The Experts below are selected from a list of 3681 Experts worldwide ranked by ideXlab platform
Yoshio Sakka - One of the best experts on this subject based on the ideXlab platform.
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fabrication of textured nb4alc3 ceramic by Slip Casting in a strong magnetic field and spark plasma sintering
Journal of the American Ceramic Society, 2011Co-Authors: Yoshio Sakka, Hidehiko Tanaka, Toshiyuki Nishimura, Salvatore GrassoAbstract:Textured Nb4AlC3 ceramic was successfully fabricated in a strong magnetic field followed by spark plasma sintering. The optimized suspension parameters for Slip Casting were determined to be 20 vol% Nb4AlC3 and 2 wt% polyethyleneimine dispersant of powder in deionized water. After texturing in a strong 12 T magnetic field followed by cold isostatic pressing, the relative green densities were 50.4% and 58.7%, respectively. A dense Nb4AlC3 sample was obtained by sintering at 1450°C under a pressure of 30 MPa in vacuum. X-ray diffraction analysis revealed that the preferred orientation of Nb4AlC3 grains parallel to the magnetic field direction was along the c-axis. The Lotgering orientation factors on the textured top surface (TTS) and textured side surface (TSS) were determined to be f(00l)=0.59 and f(hk0)=0.64, respectively. The layered texture microstructure contributed to laminar transgranular and intergranular fractures. The indentation response on the TTS showed isotropy and that on the TSS revealed anisotropy.
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the c axis texturing of seeded si3n4 with β si3n4 whiskers by Slip Casting in a rotating magnetic field
Acta Materialia, 2010Co-Authors: Tohru S Suzuki, Tetsuo Uchikoshi, Yoshio Sakka, Xinwen Zhu, S KikkawaAbstract:Abstract The c -axis texture development in seeded Si 3 N 4 with β-Si 3 N 4 whiskers by Slip Casting in a rotating magnetic field was investigated by powder X-ray diffraction, scanning electron microscopy and thermal anisotropy evaluation, including the effects of magnetic flux density, suspension rheological properties and rotational speed. By increasing the magnetic flux density from 1 to 12 T, the c -axis orientation of β-Si 3 N 4 whiskers is achieved in the well-dispersed 30 vol.% suspension but hindered in the flocculated 40 vol.% suspension. The degree of orientation tends to decrease with increasing rotational speed from 5 to 30 rpm. The green body shows no density gradient but nonuniform orientation of β-Si 3 N 4 whiskers regardless of the rotational speed, resulting in the similar nonuniform texture in the sintered body. The nonuniform texture is featured in three major layers: lower surface, inner region and upper surface, corresponding to the lower, higher and lower c -axis orientation, respectively. The resultant c -axis textured Si 3 N 4 exhibits thermal anisotropy as high as 55%, slightly lower than the intrinsic thermal anisotropy (62%) of β-Si 3 N 4 . A theoretical analysis is performed to help understand the key factors affecting the orientation of β-Si 3 N 4 whiskers by Slip Casting in the rotating magnetic field. The formation mechanisms of the nonuniform texture were discussed.
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effect of sintering additive on crystallographic orientation in aln prepared by Slip Casting in a strong magnetic field
Journal of The European Ceramic Society, 2009Co-Authors: Tohru S Suzuki, Tetsuo Uchikoshi, Yoshio SakkaAbstract:Abstract The preparation of oriented AlN bulk ceramics with and without additives was achieved by Slip Casting in a high magnetic field. The a and b axes of the AlN were aligned parallel to the direction of the magnetic field. The degree of crystallographic orientation was controlled by the viscosity of the slurry and the grain growth during sintering attributed to the sintering additives. The mechanical properties of the textured AlN depended on the direction of the crystallographic orientation.
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textured hfb2 based ultrahigh temperature ceramics with anisotropic oxidation behavior
Scripta Materialia, 2009Co-Authors: Guojun Zhang, Yanmei Kan, Yoshio SakkaAbstract:Based on recent preliminary results of textured ZrB2-based ceramics, c-axis oriented HfB2-based ultrahigh-temperature ceramics with a Lotgering orientation factor as high as 0.91 were prepared by Slip Casting in a strong magnetic field alignment, followed by spark plasma sintering. The textured sample displays significantly anisotropic properties. Compared with textured ZrB2-based ceramics, the HfB2-based material shows much better oxidation resistance.
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highly textured zrb2 based ultrahigh temperature ceramics via strong magnetic field alignment
Scripta Materialia, 2009Co-Authors: Guojun Zhang, Yanmei Kan, Yoshio SakkaAbstract:Highly c -axis oriented ZrB 2 -based ultrahigh-temperature ceramics (UHTCs) were prepared via strong magnetic field alignment during Slip Casting, followed by spark plasma sintering, using ZrB 2 and β-SiC as starting materials. Results showed that hardness was superior on the surface perpendicular to the grain alignment. Oxidation resistance was obviously better on the surface of (001) direction. The anisotropic properties of the textured materials would provide an opportunity to the material design and selection of UHTCs.
Xiaoling Peng - One of the best experts on this subject based on the ideXlab platform.
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microstructures of ni zro2 functionally graded materials fabricated via Slip Casting under gradient magnetic fields
Journal of Alloys and Compounds, 2009Co-Authors: Mi Yan, Xiaoling PengAbstract:Abstract Ni–ZrO2 functionally graded materials (FGMs) have been fabricated via Slip Casting under a series of gradient magnetic fields. The effects of field gradient, holding time and Ni concentration on microstructures of Ni–ZrO2 FGMs were investigated. A Ni composition gradient was formed along the field direction in Ni–ZrO2 FGMs, and increased when the magnetic field gradient increased from 0.5 to 3.0 T/m. Moreover, the composition gradient also increased with the prolongation of holding time. However, the composition gradient decreased as Ni concentration increased from 4 to 15 wt.%, which can be attributed mainly to the formation of Ni clusters. A schematic model was proposed to explain the distribution of particles in gradient magnetic fields.
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A new approach for the preparation of functionally graded materials via Slip Casting in a gradient magnetic field
Scripta Materialia, 2007Co-Authors: Xiaoling Peng, Mi Yan, Weitang ShiAbstract:A new approach was developed to prepare ferromagnetic-nonmagnetic functionally graded material (FGM) via Slip Casting in a gradient magnetic field based on the distinct difference in magnetic susceptibility between a ferromagnetic particle and a nonmagnetic one. ZrO2-Ni FGM with a continuously changing composition was successfully fabricated using this method. The microstructure, elemental distribution and microhardness variation of the sintered ZrO2-Ni samples prepared within and without the magnetic field were investigated. © 2006.
Jingkun Guo - One of the best experts on this subject based on the ideXlab platform.
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preparation of cerium fluoride suspensions for grain orientation by a strong magnetic field assisted Slip Casting process
Ceramics International, 2014Co-Authors: Yuqing Sun, Huamin Kou, Min Chen, Yun Shi, Xiqi Feng, Yubai Pan, Jingkun GuoAbstract:Abstract To achieve highly transparent CeF 3 scintillation ceramics for high-energy physics applications, a grain-oriented structure, which could be obtained by a Slip-Casting process assisted by a strong magnetic field, was necessary to decrease the birefringence effects caused by the CeF 3 hexagonal phase structure. The preparation of well-dispersed CeF 3 suspensions, which is a key factor for the grain-orientation, was studied in this paper, and the factors that influenced the dispersing property of the suspensions, including properties of raw powders, pH of the suspension and amount of the dispersant, were also discussed. Optimized experimental parameters were screened out by comparing the viscosity of the suspensions and were used to prepare well-dispersed CeF 3 suspensions. The resulting suspensions were then Slip-cast under a strong magnetic field of 9 T used to align the particles. X-ray diffraction (XRD) results indicate grain-oriented ceramics that were obtained after sintering at 950 °C in vacuum for 3 h, with the calculated Lotgering factor f of 94.35%, compared with 3.67% for the sample obtained without magnetic field.
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fabrication and characterization of grain oriented cerium fluoride ceramics from a Slip Casting process in a magnetic field
Journal of Materials Science, 2014Co-Authors: Huamin Kou, Min Chen, Yun Shi, Xiqi Feng, Yubai Pan, Jingkun GuoAbstract:Transparent CeF3 ceramics may become a promising candidate in high-energy physics application due to their extremely high resistance to hadron-induced damage. To achieve a high transparency, the grain-oriented structure was necessary for CeF3 ceramics to limit the light scattering caused by the birefringence effects due to its hexagonal phase structure. In the present work, this kind of structure was obtained by a Slip-Casting process within a magnetic field of either 9 T generated by a superconducting magnet or 0.4 T from a permanent magnet. X-ray diffraction and electron backscattered diffraction analysis proved that the c-axis of grains were well aligned parallel to the magnetic field direction. The Lotgering factor of 93.83 % indicated that a high degree of orientation was achieved by the magnetic field of only 0.4 T. It was due to the large susceptibility and the net magnetic anisotropy Δχ strongly enhanced by the spin–orbit interaction of the 4f electrons of Ce3+ ions that highly grain-oriented CeF3 ceramics can be realized within such a low magnetic field.
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transparent polycrystalline alumina ceramics with orientated optical axes
Journal of the American Ceramic Society, 2008Co-Authors: Xiaojian Mao, Shiwei Wang, Shunzo Shimai, Jingkun GuoAbstract:A novel method is reported for the manufacture of transparent polycrystalline alumina ceramics by means of orientating the optical axes of grains parallel to each other. Such ceramics were achieved simply by exposing the Slip Casting process to a strong magnetic field followed by the traditional processing for translucent alumina ceramics. X-ray diffraction and orthogonal polarizing microscopy showed that the grains have been successfully orientated in the alumina ceramics. The in-line optical transmission is much higher than that of the randomly orientated polycrystalline alumina because the optical axes of grains are parallel to each other.
Tohru S Suzuki - One of the best experts on this subject based on the ideXlab platform.
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the c axis texturing of seeded si3n4 with β si3n4 whiskers by Slip Casting in a rotating magnetic field
Acta Materialia, 2010Co-Authors: Tohru S Suzuki, Tetsuo Uchikoshi, Yoshio Sakka, Xinwen Zhu, S KikkawaAbstract:Abstract The c -axis texture development in seeded Si 3 N 4 with β-Si 3 N 4 whiskers by Slip Casting in a rotating magnetic field was investigated by powder X-ray diffraction, scanning electron microscopy and thermal anisotropy evaluation, including the effects of magnetic flux density, suspension rheological properties and rotational speed. By increasing the magnetic flux density from 1 to 12 T, the c -axis orientation of β-Si 3 N 4 whiskers is achieved in the well-dispersed 30 vol.% suspension but hindered in the flocculated 40 vol.% suspension. The degree of orientation tends to decrease with increasing rotational speed from 5 to 30 rpm. The green body shows no density gradient but nonuniform orientation of β-Si 3 N 4 whiskers regardless of the rotational speed, resulting in the similar nonuniform texture in the sintered body. The nonuniform texture is featured in three major layers: lower surface, inner region and upper surface, corresponding to the lower, higher and lower c -axis orientation, respectively. The resultant c -axis textured Si 3 N 4 exhibits thermal anisotropy as high as 55%, slightly lower than the intrinsic thermal anisotropy (62%) of β-Si 3 N 4 . A theoretical analysis is performed to help understand the key factors affecting the orientation of β-Si 3 N 4 whiskers by Slip Casting in the rotating magnetic field. The formation mechanisms of the nonuniform texture were discussed.
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effect of sintering additive on crystallographic orientation in aln prepared by Slip Casting in a strong magnetic field
Journal of The European Ceramic Society, 2009Co-Authors: Tohru S Suzuki, Tetsuo Uchikoshi, Yoshio SakkaAbstract:Abstract The preparation of oriented AlN bulk ceramics with and without additives was achieved by Slip Casting in a high magnetic field. The a and b axes of the AlN were aligned parallel to the direction of the magnetic field. The degree of crystallographic orientation was controlled by the viscosity of the slurry and the grain growth during sintering attributed to the sintering additives. The mechanical properties of the textured AlN depended on the direction of the crystallographic orientation.
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preparation of oriented bulk 5 wt y2o3 aln ceramics by Slip Casting in a high magnetic field and sintering
Scripta Materialia, 2005Co-Authors: Tohru S Suzuki, Yoshio SakkaAbstract:Abstract Preparation of oriented AlN bulk ceramics was achieved by Slip Casting in a high magnetic field. The c -axis of AlN was perpendicular to the direction of a magnetic field. The mechanical properties and the thermal conductivity of the textured AlN depend on the direction of the crystallographic orientation.
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preferred orientation of the texture in the sic whisker dispersed al2o3 ceramics by Slip Casting in a high magnetic field
Journal of the Ceramic Society of Japan, 2001Co-Authors: Tohru S Suzuki, Yoshio Sakka, Koichi KitazawaAbstract:Developing texture is one possible way for improving the properties of ceramics. Texture in ferromagnetic materials can be tailored by a magnetic field, but it had been difficult to produce texture in diamagnetic and paramagnetic materials, such as silicon carbide and alumina, because their susceptibility is very small. A well-dispersed suspension of SiC (w)-Al2O3 was prepared and consolidated by Slip Casting in a high magnetic field. The Al2O3 matrix with a slight degree of orientation was observed in the green body and the degree of texture increased by annealing.
Mi Yan - One of the best experts on this subject based on the ideXlab platform.
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microstructures of ni zro2 functionally graded materials fabricated via Slip Casting under gradient magnetic fields
Journal of Alloys and Compounds, 2009Co-Authors: Mi Yan, Xiaoling PengAbstract:Abstract Ni–ZrO2 functionally graded materials (FGMs) have been fabricated via Slip Casting under a series of gradient magnetic fields. The effects of field gradient, holding time and Ni concentration on microstructures of Ni–ZrO2 FGMs were investigated. A Ni composition gradient was formed along the field direction in Ni–ZrO2 FGMs, and increased when the magnetic field gradient increased from 0.5 to 3.0 T/m. Moreover, the composition gradient also increased with the prolongation of holding time. However, the composition gradient decreased as Ni concentration increased from 4 to 15 wt.%, which can be attributed mainly to the formation of Ni clusters. A schematic model was proposed to explain the distribution of particles in gradient magnetic fields.
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A new approach for the preparation of functionally graded materials via Slip Casting in a gradient magnetic field
Scripta Materialia, 2007Co-Authors: Xiaoling Peng, Mi Yan, Weitang ShiAbstract:A new approach was developed to prepare ferromagnetic-nonmagnetic functionally graded material (FGM) via Slip Casting in a gradient magnetic field based on the distinct difference in magnetic susceptibility between a ferromagnetic particle and a nonmagnetic one. ZrO2-Ni FGM with a continuously changing composition was successfully fabricated using this method. The microstructure, elemental distribution and microhardness variation of the sintered ZrO2-Ni samples prepared within and without the magnetic field were investigated. © 2006.
