X80管线钢在近中性pH溶液中腐蚀行为研究

目的研究X80管线钢在近中性p H溶液中的腐蚀与应力腐蚀裂纹萌生行为。方法采用电化学实验和浸泡实验研究X80管线钢在近中性p H溶液中的腐蚀行为,采用慢应变速率拉伸实验研究X80管线钢在近中性p H溶液中,在自腐蚀电位和外加电位下的应力腐蚀裂纹萌生行为。结果 X80管线钢在近中性p H溶液中的极化曲线只有活化区,没有钝化区,其自腐蚀电位约为-750 m V,浸泡195天后,试样表面没有氧化膜出现,但是观察到点蚀坑。在自腐蚀电位下,X80管线钢试验表面有大量的应力腐蚀裂纹;在-500 m V阳极外加电位下,X80管线钢试验表面几乎没有观察到应力腐蚀裂纹;在-850 m V阴极外加电位下,X80管线钢试验表面的应力腐蚀裂纹很少,但是随着外加阴极电位负移到-1300 m V时,X80管线钢试验表面的应力腐蚀裂纹增多。结论 X80管线钢在近中性p H溶液中发生均匀腐蚀,但是夹杂物剥落能在X80管线钢表面形成点蚀坑。在近中性p H溶液中,在自腐蚀电位下,X80管线钢应力腐蚀裂纹萌生敏感性最强;外加阴极电位抑制应力腐蚀裂纹萌生,但是随着外加阴极电位的负移,应力腐蚀裂纹萌生敏感性增强;外加阳极电位下,由于均匀腐蚀的作用,应力腐蚀裂纹萌生敏感性较弱。     

热带雨林环境中典型霉菌对PCB-HASL腐蚀行为的影响

目的探究热带雨林环境中典型霉菌作用下PCB-HASL的腐蚀机制。方法将PCB-HASL试样灭菌后放入机箱,置于西双版纳户外进行2年的暴露试验,经不同周期取回,分析观察试样表面腐蚀情况。将筛选出的典型霉菌孢子液喷洒在无菌试样上,置于湿热环境中,通过激光共聚焦显微镜(3D LSCM)、扫描电子显微镜(SEM)和能谱仪(EDS)分析试样表面形貌和成分,并观察霉菌的生长情况,使用电化学工作站及扫描开尔文探针(SKP)对PCB-HASL表面不同周期霉菌作用下的腐蚀电位进行分析。结果随着户外暴露周期的增加,PCB-HASL表面腐蚀面积逐渐增加,表面伏打电位先上升后下降。EDS能谱分析结果表明,腐蚀产物中主要含Sn 58.88%,O 30.93%,腐蚀产物主要为Sn的氧化物。木贼镰孢菌(Fusarium equiseti)和光轮层炭壳菌(Daldinia eschscholtzii)覆盖区域腐蚀程度严重,腐皮镰刀菌(Fusarium solani)菌丝生长旺盛,中期腐蚀电位明显降低,由-0.3 V降至-0.52 V。结论西双版纳热带雨林环境中对PCB-HASL腐蚀作用显著的典型霉菌为Fusarium equiseti、Daldinia eschscholtzii和Fusarium solani,在湿热环境下会造成PCB-HASL的腐蚀,其腐蚀机制主要为薄液膜下的电化学腐蚀。     

封隔器以下140钢级套管材质在完井过程中的腐蚀行为研究

通过高温高压鲜酸(10%HCl+1.5%HF+3%HAc+5.1%TG201缓蚀剂)、残酸、地层水CO2腐蚀实验及电化学分析,研究TP140钢在苛刻工况条件下的耐蚀性。结果表明:TP140钢在鲜酸、残酸和地层水CO2腐蚀实验条件下,其均匀腐蚀速率分别为3.7490,0.4361和0.5524 mm/a。残酸实验后,试样表面存在不完整Cu膜。未去除Cu膜的TP140钢试样的自腐蚀电位(-658 m V)高于去除Cu膜的TP140钢试样的(-692 m V),腐蚀驱动力小,但其自腐蚀电流密度(3.1141×10-5A/cm2)明显高于去除Cu膜的(1.0926×10-5A/cm2)。相比于TP140钢基体(Fe),Cu为正电性金属,膜的覆盖不致密形成典型的大阴极-小阳极结构,导致严重的局部腐蚀。TP140钢在鲜酸、残酸和地层水CO2腐蚀实验条件下,试样表面最大点蚀深度可达150μm。     

用Kelvin探头技术研究铝合金的大气腐蚀

选择航空工业广泛使用的铝、铝合金及其涂层的试样，利用自行研制的Kelvin探头大气腐蚀测定仪、扫描电镜等设备，研究了纯铝试样随温、湿度变化，其表面电位的变化规律，测定了铝合金及涂层试样大气曝晒试验和周浸试验前后的表面电位、形貌,对铝、铝合金以及涂层的腐蚀规律进行了初步的探讨.结果表明，纯铝试样表面无可见液膜时，腐蚀电位随相对湿度增加逐渐下降；表面有可见液膜时，随着液层蒸发逐渐减薄，电位逐渐正移.铝合金裸材在北京大气环境下电位变化较小，且各个位置的电位基本相同.带涂层的试样优先在缺陷处发生腐蚀，并不断向周围扩展，涂层的剥离面积不断增大.涂层的铝合金，划痕处在腐蚀发生的初期腐蚀电位向负方向变化很快，但是随着时间的延长，腐蚀电位变化的速率减慢，并有向正方向移动的趋势.      

碳钢渗Ti及氮化在硝酸中的耐腐蚀性研究

在碳钢表面实施等离子渗Ti,然后进行离子氮化。将处理试样在1 mol/L HNO3溶液中用PS-268A型电化学测量仪进行耐腐蚀实验,并采用SEM对腐蚀试样表面进行分析。结果表明:在1 mol/L HNO3酸性溶液中,渗Ti、渗Ti+离子氮化试样的致钝电位较未处理碳钢试样明显降低,钝化电位区间分别比未处理碳钢提高3.17倍和2.96倍,试样耐腐蚀性能分别比未处理试样提高7.44倍和4.54倍;腐蚀机理为:未处理碳钢腐蚀后表面形貌表现为较大的腐蚀坑且凸凹和起伏较明显,是典型的孔蚀;渗Ti试样为轻微面腐蚀;渗Ti+离子氮化试样腐蚀机理表现为典型的晶间腐蚀。     

恒电位对TiN涂层在人工海水环境中腐蚀磨损的影响

目的研究不同恒电位对TiN涂层在人工海水环境中腐蚀磨损行为的影响。方法用多弧离子镀系统在316不锈钢上沉积TiN涂层。通过XRD测试、纳米压痕硬度测试、膜基结合力测试、电化学工作站测试、不同恒电位下磨蚀实验和涂层的磨痕截面轮廓测试,分别评价TiN涂层的相结构、硬度、结合力、电化学性能、摩擦系数、磨损率,并通过扫描电子显微镜对涂层表面形貌、截面形貌和磨痕形貌进行分析。结果在摩擦条件下,TiN涂层的开路电位随着滑动摩擦时间的增加而逐渐降低。TiN涂层在不同恒电位(-1V、-0.5 V、OCP、0 V)下滑动摩擦,平均摩擦系数分别为0.392,0.416、0.324、0.348。磨损率分别为1.8117×10-6、3.1123×10-6、4.5958×10-6、7.7724×10-6 mm3/(N·m)。在0.5 V下,涂层被磨穿。TiN涂层在人工海水环境中的主要腐蚀磨损破坏机制为磨粒磨损和疲劳点蚀。结论提高加载电位,涂层的磨损量和磨损率同步增大。在-1、-0.5 V,OCP下,由腐蚀促进磨损的损失量占TiN涂层损失总量的比重逐渐增大,依次为0%、41.78%、61.77%。在0 V时,TiN涂层产生了由磨损促进腐蚀的损失量,占TiN涂层损失总量的比例为6.1%。     

表面充氢对TA2在草酸溶液中腐蚀行为的影响

目的提高TA2在草酸溶液中的耐蚀性,揭示表面充氢提高钛在草酸溶液中耐腐蚀性能的机理。方法采用电化学充氢的方法对TA2试样进行表面充氢,采用SEM和XRD分析充氢对试样表面形貌和相组成的影响,并采用电化学测试和腐蚀浸泡实验研究不同充氢时间的TA2试样在草酸溶液中的耐蚀性。结果电化学充氢后,TA2试样表面会生成一层以Ti H1.5为主要组成相的氢化钛层,该氢化钛层的厚度随充氢时间的延长而增厚。电化学测试结果显示,随着充氢时间的延长,TA2试样在草酸溶液中的自腐蚀电位从–0.7 V(vs.SCE)逐渐增加到0 V左右,腐蚀倾向显著下降;极化电阻Rp则从0.2 kΩ·cm^2逐渐增加到了24.1 kΩ·cm^2,耐蚀性能增强。腐蚀浸泡实验结果表明,随着充氢时间的延长,TA2试样在草酸溶液中的腐蚀程度逐渐减弱,腐蚀速率也从未充氢时的4.63mm/a逐渐下降到0.03mm/a。结论在草酸溶液中,电化学充氢TA2试样表面生成的氢化钛层对Ti基体具有保护作用,并且保护效果随氢化钛层的增厚而增强。试样表面氢化钛层对Ti基体的保护作用除了与成分有关外,还与其结构相关,完整致密的氢化钛层可以对Ti基体起到很好的保护作用,而疏松多孔的氢化钛不仅不能保护Ti基体,反而还会促进Ti基体的腐蚀。     

阴极极化对LY12CZ铝合金腐蚀疲劳寿命的影响

在LY12CZ铝合金腐蚀疲劳寿命曲线的基础上,研究了不同阴极电位下有无涂层试件在3．5％NaCl溶液中腐蚀疲劳寿命的变化规律．记录了一定阴极电位下阴极电流的变化情况．并通过对腐蚀疲劳断裂微观形貌的观察、分析,探讨了阴极极化对有无涂层保护的LY12CZ铝合金腐蚀疲劳寿命影响机理．对于无涂层试样,一定范围内的阴极电位会抑制阳极反应,明显提高腐蚀疲劳寿命,但当阴极电位达到一定值时(-1400mV以上),发生铝合金的阴极腐蚀,使腐蚀疲劳寿命显著降低．对于有涂层试样,由于涂层的保护,一定电位值范围的阴极保护作用并不显著,阴极电位超过一定值,涂层阻碍抑制了阴极腐蚀作用,试样腐蚀疲劳寿命较无涂层试样有显著提高。     

超声喷丸对变形镁合金AZ80M腐蚀行为的影响

采用超声喷丸工艺对AZ80M镁合金板材进行表面纳米化处理。结果表明，超声喷丸使AZ80M镁合金表层的晶粒尺寸显著减小，距喷丸表面50μm以内为大变形区域，存在部分微裂纹；距喷丸表面50～150μm范围内为晶粒细化区域，其组织致密且无明显缺陷。超声喷丸+抛光的AZ80M试样耐蚀性显著提高，开路电势为-1.551 V、自腐蚀电位为-1.481 V、钝化阻抗值R_c达1 772Ω·cm²。浸泡腐蚀试验表明，超声喷丸+抛光的AZ80M试样腐蚀速率明显降低，腐蚀形貌更均匀，腐蚀防护效果更好。     

宋代银制品模拟样品在Na2S溶液中的电化学腐蚀及其产物

研究了2008年南京长干寺出土的北宋七宝阿育王塔鎏金银基体及其腐蚀产物成分,并根据银基体成分按传统工艺自行冶炼、加工出模拟的银试样.用电化学、OM、XRD、XRF、SEM-EDS技术研究并比较了银试样在不同浓度Na2S溶液中的腐蚀电位与电流、腐蚀产物成分、形貌、晶粒度等.结果表明,Na2S浓度由20 mg/L升高到5.0×104mg/L(5%Na2S)时,自腐蚀电位Ecorr负移0.70V,自腐蚀电流密度Icorr从0.274μA/cm2升高至1.056μA/cm2,腐蚀倾向和速度大幅度增加.在20 mg/L Na2S溶液中-0.31 V~1.8 V范围内极化,银试样始终处于活化溶解状态.在5%Na2S溶液中,腐蚀活化区电流密度从1.056μA/cm2迅速升高至1.56×104μA/cm2,并以较大的腐蚀电流密度(约1.56×104μA/cm2)进入钝化区并维持钝态;分别在20 mg/L和5%Na2S溶液中活化区恒电位+0.3 V、-0.8 V极化不同时间后,腐蚀产物主要为Ag2S.随着Na2S溶液浓度的增大,试样表面S2-腐蚀活性中心增多,Ag2S晶体成核速率增大,而腐蚀产物的晶粒度则由20μm减小到1.86~5.10 nm.     

Optimization of corrosion protection potential for stress corrosion cracking and hydrogen embrittlement of 5083-H112 alloy in seawater

We report on the optimum corrosion protection potential range for stress corrosion cracking and hydrogen embrittlement of 5083-H112 Al alloy specimens using electrochemical methods and slow strain rate testing (SSRT) in seawater. In the results of the cathodic polarization curve, the concentration polarization due to dissolved oxygen reduction reaction correspondeds to a protection potential of OCP≈ −1.55 V. However, a potential of −1.2 V in the SSRT showed little effect of atomic hydrogen evolution. Potentials less than −1.6 V are affected by atomic and molecular hydrogen. We thus concluded that the effect of atomic hydrogen predominates. Overall, the optimum corrosion protection range for SCC and hydrogen embrittlement of 5083-H112 seems to be between −0.9 V and −0.7 V.     

Improvement of hydrogen embrittlement and stress corrosion cracking by annealing for Al-4.4Mg-0.6Mn alloy

With no annealing treatment, cathodic polarization trends in 5083F Al alloy revealed concentration polarization and activation polarization. However, the annealed specimens have lower current densities at corrosion protection potential compared to the non-annealed specimen. The results of SSRTs conducted in seawater at the applied potential range of ?1.8 V to ?0.5 V indicated that the maximum tensile strength, elongation, and time-to-fracture had high values at applied potentials of ?0.7 to ?1.4 V. The maximum tensile strength, elongation, and time-to-fracture decreased when the potential values were beyond this range in either anodic or cathodic direction. In general, the increased shear lip caused by annealing treatment indicates elongation. Time-to-fracture would likely increase with elongation. Potentials between ?0.5 V to ?0.6 V were found to be in the region of stress corrosion cracking. The corrosion protection zone was determined to be ?0.7 V to ?1.4 V because these potential ranges produced good mechanical properties. Potential less than ?1.4 V produced a fractured surface with a mixture of dimples (ductile fractures) and a quasi-cleavage pattern resulting from the effects of hydrogen gas.     

Cathodic protection of XL 52 steel under the influence of sulfate reducing bacteria

The effect of sulfate reducing bacteria (SRB) upon the cathodic protection of XL 52 steel was determined, in order to identify if the potential value of ?0.950 V versus copper/copper sulfate electrode is good enough to protect the metal surface. During the experiments, different operational parameters were monitored: hydrogen sulfide production, iron concentration, electrolyte alkalinity, microorganisms' population, as well as the metal surface damage. At the same time, the corrosion rate was determined using two electrochemical techniques: polarization resistance (PR) and electrochemical impedance spectroscopy (EIS). According to the results, it was observed that the protection potential of ?0.950 V versus copper/copper sulfate electrode is not enough to control the microbiologically induced corrosion. This situation is reinforced by the fact that significant iron concentration was found in the electrolyte. The microbiological activity is not affected by the protection potential. On the contrary, the population growth is slightly strengthened. The alkalinity generated by the applied potential did not stop the SRB growth. A type of localized corrosion was developed during the experiments with microorganisms, even when the protection potential was applied to the system.     

ECAP变形对MWCNTs/AZ31复合材料抗腐蚀性能的影响

采用碳纳米管孕育块铸造法制备多壁碳纳米管/AZ31镁基复合材料,经等径角挤压(ECAP)变形后对复合材料在3.5%NaCl(质量分数)的腐蚀介质中进行静态浸渍试验和电化学极化曲线测定,研究等径角挤压变形工艺对复合材料抗腐蚀性能的影响;利用数码相机、扫描电子显微镜对复合材料腐蚀前后的表面形貌进行观察和分析;并对复合材料的抗腐蚀机理进行分析。结果表明:等径角挤压变形工艺能有效的提高多壁碳纳米管(CNTs)/AZ31复合材料的抗腐蚀性能,经等径角挤压变形4道次后,复合材料的平均腐蚀速率由挤压态的0.6035mg/(m2·s)降为0.2963mg/(m2·s)。腐蚀电流密度Icorr由ECAP变形前的3.363μA/cm2减小到2.269μA/cm2。     

WMCNTs/AZ31复合材料电化学腐蚀研究

采用碳纳米管孕育块铸造法制备碳纳米管/AZ31镁基复合材料,测量其电化学极化曲线,研究碳纳米管加入量对复合材料抗腐蚀性能的影响,利用SEM对复合材料腐蚀前后的表面形貌进行了观察和分析。结果表明,碳纳米管的加入有效地提高了复合材料的抗腐蚀性能,随着复合材料中碳纳米管加入量的增加,腐蚀电流密度I_corr由5.279 μA/cm²减小到2.994 μA/cm²。     

靶电流对磁控溅射AlSn20/C镀层耐蚀性的影响

采用非平衡磁控溅射技术在铝基轴承合金表面制备AlSn20/C复合镀层,通过扫描电镜形貌观察、交流阻抗和极化曲线的测量研究石墨靶电流对镀层组织与耐蚀性能的影响。结果表明:在电流0.2~0.8 A范围内,薄膜均以层状结构生长,且电流越小,薄膜组织越致密;镀膜后试样的电化学阻抗比基体的高5~6个数量级,石墨靶电流为0.2 A时,可将基体的自腐蚀电位由1.42 V提高到1.18 V,石墨靶电流是影响AlSn20/C复合镀层耐蚀性的一个重要因素,石墨靶电流越小,其耐蚀性越好。     

Electrochemical behavior of corroded and protected construction steel in cement extract

The corrosion behavior of corroded, cathodically protected and control (reference) construction steel, previously embedded in concrete, was studied in cement extract (pH 12.6, considered as concrete pore water), using cyclic voltammetry (CVA) and potentiodynamic polarization (PDP). The necessity for this investigation occurred from the previously observed and commented discrepancies in the recorded corrosion parameters for corroded and protected steel in embedded conditions 1 . Therefore this study aimed to evaluate how the “naturally” formed in concrete product layers (after 460 days) will influence the electrochemical behavior of the steel in cement extract. The PDP measurements reveal the lowest corrosion resistance to be for the previously corroded steel samples, for which the most active corrosion potential (?0.7 V SCE) and the highest anodic current in the potential region 0 to 0.6 V (SCE) were recorded. The CVA tests support the results from PDP and correlate the properties of the naturally formed layers with the recorded peak current densities and peak potentials with cycling. For all specimens, except the corroded ones, the peak potential initially shifts anodically, which denotes for a high corrosion resistance in the former and low corrosion resistance in the latter case. For the control and protected specimens, the passive current in the potential region of 0 to 0.6 V (SCE) remains almost unchanged with cycling, i.e. the protective properties of the initial layers remain unchanged. Thickening of the film with cycling does not influence the corrosion resistance of the previously formed layers. For the protected specimens, however, a tendency to reach a steady state and change of peak currents' height only were observed, without a pronounced shift to more anodic values. An increase in the peak current only, not accompanied by anodic shift of the peak potential, suggests that the layers in the cathodically protected specimens are more homogeneous and compact. Overall it can be stated that in cement extract, the product layer with lowest corrosion resistance is the one on the surface of the corroded steel reinforcement. The product layers in the protected specimens (although similar to control conditions) are with the highest corrosion resistance.     

合金元素对铝合金在泰国曼谷地区初期腐蚀行为的影响

在泰国曼谷地区对5083、6063和7020 3种铝合金进行为期1 a的暴晒实验,采用SEM、电化学实验、XPS和扫描Kelvin探针显微镜(SKPFM)对3种铝合金初期腐蚀形貌及腐蚀机理进行研究。结果表明:6063铝合金中Mg、Si、Fe等合金元素含量较少,腐蚀电位相对较高,约为-0.66 V (vs SCE),腐蚀产物膜较为致密,耐蚀性较好,在泰国曼谷地区的腐蚀速率约为0.7 g/(m^2·a)。7020铝合金含有较多Mg、Zn等合金元素,腐蚀电位约为-0.78 V (vs SCE),腐蚀最为严重,腐蚀速率约为3.26 g/(m^2·a)。3种铝合金均含有Mn、Si、Fe等合金元素,从而形成Fe-Si-Al或Fe-Si(Mn)-Al第二相,第二相表面电位高于基体225~280 mV,在大气环境中第二相作为阴极相,周围的基体Al优先溶解脱落,成为点蚀坑。     

Influence of electrodeposition potential,TiO2 nanoparticles and chromium (III) inhibitor addition on the corrosion protection performance of organosilane coating on aluminium

In this work, the anticorrosion properties of phenyl trimethoxysilane (PTMS) films coated on aluminium 5000 series alloys were studied. PTMS films were deposited at various cathodic potentials. The optimum electrodeposition potential was found to be ?0.8?V vs. SCE. The coatings were also modified by different amounts of nano-TiO₂. In order to introduce corrosion inhibition and a self-repair property of the PTMS film, the addition of chromium (III) corrosion inhibitor in the presence of nano-TiO₂ was studied. The anticorrosion performance of coatings was investigated in a 3.5 wt.% NaCl solution. At optimum deposition potential, the ‘critical’ nano-TiO₂ and Cr(III) contents were both observed, under which the obtained PTMS coatings show the highest anticorrosion performance. The surface morphologies of PTMS coatings were examined by scanning electron microscopy. The results showed that the coatings deposited at ?0.8?V vs. SCE, from 20?ppm of nano-TiO₂ and 0.003 M Cr(III) inhibitor present uniform and compact morphologies.     

耐候钢表面锈层稳定化处理技术研究

目的解决耐候钢裸露使用初期锈液流失导致污染环境的问题。方法制备了耐候钢表面锈层稳定化处理溶液。通过周期浸润循环腐蚀试验、锈层微观分析和电化学测试等方法,研究了在模拟工业大气环境下,表面处理溶液对耐候钢锈层结构及耐腐蚀性能的影响。结果表面处理后,耐候钢的开路电位由处理前的-0.395 V降低到-0.475 V,表面快速生成一层连续致密的氧化层。加速腐蚀16 d后,耐候钢的腐蚀速率由未处理时的0.209 mg/(cm^2·d)降低到表面处理后的0.106 mg/(cm^2·d),降低了约49%;锈层的自腐蚀电位由未处理的-0.216 V提高到处理后的-0.073 V,提高了约66%,自腐蚀电流密度由未处理时的7.41μA/cm^2降低到1.58μA/cm^2,降低了约79%。随着腐蚀时间从1 d延长至16 d,处理后的耐候钢锈层中α-FeOOH的质量分数由2.96%增加到4.46%,增加了51%,γ-FeOOH的质量分数由2.06%降低到1.65%。表面处理后的耐候钢锈层中,Cu和Cr元素在锈层与基体结合处和锈层内部发生富集。结论处理溶液降低了耐候钢表面的开路电位,可使耐候钢快速生成致密且连续的锈层,锈层中Cu、Cr元素富集促进了γ-FeOOH向α-FeOOH的转化,提高了锈层电化学保护性能,降低了后期腐蚀速率,缩短了稳定化进程。