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Sekine K.,Stereo Fabric Research Association | Kumazawa T.,Mino Ceramic Co. | Tian W.-B.,Stereo Fabric Research Association | Hyuga H.,Japan National Institute of Advanced Industrial Science and Technology | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2012

Low-temperature joining of boron carbide (B 4C) ceramics using an Al sheet was investigated in the temperature range of 6001200° for 2 h in vacuum (10 -210 -4 Pa). Successful joining and high bending strength close to that of the B 4C base were achieved in the samples joined at 7001100°. Different techniques including scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) were used to characterize the high-strength B 4C joints. SEM observations suggested the dense interlayer and the crack-free interface as well as the penetration of Al into the surface microcracks of B 4C base. Further TEM examinations revealed that B 4C and Al joined directly. EPMA analysis demonstrated the existence of several reaction products within interlayer, including AlB 2 and Al 3BC, which resulted in the development of high-strength composite interlayer. © 2012 The Ceramic Society of Japan. Source


Sekine K.,Stereo Fabric Research Association | Kumazawa T.,Mino Ceramic Co. | Tian W.B.,Stereo Fabric Research Association | Hyuga H.,Japan National Institute of Advanced Industrial Science and Technology | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2012

The influence of the joining time and temperature on the flexural strength of B 4C ceramics joined using an Al sheet was investigated. The B 4C ceramics were joined over a temperature range 600-1400°C for 2-72 h in vacuum (101210 14 Pa) and in an Ar atmosphere. A joining interlayer with a dense structure was found in the B 4C joint formed at 1000°C after 2 h in vacuum, and mainly Al was present in this joining interlayer. On the other hand, some voids existed in the joining interlayer in the B 4C joint formed after 72 h. In addition, Al was not present in this interlayer owing to its reaction with B 4C as well as the evaporation of Al. Four-point bending tests of the B 4C joints formed at 1000°C in vacuum for periods ranging from 2 to 72 h were performed at room temperature. The average four-point bending strengths of the B 4C joints formed after 2 h at 700-1100°C were close to that of the B 4C base material, and the B 4C ceramics were considered to have successfully bonded. However, the joint strength decreased with an increase in the joining time, and the B 4C ceramics did not bond at temperatures over 1200°C in vacuum. On the other hand, the B 4C ceramics did bond at 1200-1400°C in Ar. © 2012 The Ceramic Society of Japan. Source


Sekine K.,Stereo Fabric Research Association | Kumazawa T.,Mino Ceramic Co. | Tian W.-B.,Stereo Fabric Research Association | Hyuga H.,Japan National Institute of Advanced Industrial Science and Technology | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Ceramic Engineering and Science Proceedings | Year: 2013

The influence of the joining pressure and surface roughness on the flexural strength of boron carbide (B4C) joined by an Al sheet was investigated. The joining surface of B4C was ground or polished to a surface roughness ranging from 0.1 to 6.1 μm. B4C was joined by Al under a pressure of 0.5-12 kPa or stabilized with a carbon jig at 1000 °C for 2 h in vacuum (10-2-10-4 Pa). The fracture surfaces were observed by an optical microscope and the microstructures in the B 4C joining layer were observed by scanning electron microscopy. The flexural strength of B4C joined at 12 kPa and stabilized with a carbon jig was similar to that of the B4C base material. However, the flexural strength of B4C joined at less than 6 kPa was lower than that of the B4C base material because of the presence of voids in the joining interlayer. When the surface roughness was 6.1 μm, the flexural strength was slightly lower than that of the B4C base material. However, when the joining surface roughness ranged from 0.1 to 1.7 μm, the flexural strength of joined B4C was similar to that of the B 4C base material. Source


Miyazaki H.,Japan National Institute of Advanced Industrial Science and Technology | Zhou Y.,Japan National Institute of Advanced Industrial Science and Technology | Hyuga H.,Japan National Institute of Advanced Industrial Science and Technology | Yoshizawa Y.-i.,Japan National Institute of Advanced Industrial Science and Technology | Kumazawa T.,Mino Ceramic Co.
Journal of the European Ceramic Society | Year: 2010

97.4% of theoretical density was obtained for boron carbide (B4C) ceramics by heating up to 2226 °C in an Ar atmosphere containing gaseous Al and Si species without external pressure. Impurities and secondary phases in the sintered B4C samples were examined by X-ray fluorescence and X-ray diffraction analyses respectively, which revealed that both Al and Si elements infiltrated into the green compacts and reacted with B4C to form SiC, Al4C3 and Al4SiC4 during the sintering. Triple junctions observed in the polished surfaces of the densified samples were filled by the secondary phases, indicating formation of liquid phase during heating. Dilatometric measurements at a constant heating rate in the Ar gas with the metallic gas species demonstrated that the shrinkage started at around 1700 °C, which was the liquid-phase formation temperature for the system reported in the previous studies. It was supposed that the liquid phase might be responsible for the densification. © 2009 Elsevier Ltd. All rights reserved. Source


A bonded, boron carbide-containing ceramic body includes ceramic members. These ceramic members each contain boron carbide at 2 mass % or higher, and are integrated together via a bonding layer bonded with a bonding material containing at least one metal selected from the group consisting of aluminum, copper, gold and zirconium or integrated together via a bonding layer formed from one of aluminum metal and an aluminum compound and a titanium compound as bonding materials, wherein a bonded part has a strength of 100 MPa or higher. According to this technology, the boron carbide-containing ceramic members can be bonded together with a high strength of 100 MPa or more by a simple process, and further, the bonding is feasible with excellent chemical resistance at the bonded part as needed.

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