Co-continuous monolithic titania prepared by organic polymer monolith as pore template

We achieved preparation of co-continuous titania based monolithic materials using several organic polymer monoliths as pore templates. Firstly, the organic polymer monoliths that had well controlled structures were prepared, and filled the pores of polymer monolith with tetra-n-butyl titanate (titan monomer). The following hydrolysis of the titan monomer resulted in titanium dioxide. The polymer monolith was removed by calcination at elevated temperature. We carefully studied the utility of polymer monolithic template, filling method of the titan monomer, and calcination conditions to realize co-continuous titania monolith. In addition, by the change of domain size (size of a skeleton + size of through a pore) of template, we were able to control domain size of the resulting titania monoliths.     

Preparation of SrBi 2 Ta 2 O 9 Thin Films by Liquid-Delivery MOCVD Without Additional Solvents

SrBi 2 Ta 2 O 9 thin films were prepared by ECR plasma enhanced metalorganic chemical vapor deposition (ECR-MOCVD) with a liquid-delivery system using one cocktail source without an additional solvent. The strontium-tantalum double alkoxide, Sr{Ta[OC 2 H 4 H(CH 3 ) 2 ](OC 2 H 5 ) 5 } 2 , was dissolved in stabilized trimethyl bismuth, Bi(CH 3 ) 3 / dioxane. This source system has been used in a conventional bubbling system. Deposition rate and the composition of the films were strictly controlled by the concentration and the composition of the cocktail source. Therefore, high reproducibility was realized by using this system. The constituent phase of the stoichiometric SBT film as-deposited at 500 C on a (111)Pt/TiO 2 /SiO 2 /Si substrate was a fluorite phase and transformed to the single phase of SBT by the post annealing at 800 C. It showed almost the same ferroelectricity as the stoichiometric composition film.     

Mixed powder coating film using thermoplastic polyester and its alkaline resistance

To improve alkaline resistance, a newly mixed powder coating film using thermoplastic polyethylene terephthalate (PET) was investigated. Two kinds of polyvinyl butyral (PVB) and two kinds of polyamide (PA) were chosen as the secondary polymer. The melting temperatures (T _ms) of these materials were lower than that of primary PET polymer so the mixed powder coating was able to form a dual phase film through a fluidized bed coating process. Microscope and Fourier transform infrared spectroscopy (FTIR) observations revealed that the dual phase structure was indeed successfully formed and there was a secondary layer over the entire surface area of the film. This mixed powder coating film significantly enhanced the alkaline resistance to an environment filled with NaOH solution at 40°C in which a secondary material would be effective in protecting the film. With regard to both alkaline resistance and film formability, PET/PVB was superior to the PET/PA mixture.     

Preparation of Lead Lanthanum Zirconate Titanate (PLZT, (Pb,La)(Zr,Ti)O3) Fibers by Sol-Gel Method

Lead lanthanum zirconate titanate (PLZT, (Pb,La)(Zr,-Ti)O₃) ceramic fibers were prepared by the sol-gel method from a solution of lead acetate trihydrate, lanthanum isopropoxide, zirconium n -propoxide, and titanium isopropoxide that contained 2-methoxyethanol as the solvent. The sols obtained from the solution were concentrated at 156°-174°C for 2 h. Concentration at higher temperatures resulted in more-viscous sols of higher specific gravities. The concentration resulted in the formation of spinnable sols, which had viscosities >10⁵ mPas and exhibited Newtonian flow properties. These spinnable sols were formed to be so stable that no change in viscosity and spinnability was observed for more than three months when stored in a sealed container at room temperature. Gel-to-ceramic fiber conversion was investigated by means of X-ray diffractometry, infrared spectroscopy, and thermal analysis. Single-phase perovskite PLZT ceramic fibers 5-200 μm in diameter and >20 cm in length were obtained. Scanning electron microscopy (SEM) observation and Brunauer-Emmett-Teller (BET) measurement showed that heat treatment of the fibers at a lower rate resulted in the formation of fibers of denser microstructure. Although the SEM image of the cross section of the fibers revealed a relatively dense microstructure and a laser beam could be transmitted through a fiber 6 mm in length, BET measurement of the fibers indicated that the fibers had more than a few percent of open porosities, and scattering of light was observed in the laser-beam guiding test.     

Research on some basic deformations in free forging with robot and servo-press

Due to the disadvantages in casting or hot forging of Ti alloy artificial bones, such as low strength and high energy cost, this paper prompted an alternative method to manufacture individuated artificial bones. Free forging with a 6-axis freedom robot and servo-press could be very economical in the forming of complex shape parts because of its high flexibility and simple die-setting. Based on this system, the authors studied deformations of some basic elements, which could be assembled to artificial bones with complex shape. Firstly, the compression limit and effect of compression parameters on the roundness during reducing diameter process were declared for Al alloy and pure Ti. Secondly, an approximate theoretical equation of bending angle or curvature radius was proposed, and it matches experimental results well. Finally, a dimension prediction equation was presented by considering effect of material anisotropy, and then the ladder part without width spread was manufactured accordingly.     

Microelectrode-based hydrogen peroxide detection during oxygen reduction at Pt disk electrode

We investigated the diffusion process of H₂O₂ generated during O₂ reduction at a Pt microdisk electrode used as a generator for scanning electrochemical microscopy (SECM). First, the amount of O₂ consumption and generated H₂O₂ at the Pt generator electrode are estimated using a detector electrode installed in the SECM. Based on the results, a large amount of O₂ consumption and generated H₂O₂ are detected at the center of each generator electrode. According to the measurement, the O₂ starvation and H₂O₂ detection currents can be defined. Subsequently, the O₂ starvation and H₂O₂ detection currents are measured by varying the generator size. As a result, these currents decrease with a decrease in the generator electrode size, however, the H₂O₂ diffusion process is changed for the generator diameter of less than 50 μm. Finally, the O₂ starvation and H₂O₂ detection measurements were conducted using a Nafion-coated Pt microdisk electrode. The amount of O₂ consumption is not suppressed, while the amount of generated H₂O₂ decreases with the Nafion layer prepared on the Pt electrode. This result indicates that the thickness of the H₂O₂ diffusion layer in the H₂SO₄ solution is dramatically diminished by coating the Nafion layer on the Pt generator.     

Improved Filtration Performance of Continuous Alumina-fiber-reinforced Mullite Composites for Hot-Gas Cleaning

The effect of filtration layer morphology on filtration performance at 673 K was investigated for continuous alumina-fiber-reinforced mullite composite filters that capture fly ash on their outer surfaces. Two types of filtration layers were prepared on the outer surfaces: a mono-layer consisting of mullite agglomerated particulates and a bi-layer, with mullite whiskers formed by a vapor-phase reaction and strongly adhered to the particulates exposed on the outer surfaces. For filters with mono-filtration layers, the filtration efficiency was improved slightly by increasing the filtration layer thickness. However, the maximum differential pressure increased during the filtration tests. Adhesion of whiskers to the outer surface decreased the maximum differential pressure to about one-third less than that with the mono-filtration layer. This low differential pressure remained constant throughout the duration of the test, with corresponding increases in filtration efficiency.     

Single molecule fluorescence autocorrelation measurement on anisotropic molecular diffusion in nematic liquid crystal

Diffusion kinetics of three dyes in nematic liquid crystals are studied with single-molecule fluorescence autocorrelation spectroscopy. Markedly large anisotropy was observed in the diffusion coefficient and structure of diffusion molecules showed no marked effect on the anisotropy.     

Synthesis and thermal cure of high molecular weight polybenzoxazine precursors and the properties of the thermosets

High molecular weight polybenzoxazine precursors have been synthesized from aromatic or aliphatic diamine and bisphenol-A with paraformaldehyde. The precursors were obtained as soluble white powder. Molecular weight was estimated from the size exclusion chromatography to be several thousands. The structure of the precursors was confirmed by IR, ¹H NMR and elemental analysis, indicating the presence of cyclic benzoxazine structure. The ratio of the ring-closed benzoxazine structure and the ring-opened structure in the high molecular weight precursor was estimated from ¹H NMR spectrum and also from the exotherm of DSC, showing that the ratio of the ring-closed benzoxazine structure was 77–98%. The precursor solution was cast on glass plate, giving transparent and self-standing precursor films, which was thermally cured up to 240 °C to give brown transparent polybenzoxazine films. The toughness of the crosslinked polybenzoxazine films from the high molecular weight precursors was greatly enhanced compared with the cured film from the typical low molecular weight monomer. Tensile measurement of the polybenzoxazine films revealed that polybenzoxazine from aromatic diamine exhibited the highest strength and modulus. While, polybenzoxazine from longer aliphatic diamine had higher elongation at break. The viscoelastic analyses showed that the glass transition temperature of the polybenzoxazines derived from the high molecular weight precursors were as high as 238–260 °C. Additionally, these novel polybenzoxazine thermosets showed excellent thermal stability.