A novel agglomeration granulating system utilizing a centrifugal-fluidizing drive

Necessary conditions were studied for the optimum operation of agglomeration granulation. The mechanisms that would realize these conditions were investigated by several experiments.On the basis of the results obtained, a novel granulating system involving a surface wetness control mechanism has been developed.The present paper describes the mixing and dispersing characteristics of the coating vessel, the detection method for wetness control, the particular spraying units, and the operating conditions thereof, together with the characteristics of this newly developed powder coating granulation system.This system has been shown to provide an easy and reproducible granulating technique even when products below 1 mm in size are required.     

The hydrogen-electrode reaction in the isotopically mixed system—II. Evaluation of the electrolytic separation factor of deuterium from the rest potential of the hydrogen electrode in the deuterium-containing system

The rest potential, E_r, of the hydrogen electrode in deuterium-containing hydrogen and a solution of light water as referred to the reversible hydrogen electrode in the light hydrogen and the same solution is formulated as a function of deuterium content of the gaseous hydrogen and the deuterium separation factor, S_b, in the hydrogen ionization reaction. It is shown that the relation is not significantly affected by the operative mechanism of the hydrogen-electrode reaction. Consequently, the relation provides a convenient method of evaluating S_b from the observation of E_r.

Experiments were carried out on Pt, Ni, Au and Ag in the system composed of deuterium-containing hydrogen and light water. The value of S_b as evaluated from E_r was practically independent of the deuterium content in the gaseous hydrogen. The values obtained were 1·1 for Pt in acidic and alkaline solutions, 1·6 for Ni in alkaline solution, 1·2 for Au and 1·5 for Ag, both in acidic solution. These values multiplied by the partition coefficient of deuterium between hydrogen and water (4·0 at room temperature) give approximate values of the deuterium separation factor in the hydrogen evolution reaction.     

Two-stage pyrolysis of heavy oils. 3. Pyrolysis of tar-sand bitumens. Relation between ethylene yield and structural characteristics of heavy oils

Thermal cracking of tar-sand bitumens has been carried out using a two-stage pyrolysis reactor with temperature zones of 440°C and 750–800°C, respectively. Feedstocks were pyrolysed in the first stage into cracked oils, which were carried to the second stage for subsequent pyrolysis. Only 12–14 wt% of ethylene was obtained from tar-sand bitumens at the residence time of 1.2 s in the second stage, although 27 and 16 wt% were obtained from Taching and Iranian heavy vacuum residues, respectively. The tar-sand bitumens contain shorter paraffinic straight-chains and have more branched molecules than the vacuum residues of petroleum. A straight-chain paraffin index is proposed, with which a good correlation was obtained between ethylene yield and the fraction of straight-chain paraffin carbons in the heavy oil.     

Highly Reactive β-Dicalcium Silicate: III, Hydration Behavior at 40–80°C

The effect of curing temperature (40°, 60°, 80°C) on the hydration behavior of β-dicalcium silicate (β-C₂S) was investigated. The β-C₂S was obtained by decomposition of hillebrandite, Ca₂(SiO₃)(OH)₂, at 600°C, has a specific surface area of about 7 m²/g, and is in the form of fibrous crystals. The dependence of the hydration reaction on temperature continues until the reaction is completed. The hydration is completed in 1 day at 80°C and in 14 days at 14°C. The hydration mechanism is different above and below 60°C, but at a given temperature, the reaction mechanism and the silicate anion structures of C-S-H do not change significantly from the initial to the late stages of the reaction. High curing temperature and long curing times after completion of reaction promote silicate polymerization. The Ca/Si ratio of C-S-H shows high values, being almost 2.0 above 60°C and 1.95 below 40°C.     

Selective conversion of propane to propene by the catalytic oxidative dehydrogenation over cobalt and magnesium molybdates

Catalytic performances of various metal molybdates were tested in the oxidative dehydrogenation of propane to propene with molecular oxygen under an atmospheric pressure. Most of the molybdates tested promoted the selective oxidative conversion of propane to propene and among them cobalt and magnesium molybdates were found highest in the activity and selectivity. It was also found that their catalytic activities were highly sensitive to the catalyst composition, and it turned out that Co_0.95MoO _x and Mg_0.95MoO _x catalysts which have slightly excess molybdenum showed the highest activity in the oxidative dehydrogenation of propane. Under the optimized reaction conditions, higher reaction temperatures and lower partial pressures of oxygen, these catalysts gave 60% selectivity to propene at 20% conversion of propane. Since the molybdates having the surface enriched with molybdenum oxide tended to show high activity for the propane oxidation, surface molybdenum oxide clusters supported on metal molybdate matrix seem to be the active sites for the selective oxidative dehydrogenation of propane.     

Crystal transformation from the α- to the β-form upon tensile drawing of poly(l-lactic acid)

A film of poly(l-lactic acid) (PLLA) consisting of highly oriented α crystals was uniaxially drawn by tensile force. The effects of the draw ratio (DR), draw temperature (T_d), and draw stress on the crystal/crystal transformation from the α- to the β-form crystals were studied. At the initial stage of drawing, the highly oriented α crystals of the starting film transformed into a broader orientation distribution, and significant crystal disorder was introduced. Upon further drawing, the α crystals steadily transformed into β crystals with increasing the DR. For the drawing at a constant T_d, the crystal transformation proceeded more efficiently at a higher draw rate and, hence, at a higher draw stress. Furthermore, for the drawing at a constant draw rate, the transformation proceeded with DR most efficiently for the tensile draw at a T_d around 140 °C, although the draw stress increased with decreasing the T_d. The present result combined with the previous finding in the drawing of PLLA by solid-state extrusion [Macromolecules 36 (2003) 3601] suggests that there is a T_d of around 140 °C at which the crystal transformation proceeds most efficiently with DR, suggesting that there are two factors that have opposite effects on the efficiency of the crystal transformation with increasing the T_d. However, as a result of the combined effects of the T_d and DR on the crystal transformation and the ductility increase with the T_d, an oriented film consisting predominantly of β crystals was obtained by tensile drawing at a T_d in the range of 140-170 °C to the highest DR achieved at each T_d.     

High-Temperature Active Oxidation of Chemically Vapor-Deposited Silicon Carbide in CO─CO2 Atmosphere

Active oxidation behavior of CVD-SiC in CO─CO₂ atmospheres was investigated using a thermogravimetric technique in the temperature range between 1823 and 1923 K. The gas pressure ratio, P _CO2/ P _CO, was controlled between 10⁻⁴ and 10⁻¹ at 0.1 MPa. Active oxidation rates (mass loss rates) showed maxima at a certain value of P _CO2/ P _CO, ( P _CO2/ P _CO )^*, In a P _CO2/ P _CO region lower than the ( P _CO2/ P _CO)^* a carbon layer was formed on the SiC surface. In a P _CO2/ P _CO region higher than the ( P _CO2/ P _CO)^*, silica particles or a porous silica layer was observed on the SiC surface.     

Evaluation of hydrogen absorption properties of Ti–0.2 mass% Pd alloy in fluoride solutions

The hydrogen absorption properties of Ti–0.2 mass% Pd (Ti–0.2Pd) alloy in 2.0% and 0.2% acidulated phosphate fluoride (APF) and neutral 2.0% NaF solutions (25 °C) has been evaluated by hydrogen thermal desorption analysis. During the early stage of immersion (120 h) in the 2.0% APF solution, the amount of absorbed hydrogen was lower than 500 mass ppm. A thermal desorption of hydrogen primary appearing with a peak at 500–600 °C and a broad desorption ranging from 100 to 400 °C were observed. In the 0.2% APF solution, the amount of absorbed hydrogen saturated at 100–200 mass ppm; the thermal desorption of hydrogen appeared with a single peak at 550 °C. In the 2.0% NaF solution, hydrogen absorption was negligible even after 1000 h of immersion, although corrosion pits were observed. The results of the present study suggest that the hydrogen absorption of Ti–0.2Pd alloy, as compared with commercial pure titanium, is suppressed in fluoride solutions.     

Preparation and structural characterization of perovskite-type LaxLn1−x″CoO3 by the thermal decomposition of heteronuclear complexes, LaxLn1−x″| Co(CN)6| · nH2O (Ln″ = Sm and Ho)

Perovskite-type La_xLn_1−x″CoO₃ oxides are prepared by the thermal decomposition of La_xLn_1−x″ [Co(CN)₆] · nH₂O hetero-nuclear complexes. Except for LaCoO₃ (hexagonal), the structures observed for La_xSm_1−xCoO₃ are othorhombic. While the perovskite-type oxide HoCoO₃ is not formed by decomposition at 1000°C of the corresponding hexacyano complex, the partial replacing of Ho with La is effective in forming the pervoskite-type oxide having an orthorhombic structure containing Ho even at 800°C. A monotonous correlation (quasi-linear relationship) was found between the b- and c-lattice constants of the orthorhombic structures of the perovskite-type oxides and the effective radii of Ln ions, defined as r_eff = xr_1.a + (1 − x)r_1.0″. The distortion parameter for the orthorhombie cell (3″a/b−1) increaseswith decrease in r_eff and is expected to be 0.270 for perovskite-type HoCoO₃. The crystal structure of the La_xLn_1−x″, CoO₃ oxides is mainly controlled by the effective radii of Ln ions.     

Reliability and mechanical durability tests of flexible OLED with ALD coating

To improve the reliability and mechanical durability of a flexible organic light‐emitting diode display, the entire flexible display is coated with an aluminum oxide film by atomic layer deposition (ALD). Because the step coverage of ALD is excellent, the AlO_x film was deposited not only on the front and back surfaces but also on the side surfaces of the display. A high‐temperature and high‐humidity preservation test, repetitive bending tests, and a pencil hardness test were conducted on the flexible display with ALD‐AlO_x coating. The display survived 500 h of a 65°C, 95% preservation test, endured a 100,000‐time repetitive bending test with a curvature radius of 4 mm, and was found to have a pencil hardness of 4H.