Photocatalytic activity of ferric oxide/titanium dioxide nanocomposite films on stainless steel fabricated by anodization and ion implantation

A simple surface treatment was used to develop photocatalytic activity for stainless steel. AISI 304 stainless steel specimens after anodization were implanted by Ti ions at an extracting voltage of 50 kV with an implantation dose of 3 × 1015 atoms·cm?2 and then annealed in air at 450℃ for 2 h. The morphology was observed by scanning electron microscopy. The microstructure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The photocatalytic degradation of methylene blue solution was carried out under ultraviolet light. The corrosion resistance of the stainless steel was evaluated in NaCl solution (3.5 wt%) by electrochemical polarization curves. It is found that the Ti ions depth profile resembles a Gaussian distribution in the implanted layer. The nanostructured Fe₂O₃/TiO₂ composite film exhibits a remarkable enhancement in photocatalytic activity referenced to the mechanically polished specimen and anodized specimen. Meanwhile, the annealed Ti-implanted specimen remains good corrosion resistance.     

304不锈钢双极板性能研究

以304不锈钢做为研究对象,测定了其在模拟PEMFC环境下的极化曲线,极化时间分别为4h和10h的交流阻抗谱,用伏安法测量了304不锈钢表面氧化膜／钝化膜与碳纸之间的接触电阻。实验结果表明,304不锈钢能够钝化且钝化电流密度低于16μA·cm^-2;随着极化时间增加,不锈钢表面生成的钝化膜的界面极化电阻增加,表面钝化膜有增厚的趋势;经过恒电位极化后,304不锈钢的钝化膜与碳纸的接触电阻显著增加,模拟阴极环境的接触电阻大干模拟阳极环境的接触电阻。     

Conductive and corrosion behaviors of silver-doped carbon-coated stainless steel as PEMFC bipolar plates

Ni–Cr enrichment on stainless steel SS316L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was deposited in situ to prepare a thin continuous Ag-doped carbon film on a porous carbon-coated SS316L substrate. The corrosion resistance of this film in 0.5 mol·L-1 H₂SO₄ solution containing 5 ppm F- at 80℃ was investigated using polarization tests. The results showed that the surface treatment of the SS316L strongly affected the adhesion of the carbon coating to the stainless steel. Compared to the bare SS316L, the Ag-doped carbon-coated SS316L bipolar plate was remarkably more stable in both the anode and cathode environments of proton exchange membrane fuel cell (PEMFC) and the interface contact resistance between the specimen and Toray 060 carbon paper was reduced from 333.0 mΩ·cm2 to 21.6 mΩ·cm2 at a compaction pressure of 1.2 MPa.     

不锈钢材料预应力磨削表面耐蚀性能数值模拟

为探究预应力磨削后表面腐蚀演变机理及磨削参数对不锈钢耐蚀性的影响,以304不锈钢为研究对象,建立了考虑预应力磨削表面形貌特征的不锈钢耐蚀性能数值模型.首先,推导了粗糙表面腐蚀场演变的相场方程.其次,建立了预应力磨削后工件表面形貌模型.最后,搭建了具有非高斯分布磨粒特征的自相关砂轮表面地貌模型,应用所建模型探究了不锈钢材料预应力磨削表面的耐蚀性能.与已有研究结果相对比,所得结论符合一般性规律,验证了所提方法的合理性.结果表明,预应力磨削表面在腐蚀环境中具有“抛光效应”,随着腐蚀时间延长,表面耐蚀性增强;在使用冷却液的工况下,适当增大预应力和砂轮线速度、减小进给速度有利于改善磨削后不锈钢材料加工表面的耐蚀性能;当预应力给定时,仍可通过优化砂轮线速度和进给速度的办法来进一步改善不锈钢工件的耐蚀性能.     

Super304H奥氏体不锈钢的晶间腐蚀性能

采用电化学动电位再活化法(EPR)和电化学阻抗谱(EIS)研究了固溶态和敏化态Super304H奥氏体不锈钢在0.5mol/L H2SO4+0.01mol/L KSCN溶液中的晶间腐蚀性能.EPR结果表明,固溶态与敏化态的Super304H不锈钢均无晶间腐蚀倾向;相对而言,敏化态Super304H不锈钢的晶间腐蚀敏感性高于固溶态不锈钢.电化学阻抗谱结果表明,两种Super304H不锈钢的阻抗谱特征相同,敏化态不锈钢的电荷转移电阻值比固溶态低一个数量级,表明敏化处理后不锈钢抗腐蚀性能下降.     

耐热钢高温抗冲蚀磨损性能试验

通过自行设计的气流喷砂式高温冲蚀磨损试验机对304和310s耐热钢进行了高温冲蚀磨损试验。对比了2种材料的抗冲蚀性能及其磨损机制。比较分析了温度、冲蚀角度和试样表面氧化膜等因素对冲蚀磨损率的影响规律。结果表明:310s钢的耐冲蚀磨损性能优于304钢,试样表面氧化膜在400℃时抑制了磨粒对试样表面的冲蚀,磨粒对试样表面的微切削是2种材料冲蚀磨损质量损失的主要机制。     

氯离子对石油测井仪器用Cr13不锈钢点损伤行为的影响

采用高温高压模拟环境装置和实时动电位极化和交流阻抗技术对石油测井仪器用Cr13不锈钢在模拟井下不同氯离子环境中电极的腐蚀失重和电化学行为进行了研究.实验结果表明,当地层水或者钻井液中氯离子浓度较高时,Cr13不锈钢表面的点损伤难以避免;随着氯离子浓度的升高,Cr13的均匀腐蚀速率增大,试样表面点蚀坑增多;局部氯离子以FeCl2和FeCl3形式吸附是造成钝化膜损伤的主要原因.应尽量减少仪器在含氯离子环境中的停留时间或提高材料等级.     

奥氏体不锈钢再钝化膜的耐腐蚀性能研究

奥氏体不锈钢自发钝化膜非常薄,在一些特定的阴离子环境中容易发生腐蚀而破坏,而且不锈钢仅有金属光泽,颜色过于单调.采用再钝化实验工艺使金属表层生成一层化学转化膜,不仅能提高不锈钢的耐腐蚀性能,还能利用对光的干涉作用使金属表面呈现不同的色彩.本文利用酸性化学着色,把经过再钝化的试样和未经过再钝化的试样浸入FeCl3溶液中进行腐蚀试验,全面腐蚀和点蚀结果均表明,经过再钝化的试样的耐腐蚀性能明显高于未经过再钝化的试样.该工艺具有较好的实用价值.     

铁素体不锈钢在盐酸溶液中的腐蚀过程

利用电化学工作站,结合微观腐蚀形貌分析,研究了铁素体不锈钢在盐酸溶液中的腐蚀过程.结果表明:铁素体不锈钢在盐酸溶液中的腐蚀过程分为3个阶段:表面钝化膜的穿透、腐蚀产物膜的增厚以及阴阳极反应平衡.不锈钢在表面钝化膜的穿透和腐蚀产物膜的增厚阶段仅发生均匀腐蚀,而在反应平衡阶段不锈钢表面出现大量的晶间腐蚀和少量的点蚀.当盐酸质量分数大于10%时,铁素体不锈钢在盐酸溶液中的极化曲线钝化区完全消失,其腐蚀过程主要受阳极控制.随着盐酸质量分数的增大,溶液电阻Rs和电极反应的电荷转移电阻Rt均逐渐减小,同时腐蚀电极表面双电层结构中的充放电能力不发生改变.     

非金属离子对S31603不锈钢表面锈蚀的影响

S31603不锈钢具有优异的耐腐蚀性能,广泛应用于化工、沿海设施等领域。在使用过程中,长期经历内部应力、苛刻环境的腐蚀作用。其中,水溶液中的离子对S31603不锈钢的耐腐蚀性能有着重要影响。通过分析锈蚀S31603不锈钢的微观形貌、元素组成及化学状态等,研究非金属离子对其表面锈蚀的影响。结果表明,NO³⁻、NO²⁻、SO₄²⁻对S31603不锈钢锈蚀起关键作用,Cl^-起辅助作用,且锈蚀主要发生在S31603不锈钢与水溶液长期接触的界面。通过对锈蚀表面进行物质鉴定,发现锈蚀表面含有Fe₂(SO₄)₃、FeSO₄、CrO₂等多种化合物。     

Corrosion behavior and characteristics of the product film of API X100 steel in acidic simulated soil solution

The short-term corrosion behavior of API X100 steel in an acidic simulated soil was investigated by electrochemical measurements and soaking experiments, followed by corrosion morphology observations and X-ray photoelectron spectroscopy analyses. The results show that X100 steel exhibits an obvious pitting susceptibility in an acidic soil environment. Pits nucleate after approximately 10 h of immersion. Along with the nucleation and growth of the pits, the charge-transfer resistance and open-circuit potential first increase sharply, then decrease slowly, and eventually reach a steady state. The maxima of the charge-transfer resistance and open-circuit potential are attained at approximately 10 h. The evolution of the electrochemical process is confirmed by the analysis of the product film. The product film exhibits a porous and loose structure and could not protect the substrate well. The product film is primarily composed of ferrous carbonate and ferrous hydroxide (Fe(OH)₂). The concentration of Fe(OH)₂ in the product film increases from the inside to the outside layer.     

Graphite-polypyrrole coated 316L stainless steel as bipolar plates for proton exchange membrane fuel cells

316L stainless steel (SS 316L) is quite attractive as bipolar plates in proton exchange membrane fuel cells (PEMFC). In this study, graphite-polypyrrole was coated on SS 316L by the method of cyclic voltammetry. The surface morphology and chemical composition of the graphite-polypyrrole composite coating were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). A simulated working environment of PEMFC was applied for testing the corrosion properties of graphite-polypyrrole coated SS 316L. The current densities in the simulated PEMFC anode and cathode conditions are around 3×10-9 and 9×10-5 A·cm-2, respectively. In addition, the interfacial contact resistance (ICR) was also investigated. The ICR value of graphite-polypyrrole coated SS 316L is much lower than that of bare SS 316L. Therefore, graphite-polypyrrole coated SS 316L indicates a great potential for the application in PEMFC.     

Passivation method of 317L stainless steel used in medicine

The electrochemical performance of 317L stainless steel used in medicine under different conditions of passivation (different contents of HNO₃ solution, different passivation time and different passivation temperatures) was studied. The results show that the pitting potential of 317L stainless steel used in medicine can reach about 1.0 V (SCE) when electrochemically tested in 0.9% NaCl solution after the steel was passivated in 30% HNO₃ solution at 35℃ for 6 h, which indicates that the passivation film has a relatively strong resistance to corrosion. The results also show that the corrosion resistance of the passivation film on the surface of 317SS can be increased after suitable amount of K₂Cr₂O₇ is added into HNO₃ passivation solution.     

Effect of H2S concentration on the corrosion behavior of pipeline steel under the coexistence of H2S and CO2

The effect of H2S concentration on H2S/CO2 corrosion of API-X60 steel was studied by scanning electron microscopy, a weight-loss method, potentiodynamic polarization tests, and the electrochemical impedance spectroscopy technique. It is found that the cor-rosion process of the steel in an environment where H2S and CO2 coexist at different H2S concentrations is related to the morphological structure and stability of the corrosion product film. With the addition of a small amount of H2S, the size of the anode reaction region is de-creased due to constant adsorption and separation of more FeS sediment or more FeHS＋ions on the surface of the steel. Meanwhile, the dou-ble-layer capacitance is diminished with increasing anion adsorption capacity. Therefore, the corrosion process is inhibited. The general cor-rosion rate of the steel rapidly decreases after the addition of a small amount of H2S under the coexistence of H2S and CO2. With a further increase in H2S concentration, certain parts of the corrosion product film become loose and even fall off. Thus, the protection provided by the corrosion product film worsens, and the corrosion rate tends to increase.     

采用MBDM法获得高性能高分子膜的研究

采用多束动态混合法在３０４不锈钢样品表面成功地制备出ＰＴＦＥ（聚四氟乙烯）和ＰＥＥＫ（聚醚醚酮）混合的高性能高分子复合膜，共结合力约７０Ｎ，耐蚀能力提高２０倍，摩擦系数达到０．０７￣０．１４，比授能吸收剂量在于１０＾６Ｇｙ。     

钝化预处理对316L不锈钢在漂液中电化学腐蚀性能的影响

采用电化学测试、SEM分析等方法,研究了316 L不锈钢在质量分数为30%的浓硝酸溶液及98%硫酸+20 g/L硝酸钾混合液两种钝化剂预处理后的特性,以及在ClO2漂液中的电化学抗腐蚀性能。结果表明,316 L不锈钢在25℃、30%硝酸介质中处理30 min时抗点蚀能力ΔE可达到773 mV,钝化效果较好。EIS图谱表明:316 L不锈钢在ClO2漂液中具有双容抗弧特征,钝化处理容抗弧半径较未钝化的增大,处理后的316 L不锈钢在60℃出现了Warburg阻抗;钝化膜的外层电阻和内层电阻均比未钝化的大。经钝化处理后的316 L不锈钢在ClO2漂液中的受腐蚀速率较未钝化的降低近一半,与钛材相比耐蚀性较差,但能在一定条件下起到减缓腐蚀的作用。     

Investigation of the deterioration of passive films in H<Subscript>2</Subscript>S-containing solutions

The effect of H₂S on the corrosion behavior of 316L stainless steel was investigated using electrochemical methods by changing the gas condition from CO₂ to H₂S and then back to CO₂. The presence of H₂S showed an acceleration effect on the corrosion of 316L stainless steel in comparison with CO₂. The acceleration effect remained even after the complete removal of H₂S by CO₂, indicating that the passive film was irreversibly damaged. X-ray photoelectron spectroscopy (XPS) analysis indicated that the passive film was composed of Cr₂O₃, Fe₂O₃, and FeS₂ after being immersed in H₂S-containing solutions. The semiconducting property of the passive film was then investigated by using the Mott-Schottky approach. The presence of sulfides resulted in higher acceptor and donor densities and thus was responsible for the deterioration of passive films.     

不同生物炭进入土壤后对304不锈钢腐蚀的影响

生物炭在土壤应用过程,不可避免地会对与土壤之间接触的机械设备部分产生腐蚀作用。为探究生物炭应用于农业生产中对机械设备以及金属工具损耗的影响,采用分别在700、400和100℃温度下裂解制备的小麦秸秆生物炭(WB)、水稻秸秆生物炭(RB)和松木生物炭(PB)的生物炭对304不锈钢板材进行腐蚀处理,并测量其极化曲线和电化学阻抗谱和腐蚀表现。结果表明:与空白组(CK)对比,相较于304不锈钢的腐蚀速率,在施入WB的土壤中,腐蚀速率会随着WB裂解温度的增大而增大;而加入RB的土壤会加剧不锈钢的腐蚀,其中在加入400℃RB的土壤中腐蚀速率达到最大;这是因为WB和RB的加入会提升土壤中的Cl~-含量至足以达到点蚀效应的程度加速了不锈钢板材的腐蚀。与此同时,发现100℃制备的PB生物炭可以抑制不锈钢的腐蚀。总而言之,不同生物质和制备温度的生物炭在土壤实际应用中表现出不同的腐蚀和抗腐蚀特性,因此深入研究这些方面将为其农业应用具有深远影响。     

水溶液中苯酚电化学聚合膜的耐蚀性研究

应用电化学法从苯酚水溶液中制取聚苯酚膜并对其进行了耐蚀性研究。以304不锈钢为电极,Na₂SO₄为电解质,电化学法处理苯酚水溶液,阳极不锈钢表面覆有膜状反应产物,红外分析证实该产物中含有聚苯酚。采用点蚀电位法评判不同反应条件下形成的聚苯酚膜的耐蚀性能,结果表明在0.1mol/L苯酚与0.1mol/L硫酸钠的混合水溶液中、2.4V槽电压、常温、反应1h后形成的聚苯酚膜的耐蚀性能最好。采用扫描电镜分析不同反应时间下形成的聚苯酚膜,结果表明聚苯酚膜以层状方式生长,形成的片层叠加结构有利于提高聚苯酚膜的耐蚀性。