Papers by Author: Takashi Goto

Abstract: Y₂Ti₂O₇ transparent ceramic was fabricated by reactive sintering using spark plasma sintering at 1673 K for 2.7 ks. The sintered body exhibited a cubic pyrochlore structure and uniform microstructure with an average grain size of 2.9 μm. The transmittance reached 73% at a wavelength of 2000 nm after annealing at 1023 K for 21.6 ks.

Abstract: Amorphous Cu–Zr metallic alloys were studied as precursors to catalysts for methanol steam reforming to produce hydrogen. The alloy ribbons were prepared by single-roll rapid solidification, and the optimum pretreatment method and conditions were determined. The activity of the catalysts prepared by the improved pretreatment method was greater than that of previously prepared catalysts by two degrees of magnitude. The addition of a very small amount of Pt enhanced the activity without increasing CO formation.

Abstract: Lithium Cobaltate (LiCoO₂) Films Were Prepared on the (001), (110), (110) and (112) Planes of Al₂O₃ Single Crystals Substrates by Metal Organic Chemical Vapor Deposition, and the Phases, Orientated Textures and Surface Morphologies Were Examined. (001)-Oriented LiCoO₂ Films Were Obtained on (001) and (110) Al₂O₃ Substrates, while (018)- and (104)-Oriented LiCoO₂ Films Were Grown on (110) and (112) Al₂O₃ Substrate. Triangular and Elongated Rectangular Faceted Structures Were Directionally Aligned, and (001)- and (018)-Oriented Grains Were Epitaxially Grown on (001) and (110) Al₂O₃ Substrates. Randomly Arranged Polygonal Faceted Structures Were Observed in the (001)-Oriented Licoo2 Film on (110) Al₂O₃ Substrate, while Locally Inhomogeneous Grains Were Observed in the (104)-Oriented LiCoO₂ Film on (1_,12) Al₂O₃ Substrate.

Abstract: Titania (TiO₂) Films Having Dense and Solid Microstructure Were Prepared by Laser Chemical Vapor Deposition Using CO₂ Laser. The Effects of Deposition Temperature (T_dep) and Total Chamber Pressure (P_tot) on Phase and Microstructure of TiO₂ Films Were Investigated. At P_tot = 600 Pa and T_dep = 790 K, Rutile TiO₂ Film Had a Polygonal Platelet Grains 2 μm in Size. At P_tot = 600 Pa and T_dep = 1010 K, Rutile TiO₂ Film Had (110) Orientation and Consisted of a Truncated Polyhedron 5–6 μm in Size. At P_tot = 200 Pa and T_dep = 955 K, Rutile TiO₂ Film Has a Solid Columnar Having Faceted Surface. A Dense and Solid TiO₂ Film Was Obtained at P_tot = 200 Pa and T_dep = 1120 K. The Deposition Rate of TiO₂ Solid Film Was Reached 240 μm h⁻¹.

Abstract: Silicon Carbide (SiC) Layers Were Prepared on Diamond Powders by Rotary Chemical Vapor Deposition (RCVD) Using C₆H₁₈Si₂ as a Precursor. Diamond Particles with Cleavable and Sharp Configurations Were Covered with Smooth Layers by RCVD. Infrared Absorption Bands at around 800 and 1000 cm^-1 Attributed to Si-C Bonding Were Observed in FTIR Spectrum on the Diamond Powders. The Pellet Sample Sintered by Spark Plasma Sintering Using the Diamond Powders Suggested that β-SiC Was Deposited on the Diamond Particles.

Abstract: hBN-TiN Binary Composite Was Fabricated Using Spark Plasma Sintering (SPS) at Temperatures between 1973 and 2273 K. With Increasing TiN Content from 10 to 90 Vol%, the Relative Density Increased from 75.7 to 96.4%. The Maximum Relative Density of 96.4% Was Achieved in the hBN-TiN Containing 90 Vol%TiN Sintered at 2273 K. hBN and TiN Was Stably Coexisted at 1973 K without TiB₂ Formation.

Abstract: Sintering Behavior of Monolithic TiN and TiB₂ Was Investigated Using Spark Plasma Sintering (SPS) at Temperatures between 1673 and 2573 K. Relative Density of TiN Was Increased from 82.3 to 96.7% while that of TiB₂ Increased from 70.1 to 92.8% with Increasing Temperature. At Temperatures between 1673 and 2273 K, TiB₂ Was More Difficult to Consolidate Compare to TiN. At 2473 K, TiB₂ Densified Rapidly to 92.8%.

Abstract: C-Axis-Oriented Y₂Ba₄Cu₇O_15-δ (Y247) Films Were Prepared on Multilayer-Coated Hasterolly Tape Substrate by Laser Chemical Vapor Deposition with Ultrasonically Nebulized Liquid Precursor. At a Low Precursor Concentration of 0.01 mol l⁻¹ and Deposition Temperature of 933 K, Single-Phase Y247 Film with Significant c-Axis Orientation Was Obtained. At a Precursor Concentration of 0.1 mol l⁻¹ and Deposition Temperature 983 K, a-Axis-Oriented YBa₂Cu₃O_7-δ (Y123) Was Codeposited with C-Axis Oriented Y247 Film.

Abstract: SiAlON Was Mixed with Ni Nanoparticle Precipitated cBN (SiAlON-cBN/Ni) and Sintered by Spark Plasma Sintering at 1923 K for a Holding Time (t_H) of 0 to 1.8 Ks. the Effect of Ni Nanoparticle and Holding Time on the Phase Transformation of cBN to Hexagonal (hBN), Densification, Microstructure and Hardness of the SiAlON-cBN Composites Was Studied. At t_H =1.8 Ks , the Relative Density of the SiAlON-20 Vol% cBN/Ni Was 99%, 7% Higher than that of SiAlON-20 Vol% cBN, Indicating that Ni Nanoparticle on cBN Promoted the Densification of SiAlON-cBN Composites. The BN Grains in SiAlON-20 Vol% cNB Showed a Round Morphology, whereas the BN Grains in SiAlON-20 Vol% cBN/Ni Composite Showed a Flake Morphology Characteristic of hBN. The Phase Transformation of cBN Was Accelerated by Ni. the Maximum Hardness of SiAlON-20 Vol% cBN/Ni Was 16.3 GPa Obtained at t_H = 0 Ks.