Dynamic in situ observation of automotive catalysts for emission control using X-ray absorption fine structure

Two main pivotal subjects of research in automotive catalysts were studied by modern X-ray absorption analysis techniques. One is oxygen storage/release behaviour, and the other is sintering inhibition of Pt particles. First, three types of CeO₂–ZrO₂ (Ce:Zr = 1:1 molar ratio) compounds with different oxygen storage/release capacities and different structural properties were prepared, and the valence change of Ce as a function of temperature during oxygen release/storage processes was investigated. The reduction of surface Ce mainly occurred in the range 100–170 °C, and the reduction of bulk Ce progressed at high temperatures of 170 °C and above. The Ce reduction behaviour depended not only on the homogeneity of the Ce and Zr for bulk reduction at high temperatures but also on the particle size of the CeO₂–ZrO₂ samples for surface reduction at low temperatures. Secondly, sintering inhibition of Pt in Pt/Al₂O₃, Pt/MgO and Pt/ceria-based catalysts after 800 °C ageing in air was studied. We found that the Pt–O–M (M = Mg, Ce) bond acted as an anchor and inhibited the sintering of Pt particles on MgO or ceria-based oxide. Especially, it was noteworthy that the Pt–O–Ce⁴⁺ bond on the ceria-based support breaks easily through the reduction of Ce (Ce⁴⁺ → Ce³⁺) during the usual stoichiometric and reducing conditions.     

New type of phenolic resin: Curing reaction of phenol‐novolac based benzoxazine with bisoxazoline or epoxy resin using latent curing agent and the properties of the cured resin

In this study, we aimed to reduce the cure time, and to lower the cure temperature of the benzoxazine compound. Therefore, curing reaction of benzoxazine with bisoxazoline or epoxy resin using the latent curing agent and the properties of the cured resins were investigated. The cure behavior of benzoxazine with bisoxazoline or epoxy resin using the latent curing agent was monitored by differential scanning calorimetry and measurements for storage modulus (G′). The properties of the cured resin were estimated by mechanical properties, electrical insulation, water resistance, heat resistance, and flame resistance. As a result, it was confirmed that by using the latent curing agent, cure time of benzoxazine and bisoxazoline or epoxy resin was reduced, and cure temperature was lowered. And it was found that the curing reaction using phenol‐novolac based benzoxazine (Na) as the benzoxazine compound could proceed more rapidly than that using bisphenol‐A based benzoxazine (Ba) as the benzoxazine compound. However, the cured resins from Ba and bisoxazoline or epoxy resin using the latent curing agent showed good heat resistance, flame resistance, and mechanical properties compared with those from Na and bisoxazoline or epoxy resin using the latent curing agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

PVDF/PMMA composite nanofiber fabricated by electrospray deposition: Crystallization of PVDF induced by solvent extraction of PMMA component

The crystallization of poly(vinylidene fluoride) (PVDF) was observed after the poly(methyl methacrylate) (PMMA) component was extracted from the PVDF/PMMA (50/50) composite nanofiber fabricated by electrospray deposition, even though the original composite showed a completely amorphous pattern in the wide‐angle X‐ray diffraction. The content of the β‐crystal form in the crystalline region depended on the PVDF/PMMA composite ratios and the type of solvents used for the extraction of the PMMA component, e.g., chloroform and toluene. Thus, the content of the β‐crystal form can be controlled by selecting the original PVDF/PMMA composition and the solvent used to extract the PMMA component. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

USE OF METAL ADSORBING COMPOUNDS (MAC) TO MITIGATE ADVERSE EFFECTS OF HEAVY METALS IN BIOLOGICAL UNIT PROCESSES

The presence of heavy metals on an intermittent basis in the influent of biological unit processes can lead to process upset and poor removal of organics. Heavy metal breakthrough from a pretreatment process may be caused by a number of reasons. In this study, the feasibility of adding metal adsorbing compounds (MACs) into a sequencing batch reactor (SBR) to mitigate the adverse effects of heavy metals breakthrough was investigated. A powdered activated carbon was found to be an effective MAC for heavy metals concentrations varying from 2 to 20mg/L. Organic removal efficiencies in a SBR using MACs were similar to those of a control SBR with no metals in the influent.     

Polymorph control of calcium carbonate by reactive crystallization using microbubble technique

In this study, we used the minute gas–liquid interfaces around CO₂/NH₃ microbubbles as new reaction fields where the crystal nucleation progresses and developed a crystallization technique to control the polymorphism of calcium carbonate (CaCO₃). In the regions around the gas–liquid interfaces of CO₂/NH₃ microbubbles, Ca²⁺ and CO₃²⁻ ion concentrations can be adjusted because of the characteristic of the electric charge on the bubble surface and the decrease in CO₂ concentration based on unit bubble caused by minimization of bubble size, and because of the pH difference between local pH at the gas–liquid interface and overall pH in the bulk liquid caused by mixing of NH₃ with CO₂; hence, the polymorph change of CaCO₃ is expected to occur. CaCO₃ was crystallized at 298 K by a semi-batch type reaction in which CO₂/NH₃/N₂ bubbles were continuously supplied to an aqueous Ca(NO₃)₂ solution using a self-supporting bubble generator. The solution pH during crystallization was maintained at a constant level of 6.9–12.0 by adding HNO₃ and NH₄OH solution. The average bubble size (d_bbl) was varied in the range of 40–1000 μm by controlling the N₂ flow rate, and the molar ratio of CO₂/NH₃ (αCO₂/NH₃${\alpha }_{\text{C}{\text{O}}_2\text{/N}{\text{H}}_3}$) was set at a specified value of 0.20–1.00 at a constant CO₂ flow rate. The following results were obtained by varying solution pH, d_bbl, and αCO₂/NH₃${\alpha }_{\text{C}{\text{O}}_2\text{/N}{\text{H}}_3}$: at a constant d_bbl of 40 μm and αCO₂/NH₃${\alpha }_{\text{C}{\text{O}}_2\text{/N}{\text{H}}_3}$ of 0.20, vaterite and calcite were major products at a solution pH lower than 9.0 and at a solution pH greater than 11.0, respectively, while aragonite was crystallized predominantly in the solution pH range of 9.7–10.5; at a constant solution pH of 9.7 the crystallization of aragonite was accelerated remarkably with a decrease in αCO₂/NH₃${\alpha }_{\text{C}{\text{O}}_2\text{/N}{\text{H}}_3}$ and d_bbl.     

Oxide ionic conductivities of apatite-type lanthanum silicates and germanates and their possibilities as an electrolyte of lower temperature operating SOFC

Electrical properties of La_xM₆O_12+1.5x (M = Si, Ge) as an electrolyte for solid oxide fuel cell (SOFC) have been investigated. In La_xSi₆O_12+1.5x and La_xGe₆O_12+1.5x of x = 8–11, the highest conductivities were achieved at x = 9.7 (La_9.7Si₆O_26.55) and x = 9.0 (La_9.0(GeO₄)₆O_1.5), respectively. The conductivity of La_9.0(GeO₄)₆O_1.5 was higher than that of La_9.7Si₆O_26.55 in a temperature region higher than 700 °C, and the conductivity (2.4 × 10⁻³ S cm⁻¹) of La_9.7Si₆O_26.55 at 400 °C was higher than that (8.3 × 10⁻⁵ S cm⁻¹) of La_9.0(GeO₄)₆O_1.5. The power densities of SOFC (H₂ | Pt | electrolyte (thickness: 1 mm) | Pt | O₂) using La_9.0(GeO₄)₆O_1.5 as an electrolyte were 14.3 mW cm⁻² (700 °C) and 24.0 mW cm⁻² (800 °C). The corresponding SOFC using La_9.7Si₆O_26.55 was found to work even at lower temperatures of 400 and 500 °C with power densities of 0.011 and 0.12 mW cm⁻². The SOFC (H₂ | Ni–Sm_0.2Ce_0.8O_1.9 | electrolyte | Ba_0.5Sr_0.5Co_0.8Fe_0.2O_2.5 | air) using 0.3 mm thickness La_9.7Si₆O_26.55 electrolyte gave the 3.4 mW cm⁻² power density at 500 °C.     

Die quenching limit of AA2024 aluminum alloy billet on servo press

Die quenching of AA2024 aluminum alloy billets was carried out on a servo press with ram-motion control of WC-20 mass%Co dies directly after solution heat treatment (SHT). To clarify the dependence on billet size for die quenching, two billets with a height of h₀ = 8 mm or 16 mm and with the same diameter of 16 mm were prepared. The cylindrical billets were heated in an electric furnace at 823 K and transferred to the press. Then the billets were uniaxially compressed with a reduction in height (Δh/h₀) of 2% or 5%, and further held between the dies. The sandwiching duration by dies (t_d.q.) was varied from 0 to 8 s. Based a measured temperature change, hardness and TG–DTA analysis, it is found that die quenching is successfully carried out without precipitation hardening only in the case of the billet with a height of 8 mm and t_d.q. > 6 s. The reduction in height is limited less than 5% by intergranular fracture on side surface of billet during the die quenching process.     

The micro-nanoformability of Pt-based metallic glass and the nanoforming of three-dimensional structures

Pt_48.75Pd_9.75Cu_19.5P₂₂ amorphous alloy exhibits obvious glass transition behavior at a temperature of T_g=502 K, which is below the crystallization temperature T_x=588 K, and develops a supercooled liquid state in a wide temperature range of ΔT_x (=T_x−T_g)=86 K. The present paper investigates the macroscopic and microscopic deformation behavior of the material and the possibility of micro-nano forming as a fabrication method and material for nano-devices. On a macroscopic scale, the material exhibits a Newtonian viscous flow in a supercooled liquid state. An index of the microformability is also evaluated by the geometrical transferability of a die shape to the material. For this study, we fabricated V-grooved micro dies of (100) Si by a silicon process. The V-groove dies are from 100 nm to 1 μm wide. The material exhibits superior formability on micrometer and nanometer scales and may possibly be applied to micro-nanomaterials for micro-nano devices.     

间歇过程的故障分析和互锁控制器综合的集成

Integration amongst various decision-making processes, such as planning, design, and operation is necessary to dynamic and flexible batch production. To achieve a batch production integration, utilization of common models used for various decision-making processes is an effective approach. From this point of view, a batch system common model as described by a Petri net is proposed. In this article, a fault diagnosis technique for batch processes is presented using information about fault propagation and the possibilities of integration of fault analysis and controller synthesis are discussed on the basis of the Petri net based common models.     

Demand forecasting for production planning in remanufacturing

The International Journal of Advanced Manufacturing Technology - Remanufacturing is effective for energy and material savings; however, production planning and control in remanufacturing are more...