The inhibitive performance of polyphosphate-based anticorrosion pigments using electrochemical techniques

Electrochemical impedance spectroscopy and linear polarization revealed the superiority of zinc aluminum polyphosphate compared to strontium aluminum polyphosphate. Film formation on the surface of steel samples was confirmed for both pigments through surface analysis. However, scanning electron microscopy and energy dispersive X-ray analysis showed that the composition and morphology of the precipitated layers were different for the two types of pigments.     

The impact of pigment volume concentration on the protective performance of polyurethane coating with second generation of phosphate based anticorrosion pigment

In this study the effect of conventional zinc phosphate and zinc aluminum phosphate, which represents second generation of phosphate based anticorrosion pigments, on the performance of a polyurethane coating was studied. While zinc phosphate modification was proved to be effective on the corrosion resistance, EIS data facilitated the determination of the optimum pigment volume concentration in which the coating offered the most efficient protection. The superiority of zinc aluminum polyphosphate was attributed to the release of more inhibiting species, leading to the formation of a protective layer at the coating/substrate interface. In addition to the assessment of the impact of pigment content on the resistance of polyurethane primer to cathodic disbonding, the dependency of adhesion strength on the pigment type was also studied using pull-off test.     

新一代金刚石工具及其性能分析

新一代金刚石工具以金刚石颗粒有序排列为主要特征,其性能比金刚石颗粒随意分布的传统金刚石工具优越.ARIX工艺制造的金刚石有序排列的锯片消除了传统金刚石锯片使用中提高锯切速率而导致寿命降低的问题.钎焊单层金刚石磨具由于其中的金刚石颗粒以一定间距有序排列成一定形式而且金刚石出刃较高,与其它结合剂金刚石磨具相比,可达到较高的加工效率和表面光洁度.     

Study of impedance model and water transport behavior of modified solvent-free epoxy anticorrosion coating by EIS

This paper studies the evolution of impedance model of 30 μm solvent-free epoxy coating on Q235 steel surface in 3.5% NaCl solution using electrochemical impedance spectroscopy. The electrochemical process of the system was divided into five stages. Water absorption occurred at the coating mainly during the early stage of immersion. In the meantime, coating resistance became smaller and coating impedance deviated from purely capacitive characteristics. After water permeated into the metal/coating interface, corrosion reaction began. During the middle stage of immersion, due to the barrier effect of the coating, the electrochemical reaction at the coating/metal interface was controlled by diffusion of corrosion products. Since the coating prepared was relatively thin, transport distance was short for water, which could easily reach the coating/metal interface. During the middle-late stage of immersion, coating peeled off from the metal surface, diffusion of water molecules gradually turned to a macroscopic infiltration process, and the coating lost its protective effect. A logarithm of coating capacitance and the square root of time showed a linear relationship in the early immersion stage, which was a typical characteristic of Fick’s diffusion. Water diffusion coefficient in the coating was calculated to be 8.23 × 10^?11 cm²/s, while volume fraction and total water absorption at saturation of coating were 3.5% and 105 μg/cm², respectively, indicating good water resistance and protective properties of the coating. By solving the Fick’s diffusion equation, the kinetic equation which described the diffusion of water in the coating and included time and location variables were obtained.     

Some comments on the use of the EIS phase angle to evaluate organic coating degradation

The impedance of a disc electrode protected by an organic coating, with a thickness profile along its radius, was considered by EIS. The local and global impedances, the ohmic resistance corrected phase angle, and raw phase angle were calculated. The thickness profile leads to a well-defined minimum in the calculated phase angle curves, which can be observed in the high frequency domain. This effect is enhanced with higher permittivity, thinner coatings and low conductivity immersion baths. From these results, it appears that the graphical treatment of experimental phase angle curves to evaluate the coating degradation may lead to erroneous conclusions.     

Fabrication of ZnO-functionalized polypyrrole microcomposite as a protective coating to enhance anticorrosion performance of low carbon mild steel

In the present work, PPy, ZnO, and polypyrrole/zinc oxide (PPy/ZnO) microcomposites (1, 2, and 5 wt%) were prepared and their properties have been tuned for anticorrosion applications on low carbon mild steel. The synthesized products: ZnO, PPy, and composites were characterized by various sophisticated analytical techniques such as XRD, FTIR, Raman, FESEM, EDX, UV–VIS, TGA, and BET. The band frequencies observed at 480 and 588 cm⁻¹ in FTIR spectrum correspond to stretching vibrations of Zn-O and N-H bonds, respectively, broadening of the bands in the composites indicate strong interactions between ZnO and PPy matrix. The potentiodynamic polarization study of PPy and PPy/ZnO composite was carried out in 3.5% NaCl solution to investigate the corrosion resistance efficiency. PPy/1 wt% ZnO (I_corr = 190 nA) composite coating on low carbon mild steel was observed to exhibit best corrosion protection property compared to PPy (121 μA), 2 and 5 wt% ZnO (242, 295 nA) composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48319.     

In Situ crystallization to zinc aluminate films with controlled surface microstructure and anticorrosion performance

Spinel‐type zinc aluminate (ZnAl₂O₄) thin films with controlled surface microstructure on aluminum substrates were fabricated via a facile and effective in situ crystallization method without using any templates or surfactants. The surface microstructure of ZnAl₂O₄ films could be significantly controlled by varying the experimental conditions including concentration of reactants, crystallization temperature, and crystallization time. After surface modification, the specific topography of ZnAl₂O₄ films was beneficial to obtain surface hydrophobic or superhydrophobic properties. More importantly, compared to nanoparticle‐ and nanosword‐assembled ZnAl₂O₄ films, nanorod‐assembled ZnAl₂O₄ film provided a more effective barrier to aggressive species for aluminum substrates in a wide range of pH values; very low corrosion current density of the order of ～10^?19 A cm^?12 could be achieved. A new contribution to the development of advanced coating system with ZnAl₂O₄ film materials that can be used in practical application for corrosion protection of aluminum materials is provided. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

颜填料对EP改性有机硅粘接涂层耐高温性能和防腐性能的影响

以环氧树脂(EP)改性有机硅树脂作为基体树脂,通过加入锌铬黄和铁红等填料,配制成一种耐高温、防腐蚀性的粘接底层;以有机硅树脂为基体树脂,通过加入锐钛型钛白粉和纳米SiO2,配制成具有一定遮盖力和耐高温性能的粘接面层。对涂敷底层和面层的马口铁试片进行耐高温性能和耐腐蚀性能测试,并采用金相显微镜和扫描探针分别对底层、面层和(含底层/面层的)双层粘接涂层的微观结构进行表征。结果表明:当底层中的颜基比为1.4∶1时,粘接涂层可耐400℃高温,在各种介质中浸泡72h后,粘接涂层表面没有开裂现象;当底层中的颜基比为1.7∶1时,其填料在树脂中分散得比较均匀,两者间的结合效果较好,该粘接涂层可耐400℃高温,但耐腐蚀性能相对较差。     

水性聚氨酯的蓖麻油和环氧改性及其富锌涂层耐蚀性能研究

以蓖麻油和环氧树脂为改性剂,对水性聚氨酯进行了改性,乳液红外分析证实了改性剂的有效接枝.改性后的聚氨酯其耐水性得到明显提高,吸水率降至3%以下.通过扫描电镜(SEM)、腐蚀电位和电化学阻抗谱(EIS)等方法对改性聚氨酯的富锌涂层进行了表征.结果表明,改性水性聚氨酯言锌涂料具有良好的耐蚀性;随着锌粉含量的增加,涂层耐蚀性提高.     

氟硅丙烯酸酯/钠基蒙脱土复合乳胶涂层的制备及防腐蚀性能

以甲基丙烯酸十二氟庚酯和乙烯基三甲氧基硅烷为功能单体,采用种子乳液聚合法合成氟硅丙烯酸酯乳液(氟硅),然后将钠基蒙脱土(钠土)分散于其中,制成复合乳胶涂层并涂覆在Q235钢上。研究了乳液种类和钠土用量对涂层防腐性的影响。采用红外光谱(FT-IR)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)表征了氟硅丙烯酸酯乳液和涂层。通过极化曲线、交流阻抗测量和中性盐雾试验探讨了复合涂层的耐腐蚀性。结果表明,乳胶粒子呈核壳结构,涂层连续、致密,钠土在涂层中分散均匀。当钠土用量为4%时,复合涂层的耐蚀性最好,水接触角达到102.4°,附着力为0级,电化学阻抗达到104.4Ω,腐蚀速率仅为4.3×10-5 mm/a,盐雾试验240 h后膜下金属未发生腐蚀扩散。     

活性硅醇基聚氨酯水分散体的合成及其防腐性能

水玻璃作为一种廉价的矿物质,经提纯可得到活性硅醇,以其作为内交联剂可应用于聚氨酯的合成中。对不同活性硅醇添加量合成的聚氨酯水分散体粒径及其涂膜的吸水率、接触角、动电位极化曲线、热重和扫描电镜作了测试分析,结果表明当活性硅醇添加量为30%时,水分散体平均粒径最小,为28.83nm;随着活性硅醇添加量的增加,涂膜吸水率增大,接触角反而减小;动电位极化曲线拟合结果表明,当活性硅醇添加量为70%时,涂膜腐蚀电流密度最小且极化电阻最大;红外光谱和扫描电镜分别可以确定水分散体结构中含有Si-O-Si、Si-O-C的基团以及涂膜中含有二氧化硅粒子,说明活性硅醇在体系中不仅参与主链反应,还以无机粒子的形态存在于其中;热重分析表明活性硅醇的引入显著提高了涂膜的热稳定性。     

聚吡咯–聚N-甲基吡咯复合涂料的制备及防腐性能

以三氯化铁为氧化剂,对甲苯磺酸为掺杂剂,采用化学氧化聚合法制得均聚物聚吡咯(PPy)、聚N-甲基吡咯(PNMPy)和共聚物聚吡咯–聚N-甲基吡咯(PPy–PNMPy)。通过扫描电镜、X射线衍射仪、紫外可见分光光度计、傅里叶变换红外光谱仪表征了3种聚合物的微观结构。采用电化学方法和腐蚀溶液浸泡法对比研究了裸钢片、PU(聚氨酯)涂层以及PU–PPy、PU–PNMPy和PU–PPy–PNMPy复合涂层的防腐性能。结果表明,共聚物PPy–PNMPy的致密性优于均聚物PPy和PNMPy。PU–PPy–PNMPy复合涂层的防腐性能和力学性能最优。     

The use of momentum ratio to evaluate the performance of CSTRs

In this study, the residence time distribution of a CSTR was measured and analysed for variations in CSTR feed geometry, impeller speed and inlet flow rate. The measured residence time distributions were also used to characterise the degree of plug flow behaviour and short-circuiting. The data showed that the performance of a CSTR could not be evaluated using the ratio of the mean residence time to the batch-mode mixing time (τ/t_M), and that this approach can lead to process over-design and excessive energy requirements. Instead, it was shown that all process parameters could be correlated using the ratio of the inlet jet momentum to the impeller discharge momentum. The prediction of the degree of short-circuiting and plug flow in the CSTR could be used to improve process control. In addition, the results can be used to identify whether the inlet position or diameter of an existing CSTR should be modified to improve process performance.     

汽车用车身材料不同油漆前处理微观结构及防腐能力

利用扫描电镜(SEM)观察了电镀锌、热镀锌、热镀锌镁合金的软钢,带铝硅涂层的热成型钢,以及铝板等车身常用板材经磷化或薄膜处理后的表面微观结构,通过中性盐雾试验考察了2种前处理的耐腐蚀能力。结果表明,薄膜处理的结晶没有磷化致密,且结晶大小也会因为涂层类型的不同而相同。薄膜处理的防腐能力在不同涂层上的表现有所不同,结晶越致密越好,结晶大小与防腐性能无关。薄膜处理更注重与电泳漆的结合性能。     

ATRP grafting from silica surface to create first and second generation of grafts

Summary (11'-Chlorodimethylsilylundecyl)-2-chloro-2-phenylacetate 2 as an atom transfer radical polymerisation (ATRP) initiator was bound covalently to the surface of silica. ATRP grafting of styrene monomer from the silica surface was achieved and the grafts were detached from the solid particles for analysis. It is shown that after polymerisation of a first generation of grafts and work-up of the thus grafted silica the chain ends of the grafts are still active to initiate a second monomer feed to further chain growth. Received: 17 July 1999/Revised version: 12 December 1999/Accepted: 10 January 2000     

水质稳定剂TJ-302的合成及其阻垢性能研究

以马来酸酐、丙烯酸和含磷化合物为主要原料，在水相中一步合成出含膦马-丙多元共聚物TJ-302；筛选出一种阻垢增效剂，并对其阻垢性能进行了测试。结果表明：在相同的质量浓度40mg／L下，TJ-302的阻垢率为94．9％，超过了分步合成后再复配的TJ-301的阻垢性能，且该药剂适用于较高pH(pH=9．2)；当阻垢增效剂质量浓度为2．00mg／L时，其阻垢率提高了4．3％。     

Investigation on anticorrosion performance of nano and micro polyaniline in new water-based epoxy coating

In this research, a micro polyaniline (MicroPAni) and a dispersion of nano polyaniline particles (NanoPAni) were used as anticorrosion additive in a new water-based epoxy coating. Both materials were added directly to a new water-based hardener (RIPI-W.B.H.). The resulted mixtures were homogenized and sonicated for size reduction and better particle dispersion. The average particle size of polyaniline in the hardener was determined using dynamic light scattering (DLS). Transmission electron microscopy (TEM) was used to observe the particle size of polyaniline in the final dried film. After applying the coatings on metal surface, anticorrosion performance and adhesion properties of the coatings were compared together with a reference coating using salt spray and cross-cut adhesion tests. The results showed that anticorrosion performance of coating containing NanoPAni was better than the one for coating containing MicroPAni. In addition, investigation on the morphology of metal-coating interface by scanning electron microscopy (SEM) technique in samples containing polyaniline after salt spray test showed stable oxide layer formation on metal surface, which will enhance the corrosion resistance.     

Preparation of a modified phosphate-based adhesive and its hot bonding performance on 316L stainless steel

In this study, a novel phosphate-based adhesive was prepared by using homemade aluminum phosphate as a matrix and by adding different fillers simultaneously. The effects of calcination temperature and filler composition on the bonding mechanism and high-temperature bonding strength of the adhesive for high-temperature alloys were studied. The results indicated that the crystalline transformation of AlPO₄ occurred at 500 °C. AlPO₄ has two crystalline forms at 500 °C: orthorhombic and hexagonal. The addition of CuO to the fillers resulted in the exchange of Fe and Cu at the substrate interface and enhanced the high-temperature bonding strength of the specimens. The maximum tensile strength of the specimens reached 3.9 MPa at 500 °C. These composites have potential applications in aviation, aerospace, and other fields.     

Using interface shear characteristics to evaluate the residual performance of asphalt pavements

Asphalt pavement interface is considered to provide adhesion between two asphalt mixture courses. However, the relationship between shear characteristics of interface and residual performance of asphalt pavement still requires further research. This study investigated the effect of traffic loading, service time and distress type on the shear characteristics of asphalt pavement interface. Leutner shear test was conducted on the cylindrical specimens drilled from highway field, and the specimens are divided according to locations, service time and distress types. Shear strength, fail displacement and flexibility of interface were employed to characterize shear characteristics respectively. The results indicate that, among the locations, interface of rutting locations show the lowest shear strength, fail displacement and flexibility. Moreover, the shear characteristics decrease along with increase of interface’s service time. Interface of specimens with 4-years-service time showed the similar shear characteristics with interface of rutting locations. It demonstrated that the pavement that had served for 4 years had a risk of distress due to the interface shear characteristics loss, which suggests that the residual performance of this pavement was inadequate. Alternatively, the shear characteristics at rutting location are better than that of upheaval location. This research shows a possible way of evaluating residual performance and distress risk of pavement based on interface shear characteristics, which may contribute to the future pavement evaluation and maintenance.