Advanced Materials Research Vols. 148-149

Abstract: The well-defined titania nanotube arrays with a tunable pore size and tube length have been fabricated in an organic medium-assisted anodization process. The obtained titania nanotubes have been applied for electric double layer capacitor applications. The electrochemical capacitance performance is highly dependent on the pore size and tube length of nanotube arrays. The increase of pore size can significantly enhance specific capacitance of titania nanotube arrays. Comparatively, the increase of tube length can only improve specific capacitance to a small degree. In addition, a higher specific capacitance of titania nanotube array can be achieved in an acidic solution rather than an alkali solution.

Abstract: Multiple branched SnO2 nanowire junctions have been synthesized by thermal evaporation of SnO powder. Their nanostructures were studied by transmission electron microscopy and field emission scanning electron microcopy. It was observed that Sn nanoparticles generated from decomposition of the SnO powder acted as self-catalysts to control the SnO2 nanojunction growth. Orthorhombic SnO2 was found as a dominate phase in nanojunction growth instead of rutile structure; The branches and stems of nanojunctions were found to be an epitaxial growth by electron diffraction analysis and high-resolution electron microscopy observation. The growth directions of the branched SnO2 nanojunctions went along the orthorhombic [110] and [1—,10]. A self-catalytic vapor–liquid–solid growth mechanism is proposed to describe the growth process of the branched SnO2 nanowire junctions. Introduction

Abstract: CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate (TEOS) as Si source, and aqueous solution of Cu, Co and Mn acetates as transition metal sources via sol-gel process and supercritical drying (SCD) technique. The effect of synthesis conditions on gelation was investigated. The composition of the nanocomposite aerogels was characterized by electron dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The specific surface area of the nanocomposite aerogels was determined by the Brunauer-Emmett-Teller (BET) method. The results show that the range of optimal temperature for gelation is 30-45 °C, and the pH is 3.0-4.5. CuO-CoO-MnO/SiO2 nanocomposite aerogels are porous with a specific surface area of 384.9-700.6 m2/g. Compared to CO2 SCD, ethanol SCD is even favorable to the formation of aerogel with high specific surface area. The transition metals content in the nanocomposite aerogels can be controlled to be 0.71-13.77 at.%.

Abstract: Two kinds of mesoporous HPW/SiO2 composites, which have been synthesized respectively by the amino-functionalized (AF) method and evaporation-induced self-assembly (EISA) method, have been used as catalysts in the oxidative desulfurization process of dibenzothiophene(DBT). The catalytic performance results show that the catalyst synthesized by EISA method holds higher catalytic activity than that synthesized by the AF method. The difference of catalytic activity can be attributed to the different synthesis mechanism of two kinds of composites. In the AF method, the bonding force between HPW and SiO2 is strong acid-base interaction, which damages the Keggin structure. Whereas in the EISA process, electrostatic force and hydrogen bonds between W=O groups and Si-OH groups are main bonding forces. The hydrogen bond holds the electron-withdrawing effect, which increases the activity of nonbonding W=O groups in HPW and then results in the enhancement of the catalytic activity.

Abstract: In this paper, cordierite (2MgO•2Al2O3•5SiO2) precursors are synthesized using TEOS and aluminum and magnesium nitrates as starting materials, citric acid as chelating agent and Tween-80 as dispersant. The effect of citric acid and Tween-80 on the formation mechanism of α-cordierite phase is investigated by using X-ray diffraction (XRD), while the effect of citric acid and Tween-80 on the particle morphology of α-cordierite is examined by using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The results show that citric acid used as chelating agent can reduce the formation temperature of α-cordierite to 1150°C by forming stable salt of citric acid with all the metal ion to avoid composition deviation from the sample components during solvent evaporation process and sub-micron cordierite particles without hard agglomeration can be obtained. Nano-sized α-cordierite can be obtained with the introduction of Tween-80 as dispersant by modifying the surfaces of the colloidal sol particles.

Abstract: Active vibration control based on fuzzy algorithm for piezoelectric smart plate is studied. After the characteristic of piezoelectric ceramic (PZT) is analyzed, modal and transient analysis are developed in this paper with finite element model of the piezoelectric smart plate constructed in ANSYS. Fuzzy logic control rules are established by the analysis of the deformation of the plate. With mode shape and displacement response curve obtained, active vibration suppression for the smart plate system is achieved by using commercial finite element programs. The simulation results illustrate that analysis of piezoelectric smart plate using ANSYS is practicable and the intelligent control method is effective.

Abstract: Polyvinglpyrrolidone (PVP), cetyltrimethylammonium bromide (CTAB), and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123) were used as templates, respectively. The morphology, structure and luminescent properties of the products were characterized and studied. The results show that all the products are pure LaPO4 with hexagonal structure. Comparing with the morphologies of LaPO4:Eu3+ nanocrystals prepared with PVP and CTAB as templates, the LaPO4:Eu3+ nanocrystals with P123 as template present regular spherical structure. The sizes of all products are in the range of 50–120 nm. When ultrasonic time was 2 h, the tendency, intensity and stability of fluorescent irradiation is obviously difference with different templates. In addition, the luminescent intensity of the LaPO4:Eu3+ nanocrystals using PVP as template is the strongest and using P123 as template is the weakest. All above results indicate that the template kinds have played an important role in the morphology and luminescent properties of the LaPO4:Eu3+ nanocrystals.

Abstract: In this paper, the writers analyze some issues that influence parts surface quality on HS- WEDM and its related counter plan, which are Summed up from practice and producing experiences. It has certain guiding significant to improve surface quality of part in practice production.

Abstract: In this study, the magnetic nanoparticles derivatized with dual functional moieties of dodecyl and mercapto were prepared, which characterized by X-ray diffraction (XRD), scanning electron microscope(SEM), surface area and pore size determination, fourier transform infrared spectrometry (FT-IR) and water contact angle analysis. The new material was proved to be an effective sorbent for environmental remediation.

Abstract: The strip wound die for cold forging operation is prestressed by the thin high-strength steel strips, which is characterized by the strength that is twice or more than that of the conventional compound die, as well as the achievement of even higher stiffness. In this paper, a special strip winding machine is designed and developed to manufacture the prestressed strip wound die. The structure and function of this machine is described in detail. FEM study on the frame of the machine is carried out to prove the feasibility of the design. The total tension will be determined by the constant tension which is equal to the friction force generated by the clamping device, and the variable tension which is generated by the AC servo motor in the uncoiler device. Controlling strategy and the framework of tension controlling system are also presented.