Investigation on carbon dioxide corrosion behaviour of HP13Cr110 stainless steel in simulated stratum water

The carbon dioxide corrosion behaviour of HP13Cr110 stainless steel in simulated stratum water is studied by potentiodynamic curve and electrochemical impedance spectroscopy (EIS); the micro-structure and composition of the corrosion scale formed at high-temperature and high-pressure are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that 13Cr stainless steel is in passive state in the stratum water, the passive current density increases and the passive potential region decreases with increasing temperature. The corrosion scale formed at high-temperature and high-pressure is mainly composed of iron/chromium oxides and a little amount of FeCO₃.     

Enhanced corrosion resistance of interstitially hardened stainless steel: Implications of a critical passive layer thickness for breakdown

Immense interstitial hardening of 316L austenitic stainless steel via low-temperature paraequilibrium carburization also leads to greatly improved corrosion resistance. Both the hardening and the improved corrosion resistance owe their origin to a “colossal” supersaturation of interstitial carbon. The corrosion resistance of stainless steel involves a Cr₂O₃-rich passive film, and the composition and thickness of the passive film developed during anodic polarization at various potentials were determined for both carburized and non-treated steels using grazing incidence X-ray photoelectron spectroscopy. Passive oxide film breakdown is a necessary step in pitting corrosion, and appears to occur in these steels at a critical film thickness of ≈3 nm. We suggest that this breakdown is of chemomechanical origin. Long wavelength thickness perturbations occur during film growth to reduce the strain energy density in the passive film arising from intrinsic and electric field-induced stresses. At the critical thickness, the localized thinning is sufficient to lead to dielectric breakdown and nucleation of pitting corrosion. The improved corrosion resistance for the carburized material results from thinner passive films at a given potential and hence a delay in the detrimental effect of the thickness perturbations.     

Effect of surface oxide properties on corrosion resistance of 316L stainless steel for biomedical applications

Surface passivation is a promising technique for improving the corrosion resistance both in vitro and in vivo as well as the biocompatibility of 316L stainless steel. In this work, we studied the effect of different passivative processes on the in vitro corrosion resistance of 316L stainless steel wire. Characterization techniques such as anodic polarization test, scanning electron microscopy, auger electron spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy were employed to co-relate the corrosion behavior to various surface characteristics and surface treatments. Results showed that all of these surface treatments did not improve the corrosion resistance of the alloy satisfactorily except amorphous oxidation. This improvement is attributed to the removal of plastically deformed native air-formed oxide layer and the replacement of a newly grown, more uniform and compact one which is composed of nano-scale oxide particles with higher oxygen and chromium concentrations. The properties of surface oxide layer, rather than its thickness, seem to be the predominant factor to explain the improvement of in vitro corrosion resistance.     

Effects of nitrogen on the passivity of Fe-20Cr alloy

Influences of nitrogen on the passivity of Fe-20Cr-(0, 1.1)N alloys were examined by in situ electrochemical techniques. Nitrogen was incorporated in the form of (Fe, Cr)-nitrides in the passive film, and Cr was enriched in the film of the alloy with nitrogen. Photocurrent analysis demonstrated that the structure of passive film formed on Fe-20Cr-1.1N alloy is Cr-substituted γ-Fe₂O₃ with (Fe, Cr)-nitrides. Mott-Schottky analysis revealed that the film formed on Fe-20Cr-1.1N contained higher Cr⁶⁺ and lower Cr³⁺ vacancy concentrations compared with that on Fe-20Cr alloy. All of these results were associated with the enhanced protectiveness of the film on Fe-20Cr-1.1N.     

XPS analysis of manganese in stainless steel passive films on 1.4432 and the lean duplex 1.4162

Passive films were compared on two stainless steels: the recent lean duplex EN 1.4162 and EN 1.4432 (316L). For alloys with significant amount of manganese and nickel, the Mn 2p_3/2 peak will overlap with the Ni-LMM. To resolve this overlap, Ni 2p_3/2 to Ni-LMM intensity ratios were recorded on 1.4432, compensated for overlayer thickness, and then used to fix the Ni-LMM intensities in the Mn 2p spectra on the duplex material. Manganese was found in oxidation states II and V/VI; its film content was not dependent on the bulk composition.     

Effects of alloy and solution chemistry on the fracture of passive films on austenitic stainless steel

The Taguchi analysis method was used to simultaneously study the effects of alloy chemistry, pH, and halide ion concentrations on the fracture of electrochemically grown passive films using a nanoindentation technique. Three austenitic stainless steels, 304L, 316L, and 904L were potentiostatically polarized in hydrochloric acid solutions. The fracture load was dominated primarily by alloy chemistry. Passive films mechanically weaken as the atomic iron concentration increases in the film. Prolonged anodic ageing time increases the fracture load of passive films.     

Repassivation behaviour and surface analysis of Fe3Al based iron aluminide in 0.25 M H2SO4

The repassivation kinetics of iron aluminide having a composition of Fe-16Al-0.14C (wt.%) were investigated in 0.25 M H₂SO₄ along with pure Al and Fe using a rapid scratched electrode technique. The repassivation behaviour of iron aluminide demonstrated was faster compared with Al, whereas the repassivation behaviour of Fe was slower than Al despite having a lower passive current density than Al. The repassivation behaviour was analyzed in terms of current density [i/t] as a function of charge density [q/t] that flowed from the scratched surface based on high-field ion conduction model and surface chemistry of the passive film. A mechanistic model is presented to explain the passivation/repassivation behaviour of iron aluminide based on the new findings.     

Carbon tetrafluoride plasma modification of polyimide: A method of in-situ formed hydrophilic and hydrophobic surfaces

This study demonstrates that carbon tetrafluoride (CF₄) plasma can result in relatively hydrophobic and hydrophilic surfaces formed in-situ on polyimide (PI) films using a mask and controlling the distance of the mask to the substrate. The surface properties of plasma-treated PI films are characterized by contact angle measurement, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Under specific modification conditions, contact angles for hydrophobic and hydrophilic surfaces reach values of 108.3 ± 0.6° and below 5°, respectively. The XPS analyses indicate that the “unshielded” surfaces contained a high proportion of the CF₂-CF₂ group and therefore decreased the wettability of the surface. On the other hand, the “shielded” surface contained hydrophilic groups such as carbonyl or carboxyl with few fluorinated groups, resulting in increased wettability of the surface.     

Sputter deposition and XPS analysis of nickel silicide thin films

Binary component Ni-Si films of different compositions are fabricated on AISI 304L stainless steels by means of ion-beam sputter (IBS) deposition. The compositions of the thin films and the chemical states of elements are analysed by means of X-ray photoelectron spectroscopy (XPS). The phase formation is studied and discussed in view of Pretorius' effective heat of formation (EHF) model. The proportions of the resulting phases can then be deduced. The electronic structure for the various compositions is also qualitatively investigated from the XPS valence band spectra, suggesting the bonding changes from predominating metallic to covalent bonding in Ni-Si systems when Si content increases.     

Effect of varying blends of finished RO, surface and ground waters on solid lead surfaces

PbO, PbCO₃, and Pb₃(OH)₂(CO₃)₂ were identified as primary corrosion products on lead coupons following three months of exposure to finished RO, surface and ground water by XRD and XPS. Based on these results, a Pb₃(OH)₂(CO₃)₂ solid phase equilibrium model was used as a function of water quality, was modified using diffusion theory and accurately predicted lead release for a majority of field observations. SEM photographs revealed sulfate and chloride affected the surface structure of corrosion scales and lead release.     

Surface composition and electrochemical behavior of LiNi1/3Co1/3Mn1/3O2 cathode material with copper additive

LiNi_1/3Co_1/3Mn_1/3O₂（NCM） cathode material containing copper was prepared by co-precipitation method.The material was characterized by X-ray photoelectron spectroscopy（XPS） and galvanostatic cycling.XPS data indicate that surface compositions of the samples containing copper are different from the bare NCM.Copper on surface of particles was enriched,while nickel and lithium content was reduced.The electrochemical performance of NCM was affected by the change of surface compositions.Cycling performance charged to the cutoff voltage of 4.6 V was improved by introducing copper into the material.The effects of copper content on electrochemical behaviors of NCM at 4.5 V were discussed.     

X70管线钢在HCO-3/CO2-3体系中表面膜性能研究

采用动电位扫描和交流阻抗方法研究了X70管线钢在0.5 mol/L Na2CO3+1 mol/L NaHCO3溶液中的阳极极化过程中的电化学行为,通过XPS和SEM对表面膜的组成和形貌进行了分析.结果表明,X70管线钢在阳极极化过程中分别于-600 mV和-350 mV电位处出现2个阳极电流峰;-600 mV时电极表面的反应阻力较小,表面膜主要由FeCO3、Fe2(OH)2CO3和FeOOH等化合物组成,表面膜上存在较多的微孔缺陷,处在一个不稳定状态,表面膜的保护性能较差;-350 mV时电极表面的反应电阻较大, 表面膜主要由铁的氧化物Fe2O3和Fe3O4组成,表面膜具有较好的保护性能.     

用XPS研究钢筋钝化膜和C1~-对钝化膜的影响

采用光电子能谱(XPS)研究钢筋钝化膜的组成与结构,以及氯离子对钝化膜的影响。结果表明,在本实验条件下钢筋钝化膜为双层结构,外层以γ-FeOOH为主,内层主要为FeO;氯离子对胶的破坏过程可能是先在钝化膜表面吸附,然后穿透到膜中,在铁/氧化物界面即膜的内层形成FeCl_2,而使钝化膜局部溶解;复合缓蚀剂的加入使钢筋钝化膜表面γ-FeOOH的含量增大,膜中夹杂一定深度的有机铵盐,硅酸盐只在表面沉积。     

Surface studies of the interaction of cesium hydroxide vapor with 304 stainless steel

The reaction of cesium hydroxide vapor with 304 stainless steel has been studied over the temperature range 550–950°C in an argon atmosphere containing 3% water vapor and 4% hydrogen. A wide range of surface-analytical techniques has been used to identify the corrosion products, including scanning electron microscopy with energy-dispersive analysis of X-rays, X-ray photoelectron spectroscopy, Auger electron spectroscopy, secondary-ion mass spectrometry, and Raman spectroscopy. A nickel-sputter, ion-plating process was also used to separate the surface oxide layer from the underlying material, thus enabling the exposed interfaces to be examined. At 550°C, the cesium is physisorbed onto the iron hydroxide layer at the surface of the metal. At higher temperatures, most of the cesium is found as isolated cations within the inner chromia lattice, with no evidence for the existence of stable cesium-based compounds.     

Cu、Ni元素对耐蚀高锰阻尼钢在大气环境中腐蚀行为的影响

高锰阻尼钢因其高强度、超低屈强比、阻尼性能良好和经济性能优异等特性,在承受较大振动和冲击的桥梁、轨道交通和军工等领域展现出广阔的应用前景。而高锰钢耐蚀性能欠佳一直是限制其快速发展的关键性因素,高锰钢耐蚀性设计及其大气腐蚀行为研究均鲜有报道。为解决高锰钢耐蚀性能欠佳问题,采用真空感应熔炼和两阶段轧制工艺制备 3 种添加不同 Cu、Ni 元素含量的耐蚀高锰阻尼钢,通过大气曝晒试验、电化学测试、SEM、XRD 和 XPS 等方法对试验材料的电化学性能、 腐蚀速率、腐蚀形貌、腐蚀产物物相及结构进行表征及分析。结果表明：相较于单独添加 Cu 元素的高锰阻尼钢,钢中添加 1.2 wt.% Cu 和 1.0 wt.% Ni 元素腐蚀电位正移近 200 mV,腐蚀电流密度降低近 50%;曝晒试验后,较高含量的 Cu 和 Ni 元素协同添加使腐蚀产物中 α-FeOOH 含量明显提高,活性较高的 MnFe₂O₄和 Mn₂O₃含量降低,耐蚀产物 NiOOH 及 CuO 含量增加。腐蚀产物颗粒均匀细小,产物层整体致密光滑,保护性能提高,其腐蚀速率相较于单独添加 Cu 元素的高锰阻尼钢降低 70%,表现出优异的耐蚀性能。所提出的高锰阻尼钢耐蚀性的成分设计方案及耐蚀机理可为未来高锰阻尼钢在桥梁中的应用提供数据支持。     

不同能量沉积方式对薄膜界面反应的影响

通过分子束外延(MBE)和脉冲激光沉积(PLD)将1~10个Fe原子层(ML)以楔型(wedge-shape)方式分别沉积到NiO(001)基片上, 并对其进行磁光克尔效应(MOKE)原位测试。 结果表明： 通过MBE这种低能量沉积方式沉积的Fe原子层在Fe/NiO界面处产生了约2 ML的磁死层; 而通过PLD这种较高能量沉积方式沉积的Fe原子层在Fe/NiO界面处产生了约3 ML的磁死层。 X射线光电子能谱(XPS)研究Fe/NiO界面的结果表明： 两种沉积方式都能使Fe原子与单晶NiO在界面处发生化学反应, 这是导致磁死层的一个重要原因; 对于MBE和PLD沉积方式来说, 从靶材上被蒸发或溅射下来到达基片的原子所具有的能量很低, 分别约为0.1 eV和1.0 eV, 反应层较浅; 磁控溅射沉积Fe原子的能量约为几～十几电子伏特, 导致的反应深度约1.5 nm。