反应型乳化剂及其水性环氧涂料的制备和耐蚀性能

目的 制备一种低VOC、低毒性的水性环氧树脂涂料。方法 通过N,N-二甲基乙二胺与环氧树脂E51反应,然后利用冰乙酸中和成盐,制得一种反应型水性环氧树脂乳化剂,再与环氧树脂E51及四种胺类固化剂（651、GT19、DL19、SG）按一定的比例混合搅拌均匀,于电极表面涂覆,固化成膜后封装。采用显微红外光谱仪（Micro-FTIR）表征乳化剂的结构,采用动态光散射粒度分析仪（ZETA）测试乳化剂乳化E51后得到的乳液粒径。通过电化学阻抗谱和极化曲线测试,研究四种固化剂固化成膜的水性环氧涂层在3.5% NaCl溶液中的耐蚀性。结果 当乳化剂与E51的质量比为1∶1时,乳液平均粒径最小为52 nm,分布最均匀,体系最稳定。用固化剂651固化得到的涂层硬度最高,附着力最强,交联密度最高,涂层断面较为致密,在浸泡60 h后,仍具有较高的阻抗模值5.23×104 Ω×cm2和较低的自腐蚀电流密度2.0×10-7 A/cm2,对基底具有较好的腐蚀防护作用。结论 制得的水性环氧树脂涂料对基底具有良好的防护性能,适用于环保型低VOC涂料领域。     

Tribological and electrochemical performances of Cr/CrN and Cr/CrN/CrAlN multilayer coatings deposited by RF magnetron sputtering

CrN/CrAlN and Cr/CrN/CrAlN multilayers were grown with dual RF magnetron sputtering. The application of these multilayers will be wood machining of green wood. That is why ball-on-disc and electrochemical tests in NaCl aqueous solution were realized to elucidate the tribological and corrosion behavior of these coatings as they will be exposed to wear and corrosion during wood machining process. The samples/alumina and samples/WC coupling showed different wear mechanisms. The 300 nm thick Cr/CrN/CrAlN multilayer demonstrated the best tribological behavior and corrosion resistance. The influence of growth defects on corrosion resistance has been shown.     

Fe-based soft magnetic amorphous alloys with high saturation magnetization above 1.5 T and high corrosion resistance

Fe-rich amorphous alloys with minor-addition of Cr and/or Nb were examined with the aim of developing Fe-based amorphous alloys exhibiting simultaneously high saturation magnetization above 1.5 T and good corrosion properties. Fe₈₂Cr₂B₈P₄Si₃C and Fe₈₂NbB₉P₄Si₃C amorphous alloys were found to exhibit high saturation magnetizations of 1.49 T and 1.57 T, respectively, and rather good corrosion resistance in 3.5 mass% NaCl solution at 298 K. The minor-addition of Cr or Nb enables the formation of amorphous alloy particles without harmful oxide layer by water atomization process which makes these alloys suitable for applications as soft magnetic core materials. The addition of 1 at% Nb improved the corrosion resistance through the increase in E_corr value, which makes easy to reach passive state, and the suppression of pitting corrosion. Besides, it has been proved that the simultaneous addition of Nb and Cr has an effect on forming protective passive film.     

Influence of an aerated/anoxic transient phase on the long-term corrosion of iron

This paper deals with the influence of an aerated/anoxic transient phase on the corrosion of ferrous matters. Actually in the context of radioactive waste disposal, metallic components could be exposed to fluctuating environmental conditions that could change the corrosion mechanisms and influence the corrosion rates. Archaeological analogues corroded in an aerated soil were exposed to an aerated/anoxic transient in an isotopic labeled solution. The corrosion mechanism in anoxic conditions does not seem to be influenced by the pre-existing thick corrosion layer formed in an aerated environment and the estimated corrosion rate is of few micrometres per year.     

Molecular dynamic and quantum chemical calculations for phthalazine derivatives as corrosion inhibitors of mild steel in 1 M HCl

The abilities of phthalazine derivatives, including phthalazine (PT), phthalazone (PTO) and phthalhydrazide (PTD), to inhibit the corrosion of mild steel in 1 M HCl at 30 °C were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Theoretical calculations were performed to investigate the electronic structures of the PT derivatives. Our results showed that the inhibition efficiencies of these derivatives improved with increases in concentration. The data also showed that PTD < PT < PTO in terms of the inhibiting efficiency. Theoretical calculations also revealed that PTO is expected to be the best inhibitor among the studied phthalazine derivatives.     

Raman scattering analysis of disorder in heterogeneous (GaAs)1−x(SiC2:H)x films grown by metal-organic chemical vapour deposition

A chemical and structural analysis of (GaAs)_1−x(SiC₂:H)_x films is performed by using the Raman scattering probe. A multizone structural model is evidenced in accordance with previous X-ray and electron diffraction experiments. The ability of a spatial correlation model to account for the lineshape evolution of the spectra of the GaAs phase is discussed for the first time for both longitudinal optical and transverse optical modes. The values of the “Raman size” of the GaAs crystallites lie well below those deduced from diffraction experiments, revealing the presence of many internal defects which greatly influence the electron-phonon interactions.     

Computer simulation of spinodal decomposition in ternary systems

The non-linear spinodal decomposition kinetics of a quenched homogeneous ternary alloy within three- or two-phase fields is modeled using a computer simulation technique formulated in the reciprocal lattice. Based on two-dimensional computer simulations, it is shown that, similar to binary alloys, spinodal decomposition in a ternary system usually produces interconnected morphologies at the very early stages of decomposition. For most of the compositions investigated, a decomposition of a homogeneous phase into three phases takes place in two stages. For some compositions, the two stages are the phase separation of an homogeneous phase into two phases, followed by further phase separation of one of the two phases into another two phases, resulting in a three-phase mixture. For other compositions, the first stage is a phase separation of an initially homogeneous phase into a two-phase mixture followed by a second stage, the appearance of a third phase along the existing interphase boundaries. This sequential phase separation in a ternary alloy can be justified from a thermodynamic stability analysis combined with the knowledge of the thermodynamic driving force for phase separation. It is also demonstrated that a third minor component strongly segregates to interphase boundaries during spinodal decomposition and subsequent coarsening of a homogeneous ternary alloy into two phases.     

Progress in modelling of solutions

Thermodynamic modelling of solutions is reviewed based on a recent workshop at Schloss Ringberg. Although many recommendations were made, many subjects for future efforts are identified.     

Adaptive calibration and control of 2D monocular visual servo systems

For most visual servo systems, accurate camera/robot calibration is essential for precision tasks, such as tracking time-varying end-effector trajectories in the image plane of a remote (or fixed) camera. This paper presents details of control-theoretic approaches to the calibration and control of monocular visual servo systems in the case of a planar robot with a workspace perpendicular to the optical axis of the imaging system. An on-line adaptive calibration and control scheme is developed, along with an associated stability and convergence theorem. A redundancy-based refinement of this scheme is proposed and demonstrated via simulation.