食品级磷酸浓度对国产904L不锈钢耐蚀性的影响

采用动电位极化曲线和电化学阻抗谱(EIS)研究了常温下国产904L不锈钢在不同浓度食品级磷酸中的腐蚀行为,并观察电化学测试后的腐蚀形貌。结果表明,国产904L不锈钢在25%食品级磷酸中具有良好的耐腐蚀性能,随着磷酸浓度的增加,自腐蚀电流密度Jcorr先增加后降低,浓度在40%时Jcorr最大,抗腐蚀性能最差。EIS曲线由高频端容抗弧和低频端Warburg阻抗组成,表明904L的腐蚀由电化学反应控制转为主要由扩散控制。     

铜铁试剂对LY12铝合金的缓蚀作用

采用电化学方法研究了铜铁试剂对LY12铝合金在3．5％NaCl溶液中的缓蚀作用。实验结果表明，铜铁试剂对铝合金具有较好的缓蚀效果，有效地抑制了铝合金在3．5％NaCl溶液中的点腐蚀。在所研究的浓度范围内，随着铜铁试剂浓度的增大，腐蚀电流密度降低，缓蚀效率增加。当铜铁试剂的浓度较高时，铝合金由活性转为钝态，对抑制铝合金的腐蚀反应有很大的影响。交流阻抗（EIS）测试表明，当添加铜铁试剂后铝合金的电化学转移电阻增大了近40倍。     

电化学抛光铜的实验研究

目的提高铜的表面质量,并将铜的去除量控制在适用范围,研究铜电化学抛光的溶液配比和最佳工艺参数。方法使用自行搭建的电化学抛光系统对工件进行电化学抛光,并使用3D表面轮廓仪和精密电子天平测量工件加工前后的表面粗糙度和质量。采用单因素和正交实验结合的方法设计了实验方案,研究了磷酸浓度、电解液温度、电压、占空比、频率和加工时间对铜表面粗糙度的影响,以及添加剂对实验结果的影响。结果得到磷酸浓度和温度对表面粗糙度的影响曲线。通过极差分析得到了电压、占空比、频率和加工时间对表面粗糙度的影响趋势以及最优参数。在溶液中加入抗坏血酸后,材料去除率可以降低到1000 nm/min以下,但表面粗糙度最高达到75 nm。同时加入抗坏血酸和乙烯硫脲后,材料去除率为400 nm/min,表面粗糙度最低达到17 nm。结论电化学抛光铜的最优参数为:电压10 V,占空比23%,频率23 k Hz,加工时间11~14 min,溶液配比为55%磷酸+0.3%抗坏血酸+0.2%乙烯硫脲。抗坏血酸可以有效地控制材料去除率,抗坏血酸与乙烯硫脲同时作用又可以降低铜的表面粗糙度。     

Cl-浓度对2A12铝合金电化学行为的影响

通过干湿周浸试验、扫描电镜观察和电化学阻抗谱(EIS)测试,研究了2A12铝合金在不同质量浓度NaCl溶液中干湿周浸48 h和480 h后带锈样的电化学行为与规律.试验结果表明,干湿周浸48 h后,低浓度NaCl溶液中2A12铝合金的腐蚀过程主要受电荷转移电阻控制;随浓度增加,其电化学特征转变为受电荷转移电阻和Warb...     

纯镁在1.0%NaCl中性溶液中的腐蚀与电化学行为(英文)

研究纯镁在1.0%NaCl中性溶液中的腐蚀行为及其相应的电化学阻抗谱(EIS)和极化曲线,探讨不同时间段EIS的分形维数。结果表明,腐蚀过程及相应的EIS发展可分为3个阶段。初始阶段,EIS由2个重叠的容抗弧组成,相应的极化电阻及电荷转移电阻随着时间的延长而快速增加,而腐蚀速率则降低。而后,EIS图谱上出现2个容易辨认的容抗弧,电荷转移电阻及腐蚀速率基本保持稳定。长时间浸泡后,EIS图谱中低频部分出现感抗成分,电荷转移电阻降低,而腐蚀速率增加。EIS分形维数与材料表面形貌直接相关,将是分析腐蚀形貌极有用的工具。     

弱碱性抛光液中铜化学机械抛光的电化学行为

在弱碱性介质里以铁氰化钾为钝化剂,对铜化学机械抛光技术（CMP）过程中的电化学行为进行了在线测试,考察了铜在无铁氰化钾存在下的极化行为及铁氰化钾浓度对腐蚀电位的影响,研究了在不同压力下铜抛光前后的腐蚀电位（φE）和腐蚀电流密度（JC）的变化规律,比较了抛光前及抛光过程中铜极化曲线的变化。定性地通过成膜的快慢及抛光过程中腐蚀电流密度的大小来说明抛光速率的高低,证明了以弱碱性溶液为介质,铁氰化钾为成膜剂,纳米γ-Al2O3为磨粒的CMP配方的可行性。     

利用电化学阻抗谱研究铜颗粒尺寸对铜/低密度聚乙烯复合材料在模拟宫腔液中腐蚀的影响

用电化学阻抗谱技术(electrochemical impedance spectroscopy,EIS),研究了铜/低密度聚乙烯(Cu/LDPE)复合材料在模拟宫腔液中的腐蚀行为,根据EIS特征建立等效电路模型并进行数据拟合分析,获得了复合材料及其表层对应的界面电化学信息参数,如双电层电容、电荷转移电阻、Warburg阻抗等,通过比较两种材料表层状态随时间的变化,探讨了复合材料中铜颗粒尺寸对复合材料腐蚀的影响.结果表明,纳米复合材料比微米复合材料的腐蚀速率低,且材料表层不易沉积腐蚀产物,更适合作为新型宫内节育器材料.     

铝合金防护涂层老化动力学研究

在紫外/盐雾加速综合环境条件下,研究了铝合金试样上聚酰胺清漆老化过程。采用环境扫描电子显微镜观察了防护涂层表面形貌的变化,采用电化学阻抗(EIS)分析了涂层的老化过程,同时还测量了光泽度、颜色、表面电阻和体积电阻在涂层老化过程中的变化。结果表明：在涂层老化过程中,涂层孔隙率增加,而体积电阻、表面电阻则降低, EIS给出了在涂层老化的不同阶段的特征。采用光泽度、颜色、表面电阻和体积电阻以及电化学阻抗数据作为性能参数,建立了涂层老化动力学方程,并给出了涂层失效判据,并对涂层老化动力学的参数进行了讨论,认为采用体积电阻或低频阻抗模值作为性能参数描述涂层老化动力学过程更为合理。     

Cl~-浓度渐变的混凝土孔隙液中钢筋的腐蚀过程

采用EIS和线性极化曲线技术研究了供货状态和打磨后的钢筋样品在模拟孔隙液中Cl-浓度渐变条件下的腐蚀行为。采用SEM结合EDS和XRD对钢筋表面形貌和组成结构进行了分析。结果表明:在Cl-浓度逐渐增加的孔隙液中,钢筋表面的电化学行为基本可分为3个过程,即钝化膜形成或修复过程、Cl-侵蚀过程和Ca沉积过程。供货状态钢筋比打磨后的钢筋样品更容易发生腐蚀。结合电极的腐蚀电位、腐蚀电流和电化学阻抗等参数随Cl-浓度的变化,讨论了混凝土中钢筋腐蚀发生、发展各阶段的腐蚀电化学过程的变化规律。     

腐蚀电化学测量中溶液电阻的补偿

从测量仪器、测量方法、测量范围区间以及测量结果的数值修正等几方面介绍了在腐蚀电化学测量中如何消除工作电极与鲁金毛细管间溶液电阻的影响,在实际测试过程中应该根据实际情况来选择合适的方法。在进行数值修正的时候要注意:不论是利用等距离法计算的结果还是利用EIS测量的结果,总是有一定的适用范围,特别是在强极化区,其溶液电阻由于溶液中离子运动速度的增加以及电极表面附近离子浓度的变化而减小。因而利用EIS结果及等距离法计算出的溶液电阻Rsol在相应的电位范围内是适用的,而不能将其推广到整个极化测量区间,否则将会引起较大的误差。     

咪唑对钌化学机械抛光的影响

利用自制的抛光液,研究了在磷酸体系抛光液中咪唑(imidazole,C3H4N2)浓度和pH值对钌的抛光速率的影响。采用电化学分析方法和X射线光电子能谱仪(XPS)分析了缓蚀剂咪唑对腐蚀效果的影响;采用原子力显微镜(AFM)观察钌片表面的微观形貌。试验结果表明:金属钌在未加入咪唑的磷酸体系抛光液中,抛光速率最高为6.2nm/min,平均粗糙度(Ra)为10.7nm;而在抛光液中加入咪唑后,钌的抛光速率为3.9nm/min,平均粗糙度(Ra)降至1.0nm。咪唑的加入,虽然降低了金属钌的抛光速率,但提高了金属钌的表面质量。同时也促进了金属钌表面钝化膜的生成,降低了金属钌的腐蚀电流值,抑制了阴极反应。     

The effects of nano-SiO2 additive on the zinc phosphating of carbon steel

In this paper, nano-SiO₂ was used as an accelerator for improving the microstructure and the corrosion resistance of phosphate coating on carbon steel. The chemical composition and microstructure of the coatings were analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The effects of nano-SiO₂ on weight, roughness and corrosion resistance of the phosphate coatings were also investigated. Results show that the compositions of phosphate coating were Zn₃(PO₄)₂·4H₂O (hopeite), and Zn₂Fe(PO₄)₂·4H₂O (phosphophylite). The phosphate coatings became denser due to the addition of nano-SiO₂ which reduced the size of the crystal clusters. The average weight of phosphate coatings approximately linearly increased with the nano-SiO₂ content in the bath from 0 to 4 g/L, and the phosphate coatings formed in bath containing 2 g/L nano-SiO₂ showed the highest corrosion resistance in 5 wt.% sodium chloride solution at ambient temperature. Nano-SiO₂ would be widely utilized as a phosphating additive to replace the traditional nitrite, due to its less pollutant and its better quality of the coating.     

Effects of applied voltage on the microstructure and properties of hydroxyapatite bioceramic coatings formed on Ti7Cu5Sn titanium alloy by micro-arc oxidation

The effects of the applied voltage on the morphology, composition and corrosion behaviour of Ti7Cu5Sn coated were investigated. At applied voltages lower than 250?V, the composite coatings consist of anatase-TiO₂, rutile-TiO₂, DCPD(CaHPO₄·2H₂O) and a small amount of amorphous calcium phosphate phase. When the applied voltage is increased, the ceramic coatings transform from DCPD (CaHPO₄·2H₂O) to HA (Ca₁₀(PO₄)₆(OH)₂, 300?V), and new phases of Ca₂P₂O₇, CaTiO₃ and TCP(Ca₃(PO₄)₂) form at 350?V. The passive current densities at body potential are one order of magnitude lower than that of the uncoated sample, indicating better corrosion resistance. The MAO film is a tri-layer system: a compact inner layer, a mesosphere porous oxide layer, and an outer layer.     

Synergistic inhibition between dodecylamine and potassium iodide on the corrosion of cold rolled steel in 0.1 M phosphoric acid

The corrosion inhibition of cold rolled steel in 0.1 M aerated phosphoric acid (H₃PO₄) in the presence of dodecylamine (DDA) and potassium iodide (KI) has been investigated by Tafel polarization curve and electrochemical impedence spectroscopy (EIS) at 20 °C. The results obtained from polarization curve show that the inhibition efficiency of DDA with and without KI increases with increase in concentration of DDA but the inhibition efficiency of DDA without KI is not too high. A synergistic effect exists when DDA and KI are combined together to prevent cold rolled steel corrosion in 0.1 M H₃PO₄. All impedance spectra in EIS tests exhibit one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. Inhibition efficiencies obtained from Tafel polarization, transfer resistance (R_t) are consistent.     

Electrodeposition of hydroxyapatite coating on CoNiCrMo substrate in dilute solution

In the present work, calcium phosphate coatings on CoNiCrMo substrate were prepared by electrodeposition at different voltages (− 1.4,−1.6,−1.8,−2.0 and − 2.2 V versus Ag/AgCl) in the mixed solution of 0.6 mM Ca(NO₃)₂·4H₂O and 0.36 mM NH₄H₂PO₄ at 80 °C. The electrocrystallization process of the moderate potential (− 1.8 V) was addressed. To investigate the role of pH on HA formation during electrodeposition, different kinds of uncharged substrates (including CoNiCrMo, non-conducting polyethylene, Ti substrate and glass) were placed close to the cathode separately in some of the electrodeposition experiments at − 1.8 V. Moreover, the effect of pH on saturation indexes with respect to hydroxyapatite, octacalcium phosphate and dicalcium dihydrogen phosphate of this dilute solution were calculated by a computer program PHREEQC. The results showed the moderate potential sample (− 1.8 V) exhibited a uniform coating consisted of fine crystallized hydroxyapatite with hexagonal prism shape. It was also found the local pH value plays a crucial role in the formation of HA during the electrodeposition.     

Surface Characteristics and Electrochemical Impedance Investigation of Spark-Anodized Ti-6Al-4V Alloy

In this study, the surface characteristic of oxide films on Ti-6Al-4V alloy formed by an anodic oxidation treatment in H₂SO₄/H₃PO₄ electrolyte at potentials higher than the breakdown voltage was evaluated. Morphology of the surface layers was studied by scanning electron microscope. The results indicated that the diameter of pores and porosity of oxide layer increase by increasing the anodizing voltage. The thickness measurement of the oxide layers showed a linear increase of thickness with increasing the anodizing voltage. The EDS analysis of oxide films formed in H₂SO₄/H₃PO₄ at potentials higher than breakdown voltage demonstrated precipitation of sulfur and phosphor elements from electrolyte into the oxide layer. X-ray diffraction was employed to exhibit the effect of anodizing voltage on the oxide layer structure. Roughness measurements of oxide layer showed that in spark anodizing, the Ra and Rz parameters would increase by increasing the anodizing voltage. The structure and Corrosion properties of oxide layers were studied using electrochemical impedance spectroscopy (EIS) techniques, in 0.9 wt.% NaCl solution. The obtained EIS spectra and their interpretation in terms of an equivalent circuit with the circuit elements indicated that the detailed impedance behavior is affected by three regions of the interface: the space charge region, the inner compact layer, and outer porous layer.     

The effects of niobium and nickel on the corrosion resistance of the zinc phosphate layers

In this investigation the viability of nickel substitution by niobium in zinc phosphate (PZn) baths has been studied. Samples of carbon steel (SAE 1010) were phosphated in two baths, one containing nickel (PZn + Ni) and the other with niobium substituting nickel (PZn + Nb). Potentiodynamic polarization curves (anodic and cathodic, separately) and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of the phosphated carbon steels in a 0.5 mol L^− 1 NaCl electrolyte. The phosphate layers obtained were analysed by X-ray diffraction and it was found that they are composed of Zn₃(PO₄)₂.4H₂O (hopeite) and Zn₂Fe(PO₄)₂.4H₂O (phosphophylite). Surface observation by scanning electron microscopy (SEM) showed that the PZn + Ni layer is deposited as needle-like crystals, whereas the PZn + Nb layer shows a granular morphology. The electrochemical results showed that the PZn + Nb coating was more effective in the corrosion protection of the carbon steel substrate than the PZn + Ni layer. The results also suggested that nickel can be replaced by niobium in zinc phosphate baths with advantageous corrosion properties of the layer formed.     

Influence of NaCl on dechromization of Cu-Cr-Al alloy in H_3PO_4 solution

The dechromization of Cu-Cr-Al alloys was investigated by a static immersing corrosion test. The influence of NaCl on the dechromization was analyzed by electrochemical test, scanning electron microscopy, optical microscopy and X-ray fluorescence spectroscopy. The results show that the dechromization of Cu-Cr-Al alloys will take place in a H3PO4 solution of 11.32 mol/L at 55 ℃. And the corrosion process occurs initially at the interface between Cu and Cr phase, and then extends inward Cr-phase inside. The addition of NaCl into H3PO4 solutions can shorten the dechromization incubation time, decrease the dechromization temperature and concentration of H3PO4 solution, and increase the tendency of dechromization. But, the NaCl scarcely has an effect on the form and structure of chromium depleted-layer.     

Influence of Cu and Sn content in the corrosion of AISI 304 and 316 stainless steels in H2SO4

This paper addresses the influence of Cu and Sn addition on the corrosion resistance of AISI 304 and 316 stainless steels in 30 wt% H₂SO₄ at 25 and 50 °C. The corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The corrosion products were analysed by SEM, X-ray mapping and XPS before and after accelerated tests. The behaviour of both AISI 304 and 316 stainless steels in sulphuric acid solution was greatly improved by increasing Cu concentration and the synergic effect of Cu and Sn. Addition of Sn increased corrosion resistance, but less than addition of copper.     

Corrosion properties ofAZ31 magnesium alloy and protective effects of chemical conversion layers and anodized-coatings

The corrosion properties of AZ31 magnesium alloys were studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy（E1S） techniques, meanwhile, the protective properties of two environmentally protective types of chemical conversion layers and anodized coatings of AZ31 magnesium alloys were also discussed. The component of chemical conversion bath is NaH2PO4·12H2O 20 g/L, H3PO4 7.4 mL/L, NaNO2 3 g/L, Zn（NO3）2·6H2O 5 g/L and NaF 1 g/L, and components of the anodization bath is Na2SiO3 60 g/L, C6H5Na3O7·2H2O 50 g/L, KOH 100 g/L and Na2B4O7·2H2O 20 g/L. The results show that the corrosion resistance of AZ31 magnesium increases with the increase of pH value of the corrosive medium. For the chemical conversion layer acquired at 80 ℃, 10 min is the best processing time and the charge transfer resistance of the chemical conversion layer is enhanced nearly by 10 times. The optimum processing time for the anodization of AZ31 is 60 min, the charge transfer resistance value of the anodized sample at the early immersion stage is nearly 26 times of that of the blank sample and the corrosion type of the anodized samples is pitting.