纳米铁粉改性电解磷化膜的研究

利用电化学测试技术、扫描电子显微镜和X射线衍射仪对纳米铁粉改性的电解磷化膜的性能进行了研究。结果表明:在电解磷化液中加入纳米铁粉后,磷化晶粒呈颗粒大小均匀致密的片状结晶,制得的电解磷化膜的交流阻抗明显增大,自腐蚀电流降低。     

快速电化学磷化实验研究

在常温工况下,将电化学方法与磷化处理相结合,加速磷化液中各离子的扩散,使磷化时间保持在10 min以内。对电化学磷化方法中的各影响因素进行对比实验后发现,在常温工况下的最优磷化处理条件为马日夫盐浓度30~50 g/L,硝酸锌浓度50~70 g/L,电流密度1.00~1.50 A/dm2,电化学磷化时间5~7 min。在此条件下所制得的结晶型磷化膜综合性能最佳。分析测试表明:磷化膜主要包括O、Zn、P、Mn、Fe元素,且磷化膜耐腐蚀性强,晶体均匀致密,富有层次感,易于涂层材料附着。     

硅烷工艺与电泳漆配套性实验研究

对硅烷和磷化电泳漆膜的性能进行测试,尤其是研究硅烷膜对电泳泳透力的影响,说明在硅烷新工艺进行推广应用时,要关注工艺参数的设计。     

车身磷化膜发黄、发蓝的原因探讨

磷化是汽车前处理的一个关键工序,磷化膜的质量对车身电泳漆膜的质量影响较大。根据现场积累的经验,探讨了生产中磷化膜常见的发蓝、发黄缺陷的产生原因及解决方法。     

环氧树脂/氧化锌晶须/氮化硼导热绝缘复合材料的研究

以环氧树(脂EP)为基体,分别以氧化锌晶(须ZnOw)和ZnOw/氮化硼(BN)混合物为导热填料,制备了EP导热绝缘复合材料。研究了填料含量对复合材料导热性能、电绝缘性能及力学性能的影响,并利用扫描电镜对复合材料的断面形貌进行了观察。结果表明:随着导热填料含量的增大,复合材料的导热系数和介电常数增大,体积电阻率下降,而拉伸强度呈先增大后减小的趋势;在填料含量相同的情况下,EP/ZnOw/BN复合材料比EP/ZnOw复合材料具有更好的导热性能;当填料体积分数为15%时,EP/ZnOw/BN复合材料的热导率为1.06W/(mK)而,EP/ZnOw复合材料的热导率仅为0.98W/(mK)。     

Effects of coating thickness and surface treatment on the corrosion protection of diglycidyl ether bisphenol-A based epoxy coated carbon steel

The corrosion resistance of carbon steel specimens was compared, using different surface treatment methods such as blasting and zinc phosphate treatment on carbon steel followed by application of different coating thickness. Specimen surface morphology was observed by SEM. The corrosion performance of epoxy coated carbon steel was examined by electrochemical impedance spectroscopy (EIS), along with immersion test in 0.5N-NaCl solution and NORSOK M 501 cyclic test, respectively. EIS results showed that higher thickness of epoxy coating and zinc phosphate treatment on carbon steel showed better corrosion protection than rest of the specimens. Specimens with no treatment and blasting treatment followed by epoxy coating, showed poor corrosion protection. Results of NORSOK M 501 cyclic test showed similar trend as those of EIS results however degradation of specimens was more severe than those from immersion test.     

X-ray absorption spectroscopy characterization of Zn underpotential deposition on Au(1 1 1) from phosphate supporting electrolyte

Zn K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the structure of Zn monolayers prepared on Au(1 1 1) electrodes via underpotential deposition (UPD) from phosphate supporting electrolyte. Theoretical modeling of the XAS data indicates that the Zn adatoms adopt a commensurate (√3 × √3)R30° (θ_sc = 0.33) adlayer structure and reside within the 3-fold hollow sites of the Au(1 1 1) surface. Meanwhile, phosphate counter-ions co-adsorb on the UPD adlayer and bridge between the Zn adatoms in a (√3 × √3)R30° (θ_sc = 0.33) configuration, with each phosphorous atom residing above a vacant 3-fold hollow site of the Au(1 1 1). Significantly, this surface structure is invariant between the electrochemical potential for UPD adlayer formation and the onset of bulk Zn electrodeposition. Analysis of the Zn K-edge absorption onset also presents the possibility that the Zn adatoms do not fully discharge during the process of UPD, which had been proposed in prior voltammetric studies of the phosphate/Zn(UPD)/Au(1 1 1) system.     

Effect of pH on the morphology and optical properties of modified ZnO particles by SDS via a precipitation method

ZnO particles were synthesized directly from an aqueous solution of zinc acetate dihydrate in the presence of sodium dodecyl sulfate (SDS) and sodium hydroxide at 70 °C. The morphological changes were investigated in the range of pH 8-12. The hexagonal prism-like shape was formed at pH 8 and 10 by inhibition of growth along the c direction whereas the small rod-like shape was observed at pH 12. The estimated band gap and the room temperature photoluminescence intensity in a visible region are dependent upon the geometrical shape and size of the ZnO particles.     

A novel mercury-media route to synthesize ZnO hollow microspheres

Zinc oxide (ZnO) hollow microspheres were prepared by templates of surfactant spheres in mercury-media for the first time. Field emission scan electron microscope (FESEM), X-ray diffraction (XRD), infrared spectra (IR) and N₂ adsorption–desorption analysis were used to characterize morphologies and structure features of the products. The obtained ZnO hollow microspheres are amorphous, 1–3 μm in diameter and 70–140 nm in wall thickness. After heat treatment at 500 °C for 2 h, the amorphous ZnO hollow spheres transform to hexagonal wurtzite structure ZnO, and retain hollow sphere morphologies. During the growth of ZnO hollow microspheres, Zn is oxidized at mercury/air interface and the formed ZnO nanoparticles are assembled on the surface of surfactant spheres. PEG plays an important role for the synthesis of ZnO hollow microspheres.     

CuO and CuO-ZnO catalysts supported on CeO2 and CeO2-LaO3 for low temperature water-gas shift reaction

This paper describes an investigation on CuO and CuO-ZnO catalysts supported on CeO₂ and CeO₂-La₂O₃ oxides, which were designed for the low temperature water-gas shift reaction (WGSR). Bulk catalysts were prepared by co-precipitation of metal nitrates and characterized by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), surface area (by the BET method), X-ray photoelectron spectroscopy (XPS), and in situ X-ray absorption near edge structure (XANES). The catalysts' activities were tested in the forward WGSR, and the CuO/CeO₂ catalyst presented the best catalytic performance. The reasons for this are twofold: (1) the presence of Zn inhibits the interaction between Cu and Ce ions, and (2) lanthanum oxide forms a solid solution with cerium oxide, which will cause a decrease in the surface area of the catalysts. Also the CuO/CeO₂ catalyst presented the highest Cu content on the surface, which could influence its catalytic behavior. Additionally, the Cu⁰ and Cu¹⁺ species could influence the catalytic activity via a reduction-oxidation mechanism, corroborating to the best catalytic performance of the Cu/Ce catalyst.