316L不锈钢强流脉冲电子束表面改性研究Ⅱ.在模拟体液中的腐蚀行为

采用电化学阻抗谱(ElS)和动态极化的方法研究了316L不锈钢经过强流脉冲电子束表面改性后在模拟体液中的腐蚀行为.结果表明,电子束轰击可以有效地提高316L不锈钢在模拟体液中的耐腐蚀性.经过改性的样品其界面电容下降,极化电阻升高.5次轰击后的样品表面因其火山坑的中心位置残存MnS夹杂或小孔而更易发生点蚀.20次轰击后的样品具有最佳的耐蚀性,其腐蚀电流密度降至原始样品的1/15左右,这主要归因于电子束轰击对材料表面的选择性净化效应及反复重熔对表面缺陷的修复.     

硅烷涂层对316L不锈钢耐腐蚀性能的影响

目的提高316L不锈钢的耐腐蚀性能。方法在316L不锈钢样品表面涂覆主要成分为1,2-二(三乙氧基硅基)乙烷(BTSE)的硅烷涂层。通过电化学分析测试,评价涂覆硅烷涂层的316L不锈钢的耐蚀性,并通过扫描电子显微镜和扫描电化学显微镜对其表面形貌进行分析。结果在相同的腐蚀环境下,与未涂覆硅烷涂层的316L不锈钢样品相比,涂覆硅烷涂层样品的表面更加光滑,点蚀现象明显好转。电化学测试结果显示,涂覆硅烷涂层的316L不锈钢样品的腐蚀电位为?565.02m V,未涂覆硅烷涂层样品的腐蚀电位为?796.01 mV,前者明显高于后者,其腐蚀倾向明显减小。另外,涂覆硅烷涂层的316L不锈钢样品的腐蚀电流为2.5177μA,未涂覆硅烷涂层样品的腐蚀电流为5.4291μA,涂覆硅烷涂层样品的腐蚀电流明显更小,表现出了更好的耐腐蚀性能。通过观察扫描电化学显微镜图像可以得出,未涂覆硅烷涂层的316L不锈钢样品的电流范围为?3.144×10?9～?1.957×10?9 A,涂覆硅烷涂层的316L不锈钢样品的电流范围为?3.004×10?9～?1.975×10?9A,涂覆硅烷涂层样品的电流范围更窄,腐蚀程度明显减轻。结论在316L不锈钢表面涂覆硅烷涂层可以在一定程度上减缓样品的腐蚀程度,硅烷涂层起到了物理屏障的作用,显着提高了316L不锈钢的耐腐蚀性。     

316L不锈钢表面溶胶-凝胶法制备TiO2薄膜

为提高316L不锈钢的生物相容性,采用溶胶-凝胶法在316L不锈钢上制备了TiO2薄膜,研究了改性前后316L不锈钢的耐腐蚀性及血液相容性。采用X射线衍射仪(XRD)和扫描电镜(SEM)表征了退火温度对TiO2微观结构的影响;采用电化学工作站测试了涂覆TiO2薄膜前后材料在模拟体液中的耐腐蚀性能;基于接触角测试结果,研究了退火温度对TiO2薄膜亲/疏水性能的影响,计算了TiO2薄膜的表面能及薄膜材料与血液的界面张力。结果表明:400℃和500℃退火的TiO2薄膜晶化为完整的锐钛矿结构,表面结构致密,接触角分别为76.9°和80.1°,在模拟体液中的自腐蚀电流分别为4.04μA/cm2和6.33μA/cm2,与血液间的界面张力远小于316L不锈钢。锐钛矿结构的TiO2薄膜具有良好的耐腐蚀性及血液相容性。     

316L不锈钢、ND钢和Q245R钢的耐酸露点腐蚀性能

通过浸泡试验和电化学测试,研究了316L不锈钢、ND钢和Q245R钢在酸露点腐蚀模拟溶液中的腐蚀行为,分析了温度、硫酸质量分数和Cl~-质量浓度对三种材料的酸露点腐蚀规律和机理的影响。结果表明:三种材料耐酸露点腐蚀性能从大到小依次为ND钢、316L不锈钢、Q245R钢;Q245R钢和ND钢的腐蚀速率随Cl~-质量浓度的升高先增大后减小,316L不锈钢的腐蚀速率受Cl~-、SO_4~(2-)和溶解氧的共同作用。     

316L与2205不锈钢在硫酸溶液中的腐蚀行为

采用浸泡、动电位极化等方法研究了316L与2205不锈钢在5%H2SO4溶液中的化学与电化学腐蚀行为,探索两种材料在的稀硫酸溶液中的腐蚀敏感性和耐蚀性。结果表明:在化学腐蚀过程中,316L不锈钢表面出现一些点蚀坑,而2205不锈钢的表面平整光滑,无腐蚀现象发生,2205不锈钢的腐蚀速率约为316L不锈钢的1/10;在电化学腐蚀过程中,316L不锈钢的腐蚀速度与腐蚀倾向大于2205不锈钢。在相同条件下,2205双相不锈钢表现出更好的耐蚀性。     

316L不锈钢在油田注水环境中的腐蚀行为

通过电化学试验、腐蚀浸泡试验、表面分析等方法研究了316L不锈钢在总压20.2 MPa、矿化度105mg/L模拟某油田注水系统回注水中的腐蚀行为,分析了pH、温度、Cl~-含量等腐蚀因素对其腐蚀行为的影响。结果表明:316L不锈钢在模拟回注水中具有优良的耐均匀腐蚀性能,腐蚀浸泡30d后,表面有轻微点蚀,氧气的存在增加了其发生点蚀的概率;316L不锈钢在模拟回注水中的点蚀电位为0.036V,临界点蚀温度为16℃;pH、温度、Cl~-含量对316L不锈钢均匀腐蚀速率的影响较为明显,溶液中是否含氧对316L不锈钢均匀腐蚀速率的影响较小。     

316L奥氏体不锈钢在高浓度H2S-Cl-环境中的腐蚀行为

H2S和Cl-对于促进316L不锈钢腐蚀具有协同作用。本工作利用线性极化、电化学阻抗(EIS)等电化学测试研究了316L不锈钢在高浓度H2S-Cl-环境中的腐蚀行为。在60℃、含1.5×105 mg/L Cl-的饱和H2S溶液中,316L不锈钢经过5至30天的腐蚀浸泡后,线性极化和EIS结果表明,随腐蚀时间增长,参与反应的电荷转移加快,钝化膜溶解加速,耐蚀性降低。     

304不锈钢在稀盐酸中的电化学腐蚀行为

采用电化学阻抗谱、极化曲线等测量方法研究了304不锈钢在不同浓度、浸泡时间下的腐蚀电化学行为。测定结果表明:304不锈钢在浓度0.3 mol/L的盐酸溶液中阻抗谱出现两个时间常数,极化曲线中钝化区变窄,钝化膜破裂,其金属表面发生点蚀。随浸泡时间延长,不锈钢耐腐蚀性降低。     

炼油厂冷却水系统硫酸盐还原菌对316L不锈钢点腐蚀的研究

用开路电位、动电位扫描、电化学阻抗技术和扫描电镜等方法,研究了316L不锈钢在硫酸盐还原菌(SRB)溶液中的腐蚀电化学行为,分析了炼油厂冷却水系统微生物腐蚀的特征及机制.结果表明,在含有SRB溶液中的自腐蚀电位(Ecorr)和点蚀电位(Epit)随浸泡时间的增加而负移,极化电阻(Rp)随浸泡时间的增加而减小;在含有SRB溶液中的腐蚀速率均大于在无菌溶液中;SRB的生长代谢活动影响了316L SS表面的腐蚀过程,使不锈钢表面的钝化膜层腐蚀破坏程度增加,加速了316L SS的腐蚀.     

加氢装置脱H_2S汽提塔塔顶系统的腐蚀评价及选材

模拟脱H2S汽提塔塔顶系统现场工况,采用浸泡腐蚀挂片、恒电位阳极极化法、U型弯曲应力腐蚀等方法对20号钢、304L、321、316L及2205不锈钢在湿硫化氢环境中的均匀腐蚀、点蚀和应力腐蚀开裂敏感性进行了研究,并利用体视显微镜和SEM对金属试样的微观腐蚀形貌进行了观察。结果表明:20号钢耐蚀性较差,易在低温下发生氢鼓泡,奥氏体不锈钢304L、321、316L及双相不锈钢2205的腐蚀速率较小,耐蚀性好,其中304L和321不锈钢耐点蚀性能稍差,表面出现了轻微点蚀造成的蜂窝状的局部腐蚀;H2S的存在明显提高了奥氏体不锈钢在Cl-环境中的点蚀敏感性;304L、321及316L不锈钢焊接试样均具有较好的耐应力腐蚀开裂性能。     

Investigation on Pitting Corrosion of Nickel-Free and Manganese-Alloyed High-Nitrogen Stainless Steels

Pitting corrosion behavior of three kinds of nickel-free and manganese-alloyed high-nitrogen (N) stainless steels (HNSSs) was investigated using electrochemical and immersion testing methods. Type 316L stainless steel (316L SS) was also included for comparison purpose. Both solution-annealed and sensitization-treated steels were examined. The solution-annealed HNSSs showed much better resistance to pitting corrosion than the 316L SS in both neutral and acidic sodium chloride solutions. The addition of molybdenum (Mo) had no further improvement on the pitting corrosion resistance of the solution-annealed HNSSs. The sensitization treatment resulted in significant degradation of the pitting corrosion resistance of the HNSSs, but not for the 316L SS. Typical large size of corrosion pits was observed on the surface of solution-annealed 316L SS, while small and dispersed corrosion pits on the surfaces of solution-annealed HNSSs. The sensitization-treated HNSSs suffered very severe pitting corrosion, accompanying the intergranular attack. The addition of Mo significantly improved the resistance of the sensitization-treated HNSSs to pitting corrosion, particularly in acidic solution. The good resistance of the solution-annealed HNSSs to pitting corrosion could be attributed to the passive film contributed by N, Cr, and Mo. The sensitization treatment degraded the passive film by decreasing anti-corrosion elements and Cr-bearing oxides in the passive film.     

Investigation of corrosion behaviors at different solutions of boronized AISI 316L stainless steel

In this study, corrosion behaviors of boronized and non-boronized AISI 316L stainless steel (AISI 316L SS) were investigated with Tafel extrapolation and linear polarization methods in different solutions (1 mol dm^?3 HCl, 1 mol dm^?3 NaOH and 0.9% NaCl) and in different immersion times. AISI 316L SS were boronized by using pack boronizing method for 2 and 6 hours at 800 and 900°C within commercial Ekabor®-2 powder. Surface morphologies and phase analyses of boride layers on the surface of AISI 316L SS were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. SEM-EDS analyses show that boride layer on AISI 316L SS surface had a flat and smooth morphology. It was detected by XRD analyses that boride layer contained FeB, Fe₂B, CrB, Cr₂B, NiB and Ni₂B phases. Boride layer thickness increases with increased boronizing temperature and time. The corrosion experiments show that boride layer significantly increased the corrosion resistance of the AISI 316L SS in 1 mol dm^?3 HCl solution. While no positive effect of the boride layer was observed in the other solutions the corrosion resistance of the borid layer on AISI 316L SS was increased in all solution with the increase of the waiting periods.     

316不锈钢在通氢稀盐酸中的腐蚀行为

采用电化学测量技术研究了316不锈钢在通高纯氢气的稀盐酸中的腐蚀行为，极化曲线和电化学阻抗谱测定结果表明，316不锈钢在腐蚀电位下处于活化区，其表面能形成多孔的腐蚀产物膜，氢渗入不锈钢试样表面将导致腐蚀阻力减小，且试样表面层的含氢量随腐蚀的进行而增加，SO4^2-对316不锈钢在测试介质中的腐蚀有抑制作用。     

Corrosion behavior and electrical conductivity of niobium implanted 316L stainless steel used as bipolar plates in polymer electrolyte membrane fuel cells

The corrosion behavior and interfacial contact resistance (ICR) of niobium implanted SS316L used as the bipolar plate in a polymer electrolyte membrane fuel cell (PEMFC) are investigated. The ICR values of the bare and niobium implanted SS316L are measured to evaluate the electrical conductivity. The effects of ion implantation on the corrosion behavior are investigated by potentiodynamic and potentiostatic tests in the simulated PEMFC anode and cathode environments. The solutions after the potentiostatic test are analyzed by inductively-coupled plasma atomic emission spectrometry (ICP-AES). The surface topography of the samples before and after the potentiostatic test is monitored by SEM in order to investigate the mechanism and degree of corrosion. The XPS results indicate that the composition on the surface is altered by ion implantation. The electrochemical results reveal that the passivation current density of the Nb implanted SS316L decreases and has higher chemical stability in the simulated PEMFC environment. However, the ion implantation fluence affects the current density. The ICP results are in agreement with those of the electrochemical test disclosing that the bare SS316L has the highest dissolution rate in both the cathode and anode environments and niobium implantation reduces the dissolution rate significantly. SEM shows that the bare SS316L undergoes serious corrosion whereas after Nb ion implantation, corrosion is greatly retarded. The XPS depth profiles indicate that a passive film with a new composition consisting mainly of niobium oxide is formed after the potentiostatic test. Our results suggest that niobium implantation with proper ion fluences can significantly improve the corrosion resistance and the electric conductivity of SS316L in the simulated PEMFC environments.     

Numerical simulations study of the localized corrosion resistance of AISI 316L stainless steel and pure titanium in a simulated body fluid environment

The resistance of both AISI 316L stainless steel (AISI 316L SS) and commercially pure titanium (cpTi) to localized corrosion in a simulated body fluid solution was investigated using numerical simulations. The resulting model, based on transport equations in dilute solutions, is designed to predict the susceptibility of these two biomaterials to crevice corrosion initiation. The results show that cpTi and AISI 316L SS alloy are very resistant to the initiation of crevice corrosion in 0.9% NaCl solution and AISI 316L SS alloy is more susceptible to corrosion initiation over the long term than cpTi.     

Enhancing the localised corrosion resistance of 316L stainless steel via FBR-CVD chromising treatment

The resistance of stainless steels to localised corrosion can be adversely affected by environmental and metallurgical heterogeneities existed in complex industrial infrastructures such as seawater desalination plants exposed to aggressive evnironments. It is therefore critical to enhance the localised corrosion resistance and understand the corrosion behaviour of stainless steels in complex and aggressive industrial environmental conditions. In this work, the localised corrosion resistance of chromised stainless steel 316L (SS316L) in simulated seawater desalination systems has been investigated by electrochemical and surface analytical techniques. It has been found that chromising processes have improved the localised corrosion resistance of SS316L by reducing its susceptibility to pitting, crevice, and welding zone corrosion in simulated seawater desalination environments. This increased corrosion resistance has been explained by electrochemical polarisation studies and surface analysis showing that the chromising treatment at 1050°C resulted in a continuous and stable chromium-enriched layer on the SS316L surface.     

Porous ceramic coating formed on 316L by laser cladding combined plasma electrolytic oxidation for biomedical application

In order to improve the bioactivity of 316L stainless steel, a titanium layer was prepared on the surface of 316L by laser cladding (LC), followed by plasma electrolytic oxidation (PEO) to form a porous ceramic coating on titanium layer. The morphologies, microstructure and compositions of the coated samples were characterized by 3D surface profiler, SEM, EDS, XRD and XPS. The corrosion resistance and bioactivity of the coatings were evaluated by potentiodynamic polarization and immersion test in simulated body fluid (SBF), respectively. The results showed that the porous ceramic coating mainly consisted of anatase and rutile, and highly crystalline HA was also detected. The main elements of the PEO coating are Ca, P, Ti and O. The LC+PEO composite bio-coating has more excellent corrosion resistance than the 316L substrate in simulated body fluid. Furthermore, the composite coating could effectively improve the bioactivity of 316L stainless steel.     

Bioactive glass nanopowder and bioglass coating for biocompatibility improvement of metallic implant

Preparation and characterization of bioactive glass nanopowder and development of bioglass coating for biocompatibility improvement of 316L stainless steel (SS) implant was the aim of this work. Bioactive glass nanopowder was made by sol–gel technique and transmission electron microscopy (TEM) technique was utilized to evaluate the powders shape and size. The prepared bioactive glass nanopowder was immersed in the simulated body fluid (SBF) solution at 37 °C for 30 days. Fourier transform infrared spectroscopy (FTIR) was utilized to recognize and confirm the formation of apatite layer on the prepared bioactive glass nanopowder. Bioactive glass coating was performed on SS substrate by sol–gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques were used to investigate the microstructure and morphology of the coating. Electrochemical polarization tests were performed in physiological solutions at 37 °C in order to determine and compare the corrosion behavior of the coated and uncoated SS specimens. Cyclic polarization tests were performed in order to compare the pitting corrosion resistance of the coated and uncoated SS specimens. The results showed that the size of bioactive glass powder was less than 100 nm. The formation of apatite layer confirmed the bioactivity of bioglass nanopowder. Bioactive glass coating could improve the corrosion resistance of 316L SS substrate. Bioactive glass coated 316L SS showed more pitting corrosion resistance in compare with pristine samples. It was concluded that by using the bioactive glass coated 316L SS as a human body implant, improvement of corrosion resistance as an indication of biocompatibility and bone bonding could be obtained simultaneously.     

Electrochemical corrosion of Ti6Al4V,Ti and AISI 316L SS after immersed in concentrated simulated body fluid

The biomimetic method is used to obtain hydroxyapatite (HAP) coatings on Ti6Al4V, Ti and AISI 316L SS substrates. These substrates with different pretreatment surface operations (HNO₃, anodic polarization, base-acid) were immersed in concentrated simulated body fluids (SBF) for different days at physiologic conditions of 37°C, initial pH of 7.4. Then the corrosion behaviours of substrates after immersion in concentrated SBF were examined by electrochemical methods in Ringer’s and 0.9 wt% NaCl solutions at a temperature of 37°C. Ions concentrations and pH analyses were carried out after incubation in concentrated SBF. After immersion in SBF for different days, the surface morphology remains almost unchanged and no apatite formation is observed. Corrosion currents of substrates increased after immersion. Ions concentrations and pH values were shown variability according to soaking time and pretreatment surface operations.