16Mn钢在模拟油田采出介质中的腐蚀行为研究

采用循环流动腐蚀试验装置,研究了16Mn钢在三元复合驱采出液流动介质中的电化学腐蚀行为.通过试验得出温度、流速对腐蚀电流密度的影响规律.结果表明,在流动的三元复合驱采出溶液中,16Mn钢的腐蚀电流密度因溶液温度和流速不同而变化.通过X射线衍射分析确定腐蚀产物,并对腐蚀产物膜保护性进行了分析.     

Applications of carbonic acid solution for developing conversion coatings on Mg alloy

Works on exploring an environmentally clean method for producing an Mg,Al-hydrotalcite(Mg6Al2(OH) 16CO3·4H2O) layer and/or calcium carbonate(CaCO3) layer on Mg alloy in a carbonic acid solution system(aqueous HCO3-/CO3 2-or Ca 2+ /HCO3-) at 50℃ were reviewed.Conversion treatment for the Mg,Al-hydrotalcite conversion coating was as follows.Mg alloy was treated first in acidic HCO3-/CO3 2-aqueous for precursor layer formation on Mg alloy surface and then in alkaline HCO3-/CO3 2-aqueous to form a crystallized Mg,Al-hydrotalcite coating.Duration of an Mg,Al-hydrotalcite coating on Mg alloy surface was reduced from 12 h to 4 h by the conversion treatment.On the other hand,for reducing the formation time of CaCO3 coating on Mg alloy,the aqueous Ca 2+ /HCO3-with a saturated Ca 2+ content was employed for developing a CaCO3 coating on Mg alloy.A dense CaCO3 coating could yield on Mg alloy surface in 2 h.Corrosion rate(corrosion current density,Jcorr) of the Mg,Al-hydrotalcite-coated sample and CaCO3-coated AZ91D sample was 7-10μA/cm 2,roughly two orders less than the Jcorr of the as-diecast sample(about 200μA/cm 2) . No corrosion spot on the Mg,Al-hydrotalcite-coated sample and CaCO3-coated sample was observed after 72 h and 192 h salt spray test,respectively.     

轴转动调制腐蚀电流产生的极低频电场的测定

钢制船壳和青铜制螺旋桨之间在海水中会因电化学作用而产生腐蚀电流,该电流会从螺旋桨、经转轴、轴承、密封圈及其他一些机械线路回到船壳.随着螺旋桨转轴的转动,这个回路的电阻抗会发生周期性的变化,使得海水中的电流受到调制,从而产生极低频的电磁场由船体向外传播.文中利用船模和Ag/AgCl电极在实验室具体测量了螺旋桨转动时调制船模在海水中的腐蚀电流而产生的极低频电场.测量结果表明,由不同金属制成的船壳和螺旋桨之间的腐蚀电流经螺旋桨转动的调制后, 会产生与螺旋桨转速具有相同频率的极低频电场, 成为舰船的一个重要目标特性.     

海水与腐蚀电流耦合作用下铝合金与混凝土界面黏结性能

为提高海洋混凝土结构的耐久性和使用性,基于牺牲阳极的阴极保护技术,对腐蚀防护与结构一体化的铝合金板-钢筋混凝土组合构件的界面黏结性能进行试验研究,建立海水环境与腐蚀电流耦合作用下界面黏结强度的计算方法。通过设计15组45个铝合金板与混凝土界面剪切试件,分别进行室内养护和耦合环境(海水环境与腐蚀电流)加速锈蚀,并进行单剪试验,研究黏结长度(60、80 mm和100 mm)、黏结宽度(60、80 mm和100 mm)、铝合金板表面刻槽深度(1.5 mm和2.5 mm)以及锈蚀时间(30、60 d和90 d)等参数对界面破坏形式、极限荷载及应变分布的影响。结果表明：室内环境养护下,试件的破坏形式为黏结层-混凝土之间的界面剥离,而耦合环境下试件的破坏形式转变为铝合金板与黏结层之间的界面剥离,且当锈蚀龄期达到90 d时,剥离的混凝土面积明显减少,故海水和腐蚀电流的耦合作用会降低铝合金板与黏结层界面的黏结性能;增大黏结长度、宽度以及表面刻槽深度,可提高室内环境下试件界面的极限破坏荷载,也能缓解耦合环境对试件界面黏结性能的不利影响;但黏结长度或宽度超过80 mm后,其缓解作用减弱。利用试验测试获得的...     

油气输运条件下X56钢的CO2腐蚀行为研究

油气输运管线工作于苛刻的腐蚀环境中,容易造成严重的破坏.利用SEM,EDS,XPS,XRD,EIS等现代分析技术,在油气输运条件下(温度30～80℃、PCO2 为0.5～2.0 MPa、流速1.4m/s),对油气输运管常用材料X56钢进行了测试分析.失重试验证明:X56钢的腐蚀速率随温度的升高而升高,表现为指数关系;随CO2分压增大而加大,表现为线性关系.SEM,EDS,XPS,XRD分析表明:腐蚀产物晶体主要是由反铁磁性物质FeCO3及(Fe,Ca……)CO3复相物组成,表现为台地浸蚀及孔穴腐蚀,腐蚀产物膜由3层构成.极化曲线表明:在PCO2=0.5 MPa、30～90℃条件下,随温度升高,X56钢的自腐蚀电位Ecorr变负,Icorr升高;温度80℃、PCO2=0.5～2.0 MPa时,自腐蚀电位Ecorr随PCO2的增加而变正,自腐蚀电流Icorr明显增大,且阴极极化及阳极极化有明显的弱极化Tafel区.电化学交流阻抗试验表明,由于腐蚀产物膜的存在,低频区出现了半无限扩散的的Warburg阻抗特征,高频端出现了容抗弧,反应受扩散控制.     

Corrosion mechanism of mechanically alloyed Mg50Ni50 and Mg45Cu5Ni50 alloys

As the loss of active material Mg may affect electrode‘s discharge capacity and the cycling stability, a more refined mechanism study on cycling capacity degradation should be made. The present investigation is based on the supposition that the capacity degradation of the binary MgSONi50 alloy and ternary Mg45CuSNi50 alloy electrodes is solely due to the corrosion of Mg, the active hydrogen storage element. That means amount of capacity degradation is determined by the corrosion current time, which is also the time of operation. The corrosion current Jcoxt dependance on cycling time was deduced. A mathematic relation between the cycling capacity retention CN/C1( % ) and the duration of operation was also deduced. The data calculated from the equations deduced agree well with those of the expeximemt result. The loss of the active hyckogen-absorhing element Mg is proved to be the main cause for cycling capacity deterioration in the present investigation.     

AZ91D镁合金脉冲阳极氧化处理及腐蚀性能评价

采用高频脉冲电源和阶梯降流的方法,于碱性偏铝酸钠溶液中在AZ91D合金表面制备阳极氧化膜.研究了成膜过程、膜层的结构和形貌,评价了膜层的耐酸性和在3.5%NaCl溶液中的耐腐蚀性能.结果表明:在本试验条件下,AZ91D合金表面可形成内层致密且较厚、外层相对较薄、厚度约100μm的氧化膜;阳极氧化膜的耐酸能力远高于基体;经阳极氧化处理后的合金的自腐蚀电位正移,在腐蚀性介质中极化阻力增大,腐蚀电流密度降低,耐腐蚀性能显著提高.     

Surface characteristics of mussel-inspired polydopamine coating on titanium substrates

Mussel adhesive proteins are non-toxic, biodegradable and have low immunogenic qualities that make them highly attractive for medical purposes compared with man-made materials. 3,4-DOPA, which is a dopamine precursor, is a critical element for achieving mussel-like adhesive properties. In present study, polydopamine was coated onto the titanium surfaces by dipping in a 2 mg/mL dopamine solution in 10 mM Tris- HCl buffer at pH 8.5. EDX element analysis and Raman spectroscopic analysis of the surface were conducted to verify the formation of polydopamine. The surface characteristics of polydopamine-coated titanium plates were observed by SEM and AFM. Hydrophilicity and corrosion-resistance were also evaluated by static contact angle measurements and potentiodynamic polarization corrosion tests. The absorption intensity for pH-induced polymerization rapidly increased for the initial four hours and thereafter smoothly increased. EDX element analyses revealed that the content of carbon and oxygen increased and the content of titanium decreased after the coating process. In the Raman spectra, polydopamine resulted in two new peaks at approximately 1 370 and 1 570 cm^-1 resulting from the stretching and deformation of catechol. Microstructural features revealed that nanometer-sized bright granules were randomly distributed after coating, and these nanoparticles grew with increased coating time. The Ra values of polydopamine-coated titanium plates were showed to increase with coating time. Compared to the pure titanium curve, the inflection point of polydopamine-coated titanium was located at a higher corrosion potential and lower corrosion current density. Findings from our research suggested that polydopamine coatings offer a versatile approach for titanium surface modification.     

碳钢管内表面化学镀Ni-P耐蚀层的研究

为了在Q235钢管内表面制备Ni-P化学镀层,以提高普通碳钢管道的耐蚀性,通过正交试验研究化学镀的镀液配方,并检测镀层的化学成分及其在盐水中的耐蚀性。研究表明:Q235钢管内表面制得的Ni-P化学镀层最佳配方为硫酸镍7.6×10~(-2)mol/L,次亚磷酸钠0.17 mol/L,柠檬酸钠3.4×10~(-2)mol/L,硫脲1.32×10~(-5)mol/L;镀层沉积速率为25.4μm/h,镀层硬度为747 HV;镀层中Fe、Ni和P元素的质量百分比分别为0.89%、85.63%和13.48%;在3.5%的NaCl溶液中镀层的自腐蚀电位为-0.62 V(SCE),自腐蚀电流密度为5.82×10~(-6)A/cm~2,比Q235钢的自腐蚀电流密度降低了98.1%。     

表面阳极化对7050铝合金电偶腐蚀的影响

为了研究表面阳极化对7050铝合金电偶腐蚀性能的影响,通过测定7050铝合金与TC18钛合金组成电偶对的腐蚀电流的方法,评定了7050铝合金与TC18钛合金接触的电偶腐蚀敏感性.结果表明：7050铝合金与TC18钛合金接触时会产生严重的电偶腐蚀,电偶腐蚀的敏感性为D级;而阳极化的7050铝合金与TC18钛合金接触产生的电偶腐蚀敏感性级别降低为B级,提高了表面抗腐蚀性能.