不锈钢电解着色工艺及电化学性能

对１Ｃｒ１７铁素体不锈钢电解着黑色工艺和膜层的电化学性能进行探讨。本工艺具有发黑速度快,色泽均匀,较好的抗蚀性能。电解着色不锈钢表面形成铬的复合氧化膜,增强了钝性,使得自然电位和阳极极化电位正移,提高了膜层的电化学稳定性能。     

超声波清洗对镀锡钝化膜耐蚀性能的影响

钢板经镀锡、软熔及重铬酸盐电解钝化后,在其表面残留的六价铬和黑灰严重影响锡层的耐腐蚀性能。利用超声波清洗钝化后的镀锡板,达到去除镀锡板缺陷处的六价铬和黑灰而不影响镀锡板表面性能的目的。研究了超声波频率、清洗时间和温度对镀锡板耐腐蚀性能的影响。结果表明:超声波清洗能够提高镀锡层的耐蚀性。     

电解酸洗方式对镀锡带钢性能的影响

研究了不同的电解酸洗方式对电镀锡性能的影响。分别采用阳极酸洗、阴极酸洗、阴阳极交替酸洗对带钢表面进行清洗,并采用硫酸铜点滴试验和返锈试验观察带钢表面的酸洗效果。将试样电镀锡后,采用中性盐雾试验测试其耐蚀性,并用金相显微镜观察其表面形貌。结果表明:阴阳极交替电解酸洗清除带钢表面氧化皮的效果最好;电镀锡后,带钢的耐蚀性较好,并且表面镀锡层覆盖较完整。     

304不锈钢化学着黑色的研究

在INCO法的基础上,通过添加辅助成膜剂和添加剂对不锈钢化学着色液的配方进行改进,采用时间-电位差法控制着色过程,在304不锈钢表面得到了黑色膜(简称304黑钛板)。实验结果表明:304黑钛板具有良好的耐蚀性能、耐磨性能和加工性能。Tafel极化曲线表明:着色膜的形成提高了304不锈钢板的阳极极化作用以及电化学稳定性。SEM和EDS分析结果表明:黑色膜均匀、致密,主要由Fe,Cr,Ni,Mn,Ce,C,O,P等元素组成。此外,初步探讨了304不锈钢表面黑色膜的成膜机理。     

Cl~-对不锈钢耐蚀性能的影响

采用循状阳极极化,交流阻抗和动电位扫描技术研究了模拟循环冷却水中氯离子对304L不锈钢耐蚀性的影响。结果表明:随着氯离子浓度增大,不锈钢的点蚀电位Eb降低;循环阳极极化曲线上的保护电位与击穿电位的差值的大小反应了不锈钢钝化膜自我修复的能力的强弱,差值越小不锈钢表面钝化膜的修复功能越强即钝化膜的性能;从交流阻抗图谱得到的不锈钢电荷转移电阻值随氯离子浓度增大而降低。     

化学镀Ni–Sn–P和磁控溅射TiN对Mn–Cu合金耐腐蚀性能和阻尼性能的影响

分别对Mn–Cu阻尼合金表面化学镀1 h和磁控溅射2 h,获得了5.42μm厚的Ni–Sn–P合金层和1.43μm厚的TiN层。对比了Mn–Cu合金及其表面化学镀Ni–Sn–P合金和磁控溅射TiN后的微观形貌、元素组成、结构、耐蚀性和阻尼性能。结果表明,化学镀和磁控溅射都能提高Mn–Cu合金的耐蚀性,Ni–Sn–P合金镀层的耐蚀性最好。化学镀Ni–Sn–P合金能够在一定程度上改善Mn–Cu合金的阻尼性能,而磁控溅射TiN会使基体的阻尼性能轻微下降。     

不锈钢卡的化学抛光

不锈钢因其优异的耐蚀性和装饰性而在工业生产和日常用品中得到广泛应用,并将发挥越来越重要的作用。曲阜锻件厂生产不锈钢卡,在加工过程中受高温氧化作用使其表面生成较厚的黑色氧化皮,严重影响了其性能和外观,必须进行抛光处理。     

钝化工艺对镀锡板的阳极溶出及耐蚀性的影响

通过在无氧柠檬酸溶液中的阳极溶出测试,模拟了食品饮料罐内镀锡板的腐蚀行为,并对比研究了常规钝化、钝化前阴极电解清洗与冲击钝化工艺下镀锡板的阳极溶出及耐蚀性。结果表明:在无氧柠檬酸溶液中,锡相对于铁基体为阳极镀层,镀锡板阳极溶出电位下降较为平缓。钝化前镀锡板软熔合金层表面氧化物的减少及冲击钝化工艺,可有效延缓镀锡板基底铁的阳极溶出,提高镀锡板的耐蚀性。     

铝合金直流电阳极氧化膜电解着色的研究

以工业纯铝L2为实验材料,采用硫酸直流电阳极氧化-电解着色工艺在铝合金表面制备黑色膜层.着重分析着色电压对黑色膜层表观颜色、厚度、硬度的影响.通过SEM表征、EDS测试及性能测试表明:在优化后的电解着色工艺条件下可以获得与工业纯铝L2基体结合力良好,且耐蚀性、耐热性、吸光性均较好的黑色膜层.     

喷砂对镀镉层防护性能的影响及分析

航空制造业钢制件防护通常采用电镀镉工艺,生产中经喷砂的工件电镀镉后在镀层表面往往出现黑色斑点,影响零件的外观质量及镀层的防护性能。通过中性盐雾试验研究了黑色斑点对零件耐蚀性的影响;采用光学数码显微镜、扫描电子显微镜及能谱分析等研究了黑色斑点出现的原因。结果表明,黑色斑点处首先发生腐蚀,黑色斑点处和刚玉砂表面形貌相似,都主要为铝和氧元素;由于刚玉砂砂残留处未能成功电镀沉积镀层,形成黑斑缺陷。     

Corrosion Protection of Stainless Steel by Poly(Carbazole-co-pyrrole) Films Deposited on TiO2 Sol–Gel Film

The poly(carbazole-co-pyrrole) copolymer was synthesized on TiO₂ sol–gel precoated 304 stainless steel (TiO₂) by cyclic voltammetry in tetrabutylammonium perchlorate containing acetonitrile solution. The synthesized coating was characterized by attenuated total reflectance–Fourier transform infrared spectroscopy, scanning electron microscopy, and solid-state conductivity measurements. Corrosion protection behavior of the TiO₂/poly(carbazole-co-pyrrole)-coated steel was evaluated by open circuit potential–time curves, potentiodynamic polarization, and electrochemical impedance spectroscopy methods. Corrosion test results showed that TiO₂/poly(carbazole-co-pyrrole) composite film enhanced corrosion resistance of stainless steel up to 50 days of immersion in 0.1M HCl corrosive medium.     

Polymer-derived SiOC ceramic coating for corrosion protection

In the present study, a polymer-derived silicon oxycarbide (SiOC) ceramic layer has been coated on stainless steel 304 (SS304) to improve corrosion resistance in a seawater environment. The surface of SS304 is dip-coated with vinyl-functionalized polysiloxane, followed by pyrolysis under argon at 800°C to obtain SiOC layer with a thickness of about 1 μm after two-fold coating/pyrolysis steps. Structural characterization of the samples was performed by fourier transform infrared (FTIR), X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Electrochemical characterization of SS304 and SiOC-coated SS304 is performed in 0.6 M NaCl solution. Potentiodynamic polarization measurements showed improved corrosion resistance of SiOC-coated SS304 with a very low corrosion current density of 4.14 × 10⁻⁹ A/cm² whereas for uncoated SS304 corrosion current density of 4.56 × 10⁻⁷ A/cm² was measured. Electrochemical impedance spectroscopic study confirmed superior corrosion resistance behavior of SiOC-coated SS304 over uncoated SS304.     

塑性变形对AISI304不锈钢组织及耐蚀性的影响

AISI304不锈钢分别在加热180 ℃和低温-70 ℃条件下进行拉伸变形。采用透射电镜观测位错分布,利用铁素体测量仪测定马氏体相(铁磁相)含量,并通过电化学滞后技术分别研究它们在50 ℃条件下0.5 mol·L^-1 MgCl₂水溶液中的腐蚀行为.结果表明：加热180 ℃和低温-70 ℃条件下塑性变形均使AISI304不锈钢中位错密度随变形量增大而增加,AISI304不锈钢在-70 ℃条件下塑性变形时部分奥氏体相转变为马氏体相,而在180 ℃条件下塑性变形时不发生马氏体相变;位错密度的增加使AISI304不锈钢钝化膜的击穿电位略微正移,而马氏体相的增加使击穿电位呈负移趋势,材料耐孔蚀性能降低.     

Corrosion monitoring of type 304L stainless steel in nuclear near-high level waste by electrochemical noise

Electrochemical noise (EN) monitoring of 304L stainless steel (SS) and sensitized 304 SS in 3 N nitric acid and nuclear near-high level waste (HLW) solution was carried out using a three nominally identical electrode configuration under open circuit conditions. EN signals characteristics of passivation process was obtained for 304L SS in 3 N nitric acid throughout the measurement period, while in near-HLW solution, features of passivation and depassivation were observed. Potentiodynamic polarization of 304L SS in 3 N nitric acid and near-HLW showed spontaneous passivation. Noise resistance was evaluated from EN time record and this parameter was used in the present investigation to qualitatively assess the corrosion behavior during the immersion period. The average noise resistance was found to be lower in near-HLW solution when compared to 3 N nitric acid. The results of the investigation are presented in this article.     

Mechanical and electrochemical behavior of nanocrystalline surface of 304 stainless steel

This paper reports our recent studies on nanocrystalline surface layer of 304 stainless steel (304SS) produced using a sandblasting and annealing process. The grain size of the sandblasted surface layer was less than 20 nm. Mechanical and electrochemical properties of the nanocrystalline surface and its passive film were investigated using nano/micro/-indentation, micro-scratch, scanning Kelvin probe (SKP), potentiodynamic scanning and electrochemical scratch techniques. It was demonstrated that the nanocrystalline surface was markedly superior to that of original 304SS with enhanced passive film. The polarization, electrochemical scratch and SKP measurements indicated that the nanocrystalline surface had higher resistance to corrosion, greater capability of repassivation and higher chemistry stability. All results demonstrated that the nanocrystallization surface did not only enhance the mechanical properties of the surface layer and its passive film, but also benefited the passivation capability of the steel with improved corrosion resistance.     

Poly(N-ethylaniline) coatings on 304 stainless steel for corrosion protection in aqueous HCl and NaCl solutions

Poly(N-ethylaniline) (PNEA) coatings were grown by potentiodynamic synthesis technique on 304 stainless steel (SS) alloy from 0.1 M of N-ethylaniline (NEA) in 0.3 M oxalic acid solution. Characterization of adhesive and electroactive PNEA coatings was carried out by cyclic voltammetry, FT-IR spectroscopy and scanning electron microscopy (SEM) techniques. The protective properties of PNEA coatings on SS were elucidated using linear anodic potentiodynamic polarization, Tafel and electrochemical impedance spectroscopy (EIS) test techniques, in highly aggressive 0.5 M HCl and 0.5 M NaCl solutions. Linear anodic potentiodynamic polarization test results proved that PNEA coating improved the degree of protection against pitting corrosion in HCl and NaCl solutions. Tafel test results showed that PNEA coating appears to enhancement protection for SS in 0.5 M NaCl and 0.5 M HCl solutions. However, according to long-term EIS results, PNEA coating is better for the protection of SS electrodes during the long immersion period in NaCl compared to that in HCl medium.     

Evaluation of the corrosion resistance of Ni-Co-B coatings in simulated PEMFC environment

The corrosion resistance behavior of Ni-Co-B coated carbon steel, Al 6061 alloy and 304 stainless steel was evaluated in simulated proton exchange membrane fuel cell (PEMFC) environment. The phase structure of the NiCoB based alloy was determined by Rietveld analysis. The PEMFC environment was constituted of 0.5 M H₂SO₄ at 60 °C and the evaluation techniques employed included potentiodynamic polarization, linear polarization resistance, open circuit potential measurements and electrochemical impedance spectroscopy. The results showed that in all cases the corrosion resistance of the Ni-Co-B coating was higher than that of the uncoated alloys; about two orders of magnitude with respect to carbon steel and an order of magnitude compared to 304 stainless steel. Except for the uncoated 304 type stainless steel, the polarization curves for the coated specimens did not exhibit a passive region but only anodic dissolution. The corrosion potential value, E_corr, was always nobler for the coated samples than for the uncoated specimens. This was true for the stainless steel in the passive region, but in the active state for the carbon steel and Al 6061 alloy. The corrosion of the underlying alloy occurred due to filtering of the solution through coating defects like microcracks, pinholes, etc. During the filtering process the E_corr value of the coating decreased slowly until it reached a steady state value, close to the E_corr value of the underlying alloy.     

氯离子对催化裂化分馏塔顶冷却系统腐蚀的研究

针对延安炼油厂年产量200万t催化裂化装置分馏塔顶空冷器内侧腐蚀问题,进行现场取样检测,配制模拟溶液,研究氯离子单一因素的变化对腐蚀结果的影响,选用了空冷管束常用的10钢、20钢和304不锈钢三种材料进行腐蚀试验。通过对试验的极化曲线和电化学阻抗的分析,得到氯离子对10#钢和20#钢的腐蚀机理相同;三种材料都会随着氯离子的加入,出现局部腐蚀点蚀,且随着氯离子浓度的增大都有腐蚀加剧的趋势;304钢随着氯离子浓度的变大,点蚀电位下降不明显,钝化膜变的不稳定。综合对比,304钢抗腐蚀性表现优于10#钢,10#钢优于20#钢,但10#钢对于氯离子变化更敏感。     

两种钢在高温环烷酸中腐蚀行为的研究

采用高温高压反应釜,考察温度、酸值和转速对20#碳钢、304不锈钢腐蚀速率的影响。结果表明:在220~300℃随着温度的升高,20#碳钢腐蚀速率先增大后减小,在280℃达到最大值0.654 mm/a,304不锈钢材料腐蚀速率逐渐较小;随着酸值的增大,20#碳钢腐蚀速率不断上升,在酸值为8~10 mg KOH/g时增速最大,304不锈钢呈直线趋势逐渐减小;在转速为0.8~2 m/s的范围内,20#碳钢腐蚀速率由0.654 mm/a变化到0.56 mm/a,304不锈钢由0.039 6 mm/a变化到0.011 2 mm/a,说明在低转速范围内环烷酸腐蚀影响并不太明显。