Applied Mechanics and Materials Vols. 229-231

Abstract: The self-lubrication Ni-P/PTFE co-coatings were obtained by chemical plating. The tribological properties of the co-coating were carried on by the MM-200 type abrasion, and the microstructure and compounds of this composition and surface morphology were described by using X-ray diffraction and scanning electron microscope separately. The Ni-P/PTFE co-coating still had a low friction coefficient and good wear resistance. This was due to the PTFE material structure with the twisted chain, helical characteristics of carbon nanotubes, and the hexagonal structure in connection with many unusual mechanical and chemical properties.

Abstract: The adsorption performance of Cr (VI) on activated sludge and the effect of adsorption time, pH, temperature on the adsorption and desorption were studied. The initial pH is important for biosorption, and the optimum effect on Cr (VI) biosorption is acquired within initial pH of 0.5-1.0. Activated sludge has high efficiency of treating low concentration Cr (VI) wastewater. The removal rate of Cr (VI) could reach 99% when the total concentrations of Cr (VI) were 10 mg/L. The results of static test showed that the adsorption equilibrium was reached within 60 min. The biosorption process was fitted into Langmuir and Freundlich isotherm adsorption equations. It is presumed that the progress of biosorption was reversible adsorption and irreversible adsorption simultaneously, however the reversible adsorption was more important in the biosorption and the adsorption belongs to physics adsorption.

Abstract: Brass and cooper are widely used in heat pump water heater as heat exchanger between refrigerant and water, and the scaling is seriously at 60°C. Study the precipitation characteristics of CaCO₃ is the first step to research anti-fouling technology. CaCO₃ precipitated on brass and copper coupons from 0.5mmol/l CaCO₃ solution by static reaction at 60°C. By weighing the coupons before and after experiments to get the mass of scaling and use Scanning Electron Microscope (SEM) to get the morphology. The results show that at the same condition there is more scaling on copper than brass; high pH not only makes more new crystal nuclei but also promotes square aragonite and calcite and square aragonite gradually recrystallizes to calcite; high pH makes both homogeneous and heterogeneous nucleation rate increasing, but the former increases more, so the scaling mass is bigger at low pH than high pH; under high temperature and supersaturation degree, very small and many crystals are the main substances covered metal surface and not big when scaling layer has been formed, but part of small crystals grow big and all three polymorphs existed but size and proportion were effect by temperature, concentration, pH and so on.

Abstract: The aromatization of n-hexane was studied over Zn-WC/HZSM-5 catalyst prepared by impregnation and reduction-carbonization method. The effect of zinc content on aromatization selectivity of Zn-WC/HZSM-5 was investigated. The results show that the 1% Zn-WC/HZSM-5 was the most active catalyst attaining an aromatic selectivity of 35% at 550°C, which was much higher than that of WC/HZSM-5. It was found experimentally that a proper amount of Zn and WC resulted not only in the higher selectivity of aromatization of n-hexane but also in decreasing of coke deposition.

Abstract: Pt-Sn/WC(O)/C catalysts with different Pt/Sn molar ratio have been prepared by microwave-assisted reduction method. In the synthesis, PtSn alloy was supported on WC(O)/C which was synthesized by the temperature-programmed carburization after the pretreatment of AMT precursor. XRD result shows that Pt particles are reduced successfully. Compared to the reflections of Sn-free sample, the diffraction peaks of PtSn alloy catalysts shift to lower angle slightly. The electrocatalytic activities towards ethanol oxidation reaction were investigated using cyclic voltammetry and chronoamperometry techniques in acid media. The sample of Pt3Sn2/WC(O)/C presents the highest peak current density (332.2 mA/mg-Pt) and stability.

Abstract: This paper studies effect of corrosion inhibitor TG201 on electrochemical corrosion behavior of tubular steel HP13Cr by polarization curve test and exchange impedance spectrum method. It analyzes corrosion morphology by SEM. The results show that the increase of compression stress on HP13Cr lead to its self-corrosion potential shifting negatively, then electrochemical corrosion rate increases. Finally, corrosion resistance performance of HP13Cr steel weakens in acidification environment. Effects of compression stress on electrochemical corrosion become weak by adding TG201 inhibitors. And inhibitor efficiency of TG201 has obvious increase. So controlling compression stress has certain influence on inhibitors efficiency.

Abstract: This paper discusses the amount of hydrogen permeation and corrosion rate of 95S3Cr casing in different time, and analyzes its morphology before and after corrosion. We conclude that hydrogen permeation increases with increases of corrosion time, and increasing speed is faster in the initial stages then slower. Corrosion rate is quickly dropped at the beginning and then gradually increased. Corrosion products are loose structure. Because of hydrogen permeate into the material, the cracks create. It accelerates the corrosion.

Abstract: CO₂ sequestration in deep saline aquifers is regard as the most promising option among all the CO₂ storage technologies. Capillary pressure can influence the CO₂ storage efficiency in the aquifers. The core-scale experimental and numerical simulation studies are usually used to understand the mechanism and degree of such influence. Based on both magnetic resonance imaging (MRI) technique and numerical simulation method, this study investigates the effect of capillary pressure on the CO₂ displacement efficiency in water-saturated porous media especially in quantitative form. Our results indicate: (1) the magnitude of capillary pressure may significantly affect the CO₂-water displacement efficiency, and the displacement efficiency declines with increasing capillary pressure; (2) Sensitivity of the numerical model to capillary pressure becomes more unobvious with increasing capillary pressure. Thus, an accurate capillary pressure parameter is particularly required for improving the reliability of the model predictions in the case of the high permeability porous media.

Abstract: One of the most important steps in the wet limestone–gypsum flue gas desulfurization (WFGD) process is limestone dissolution, which provides the dissolved alkalinity necessary for SO2 absorption. Accurately evaluating the rate controlling step in sorbent dissolution process is important in the design and efficient operation of WFGD plants. In the present work, the kinetics of paper white mud(PWM) in dissolution process has been studied by using a pH-stat method. The results obtained indicated that PWM dissolution in WFGD conditions obeys the modified shrinking core model. PWM dissolution kinetics follows the film diffusion and surface reaction control and the rate controlling step of PWM is film diffusion control. The activation energies of PWM in film diffusion and surface reaction steps are 11.9±0.7 kJ/mol and 13.7±1.3 kJ/mol, respectively.

Abstract: The first-order approximation description of Gaussian beam in the two parallel Cartesian coordinates was introduced. On the basis of Generalized Mie theory, adopting the relation between the spherical vector wave functions belonging to a rotating Cartesian coordinate system, the electromagnetic fields of Gaussian beam with spherical vector wave functions was deduced at any right coordinates system. Then taking advantage of the cylindrical vector wave functions given by Stratton, the relationship of the spherical vector wave functions expressed in cylindrical vector wave functions was deduced. Finally the electromagnetic fields of infinitely long cylinder was expanded by the cylindrical vector, and the approximate expression of the cylinder to the far zone scattered field was solved.