Table of contents

Advanced thin dicing blades for cutting sapphire were fabricated and evaluated for cutting performance with respect to dicing blade wear and meandering of cutting lines. Three kinds of different commercial blades were used to compare the cutting performance. These blades had the same thickness and the same diamond grain size. The matrix material of one dicing blade was nickel–phosphorus alloy and two other were a vitric material. Newly developed dicing blades consisted of a vitric material with pore. A dicing machine was used for cutting sapphire. Turning velocity, cutting depth and feeding rate were 20,000 min⁻¹, 200 μm and 1 mm s⁻¹, respectivity. Cutting directions were ⟨110⟩ and ⟨010⟩. All blades could cut 1000 mm and more in the ⟨110⟩ direction. On the other hand, commercial dicing blades generated meandering lines and were broken only by 50 mm of cutting length in ⟨010⟩ direction. Fabricated blade can cut 1000 mm and more in ⟨010⟩ direction. The wear of fabricated dicing blade was the largest in the dicing blades. Although cutting performance of commercial dicing blades depended on the sapphire orientation, that of fabricated blade was independent of the sapphire orientation. It has been confirmed that the fabricated dicing blade was kept a cutting ability by flash diamonds on the dicing blade surface, which were created by wear of blade during cutting sapphire. Low cutting ability of commercial blades increased cutting force between with increase of cutting length. The increased cutting force produced to bend a blade and cutting lines, and finally a fracture of blade.

The surface of three different grades of commercial high-purity α-Al₂O₃ powders produced by hydrolysis of aluminum alkoxide, which differ each other in SSA are evaluated by temperature programmed desorption mass spectrometry (TPDMS) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. For the DRIFT evaluation the powders were heated in situ under vacuum from 25 to 700 °C. The TPDMS spectra of desorbed H₂O were obtained by heating the samples under ultra high vacuum at a rate of 20 K min⁻¹ up to 1200 °C.

The presence of hydrogen bonded water molecules, amorphous Al(OH)₃ and AlOOH structures, as well as associated and isolated hydroxyl groups on the surface of all the α-Al₂O₃ powders investigated is demonstrated. On the surface of one of the powders the presence of crystalline Al(OH)₃ structures, as evidenced by an additional sharp peak in the H₂O TPDMS spectrum, is confirmed.

Oxidation behavior of ceramic matrix composites dispersed with metallic particles is discussed to establish materials design for high-temperature applications. Oxidation kinetics of ceramic matrix composites dispersed with metallic particles is understood from the viewpoint of the diffusion properties and defect chemistry of matrix oxides. High-temperature oxidation of Ni(p)/partially stabilized zirconia, Ni(p)/Al₂O₃ and Ni(p)/MgO was described as examples.

This paper presents new powerful characterization tools for ceramic and hybrid materials based on optical microscopy. Specimens are made transparent by thinning or the immersion liquid and the structure is observed in transmission mode. The tools can reveal detrimental defects, which are characteristically very few in number but large in size. Comfocal laser scanning fluorescent microscopy and infrared microscopy are also applied to extend the potential of the tool.

Some ternary Gd₂O₃–Bi₂O₃–B₂O₃ glasses are prepared, and crystallization behavior and second harmonic intensity are examined to develop new non-linear optical crystallized glasses. The glasses with Gd₂O₃ contents of 8–14 mol% have large densities of over 6 g/cm³ and large refractive indices of ∼1.9. Transparent surface crystallized glasses consisting of two kinds of crystalline phases with different morphologies, i.e. plate shape and needle shape crystals, are fabricated by heat-treatment at temperatures between glass transition and crystallization temperatures. From second harmonic generation microscope observations, micro-Raman scattering spectra and XRD analyses, plate shape crystals are determined to be non-linear optical Gd_xBi_1−xBO₃ and needle shape crystals are Bi₃B₅O₁₂ having no second-order optical non-linearity. Since crystallized glasses consisting of Gd_xBi_1−xBO₃ crystals exhibit relatively strong SHGs, they have a high potential for application to light control devices.

In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO₂ powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated into two different sites of the bulk phase of TiO₂. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO₂ powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system.

The investigation of the surface alignment of liquid crystal (LC) multilayers evaporated on photoaligned polyimide vertical alignment (PI-VA) film was carried out by means of the novel three-dimensional (3D) surface profiler. We report the first use of the surface profiler to visualize a microscopic image of the monolayer arrangement of LC molecules in contact with the surface of photo-treated PI-VA film. The photoinduced anisotropy of partially UV-exposed PI-VA film can be visualized as a topological image of LC multilayers. It seems that the topology of LC multilayers is indicating the orientational distribution of LC molecules on the treated film. It was found that the periodically photoaligned PI-VA film surface can align an adsorbed LC monolayer and the LC molecular alignment can be extended to the bulk via the epitaxylike LC–LC interaction, i.e. a short-range molecular interaction. With regard to the unexposed PI-VA film surface, noticeable anisotropy in the monolayer alignment was not observed, indicating that the long-range elastic interaction may be responsible for the bulk alignment. The appearance of small droplets in the masked region may be presumably related to the dewetting phenomena.

This paper describes the photorefractive effect of the liquid crystalline composite materials comprising low-molecular-weight nematic liquid crystals (L-LC), copolymer with mesogenic side groups and a small amount of photosensitizer. Copolymers with four kinds of mesogenic side groups were investigated with respect to the compatibility between the L-LC and the copolymer and the photorefractivity of the composites. Two of them could be miscible with L-LC and the composite exhibited LC phase even though the copolymer itself did not show a LC phase. High gain coefficients (>200 cm⁻¹) under the low applied dc electric field (<1 V/μm) was observed when the composites showed a mesophase without any macroscopic phase separation.

Imprinted copolymers, which highly recognized and bound bisphenol A (Bis A), were synthesized by using covalent imprinting technique. Bisphenol A dimethacrylate (BADM) was used as a template monomer in the copolymerization with a crosslinkable monomer of divinyl benzene (DVB), ethylene glycol dimethacrylate (EGDM) or N,N'-methylenebisacrylamide (MBAA). The resultant copolymer was hydrolyzed in acidic or basic condition. It was found that the Bis A imprinted copolymers of EGDM and MBAA had no selectivity to Bis A, because the crosslinker dissociated by the hydrolysis reaction and thus comprehensive imprinted sites were not formed. On the other hand, imprinted copolymer of DVB showed excellent selectivity to differentiate Bis A from bisphenol E and bisphenol F (Bis F). Characterization of the copolymers suggested that the DVB copolymer had resistance to the acid and alkali conditions. Effect of recognition by the Bis F imprinted polymer was also compared with that of the Bis A imprinted polymer, when DVB and bisphenol F dimethacrylate were copolymerized. The Bis F imprinted copolymer was able to recognize Bis F in ethanol solution, however showed higher binding capacity for both Bis A and Bis F in water solution without recognition. Therefore, hydrophobic interaction between Bis A and the imprinted site enhanced the binding capacity with high selectively for the BADM-co-DVB imprinted copolymer.

Novel Cu- and Co-phthalocyanines (7a–e, 8a, b) possessing intramolecular crown ether bridges between their different aromatic rings were successfully synthesized from the reaction of the corresponding bisphthalonitriles (6a–e) bearing polyethyleneoxy chains in the presence of CuCl and CoCl₂, respectively. As 1,8-diazabicyclo [5.4.0]-7-undecene (DBU) was used as a base in n-pentanol at reflux temperature for 30 h under N₂ atmosphere, these new phthalocyanines were found to be characteristic of satisfactory solubility in some of organic solvents, and showed strong absorption bands in ultraviolet and visible wave length region (λ_max=719–739 nm). Extraction experiment of metal chlorides (NaCl, KCl, MgCl₂, CaCl₂, CeCl₃, ZnCl₂, FeCl₃) in chloroform was carried out by using Cu-phthalocyanine (7b) bearing two intramolecular bridges with tri(ethyleneoxy) chains. Among these metal salts, 7b formed a complex (9b) with only FeCl₃, which showed a dark-red amorphous solid. Spectroscopic analysis of the complex (9b) indicated that original strong absorption bands near 738 nm characteristic for phthalocyanines completely disappeared, and new two strong bands appeared near 799–853 nm. FAB-MASS spectrum of the complex (9b) showed that new strong peaks came out in the region centered at m/z=1879 and 1881 besides original peaks in the region centered at 1488, which corresponded to molecular peak of the starting phthalocyanine (7b). These facts indicated that the complex (9b) included two molecules of FeCl₃ into the protonated crown ether bridges of the phthalocyanine skeleton. Furthermore, it was found that the complex (9b) was transformed to the original phthalocyanine (7b) quantitatively by treatment with triethylamine.

Crystallized B₁₃C₂ thin films were fabricated by intense pulsed-ion beam evaporation (IBE) method. Electrical conductivity and Seebeck coefficients of the obtained films were 1×10⁻⁴ l/Ωm and 200 μV/K at 1000 K, respectively. These values were comparable to those of bulks. For the application of the thin films, since reasonable thermoelectric (TE) properties were confirmed for the B₁₃C₂ films fabricated, we attempted to develop 'in-plane' type TE device using B₁₃C₂ and SrB₆ as p-type and n-type elements, respectively. With applying temperature difference to the fabricated device, thermo-electromotive force and electrical power were generated from the device we made, indicating that the device worked as a TE device. To the best of our knowledge, this is the first demonstration of the TE device composed of only boron-rich solids.

Extruded Mg–6%Al–1%Zn (AZ61) alloy bar was subjected to 4-pass Equal Channel Angular Extrusion (ECAE) processing at 448–573 K. At the processing temperature of 448 K, extremely fine grains with the average grain size of 0.5 μm are formed as a result of dynamic recrystallization originated by fine Mg₁₇Al₁₂ (β) phase particles having 50–100 nm diameter dynamically-precipitated during ECAE processing. The sizes of both α matrix and β phase decrease with decreasing processing temperatures. In tensile test at room temperature under the strain rate of 1×10⁻³ s^–1, tensile strength increases with decreasing ECAE processing temperatures due to fine grains, fine precipitates and residual strain hardening. Especially, highest strength of 351 MPa was achieved in the specimen ECAE-processed at 448 K. In addition to such high strength, elongation reaches 33% in that specimen. This specimen exhibits clear strain rate dependencies of both flow stress and elongation even at room temperature. As a result, higher elongation of 67% is obtained under low strain rate of 1×10⁻⁵ s⁻¹. In such specimen, non-basal slip and grain boundary sliding occur in addition to basal slip. Furthermore, there are grains with no dislocations, suggesting the occurrence of dynamic recovery. The contribution of all the deformation mechanisms would cause high ductility in fine-grained AZ61 alloy specimen with high strength.

A hot spot, which is a local area glowing orange, appears in a GdBa₂Cu₃O_7−δ ceramic rod when a voltage exceeding a certain value is applied to the rod at room temperature. The rod with the hot spot shows various functional characteristics that give rise to applications in devices. We found that the hot spot created a sponge-like structure in the rod. The elemental map revealed that the sponge-like structure was composed of Gd₂BaCuO₅ grains. The hot spot is considered to decompose GdBa₂Cu₃O_7−δ into Gd₂BaCuO₅ and liquid phase, and the liquid phase moves toward the periphery of the rod, leaving sponge-like structure composed of Gd₂BaCuO₅ grains. The novel sponge-like structure created in the GdBa₂Cu₃O_7−δ rod by the hot spot may bring about new applications for magnetic separations of fluids.

Joining technology of lightweight dissimilar metals between magnesium and aluminum alloys is essential for realizing hybrid structure cars and other engineering applications. In the present study, the normal center-line welding of lap joint was carried out by laser welding. It was found that the intermetallic layer formed near interface between two metals significantly degraded the joining strength. FEM heat transfer analysis was carried out to find out an available method to control penetration depth and width of molten metal, which contributes to control thickness of intermetallic compound layer. Based on the results of FEM analysis, the edge-line welding of lap joint was carried out, which could easily control the thickness of intermetallic layer and successfully obtained high joining strength.

Y₂O₃:Eu red phosphor powder was synthesized with powders of metal–ethylenediaminetetraacetic acid (EDTA) complexes as a starting material. The compositional analysis of each metal–EDTA complexes particle and Y₂O₃:Eu particle was performed using a particle analyzer. In this study, first, the particles of a mixture of Y– and Eu–EDTA complexes were obtained by a spray drying method from solution consisting of Y– and Eu–EDTA·NH₄. Then, the metal–EDTA complex powder was fired in obtaining the Y₂O₃:Eu red phosphor. The metal composition of each particle was scattered for the powder of the metal–EDTA mixture, while it became narrow for the Y₂O₃:Eu powder. The intensity of cathodoluminescence obtained from the Y₂O₃:Eu powder increased with increasing the fired temperature. In addition, the maximum intensity was obtained from the sample with x=0.12 for Y_2−xO₃:Eu_x.

Y₂O₃:(Eu,B) red phosphor was obtained by a thermal decomposition technique of a mixture of yttrium–ethylenediaminetetraacetic acid (Y–EDTA), Eu–EDTA and boric acid. The doping ratio of boron, [B]/([Y]+[Eu]), in the starting material was varied from 0 to 1. The properties of morphology, crystallization behavior, metal composition and photoluminescence of resulting Y₂O₃:(Eu,B) powder were examined. The Y₂O₃:(Eu,B) powder had spherical shape with a diameter of 1–5 μm with some hollows on the surface. No secondary cohesive particles were seen. X-ray diffractometry revealed that although the crystallinity of powder was improved with addition of small amounts of boron, it decreased with excess amounts of boron. Several peaks indexed as the impurity phases of Y₃BO₆ and YBO₃ were observed on the samples obtained under condition of excess amounts of boron. The photoluminescence intensity observed at 611 nm was dependent upon crystallinity of the sample.

The crystalline state of terbium-containing yttria is one of the important candidates for uses to ultraviolet- and electron-excited green phosphors. To increase the intensity of green emission, structural design of the polycrystalline Y₂O₃:Tb was carried out using a chemical-vapor-deposition technique operated under atmospheric pressure. The green luminescence intensity was strongly dependent upon the concentration of Tb. The intensity of the photoluminescence at 542 nm obtained from ⟨100⟩ oriented Y₂O₃:Tb whiskers was higher than that obtained from the uniform Y₂O₃:Tb polycrystalline film with random orientation.

A thermal barrier coating (TBC) system for rocket chambers made of Cu-based high strength alloys has been developed in a pilot project in line with EB-PVD (electron-beam physical vapor deposition) technology aiming at TBC application on Cu-based walls of real rocket combustion chambers. The TBC system consists of a metallic bond coating compatible with Cu-based material and an yttria partially stabilized zirconia TBC. The TBC overlayer is a distinctive ceramic structure designed for an exceptionally low Young's modulus to withstand the extreme mismatch stresses between the internally LN-cooled high thermal expansion Cu metal base and the low thermal expansion hot ceramic shell. The TBC system has been qualified under close-to-service conditions on cylindrical LH₂-cooled combustion chamber segments, where they have performed superior.

As EB-PVD technology is a line-of-sight process that is rather able to coat internal cavities, a transient liquid phase (TLP) joining technique for fully coated parts has been developed, that allows to assemble complete components out of vapor-accessible fully coated parts. It is capable, e.g. to incorporate sinuous cooling passages in the throat areas of combustion chambers, and/or to assemble oversized parts out of smaller components by maintaining parent metal properties. A manufacturing process is outlined for making internal TBC armored combustion chambers.

Thermal plasma processing has been used to synthesize nano-size powders through the condensation of reactant species from a vapor phase. Further development of this synthesis method will require the careful selection of an appropriate precursor and precise control of products species and their particle sizes. Direct introduction of liquid mist into thermal plasma gives us a wider choice of precursors than does vapor-phase precursor injection and lets us inject the precursors in larger amounts. In the present work, nano-size tantalum carbide powder was prepared from a liquid precursor, tantalum ethoxide Ta(OC₂H₅)₅, by using r.f. thermal plasma. The liquid precursor was atomized to generate micron-sized mist droplets, and the mist was introduced into plasma. This atomized precursor evaporated quickly in the high-temperature plasma flame, and nanoparticles were formed as temperature decreased. The process was controlled by changing the hydrogen addition, process pressure, carrier gas flow rate for mist injection, and quenching condition. Adding hydrogen improved the powder quality by removing solid carbon, but excess hydrogen suppressed the formation of tantalum carbide. The quenching conditions gave significant effects on the reduction of particles size by two thirds and yielded average particle sizes as small as 8 nm.