，促使MACu40Ni合金的腐蚀速度高于CACu-40Ni合金。     

Effect of Mechanical Arc Oscillation on the Grain Structure of Mild Steel Weld Metal

The effect of mechanical arc oscillation on the weld metal grain structure in mild steel gas tungsten arc welds has been studied. For welds made without arc oscillation, columnar grains were observed in the weld metal; however, for the same welding parameters, the weld made with arc oscillation had smaller sized relatively equiaxed grains in the weld metal. The strengths for weld made with arc oscillation was higher than that for weld made without arc oscillation, with appreciable increase in ductility; this could be attributed to the reduction in grain size diameter due to arc oscillation. Lower weld metal hardness and increase in heat affected zone hardness was observed in weld made with arc oscillation; this could be attributed to increase in pro-eutectoid ferrite formation with absence of Widmanstatten ferrite structures in the weld metal and less coarsening of grains in the heat affected zone due to increased cooling rate.     

大叶胡颓子叶乙酸乙酯部抗菌作用的研究

[目的]研究大叶胡颓子叶乙酸乙酯部的抑菌作用.[方法]大叶胡颓子叶经乙醇提取,石油醚、氯仿、乙酸乙酯依次萃取,采用滤纸片法和平板法对乙酸乙酯部进行体外抑菌作用研究.[结果]大叶胡颓子叶乙酸乙酯部对5种常见的呼吸道感染菌(金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌、肺炎克氏杆菌、鲍曼不动杆菌)均有较强的体外抑制作用,最小抑菌浓度为0.357～1.429 mg/ml.[结论]乙酸乙酯部为大叶胡颓子叶抗菌的活性部位,是寻找新抑菌活性成分的基础,可用于研发抗菌消炎新药物.     

Erosion and Corrosion of Mild Steel and Stainless Steel in Sodium Carbonate／Bicarbonate Solution Bearing Alumina Particle

With a rotating cylinder electrode apparatus, the polarization behaviors of the mildsteel and the stainless steel 0Crl8Ni9 in NaHCO3 (0.5M) NazCO3 (0.5M) solution with andwithout erodent particles were investigated and compared. The results show that the rotationspeed of cylinder hardly affects the polarization behavior of sample in solution without particlesbut exerts a great influence on that with particles. Increasing rotation speed, the free corrosionpotential shifts to positive direction and the oxygen limiting current density increases. Both themild steel and stainless steel 0Crl8Ni9 experience a significant increase of the mass loss by in-creasing erosion, and erosive wear was dominated by severe micro-plowing. The insufficientmechanical strength of both materials leads to a low resistance to particle removal. Increasingperipheral velocities of the rotating cylinder enhances the corrosion rate of the mild steel. Thestainless steel 0Crl8Ni9, due to a high erosive wear, also suffers from similar erosion-corrosiondamage, despite that its corrosion resistance is much higher than that of the mild steel.     

低碳高合金钢及其在湿磨衬板上的应用

根据在湿磨条件下对球磨机衬板性能的要求，设计并制造出一种综合性能较好的低碳高合金钢衬板材料。该材料组织为板条马氏体，HRC45～50，冲击韧性αk=50～90J／cm^2。冲击腐蚀磨损实验结果表明：低碳高合金钢比高锰钢具有更好的耐冲击腐蚀磨损性能。装机结果显示：该低碳高合金钢衬板的使用寿命是高锰钢的2倍左右。     

无花果叶不同溶剂提取物抗氧化活性的比较研究

[目的]研究不同溶剂提取对无花果叶抗氧化能力的影响.[方法]以不同溶剂对无花果叶进行超声提取,比较各提取物抗猪油氧化及清除DPPH(1,1-Dipheny1-2-picrylhydrazyl)和ABTS[2,2-Azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)]自由基的能力.[结果]各提取物对猪油的抗氧化能力为:蒸馏水提取物>70%乙醇提取物>甲醇提取物>乙酸乙酯提取物>无水乙醇提取物;对DPPH和ABTS自由基的清除能力为:蒸馏水提取物>70%乙醇提取物>甲醇提取物>无水乙醇提取物>乙酸乙酯提取物,水提物清除DPPH的IC<,50>值为0.49 ms/ml,清除ABTS的IC<,50>值为1.54 mg/ml.[结论]无花果叶水提物具有较强的抗氧化性能,有开发功能性抗氧化剂的潜在价值.