용융함침법에 의한 반응소결 SiC/SiC 복합재료의 특성 평가

A. Kohyama,이상필,신윤석 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.2

NITE-SiC 세라믹스의 치밀화 기구

이영주(Young-Ju Lee),윤한기(Han-ki Yoon),박이현(Yi-Hyun Park),박준수(Jun-Soo Park),A. Kohyama 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

Nano Infiltration Transient Eutectic Phase - Silicon Carbide (NITE-SiC) have been fabricatied by a Hot Pressing (HP) process, using SiC powder with an average size of about 30㎚. Alumina (Al₂O₃) and Yttria (Y₂O₃) were used for additives meterials. These mixed powders were sintered at the temperature a of 1300℃, 1650℃, 1800℃ and 1900℃ under an applied pressure of 20㎫. Densification of microstructure gives an effect to density and strength. Specially, Densification Mechanism basically is important from the sintering which use the HP. In this study, nano size particle was used to HP and the densification of NITE-SiC mechanism by a press displacement appers investigated. The slope changes places by a press displacement shared a at three steps. The mechanism on the densification of each sintering temperature was investigated. The each step is shows a with each other different mechanism quality.

FUSION MATERIALS AND FUSION ENGINEERING R & D IN JAPAN

A. KOHYAMA,S. KONISHI,A. KIMURA 한국원자력학회 2005 Nuclear Engineering and Technology Vol.37 No.5

Japanese activities on fusion structural materials R & D have been well organized under the coordination of university programs and JAERI/NIMS programs more than two decades. Where, two categories of structural materials have been studied, those are; reduced activation martensitic/ferritic steels (RAFs) as reference material and vanadium alloys and SiC/SiC composite materials as advanced materials. The R & D histories of these candidate materials and the present status in Japan are reviewed with the emphasis on materials behavior under radiation damage. The importance of IFMIF and technology development for blanket R & D including ITER-TBRG activity is emphasized and the current status of those activities in Japan is also presented.

TIG용접한 저방사화 페라이트강(JLF-1)의 고온강도 및 피로수명특성

윤한기,이상필,김사웅,A.Kohyama 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.9

핵융합로용 저방사화 철강재료(JLF-1)의 강도와 파괴인성 K<SUB>IC</SUB> 평가

김동현(D. H. Kim),윤한기(H. K. Yoon),이상필(S. P. Lee),공유식(Y. S. Kong),A. Kohyama 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3

A reduced activation ferritic steel (JLF-1) has been developed for a candidate of structural materials in nuclear fusion reactor applications. The tensile properties and fracture toughness (K<SUB>IC</SUB>) of the JLF-1 steel were evaluated from the variation of temperature and rolling direction. From experimental results, it was found that the tensile properties and fracture toughness of JLF-1 steel showed the isotropy in the rolling direction. However, The result of test at room temperature showed higher strength and fracture toughness than test at high temperature(400℃).

SiC세라믹스 동종재 접합재의 전단강도 특성 평가

Yoon, Han Ki,Jung, Hun Chea,Hinoki, T.,Kohyama, A. 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.5

SiC/SiC복합재료는 뛰어난 고온특성, 내산화성 및 크립(Creep)에 대한 저항성이 우수하고 또한 중성자에 의한 조사 손상이 다른 세라믹스에 비해서 적게 받는다는 장점으로 인하여 핵융합로의 블랑켓(Blanket), 제1벽(First-wall) 및 다이버터(Di-vertor)등의 후보재료로 적용이 기대되고 있다. SiC/SiC복합재료 제조시 가장 큰 문제점은 높은 소결온도와 압력으로 인하여 탄화규소 섬유가 손상되어 복합재료의 특성이 저하되는 것이므로 이들 재료의 전단강도 특성 평가는 매우 중요하다, 본 연구에서는 SiC제조특성과 소결온도에 대한 전단강도 특성의 평가한다. In this study, joining methods with SiC powder as the joining adhesives were studied in order to avoid the residual stresses coming from CTE (Coefficient of Thermal Expansion) mismatch between substrate and joining layer. The shear strength and microstructure of joined material between SiC substrates are investigated. The commercial Hexoloy-SA (Saint-Gobain Ceramics, USA) used in this work as substrate material. The fine ${\beta}$-SiC nano-powder which the average particle size is below 30 nm, $Al_2O_3$, $Y_2O_3$, and $SiO_2$ were used as joining adhesives. The specimens were joined with 20MPa and $1400-1900^{\circ}C$ by hot pressing in argon atmosphere. The shear test was performed to investigate the bonding strength. The cross-section of the joint was characterized by using an optical microscope and scanning electron microscopy (SEM).

FUSION MATERIALS AND FUSION ENGINEERING R&D IN JAPAN

KOHYAMA A.,KONISHI S.,KIMURA A. Korean Nuclear Society 2005 Nuclear Engineering and Technology Vol.37 No.5

Japanese activities on fusion structural materials R&D have been well organized under the coordination of university programs and JAERI/NIMS programs more than two decades. Where, two categories of structural materials have been studied, those are; reduced activation martensitic/ferritic steels (RAFs) as reference material and vanadium alloys and SiC/SiC composite materials as advanced materials. The R&D histories of these candidate materials and the present status in Japan are reviewed with the emphasis on materials behavior under radiation damage. The importance of IFMIF and technology development for blanket R&D including ITER-TBRG activity is emphasized and the current status of those activities in Japan is also presented.

SiC세라믹스 동종재 접합재의 전단강도 특성 평가

윤한기(Han Ki Yoon),정헌채(Hun Chea Jung),T. Hinoki,A. Kohyama 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.5

SiC/SiC복합재료는 뛰어난 고온특성, 내산화성 및 크립(Creep)에 대한 저항성이 우수하고 또한 중성자에 의한 조사 손상이 다른 세라믹스에 비해서 적게 받는다는 장점으로 인하여 핵융합로의 블랑켓(Blanket), 제1벽(First-wall) 및 다이버터(Di-vertor)등의 후보재료로 적용이 기대되고 있다. SiC/SiC복합재료 제조시 가장 큰 문제점은 높은 소결온도와 압력으로 인하여 탄화규소 섬유가 손상되어 복합재료의 특성이 저하되는 것이므로 이들 재료의 전단강도 특성 평가는 매우 중요하다, 본 연구에서는 SiC제조특성과 소결온도에 대한 전단강도 특성의 평가한다. In this study, joining methods with SiC powder as the joining adhesives were studied in order to avoid the residual stresses coming from CTE (Coefficient of Thermal Expansion) mismatch between substrate and joining layer. The shear strength and microstructure of joined material between SiC substrates are investigated. The commercial Hexoloy-SA (Saint-Gobain Ceramics, USA) used in this work as substrate material. The fine β-SiC nano-powder which the average particle size is below 30 nm, Al2O3, Y2O3, and SiO2 were used as joining adhesives. The specimens were joined with 20MPa and 1400-1900oC by hot pressing in argon atmosphere. The shear test was performed to investigate the bonding strength. The cross-section of the joint was characterized by using an optical microscope and scanning electron microscopy (SEM).

저방사화 철강재 의 시험편 크기 변화에 따른 (JLF-1) 파괴저항곡선의 변화

김동현(D.H.Kim),윤한기(H.K.Yoon),이상필(S.P.Lee),A.Kohyama 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11

Reduced activation ferritic steel (JLF-1) is considered as a promising candidate material for blanket<br/> or first-wall structure of D-T fusion reactors. The fracture tests of fracture resistance curve (J-R curve)<br/> and JIC are desirable to investigate the exact fracture toughness of JLF-1 steel, since it has a high<br/> ductility. The fracture toughness of JLF-1 steel is affected by the configuration of test specimen such<br/> side groove, specimen thickness or specimen size. In this study, the fracture toughness tests were<br/> performed with various size(plane size and thickness) and various side groove of specimens. The test<br/> results showed the standard specimen with the side groove of 40 % represented a valid fracture<br/> toughness. The fracture resistance curve increased with increasing plane size and decreased with<br/> increasing thickness. However, the fracture resistance curve of half size specimen was similar to that of<br/> the standard specimen.

LPS-SiC 세라믹스 제조시 소결조제 SiO₂의 영향

정헌채(Hun-Chae Jung),윤한기(Han-Ki Yoon),박준수(Jun-Soo Park),A.Kohyama 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

Monolithic liquid phase sintered SiC (LPS-SiC) was made by hot pressing method with nano-SiC powder whose a particle size is 30nm and less on the average. Alumina (Al₂O₃), yttria (Y₂O₃) and silica (SiO₂) were used for sintering additives. To investigate effects of SiO₂, Al₂O₃/Y₂O₃ composition was fixed and then ratios of SiO₂ were changed as four kinds. Materials have been sintered for 1 hour at 1760 ℃, 1780 ℃ and 1800 ℃ under the pressure of 20MPa. The system of sintering additives which affects a property of sintering as well as the influence depending on compositions of sintering additives were investigated by measurement of density, mechanical properties such as flexural strength elastic modulus were investigated to make sure of the optimum condition which is about matrix of SiCf/SiC composites. Sintered density, flexural strength of fabricated LPS - SiC increased with increasing the sintering temperature. Particularly, relative density of sintered body at 1800 ℃ with the less content of SiO₂, specimen of AYSa-1800 was 95 %. Also, flexural strength and elastic modulus were 587.5 ㎫ and 216.3 ㎬, respectively. It is superior values than that of LPS-SiC with Al₂O₃-Y₂O₃ system.