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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.


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.


Tian W.-B.,Stereo Fabric Research Association | Kita H.,Japan National Institute of Advanced Industrial Science and Technology | Hyuga H.,Japan National Institute of Advanced Industrial Science and Technology | Kondo N.,Japan National Institute of Advanced Industrial Science and Technology | Sekine K.,Stereo Fabric Research Association
Materials Science and Engineering A | Year: 2012

B 4C ceramics were strongly bound by TiC tape interlayers that were infiltrated by Al-xSi (x=0, 6, 12 and 18wt.%) melts at 1000°C for 0.5h in vacuum. The measured bending strengths of B 4C joints are higher than 210MPa and these joints usually fracture from substrates for the good binding at interface and within interlayer on the basis of microstructure examinations. After corrosion tests, all B 4C joints display a decreasing tendency in bending strength but their retained strengths increase from 35MPa to 146MPa with the increase of Si addition. The improved corrosion resistance is mainly attributed to the presence of Ti(Al, Si) 3 and TiSi 2 compounds instead of pure Al as binder phases in the interlayer. © 2012.


Miyazaki H.,Japan National Institute of Advanced Industrial Science and Technology | Hotta M.,Japan National Institute of Advanced Industrial Science and Technology | Kita H.,Japan National Institute of Advanced Industrial Science and Technology | Izutsu Y.,Stereo Fabric Research Association
Ceramics International | Year: 2012

In the joining of structural ceramics, a porous interlayer is generally believed to deteriorate the mechanical properties of the joint. This paper, however, shows that a porous interlayer can sustain high adhesion strength when cavities or interfacial cracks are eliminated. The characteristic of the new slurry approach, described in this work, is that a pure alumina slurry interlayer is dried between two adjoining dense alumina plates and sintered with a negligible external pressure to form the porous interlayer. The effect of slurry concentration was studied to optimize the microstructure of interlayer. By controlling the interlayer microstructure and nature of the flaws, it was possible to fabricate high-strength bonds. The new slurry approach opens up the possibility of pure diffusion bonding which requires neither high pressure during heat treatments nor flat surfaces. © 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


Kita H.,Japan National Institute of Advanced Industrial Science and Technology | Himoto I.,Stereo Fabric Research Association
International Journal of Applied Ceramic Technology | Year: 2012

Several technologies were utilized to develop a method for producing a large-sized heat transfer container. Specifically, material development, vessel and sub-component design, fabrication, and assembly were integrated to create a container with superior properties. As a result, the finished vessel proved to be more energy efficient and lighter in weight than the one that is used currently for transferring molten aluminum. © 2012 American Ceramic Society.


Kita K.,Japan National Institute of Advanced Industrial Science and Technology | Kondo N.,Japan National Institute of Advanced Industrial Science and Technology | Hyugh A.,Japan National Institute of Advanced Industrial Science and Technology | Izutsu Y.,Stereo Fabric Research Association | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2011

This paper describes a novel experiment on surface modification for alumina plates. Polycarbosilane (PCS), an organosilicon polymer, was used in this experiment as a precursor. Tiny cracks on an alumina surface caused by grain boundaries and introduced by rough grinding were filled by PCS, and PCS was transformed into silicon oxycarbide (SiCO, silicon carbide including several mass percents of oxygen) by thermal oxidation curing at 453K and pyrolysis at 1273 K. Moreover, Al 6Si 2O 13 (mullite) layer was made from alumina and SiCO and prevented exfoliation of the alumina and SiCO during pyrolysis. In addition, the wettability between samples and molten aluminum was investigated in order to make sure the effect of surface modification. This experiment confirms that surface modification of alumina with a SiCO membrane can be successfully. © 2011 The Ceramic Society of Japan.


Kita K.,Japan National Institute of Advanced Industrial Science and Technology | Kondo N.,Japan National Institute of Advanced Industrial Science and Technology | Izutsu Y.,Stereo Fabric Research Association | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2011

This paper describes a novel experiment involving the joining of alumina using polycarbosilane (PCS). PCS filled in the cracks on the surface of alumina, the silicon in PCS oxidized to silicon dioxide (SiO 2), and part of SiO 2 reacted with alumina to form mullite during pyrolysis of PCS at 1673 and 1873 K. The SiO2 and mullite acted as a binder between the alumina boards. 4-point bending tests showed the average flexural strength of the samples pyrolyzed at 1673K was 81.8 MPa, whereas that of the samples that pyrolyzed at 1873K was 109 MPa. The difference in flexural strength was caused by the difference in the thickness and the compounds of the joining area, which was brought by the diffusion of the decomposition products derived from PCS and alumina during pyrolysis. © 2011 The Ceramic Society of Japan. All rights reserved.


Kita K.,Japan National Institute of Advanced Industrial Science and Technology | Kondo N.,Japan National Institute of Advanced Industrial Science and Technology | Sekine K.,Stereo Fabric Research Association | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Materials Letters | Year: 2013

Silicon carbide (SiC) coatings on a joined Boron carbide (B4C), aimed at improving the corrosion resistance, were prepared by using polycarbosilane (PCS) in order to increase its corrosion resistance. Some B 4C was diffused to PCS membrane in the curing process and the PCS membrane was made into SiC including crystal one in spite of 1473 K pyrolysis. The 4-point bending test of the samples after corrosion test shows that the sample without any coating was close to 0 MPa, while the samples with SiC coating maintained more than 300 MPa. © 2013 Elsevier B.V.


Kita K.,Japan National Institute of Advanced Industrial Science and Technology | Kondo N.,Japan National Institute of Advanced Industrial Science and Technology | Izutsu Y.,Stereo Fabric Research Association | 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

This paper describes a novel experiment in which alumina was joined using polycarbosilane (PCS) and an aluminum foil. PCS was used to design the surface structure of alumina, and the aluminum foil enabled the formation of an area that included the alumina surface designed using PCS; this area could be joined to ceramic materials. A four-point bending test revealed that the flexural strength of both the silicon carbide (SiC) and the silicon oxide (SiO 2) pieces that were obtained from alumina whose surfaces were modified to SiC or SiO 2 increased, compared with the flexural strength of ceramics joined by alternative methods involving the use of organometallic polymers whose compositions are similar to SiC and SiO 2. Moreover, it was apparent that alumina was formed by the reaction of SiO 2 with aluminum. However, traces of Al and Si remained in the joining area in both the SiC and SiO 2 pieces. © 2012 The Ceramic Society of Japan.


Kita K.,Japan National Institute of Advanced Industrial Science and Technology | Kondo N.,Japan National Institute of Advanced Industrial Science and Technology | Izutsu Y.,Stereo Fabric Research Association | Kita H.,Japan National Institute of Advanced Industrial Science and Technology
Materials Letters | Year: 2012

We investigated the properties of a SiC membrane on alumina, derived from polycarbosilane. The thickness of the deposited SiC layer was approximately 1 μm. The topmost layer, having a thickness of approximately 0.6 μm, comprised high-purity SiC. The 2.8 μm thick layer present below it appeared to consist of SiO 2. The contact angles between the SiC membrane and molten alumina at 973 K and 1373 K were approximately 67% and 86% of that between non-modified alumina and molten alumina. © 2012 Elsevier B.V. All rights reserved.

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