采用高纯银箔 (99.99%) 的电化学氧化法制备了全固态卷压式Ag/AgCl电极,并用于混凝土中的Cl-浓度检测。该Cl-选择电极具有较大的比表面积和交换电流密度,以及较低的温度系数。在模拟混凝土孔隙液中的测试表明：相比粉压式Ag/AgCl电极,卷压式电极具有更接近理论值的线性电压响应斜率 (-58.2 mV) 和电位稳定性,在230 d内电位波动不大于4 mV。混凝土中Cl-浓度测量表明：通过将电极表面包裹了一层PVA凝胶电解质薄膜,可显著提高其Cl-电位响应稳定性和抗干扰能力,且电极电位与混凝土中的lg[Cl-]之间具有良好线性度。表面分析证明,该卷压式电极不仅增加了电极的活性表面积,提高了电极的稳定性与反应活性；同时,借助于AgCl/Ag的多层堆叠,增强了AgCl颗粒与Ag基体间的附着力,提高了混凝土中Cl-的检测可靠性和电极的使用寿命。
An all solid-state and roll-shape Ag/AgCl electrode for detecting chloride ions in concrete was prepared by electrochemical oxidation of high purity (99.99%) silver foil. Electrochemical measurement results indicate that in comparison with the conventional powder moulding Ag/AgCl electrode, the novel chloride ion selective electrode has a larger exchange current density, higher specific surface area and lower temperature coefficient; by means of the electrode a better linearity is revealed of the potential response slope (-58.2 mV) versus Cl- concentration in an artificial pore solution of concrete, which is close to the theoretical value; besides, the novel electrode also exhibits a rather stable potential for a period of 230 d with fluctuations less than 4 mV. The experimental results in concrete shows that the performance of the all solid-state and roll-shape electrode, such as its linearity of potential response to lg[Cl-] and anti-interfere capability can significantly be improved by wrapping the electrode with a thin film of polyvinyl alcohol gel electrolyte. The morphology observation reveals that the novel Ag/AgCl electrode has a higher active surface area, which may be beneficial to the stability and the sensitivity of ion selection. In addition, the close stacked and layer by layer structure of the all solid-state and roll-shape AgCl/Ag electrode also enhances the adhesion of AgCl particulates to the Ag foil, which further improves its reliability on chloride detection and its service life in concrete.
通过电化学方法、腐蚀失重法、超景深三维立体显微镜和菌量测定等方法,研究了常用缓蚀剂 (月桂酸、硫脲) 在含有硫酸盐还原菌 (SRB) 的饱和CO2产出水中的缓蚀行为。结果表明：在无菌饱和CO2介质中,月桂酸、硫脲对碳钢的最大缓蚀率分别为：98.6%和94.6%,且二者均是主要控制阴极抑制型缓蚀剂。在含SRB饱和CO2介质中,月桂酸和硫脲的缓蚀性能下降,缓蚀率分别只有62.9%和53.5%,且碳钢试片表面出现大量腐蚀坑。菌量测定结果表明,月桂酸和硫脲能够促进SRB生长,且SRB代谢产物阻碍月桂酸和硫脲在碳钢金属表面吸附,因此,这两种缓蚀剂均不适用于含有SRB的工况环境中。
Corrosion inhibition performance of common inhibitors such as lauric acid and thioure for carbon steel in a CO2-saturated and SRB-containing artificial sewage was studied by means of electrochemical methods, mass loss method, three-dimensional stereoscopic microscope and quantitative measurement of the bacteria amount. The results show that in a sterilized and CO2-saturated medium, the inhibition efficiencies of lauric acid and thiourea were 98.6%, 94.6% respectively; the two inhibitors lauric acid and thiourea were all mix-type inhibitors which mainly suppress the cathodic process. In the SRB-containing and CO2-saturated medium, lauric acid and thiourea exhibit low inhibition efficiency: 62.9% and 53.5%, respectively, while there exist a lot of corrosion pits on the steel surface; and the inhibitors lauric acid and thiourea can promote the growth of SRB, while the metabolites of SRB prevent the adsorption of lauric acid and thiourea on the metal surface. Therefore, the two inhibitors may not be suitable to apply in those SRB-containing environments.
采用动电位极化、电化学阻抗谱技术、Mott-Schottky等测试方法,研究了温度对X70钢在高pH值溶液 (0.5 mol/L Na2CO3+0.5 mol/L NaHCO3) 中钝化膜性能和电化学腐蚀行为的影响。结果表明：随着温度升高,X70管线钢的点蚀电位降低,维钝电流密度和钝化膜的极化电阻减小。在实验温度范围内,钝化膜为Fe2O3和Fe3O4的混合物,半导体类型为n型半导体,且不随温度升高而改变。但是随着温度的升高,钝化膜缺陷密度增加,膜厚度减小,腐蚀倾向增大。因此,温度升高会降低钝化膜的稳定性,导致其保护作用下降。
Effect of temperature on corrosion behavior of X70 pipeline steel in high pH solution (0.5 mol/L Na2CO3+0.5 mol/L NaHCO3) was studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy and Mott-Schottky measurements. Results showed that the pitting potential, passive current density and the polarization resistance of X70 pipeline steel all decreased with the increase of temperature. In the experimental temperature range, the formed passive film consisted mainly of Fe2O3 and Fe3O4 with features of n-type semiconductor. With the rising temperature, the thickness and donor density of the passive film increased, correspondingly, corrosion tendency of the steel increased. Therefore, the stability of the passive film decreased with the increasing temperature, which weakened the corrosion resistance of the X70 steel.
通过土壤理化性质分析、现场埋样的腐蚀形貌观察、腐蚀产物的扫描电镜观察和X射线衍射分析以及腐蚀失重实验等分析手段,研究了国产X70钢和Q235钢在新加坡土壤中现场埋样1 a后的短期腐蚀行为特征。结果表明,新加坡土壤属于酸性土壤；埋样1 a后Q235钢平均腐蚀速率略大于X70钢,两种钢以局部腐蚀为主,Q235钢的局部腐蚀较严重；两种钢的腐蚀产物组成相似,均为Fe2O3,Fe3O4,FeOOH和FeOCl,腐蚀产物表面粗糙,存在裂纹与空隙,从而加速局部腐蚀的进行。
The short-term corrosion behavior of X70 steel and Q235 steel buried for 1 a in soil of a select site at Singapore were investigated in terms of characterizing the corrosion products by means of scanning electron microscopy and X-ray diffraction, as well as the physical and chemical parameters of the soil, and measuring the corrosion mass lass. It was found that the soil at the select site was an acidic soil; where the average corrosion rate of Q235 steel was higher than that of X70 steel; the two steels all suffered form local corrosion, while that of Q235 steel was more serious; the corrosion products of these two steels were similar and mainly composed of Fe2O3, Fe3O4,FeOOH and FeOCl, the surface of products were rough and there were some cracks in the products scale, which seemed harmful to its protectiveness.
The corrosion resistance of X80 pipeline steel modified by using plasma nitriding technique was investigated in a simulated soil solution of the Yingtan area in the south-east of China. The results show that the as-plasma nitriding treated steel exhibit higher corrosion resistance rather than the bare X80 steel. The nitriding treatment resulted in the formation of a surface layer composed of nitrides of ε phase and γ ' phase as well as solved nitrogen, which could not only shift the corrosion potential positively, but also reduce greatly the corrosion current density, thus lowering the corrosion velocity. The corrosion current density of the as-plasma nitriding treated steel increases with the increasing immersion time. However, for the long term, micro-pores and cracks could occur in the corrosion product film, thereby the corrosion was accelerated.
A new solid compound inhibitor was prepared using solid 1,3-benzendiamine, potassium thiocyanate and methenamine as main raw materials. The corrosion inhibition behavior of the inhibitor for 20 carbon steel in pickling solutions (10% hydrochloric acid, 10% sulfuric acid and 10% nitric acid) were studied by static mass loss method, Tafel polarization curves and EIS test. The results show that with a dose 0.5% of the inhibitor the corrosion inhibition efficiencies for 20 carbon steel are all higher than 80% in the above-mentioned three acid solutions, among them the highest is 99.1% for the steel in 10% nitric acid. Results of Tafel polarization curves and EIS measurement show that the addition of the inhibitor can significantly reduce the corrosion rate of 20 carbon steel, which demonstrated the new inhibitor could form a film with excellent corrosion protectiveness on the surface of 20 carbon steel.
采用阴极极化、扫描电子显微镜 (SEM) 和定氢仪分析,研究了不同时效状态的7050铝合金C-环在3.5%NaCl水溶液中的应力腐蚀行为。结果表明：7050铝合金恒位移试样C-环时效后的应力腐蚀敏感性 (Iscc) 变化规律为：Iscc欠时效 (135 ℃/8 h)>Iscc峰时效 (135 ℃/16 h)>Iscc过时效 (135 ℃/24 h)。在一定范围内施加阴极极化电位,7050铝合金材料发生阴极腐蚀,从而促进裂纹萌生。对相同时效状态的7050铝合金,C-环断口的氢渗透速率随着极化电位的负移而增加,从而导致合金的Iscc增加。
The effect of cathodic polarization on stress corrosion cracking (SCC) behavior of C-ring specimens of 7050 aluminum alloys of different aging states in 3.5% sodium chloride aqueous solution has been investigated, then the hydrogen content of the tested samples was measured by a hydrogen analyzer and the fractured alloy samples were examined by means of scanning electron microscope (SEM). The results showed that according to their aging states, the degree of susceptibility to SCC (Iscc) of 7050 aluminum alloy may be ranked as following: Iscc of under-aging (135 ℃/8 h)>Iscc of peak-aging (135 ℃/16 h)>Iscc of over-aging (135 ℃/24 h). When applying a cathodic polarization potential to C-ring specimen, the cathodic corrosion of 7050 aluminum alloy may promote the crack growth. For 7050 aluminum alloys after the same aging treatment, the hydrogen permeation rate of the C-ring fracture surface increased with shifting negatively the cathodic polarization, thus resulting in the increase of Iscc.
研究了在钛铝金属间化合物上涂覆的一种20~40 μm厚的新型搪瓷涂层在700 ℃条件下1000 h高温氧化和硫酸盐+NaCl热腐蚀600 h的高温腐蚀行为。结果表明,搪瓷涂层具有很高的高温稳定性,在长时间的实验中有效地避免了基体的高温腐蚀,涂层未出现开裂或剥落。在涂层制备过程和高温腐蚀测试过程中,在涂层/基体界面发生了界面反应,形成了由α-Al2O3、TiO2、Al2SiO5和Al2TiO5组成的薄氧化物层。
A novel enamel coating of 20~40 μm thick was prepared on γ-TiAl intermetallics. Of which the air oxidation and (Na, K)2SO4+25%NaCl (mass fraction) deposits induced hot corrosion were studied in air at 700 ℃ for 1000 and 600 h respectively. It is revealed that the enamel coating was stable, and able to prevent the substrate from high temperature oxidation and hot corrosion during tests. Neither cracks nor spallation of enamel coatings was observed after tests. Interfacial reactions at the coating/substrate interface took place during the coating preparation and high temperature tests, thereby resulted in the formation of a thin oxide layer consisted of α-Al2O3, TiO2, Al2SiO5 and Al2TiO5.
The electrochemical performance of sacrificial anode material Al-Zn-Ga-Si alloy was evaluated by constant current test in seawater at different temperatures, while its electrochemical impedance spectroscopy was investigated by EIS. The results showed that the working potential of the alloy exhibits a tendency of positive shift with the decreasing of seawater temperature, however, which varied from -0.770~-0.850 V (vs Ag/AgCl seawater). After electrochemical performance test in seawater at low temperature, the alloy exhibited a surface morphology with characters of localized corrosion, which may be due to that the diffusivity of the dissolved metal ions on anode surface was suppressed.
针对化学微蚀刻法和微细电镀法制备微流控芯片金属模具进行了工艺对比研究。采用激光共聚焦显微镜分别检测表征由这两种加工工艺制备所得的模具微结构特征,对其侧壁陡度、尺寸均匀性、粗糙度进行对比分析。结果表明,化学微蚀刻法制备的模具微结构的侧壁呈不规则弧形、尺寸均匀性差,表面粗糙度较大 (Ra=3.58 μm)。而微细电镀法制备的模具微结构的侧壁则呈规则的梯形、尺寸均匀性好,表面粗糙度较小(Ra=0.65 μm)。微细电镀法制备的微流控芯片金属模具综合效果比化学微蚀刻好。
The features of micro-chemical etching and micro-electroplating processes for preparing metal mold of microfluidic chips have been comparatively studied. The micromorphology of the fabricated molds was characterized in terms of sidewall steepness, dimensional uniformity and surface roughness by means of laser scanning confocal microscopy. The results show that, for the mold fabricated by micro-chemical etching, there exist irregular curved sidewall and worse dimensional uniformity and its surface roughness Ra is up to 3.58 μm；by contrast, for the mold prepared by micro-electroplating there exist regular trapezoidal sidewall and better dimensional uniformity and its surface roughness Ra is only 0.65 μm. In short, the mold of microfluidic chips fabricated by micro-electroplating is better than that by micro-chemical etching.
针对以次磷酸钠为还原剂的印制线路板 (PCB) 化学镀铜体系,探讨了络合剂乙二胺四乙酸二钠 (EDTA2Na) 和酒石酸钾钠对次磷酸钠化学镀速和镀液稳定性的影响,使用线性扫描和循环伏安法研究其电化学行为。结果表明,EDTA2Na和酒石酸钾钠均能稳定化学镀铜液,改善镀层质量,前者降低化学镀速,后者对化学镀速先增大后降低,其适宜浓度分别为12和9.6 g/L。随着络合剂EDTA2Na浓度增加,铜阴极还原峰电流逐渐减小,次磷酸钠阳极氧化影响不明显。随着酒石酸钾钠浓度增加,铜阴极还原峰和次磷酸钠阳极氧化峰电流均先增大后减小。
The influence of complex agents (edetate disodium, potassium sodium tartrate) on the stability of the bath containing sodium hypophosphite and the electroless Cu-plating rate was investigated. Then, the electrochemical properties of the Cu-coating were examined by means of linear sweep and cyclic voltammetry. The results show that with addition of EDTA2Na, the cathodic reduction peak current increases and the anodic oxidation peak current changes less; with the increase of potassium sodium tartrate the cathodic reduction peak current and anodic oxidation peak current first increases and then decreases; both of EDTA2Na and potassium sodium tartrate can improve the stability of electroless plating bath and the quality of Cu coatings, of which the former reduced, while the later increased initially and then decreased the plating rate; correspondingly the appropriate dosages are 12 and 9.6 g/L, respectively for the two complex agents.
以某炼油厂的渣油循环水换热器腐蚀为例,对循环水水质进行分析,利用扫描电镜 (SEM)、能谱分析 (EDS) 和X射线衍射 (XRD) 等手段,结合循环水的水质分析结果和内表面腐蚀产物分析确定了换热管内壁腐蚀属于垢下的微生物SRB腐蚀,XRD分析出外壁腐蚀产物有Cl和S共存,确定了外壁腐蚀属于HCl与H2S的循环腐蚀。本文综合各类防腐方法,采用粉末渗锌法缓解此类腐蚀的措施,提出了利用磁性换热管抗腐蚀新的防腐方法。