Na2MoO4-有机膦A复合缓蚀剂对55%LiBr溶液中碳钢的缓蚀行为

采用失重法、电化学测试技术、原子力显微镜和电子探针显微分析等方法考察了Na₂MoO₄-有机膦A复合缓蚀剂对55%LiBr+0.07 mol/L LiOH溶液中碳钢的缓蚀性能。结果表明,240 ℃下碳钢在添加800 mg/L Na₂MoO₄-有机膦A复合缓蚀剂的55%LiBr+0.07 mol/L LiOH溶液中的腐蚀速率为43.2 μma^-1。在沸腾的55%LiBr+0.07 mol/L LiOH溶液中添加该缓蚀剂后,碳钢的钝化电位区间拓宽,钝化电流密度降低,反应电阻R_t值显著增加,缓蚀效率可达94.4%。该缓蚀剂能使碳钢表面形成显微结构为孤岛状的膜层,主要成分为Fe和Mo的氧化物。     

Effects of Na3PW12O40 on the corrosion behavior of carbon steel in 55 %LiBr solution

Electrochemical technologies, chemical immersion tests and surface detection technologies were adopted to study the inhibition performance of Na₃PW₁₂O₄₀ inhibitor on carbon steel in 55 % LiBr + 0.07 mol/L LiOH solution, and the inhibition mechanism was discussed. Results indicated that Na₃PW₁₂O₄₀ inhibitor caused the decrease of both anodic and cathodic polarization current density and a widening of the passive potential region. It behaved as a mixed inhibitor. When the concentration of Na₃PW₁₂O₄₀ in 55 % LiBr + 0.07 mol/L LiOH solution was 300 mg/L, excellent inhibition performance on carbon steel was obtained. When the solution temperature were 145°C, 160°C, 180°C and 200°C, respectively, the corrosion rates of carbon steel were 13.07 μm/y, 17.74 μm/y, 24.55 μm/y and 73.52 μm/y accordingly. Na₃PW₁₂O₄₀ inhibitor exhibited an excellent inhibition performance at high temperature. Na₃PW₁₂O₄₀ is a strong oxidant. Fe was oxidized to Fe₂O₃ and itself was deoxidized to heteropoly blue. By this mechanism, an integrate compact passive film mainly comprising Fe₂O₃ may be formed on the carbon steel surface, and the corrosion of carbon steel in 55 % LiBr solution may be retarded by this passive film.     

Effect of inhibitors on corrosion behavior of copper—nickel in concentrated lithium bromide solution at high temperature

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胡萝卜茎叶提取物对碳钢在0.5 mol/L H2SO4溶液中的缓蚀作用

目的研究胡萝卜茎叶提取物(DCSLE)在硫酸介质中对碳钢的腐蚀抑制作用及机理。方法通过超声辅助的手段,用水浸提获得DCSLE,利用红外光谱(FTIR)对其含有的主要官能团进行表征。在25~40℃下,采用失重法、电化学极化和阻抗法(EIS)评价DCSLE在0.5 mol/L H2SO4溶液中对碳钢的缓蚀性能,并讨论了其缓蚀机理。结果DCSLE对碳钢在0.5mol/LH2SO4溶液中的腐蚀具有良好的抑制效果,其缓蚀效率随浓度的增加而增加,随温度的增加而先增加后降低(40℃<25℃<30℃<35℃),35℃下,质量浓度为0.6g/L时,缓蚀效率为92.85%。电化学测试表明,DCSLE是混合型缓蚀剂,但主要是抑制阴极的反应。其缓蚀机理是:DCSLE以物理和化学混合吸附的方式吸附在碳钢表面,形成一层保护膜,从而阻止酸溶液的侵蚀,且吸附遵循Langmuir吸附等温模型。扫描电镜(SEM)观察到加入DCSLE后,碳钢的腐蚀得到了明显控制。结论DCSLE可以有效抑制碳钢在0.5mol/LH2SO4溶液介质中的腐蚀,是一种具有广泛应用前景的天然绿色缓蚀剂。     

LiNO3对高温高浓度LiBr溶液中碳钢的缓蚀机理

采用电化学法和化学浸泡法研究了高温65%LiBr+0. 07mol/L LiOH溶液中，LiNO3对碳钢腐蚀的影响.结果表明，随LiNO3浓度增加碳钢腐蚀 速率降低，复合添加150 mg/L Na2MoO4后，碳钢在100mg/L LiNO3时腐蚀速率出现最 小值.通过计算NO-3和MoO2-4还原平衡电极电位，发现NO-3优先还原形成 内层以Fe的氧化物为主的膜是由于NO-3具有较高的还原电极电位.LiNO3小于10 0 mg/L时，复合添加的MoO2-4在外层得以还原形成缺氧型MoO2，建立起稳定的双 层膜结构.当LiNO3浓度大于100 mg/L后，NO-3对膜层中MoO3优先侵蚀，加速Br- “楔入” 钝化膜历程，从而破坏了双层膜结构.     

Influence of pH on corrosion behavior of carbon steel in simulated cooling water containing scale and corrosion inhibitors

In this paper, the influence of pH on the corrosion behavior of AISI 1020 carbon steel in simulated cooling water was investigated by using electrochemical and surface analysis methods. The results of polarization showed that the corrosion resistance of carbon steel increased with an increase in pH of the simulated water, and the corrosion control process changed from cathodic polarization to anode polarization control. The scale and corrosion inhibitor 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) had a certain anodic corrosion inhibition effect on carbon steel, whereas Zn²⁺ acted as a cathodic inhibitor for carbon steel in simulated water with pH 7–9. In simulated water containing both PBTCA and Zn²⁺, a good synergistic corrosion inhibition was found between PBTCA and Zn²⁺, and their corrosion inhibition effect on carbon steel was the best at pH 8. This was attributed to the formation of Zn(OH)₂ precipitate film in the cathode region and the formation of Zn–PBTCA complex film in the anode region at this pH.     

SCC MECHANISM OF STAINLESS STEEL AISI 321 IN ACIDIC CHLORIDE SOLUTION

It is verified that stainless steel AISI 321 is in the active anodic dissolution state in 0.5mol/L HCll+0.5 mol/L NaCl solution at 55℃.The SCC of the steel in the solution cannot be reasonably explained by passive film rupture-nepasivation theory and by hydrogenembrittlement theory.There are evidences that the fracture stress at the tip of the cracksis reduced by anodic dissolution due to its role in relieving strain hardening layer at cracktip.     

铜镍合金在添加不同缓蚀剂的55%LiBr溶液中的腐蚀行为

采用电化学阻抗技术研究了LiOH、Na_2MoO_4和BTA对铜镍合金在55%LiBr溶液中的腐蚀行为的影响。结果表明,单独添加LiOH和BTA都能显著减缓铜镍合金在LiBr溶液中的腐蚀,而Na_2MoO_4含量较低时可能会加速腐蚀。三种缓蚀剂复配使用,对铜镍合金在55%LiBr溶液中的腐蚀具有更好的缓蚀效果,复配后具有协同效应。试验表明,复合添加0.10 mol/L LiOH、150 mg/L Na_2MoO_4和150mg/L BTA时,对铜镍合金在55%LiBr溶液中的腐蚀具有最优的缓蚀效率。     

向日葵盘提取物在0.5mol/L H2SO4溶液中对碳钢的缓蚀作用

以超声辅助法提取得到的向日葵盘提取物(HALE)为缓蚀剂,采用腐蚀浸泡试验、电化学试验研究HALE在0.5mol/L H2SO4溶液中对碳钢的缓蚀作用。结果表明:HALE对碳钢缓蚀效果良好,缓蚀率随HALE加量增加而增大,但随温度升高而降低;HALE在碳钢表面的吸附符合Langmuir吸附模型,是以物理吸附为主的混合吸附;电化学测试结果表明HALE是偏阳极混合抑制型缓蚀剂。     

Optimization of Cr/Mo molar ratio in FeCoCrMoCBY alloys for high corrosion resistance

The corrosion behavior of bulk metallic glasses (BMGs) (Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂)_100–xCr_x (x=0, 4, 8, 12, molar fraction, %) was investigated in 1 mol/L HCl aqueous solution with electrochemical tests. The electrochemical measurements demonstrate that the passive current density of Fe-based amorphous alloy is reduced by about one order of magnitude, and meanwhile, the stability of passive film can be guaranteed by the Cr/Mo molar ratio. The Mott–Schottky (M–S) curves show that the passive film is the densest when the molar ratio of Cr/Mo is between 1.37 and 1.69. X-ray photoelectron spectroscopy (XPS) analysis was performed to clarify chemical states of elements in the passive films. The results show that the corrosion resistance of the alloy is related to the molar ratio of Cr/Mo. The stability of passive film is determined by the synergistic action of Cr and Mo elements. The main component of the passive film is Cr³⁺ oxide. When the potential is greater than 0.5 V (vs SCE), Mo⁶⁺ ions play an important role in keeping the stability of the passive film. The appropriate molar ratio of Cr/Mo can reduce the dissolution rate of the passive film.     

Influence of cavitation on the passive behaviour of duplex stainless steels in aqueous LiBr solutions

The objective of this work is to study the influence of cavitation on the passive behaviour of EN 1.4462, its filler metal (EN 1.4462F), and the welded metal (EN 1.4462W) obtained by Gas Tungsten Arc Welding using electrochemical techniques. The hydrodynamic conditions of the medium were modified using an ultrasonic-induced cavitation facility.Potentiostatic experiments were used to study the effects of cavitation on the passive behaviour of the alloys. The experiments were carried out in 850 g/L LiBr solutions with and without an inhibitor (Lithium Chromate). The solution with Li₂CrO₄ (commercial solution) contains LiOH as the pH regulator. The potentiodynamic cyclic curves of the stainless steels under the static condition were used to set the values of the imposed potentials.In this work, the electrochemical behaviour of the alloys described by the potentiodynamic curves has been related to their passive behaviour under potentiostatic conditions when the pulses of cavitation were applied. The results demonstrate that cavitation affects the passive behaviour of the alloys; the influence depends on the potential applied and on the presence or absence of chromates in the medium. Only under certain circumstances the hydrodynamic conditions can suppose a breakdown of passive film formed under static conditions.     

MoO42-与 Zn2+对镁合金在 NaCl 溶液中的协同缓蚀作用

采用动电位极化曲线法,结合腐蚀后的表面微观形貌及EDS能谱分析,研究了MoO42-与Zn2+对AZ31镁合金在3.5%NaCl溶液中的协同缓蚀性能。结果表明:0.005 mol/L Zn2+与0.05 mol/L钼酸钠联合作用,可有效抑制镁合金在NaCl溶液中的腐蚀,Zn2+促进MoO42-在合金表面的吸附,缓蚀效果优于单一的钼酸盐缓蚀剂。缓蚀机制是:钼酸盐与Zn2+协同作用,使镁合金表面形成更为致密的钝化膜,从而抑制镁合金的腐蚀。     

无磷海水缓蚀剂的开发

通过失重法测定腐蚀速率,并计算缓蚀率,确定了具有较好协同缓蚀效应的四元无磷海水缓蚀剂配方,并通过电化学极化、SEM、EDS等分析手段,对该无磷海水复合缓蚀剂的缓蚀机理进行了研究.结果表明:配方以40 mg/L钨酸盐+40 mg/L葡萄糖酸盐+4 mg/L Zn2++30 mg/L三乙醇胺为宜,该缓蚀剂在海水中对碳钢的缓...     

The effect of chromate in the corrosion behavior of duplex stainless steel in LiBr solutions

The electrochemical behavior of duplex stainless steel (DSS) in LiBr media was investigated by anodic cyclic polarization curves and AC impedance measurements. The effect of bromide concentration and chromate presence in the solutions on the corrosion behavior of DSS was studied. It was found, by cyclic polarization curves analyses, that there was different pitting susceptibility of passive films formed on DSS depending on the chromate/bromide ratio: pitting corrosion susceptibility highly decreased from a chromate/bromide ratio lower than 0.01.The comparative investigations carried out in LiBr and LiBr + 0.032Li₂CrO₄ verify the assumption that the halide ions facilitate inhibitor adsorption. The addition of halides increased inhibition efficiency to a considerable extent. Passive film becomes more resistant when bromide concentration increases, although film thickness decreases.     

The corrosion inhibitory property of N,N‐bis(2‐benzimidazolylmethyl)amine for Q235 steel

The main purpose of this paper is to systematically evaluate the anti‐corrosion property of N,N‐bis(2‐benzimidazolylmethyl)amine (IDB), which is a novel good thermal stabilized inhibitor in acidic medium. Results obtained from electrochemical tests and corrosion surface morphology analyses reveal that IDB performs excellently as corrosion inhibitor for Q235 steel in 1 mol/L hydrochloric acid corrosive solution. Potentiodynamic polarization measurements show that IDB inhibits both the anodic and cathodic processes of corrosion and exhibits as a mixed‐type inhibitor. Besides, the inhibiting efficiency (IE%) and consequently the degree of surface coverage (θ) increase with the inhibitor concentration rising. And when the concentration is 20 × 10^?5 mol/L, the corrosion inhibition effect is best to reach 96.39%. The adsorption of inhibitor on Q235 steel is found to obey the Langmuir adsorption isotherm, and the calculated Gibbs free energy demonstrates that IDB spontaneously adsorbs and forms a protective chemisorbed film on Q235 steel to restrain its corrosion. Hereby, IDB will become a promising corrosion inhibitor in further.     

一种咪唑烷硫酮衍生物的缓蚀性能

以硫脲、二乙烯三胺和有机羧酸为原料制备一种咪唑烷硫酮衍生物缓蚀剂(CI-R缓蚀剂),采用失重法、极化曲线法、扫描电镜(SEM)观察等方法,研究了缓蚀剂CI-R在85℃、500μg/g HCl+1%NH4Cl(质量分数,下同)溶液中对碳钢的缓蚀作用及其吸附模型。结果表明:缓蚀剂CI-R是一种混合型缓蚀剂,对试验溶液中的碳钢具有良好的缓蚀作用,加入量为20μg/g时,缓蚀率可达90.9%;其在碳钢表面的吸附遵循Langmuir吸附等温式,通过在碳钢表面形成一层致密的保护膜,阻碍腐蚀介质与金属基体的接触,抑制了金属的腐蚀。     

Cerium-tannic acid passivation treatment on galvanized steel

A novel cerium-tannic acid passivation treatment was performed on galvanized steel. The corrosion resistance of cerium-tannic passivated samples was tested by dropping test with 0.5 wt.% CuSO₄ aqueous solution. The mass loss per unit area of passivated samples was measured after the corrosion in 0.5 mol/L NaCl + 0.005 mol/L H₂SO₄ at room temperature for 96 h. The electrochemical behaviors of cerium, tannic acid, and cerium-tannic acid passivated samples on galvanized steel in 0.5 mol/L NaCl solution were investigated by polarization curves and electrochemical impendence spectra. The corrosion equivalent circuit was established according to the impedance characteristics. The results show that cerium-tannic acid treated samples exhibit better corrosion resistance than the sole cerium or tannic acid treated samples under the same condition. The mechanism of synergistic effect for cerium-tannic acid passivation on galvanized steel was discussed.     

Inhibition effect of chromate on the passivation and pitting corrosion of a duplex stainless steel in LiBr solutions using electrochemical techniques

The electrochemical behavior of duplex stainless steel (DSS) in LiBr media was investigated by anodic cyclic polarization curves and AC impedance measurements. The effect of bromide concentration and the presence of chromate in the solutions on the corrosion behavior of AISI 2205 was studied. Cyclic polarization curve analyses showed that there was different pitting susceptibility of passive films depending on the LiBr concentration. Pitting potential decreases with LiBr concentration in a semilogarithmic scale following two different slopes. Chromate presence displaces pitting potentials towards more positive values at low LiBr concentrations but it has no effect when LiBr concentration increases.The comparative analysis carried out in LiBr and LiBr chromate-containing solutions at two different concentrations, 0.016 M and 0.032 M, verifies the assumption that halogen ions facilitate inhibitor adsorption. The addition of halides strongly increased the inhibition efficiency of chromate. The passive film becomes more resistant when bromide concentration increases, although film thickness decreases.     

酸性介质中HR-2不锈钢表面活性的SECM三维图像表征研究

采用扫描电化学显微镜（SECM）,面扫描与线性扫描技术相结合,研究了HR-2不锈钢在0.5 mol/L H₂SO₄+0.1 mol/L NaCl溶液中的腐蚀行为。结果表明：HR-2不锈钢在该溶液中的开路电位、活化电位及钝化区电位分别为：-0.4 V、-0.23 V、0.0 V ~ 0.8 V,基底保持开路电位和活化电位时,探头最大电流为9.5 nA和35.2 nA,基底形成钝化膜后探头电流明显减小;当探头电位为-0.2 V时能有效氧化基底产生的H₂,0.6 V时能有效氧化基底反应产生的Fe₂₊,探头-基底间距为20 μm时,可较好地表征基底活性;当溶液中硫脲浓度为0.75 mmol/L时,有最佳的缓蚀作用。     

Einfluß von Passivierungs- und Kohlenstoffschichten auf austenitischen CrNiMo-Stählen auf die Beständigkeit gegen Lochfraß und Spannungsrißkorrosion

Effects of passivation and carbon films on austenitic CrNiMo steels on their piting and stress corrosion resistance The influence of passive film and combinations of a passivation and a carbon layer on the resistance to pitting and SCC of austenitic CrNiMo steels has been investigated in physiological sodium chloride solution (Tyrode solution) at pH 6.9 to 7.4 at 37 ± 1°C. The passive film was obtained after electrolytic polishing in H₃PO₄ + H₂SO₄ + C₆H₅NHCOCH₃ + oxalic acid + corrosion inhibitor CS by treatment with 40% nitric acid the carbon film was obtained by CVD. Impurities in the steel (non-metallic inclusions) and the different metallic phases were investigated and the chemical composition of the passive film was determined by quantitative analysis. The resistance to pitting of the steel with and without passive film was determined potentiodynamically in Tyrode's solution at 37 ± 1°C. The resistance to SCC was determined in Tyrode's solution at 37 ± 1°C, in neutral glycerole and in boiling magnesium chloride solution at 154 ± 1°C and evaluated in terms of K_σ and K_τ. The corrosion damage was investigated by optical and scanning electron microscopy. The investigations have revealed that the different surface conditions considerably improve the pitting and SCC resistance of the steels in the media used in this work, so that they make possible the use of these materials as surgical implants.