Eis and XPS study of surface modification of 316LVM stainless steel after passivation

The effects of surface finish, nitric acid passivation and ageing in air on corrosion resistance of 316LVM stainless steel in 0.5% H₂SO₄ have been investigated by EIS, potentiodynamic polarization measurements and XPS. The results indicate that a smoother surface exhibits to a higher corrosion resistance. The effectiveness of the passivation treatment strongly depends on nitric acid concentration, passivation time and temperature. The passivation treatment significantly increases the corrosion resistance due to a high Cr content in the passive film and increased film thickness. Ageing after passivation increases the corrosion resistance whereas ageing before passivation has little effect.     

HCO3–对超级13Cr马氏体不锈钢钝化行为及点蚀行为的影响

目的研究在0.1 mol/L NaCl硼酸缓冲溶液中,研究HCO_3~–对超级13Cr马氏体不锈钢的钝化及点蚀行为的影响。方法采用动电位极化、恒电位极化、Mott-Schottky曲线、电化学阻抗谱等电化学测试手段,并结合3D超景深显微镜进行点蚀形貌观察,研究超级13Cr马氏体不锈钢的电化学腐蚀行为。结果随着HCO_3~–浓度的增加,超级13Cr的钝化区间变宽,点蚀电位向正向移动,稳态点蚀发生的敏感性降低。HCO_3~–减少了超级13Cr亚稳态点蚀数量,降低了亚稳态点蚀电流密度峰值的平均值。随着HCO_3~–浓度的增大,超级13Cr钝化膜电阻Rf升高,电荷转移电阻Rct升高,钝化膜电容Cf逐渐减小。HCO_3~–使得超级13Cr钝化膜半导体特性由n型转变为n+p型双极性,且随着溶液中HCO_3~–浓度的增大,钝化膜中的施主密度ND和受主密度NA减小。结论 HCO_3~–的加入使得超级13Cr不锈钢钝化膜厚度增大,钝化膜内点缺陷密度降低,对基体的保护作用增强,抑制了超级13Cr的亚稳态和稳态点蚀发生。     

304不锈钢环保型酸洗钝化工艺及其性能研究

采用化学浸泡法和动电位扫描法研究了304不锈钢在环保型酸洗钝化工艺下所得钝化膜的耐点蚀性能,运用X射线光电子能谱(XPS)分析了钝化膜的组成和结构.结果表明:由正交试验优选出的最优配方和工艺可大大提高304不锈钢表面钝化膜的耐点蚀性能;304不锈钢表面钝化膜中的Cr、Fe、Ni分别以Cr2O3、FeO、NiO的形式存在;钝化处理后,试片表面钝化膜中的铬元素和镍元素的含量明显增加.综合考虑,不锈钢柠檬酸钝化的最佳工艺为:柠檬酸质量分数4%,氧化剂X体积分数5%,乙醇体积分数2.5%,温度40℃,钝化时间60min.     

2205和316L不锈钢在氢氟酸中的电化学腐蚀行为

通过动电位极化和电化学阻抗方法考察了2205双相不锈钢和316L不锈钢在5%(体积分数)HF溶液中的电化学行为,借助Mott-Schokkty曲线分析了两种不锈钢表面钝化膜的半导体特性。结果表明：两种不锈钢在氢氟酸溶液中都能发生钝化,且2205双相不锈钢的钝化区间范围更宽,维钝电流密度更低。2205双相不锈钢表面钝化膜表现出更高的钝化膜电阻和电荷转移电阻,其抗氢氟酸腐蚀性能优于316L不锈钢,这主要与2205双相不锈钢中的Mo和Cr含量高、表面钝化膜缺陷少、钝化膜易修复等因素有关。     

γ_N相在硼酸缓冲溶液中的腐蚀与钝化性能

采用等离子体源渗氮技术在304L奥氏体不锈钢表面制备高氮面心结构的γ_N相层,利用阳极极化曲线和电化学阻抗谱(EIS)研究γ_N相在pH=8.4硼酸缓冲溶液中的腐蚀行为。结果表明:γ_N相的阳极极化曲线呈现出自钝化-过钝化溶解过程,自腐蚀电位Ecorr较原始不锈钢提高了75mV,维钝电流密度Jp降低近一个数量级,耐蚀性能明显提高。与原始不锈钢钝化膜相比,γ_N相钝化膜的EIS容抗弧直径及|Z|值增大,相位角平台变宽,其电荷转移电阻Rct增至1.064×107Ω·cm2,双电层电容Cdl降至65.4μF/cm2,说明γ_N相钝化膜更致密,表现为近电容特性。随着浸泡时间增加,γ_N相钝化膜的Rct稳定在107Ω·cm2量级,具有良好的稳定性。     

变形量对 690 合金在核电一回路水环境中电化学腐蚀行为的影响

目的研究变形量对690合金电化学行为的影响。方法采用动电位极化、电化学阻抗和高温高压浸泡实验,结合扫描电子显微镜(SEM)、X射线光谱仪(EDX)和X射线光电子能谱(XPS),研究不同变形量的690合金传热管在核电模拟液中的腐蚀行为。结果在常温常压下,50%变形量试样的自腐蚀电位比25%变形量试样正140 m V,维钝电流密度显著降低,阻抗模值高出约10倍。高温高压下浸泡后,XPS分析显示,50%变形量试样表面腐蚀产物膜中的Cr2O3含量远高于25%变形量试样,其富Cr内层致密,氧化层更厚。结论 50%变形量的690合金表面形成的钝化膜及腐蚀产物膜对基体的保护作用更强。     

Passivation Behavior of 2507 Super Duplex Stainless Steel in Hot Concentrated Seawater: Influence of Temperature and Seawater Concentration

The electrochemical behavior and passivation properties of 2507 super duplex stainless steel (SDSS) in the hot concentrated seawater with different concentrations at different temperatures are characterized by electrochemical methods and X-ray photoelectron spectroscopy. The passive film formed on 2507 SDSS belongs to n-type semiconductor and mainly composed of hydroxides and oxides of Fe and Cr under all circumstances. The protectiveness of the passive film decreases with the increase in temperature mainly because of the increase in defect density in the passive film. The corrosion resistance of 2507 decreases with the increase in seawater concentration, and the critical pitting temperature also decreases.     

Enhancements of Passive Film and Pitting Resistance in Chloride Solution for 316LX Austenitic Stainless Steel After Sn Alloying

In the present work, the electrochemical behavior and properties of the passive film of a new Sn-alloyed 316 LX austenitic stainless steel were investigated. With the increase in Sn content in 316 LX austenitic stainless steel from 0 to 0.21%, the critical pitting temperature value increased from 32.6 to 38.8 °C, and the pitting potential increased from 0.252 V_(SCE) to 0.317 V_(SCE). Electrochemical impedance spectroscopy results showed that the corrosion resistance of passive film rose with the increase in Sn content, indicating a more stable passive film. The Mott–Schottky measurement revealed an n-type passive film with a decreased carrier concentration on the 316 LX austenitic stainless steel surface. The Cr, Sn~(2+) and Sn~(4+)(SnO, SnOHCl or SnO_2) enrichments were observed in the passive layer by X-ray photoelectron spectroscopy. The enrichment of Sn and Cr in the passive film can account for the enhanced pitting resistance of 316 LX austenitic stainless steel in chloride solution.     

不锈钢盐酸露点腐蚀行为的原位研究

利用一种新型的露点腐蚀模拟装置结合原位的电化学阻抗谱,电化学噪声等测试手段评价了304和316L两种不锈钢的盐酸露点腐蚀行为.结果表明,316L不锈钢表现出更优异的耐盐酸露点腐蚀性能,主要原因可归结为两点:一是316L不锈钢钝化膜中含有较高的Cr/(Cr+Fe) 比以及较低含量的Fe;二是316L不锈钢钝化膜中含有能改善抗点蚀性能的Mo.     

不锈钢载波钝化参数对钝化膜层耐蚀性的影响

运用电化学交流阻抗谱、原子力显微镜研究了在不同的载波钝化参数下形成的不锈钢钝化膜的耐蚀性,测定了极化电阻值Rp和相应的钝化膜的表面形貌。结果表明：载波钝化条件参数对膜层的耐蚀性有较大的影响,各参数(频率、占空比、高电位、低电位)的变化使得电极表面钝化膜的形貌发生很大的变化,从而影响到膜层的耐蚀性。     

Influence of pH on the passivation behavior of 254SMO stainless steel in 3.5% NaCl solution

The potentiodynamic polarization measurement of 254SMO stainless steel (UNS 31254) was conducted in 3.5% NaCl solutions with pH ranging from 0.1 to 5. The results indicated that this stainless steel offered excellent pitting corrosion resistance in corrosive environments. Further, it also exhibited various features on the polarization curves in different pH solutions. The electrochemical constant-potential passivation treatment performed at different pH followed by XPS analysis revealed that the primary constituents of the outermost layer of the passive films formed in the weak (pH 5) and strong (pH 0.8) acid solutions are iron oxides and Cr₂O₃ and Cr(OH)₃, respectively. Molybdenum oxides, primarily in the six-valence state, existed in the outermost layer of the passive film. Only very weak signals corresponding to that of nickel oxides were detected in the film formed in the weak acid (pH 5) solution. The ICP-MS analyses indicated selective dissolution of a significant amount of Fe and a few Mo and Ni ions during the passivation treatment in the strong acid (pH 0.8) solution. No Cr dissolution was observed; this indicated that the Cr in the film is relatively stable. XPS depth profiling results showed that a similar bilayer-structured film was formed in both the solutions (pH 0.8 and 5); the outer layer of this film is primarily composed of Cr(OH)₃ and Mo(VI), and the inner layer, Cr₂O₃ and Mo(IV). The results of the examinations of passive film formations and dissolution by XPS and ICP-MS were consistent with the polarization curves.     

喷丸和盐酸酸洗对2205双相不锈钢热轧板氧化层微观结构的影响

利用光学显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)配合能谱仪(EDS)和X射线光电子能谱(XPS)研究了 2205双相不锈钢热轧板经过退火和喷丸处理后的氧化层组成和结构,并分析了盐酸及混酸(HNO₃+HF)酸洗后表面钝化膜微观组织结构,利用电化学测试手段分析了酸洗后钢的耐蚀性,进一步提出了热轧退火2205双相不锈钢板在喷丸和酸洗过程中氧化层去除演变模型。结果表明:喷丸处理对于2205双相不锈钢表层富Fe氧化物的去除效果明显,但是不能去除内层致密的富Cr氧化层。盐酸预酸洗由外向内可以进一步去除喷丸后致密氧化层,硝酸和氢氟酸终酸洗可去除退火产生的贫Cr层,使得钢表面形成富含Cr₂O₃的钝化膜。2205双相不锈钢经混酸终酸洗后表现出比盐酸预酸洗后更高的自腐蚀电位和更大的容抗弧半径,说明混酸酸洗有利于提高2205双相不锈钢的耐蚀性能。     

The passivation behaviour of copper-containing high-performance ferritic stainless steels in the cathode environment of polymer electrolyte membrane fuel cells

The passivation behaviour of copper-containing high-performance ferritic stainless steels in the cathode environment of polymer electrolyte membrane fuel cells was investigated using electrochemical tests and XPS surface analyses. The addition of copper to the alloy deteriorated the corrosion resistance at a passive region of 0.6 V_SCE. With an increase of the copper content, the passivity of the alloy degraded due to an increase of the formation of Cr-containing inclusions, and a decrease of the Cr oxide and hydroxide in the passive film.     

Electrochemical corrosion behavior of LDX 2101® duplex stainless steel in a fluoride-containing environment

The effect of fluoride on the electrochemical corrosion behavior of an LDX 2101® duplex stainless steel (DSS) was studied. Open-circuit potential (E_OC) and electrochemical impedance spectroscopy (EIS) measurements were carried out in artificial saliva and with the addition of fluoride (1 wt% NaF). The electrochemical corrosion behavior of the AISI 316L austenitic stainless steel (SS) was also evaluated for comparison. Both open-circuit potential and EIS results indicate that DSS and austenitic SS undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the simulated aggressive environments. However, LDX 2101® exhibits superior corrosion resistance as compared with AISI 316L, and this improvement is ascribed to the formation of a passive film which shows a higher protective effect than the one formed on AISI 316L.     

Fe-Cr-Mo系铁素体不锈钢在中性氯离子介质中钝化膜及其破坏的XPS研究

为探讨合金元素铬和钼改善高纯度铁素体不锈钢点蚀性能的作用机理,应用XPS定量分析技术,研究了三个系列十二种不同铬钼含量的高纯度铁素体不锈钢在中性(pH=6.9)含1NCl~-的介质中不同电位下钝化膜及膜下过渡层的组成和钝化膜的厚度等。结果表明,合金元素钼不仅能提高钝化膜的稳定性,还能有效地抑制过渡层中铬的贫化,使再钝化能力得到改善,从而提高材料的耐点蚀性能。在本实验条件下不发生点蚀的材料,其过渡层都是由于基体含钼而不出现贫铬现象。     

Effect of Co and W on the corrosion behaviour of 1% Cr steel in flowing synthetic seawater

The aqueous corrosion characteristics of 1% Cr‐steel alloyed with small amounts of Co and W in synthetic seawater was studied by using immersion weight‐loss tests, electrochemical corrosion tests (potentiodynamic tests and electrochemical impedance spectroscopy (EIS) measurements) and analytical techniques. 1% Cr steels containing Co or W from 0.2 to 0.4 wt.% showed higher corrosion resistance than the 1% Cr steel in the immersion and potentiodynamic tests. EIS measurements showed that the Nyquist plot presented one time constant. Furthermore, the Co‐ and W‐bearing steels present higher R_p values than the 1% Cr steel through all the test period. The better corrosion resistance of the Co‐and W‐bearing steels is attributed to the protectiveness of the surface layer. The corrosion products were examined using electron probe microanalysis (EPMA) and X‐ray photoelectron spectroscopy (XPS). The results of EPMA indicated that Cr was concentrated in the inner region of the rust layer, while Co and W were distributed all over the rust layer. XPS results showed that Co existed as a trivalent oxide in the rust layer and W in the rust appeared in the form of a WO₄ compound. These compounds act as a factor for corrosion resistance in aqueous solutions.     

无铬复合钝化膜的微观组织结构及耐腐蚀性能

目的解决热镀锌钢板表面六价铬钝化工艺所产生的环境污染问题。方法以钼酸铵、纳米硅溶胶、单宁酸、硅烷偶联剂KH151和KH792为主要原料配制新型环保的无铬复合钝化液,在镀锌板表面制备钝化膜。采用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线光电子能谱仪(XPS)分析无铬复合钝化膜表面的微观形貌、元素组成和化学成分,用电化学工作站测试Mo元素对镀锌板耐蚀性的影响,使用中性盐雾实验研究不同皮模量时膜层的耐蚀性。结果无铬复合钝化膜中的Mo元素可以抑制微裂纹的产生和发展,阻挡腐蚀性介质向金属基体扩散,提高复合硅烷膜的电阻。复合钝化膜的电化学交流阻抗比硅烷钝化膜提高了1.6倍,与六价铬钝化膜接近,可以有效抑制腐蚀电化学反应的发生,降低反应速度,提高膜层的耐蚀性。皮膜量为892 mg/m2时,膜层的腐蚀面积为0,耐蚀性达到六价铬钝化膜水平;皮膜量为1252 mg/m2时,耐蚀性能优异。结论制备的无铬复合钝化膜结合了硅烷钝化膜和钼酸盐钝化膜两方面的优点,提高了膜层的致密性和结合性,膜层耐腐蚀性接近/达到了六价铬钝化的效果。     

Improvement on the pitting corrosion resistance of 304 stainless steel via duplex passivation treatment

A remarkable improvement in the pitting corrosion resistance of 304 stainless steel was attempted using a novel duplex passivation treatment method. First, chemical passivation in nitric acid followed electrochemical passivation via potential polarization of step cycling in sodium nitrate electrolyte. Compared with traditional chemical passivation, breakdown potential was increased from 0.31 V_SCE to positive than 0.9 V_SCE at 70°C in a solution bearing 0.6 M [Cl^?] concentration. The critical pitting temperature was enhanced from 21.5°C to above 70°C in a solution with 6 M [Cl^?] concentration. Impedance analysis and X‐ray photoelectron spectroscopy results show that a more compact passive film with a higher ratio of chromium oxide on iron oxide was achieved by electrochemical passivation compared with chemical passivation. Morphology observation suggested that the potential polarization of step cycling slightly increased the dissolution of inclusions after being subjected to chemical passivation. The probable reason for the improvement on pitting resistance is discussed in detail based on inclusion dissolution and the protectiveness in passive film.     

等离子体改性1Cr18Ni9Ti不锈钢钝化膜的耐蚀性

等离子体改性１Ｃｒ１８Ｎｉ９Ｔｉ不锈钢钝化膜的耐蚀性雷明凯，袁力江，孔常静，张仲麟（大连理工大学大连１１６０２４）电子回族共振（ＥＣＲ）微波等离子体具有高电子密度和离化率，低放电粒子溅射率及无极放电设计等优点［１－２］，为金属钝化膜的改性提供了有效和...     

XPS analysis of the passive film formed on austenitic stainless steel coated with conductive polymer

Improvement of the passivation behavior of Type 304 austenitic stainless steel (SS) by coating with conductive polymers (CPs), like polyaniline (PANI) and poly(o-phenylenediamine) (PoPD), followed by exposure in an acid solution has been demonstrated. The passive films formed on SSs (after peeling off the polymer layer) are compared with those formed during anodic polarization under the same exposure condition. The passive films beneath the CPs are thicker and less hydrated than those formed on uncoated stainless steel. The polymer layer enhances the enrichment of chromium and nickel in the entire passive oxide, forming a more protective film than that formed during anodic polarization. The elemental distribution within the passive film is different in the two modes of passivation. The type of the polymer influences on the composition of the passive film. The best passivation is obtained by PoPD, with the passive film resulting in significant resistance of the SS to pitting corrosion in the 3% NaCl solution. The oxide film of this steel is characterized, in its inner and outer layers, by the highest ratio of Cr(OH)₃/Cr₂O₃ and the lowest content of iron species.