http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : KyoungHunKim (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
Sintering behavior and mechanical properties of B4C ceramics fabricated by spark plasma sintering
Kyoung Hun Kim,심광보,Jae Hong Chae,Joo Seok Park,Jong Pil Ahn 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6
The sintering behavior, microstructure and mechanical properties of boron carbide ceramics, which were fabricated by a spark plasma sintering process, were investigated. The relative density of B4C ceramics using a spark plasma sintering method reached as high as 99% theoretical at a lower temperature than a conventional sintering method, and in addition, without any sintering additives. The mechanical properties of B4C ceramics could be improved by soaking at 1,300 oC during the sintering process which removed the B2O3 phase from the B4C powder surface. A remarkable improvement of mechanical properties could be achieved by the introduction of a soaking process during the spark plasma sintering process. In particular, the fracture toughness values of the specimens which experienced the B2O3 removal process improved by over 30% compared with the specimens without this process. These achievements resulted from the formation of a fine and homogeneous microstructure because the grain coarsening was suppressed by the elimination of the B2O3 phase.
-
-
Kyoung Hun Kim,Joo Seok Park,Byung Ha Lee,K. B. Shim,Jong Pil Ahn,Jae Hong Chae 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
Spark plasma sintering (SPS) of AlN ceramics was carried out with Y₂O₃ as a sintering additive at sintering temperatures of 1,550 to 1,700 ℃. The effects of Y₂O₃ additions on the sintering behavior and thermal conductivity of AlN ceramics were studied. Y₂O₃ added to AlN showed a noticeable higher densification rate than pure AlN, but the formation of yttrium aluminate phases by the solid-state reaction of Y₂O₃ and Al2O3 occurred on the AlN surface which could retard the densification during the sintering process. The thermal conductivity of AlN specimens was improved by the addition of Y₂O₃ up to 3 wt% in spite of the formation of a YAG secondary phase in the AlN grain boundaries because Y₂O₃ additions could reduce the oxygen content in the AlN lattice which is primary factor controlling the thermal conductivity. However, the thermal conductivity decreased at a 5 wt% addition because the extra formation of the YAG phase in grain boundaries could decrease the thermal conductivity by phonon scattering thus surpassing the helpful contributions of smaller Y₂O₃ additions. Spark plasma sintering (SPS) of AlN ceramics was carried out with Y₂O₃ as a sintering additive at sintering temperatures of 1,550 to 1,700 ℃. The effects of Y₂O₃ additions on the sintering behavior and thermal conductivity of AlN ceramics were studied. Y₂O₃ added to AlN showed a noticeable higher densification rate than pure AlN, but the formation of yttrium aluminate phases by the solid-state reaction of Y₂O₃ and Al2O3 occurred on the AlN surface which could retard the densification during the sintering process. The thermal conductivity of AlN specimens was improved by the addition of Y₂O₃ up to 3 wt% in spite of the formation of a YAG secondary phase in the AlN grain boundaries because Y₂O₃ additions could reduce the oxygen content in the AlN lattice which is primary factor controlling the thermal conductivity. However, the thermal conductivity decreased at a 5 wt% addition because the extra formation of the YAG phase in grain boundaries could decrease the thermal conductivity by phonon scattering thus surpassing the helpful contributions of smaller Y₂O₃ additions.
-
Sintering of attrition-milled TiN powders using a spark plasma sintering technique
KwangBoShim,KyoungHunKim,JaeHongChae,JongHanWon 한양대학교 세라믹연구소 2002 Journal of Ceramic Processing Research Vol.3 No.3
Poorly sinterable TiN powders have been fully densified using a spark plasma sintering (SPS) technique. Sintering characteristics and microstructural evolution during SPS processing were evaluated using electron microscopy. It was found that Al2O3 incorporated as a contaminant during the milling process reacted with TiN particles at temperatures above 1700oC to form a secondary phase containing Al2O3 that accelerated the mass transport. This secondary phase makes it possible to start sintering at a lower temperature. It also enables the growth of TiN grains to be controlled. This phenomenon could be confirmed by the presence of the round or curved grain boundaries and the presence of Al2O3 containing secondary phase clusters in grain boundary triple junctions.
-
Thermoelectric properties of silicon hexaboride prepared by spark plasma sintering method
KwangBoShim,KyoungHunKim,J.Matsushita,K.Niihara,KeunHoAuh,DaeWoongLee 한양대학교 세라믹연구소 2002 Journal of Ceramic Processing Research Vol.3 No.3
Silicon hexaboride is attractive for various industrial applications because of its high temperature capability, high hardness and excellent electrical conductivity, in particular it is a promising material for use as a thermoelectric semiconductor at high temperature. We have used a spark plasma sintering technique to produce silicon hexaboride ceramics. The Seebeck coefficient, electrical conductivity and thermal conductivity were measured and the effect of additives, phase composition and microstructure on the thermoelectric properties were discussed. The approximate value of Z (figure of merit value) of the SPS specimen reached about 9.6×10-6/K at 1273 K. The thermoelectric properties (Z) of the SPS specimen are improved in comparison with the specimen by hot-pressing. The effect of the addition of lanthanum and boron on thermoelectric properties of SiB6 were also evaluated.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
