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SiC<sub>f</sub>/SiC 복합체 튜브의 표면조도 및 섬유 부피 분율에 미치는 필라멘트 와인딩 방법의 영향
김대종,이종민,박지연,김원주,Kim, Daejong,Lee, Jongmin,Park, Ji Yeon,Kim, Weon-Ju 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.6
Silicon carbide and its composites are being considered as a nuclear fuel cladding material for LWR nuclear reactors because they have a low neutron absorption cross section, low hydrogen production under accident conditions, and high strength at high temperatures. The SiC composite cladding tube considered in this study consists of three layers, monolith CVD SiC - $SiC_f$/SiC composite -monolith CVD SiC. The volume fraction of SiC fiber and surface roughness of the composite layer affect mechanical and corrosion properties of the cladding tube. In this study, various types of SiC fiber preforms with tubular shapes were fabricated by a filament winding method using two types of Tyranno SA3 grade SiC fibers with 800 filaments/yarn and 1600 filaments/yarn. After chemical vapor infiltration of the SiC matrix, the surface roughness and fiber volume fraction were measured. As filament counts were changed from 800 to 1600, the surface roughness increased but the fiber volume fraction decreased. The $SiC_f$/SiC composite with a bamboo-like winding pattern has a smaller surface roughness and a higher fiber volume fraction than that with a zigzag winding pattern.
SiC<sub>f</sub>/SiC 복합체의 화학기상침착 거동에 미치는 권선 구조와 침착 변수의 영향
김대종,고명진,이현근,박지연,김원주,Kim, Daejong,Ko, Myoungjin,Lee, Hyeon-Geun,Park, Ji Yeon,Kim, Weon-Ju 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
SiC and its composites have been considered for use as nuclear fuel cladding materials of pressurized light water reactors. In this study, a $SiC_f$/SiC composite as a constituent layer of SiC triplex fuel cladding was fabricated using a chemical vapor infiltration (CVI) process in which tubular SiC fiber preforms were prepared using a filament winding method. To enhance the matrix density of the composite layer, winding patterns, deposition temperature, and gas input ratio were controlled. Fiber arrangement and porosity were the main parameters influencing densification behaviors. Final density of the composites decreased as the SiC fiber volume fraction increased. The CVI process was optimized to densify the tubular preforms with high fiber volume fraction at a high $H_2$/MTS ratio of 20 at $1000^{\circ}C$; in this process, surface canning of the composites was effectively retarded.
김대종(Daejong Kim),오승진(Seung Jin Oh),장창희(Changheui Jang),김인섭(In Sup Kim),김응선(Eeung Sun Kim),지세환(Se Hwan Chi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.8
Fracture toughness of the fine grain isotropic graphite IG-11 was evaluated. Fracture toughness value, K<SUB>IC</SUB> was obtained by 3-point bending test using SENB specimen. To determine the optimum loading rate, the effects of loading rate on fracture toughness were investigated. The crack initiation point was determined by DCPD method. Weibull modulus of IG-11 graphite was determined by two parameter Weibull equation using test results of 30 SENE specimens. Crack lengths estimated by DCPD method were lower than real crack length because of leakage of current through contacting and non-broken regions within the specimens. Fraction of those area on the cracked surfaces can be inferred from the difference between the crack lengths measured by DCPD and dye penetration method. Contacting and non-broken regions which are mainly induced by shear cracking and crack bridging increase fracture toughness of graphite.
원자력 사고 안전성 향상을 위한 SiC<sub>f</sub>/SiC 복합소재 개발 동향
김대종,이지수,천영범,이현근,박지연,김원주,Kim, Daejong,Lee, Jisu,Chun, Young Bum,Lee, Hyeon-Geun,Park, Ji Yeon,Kim, Weon-Ju 한국복합재료학회 2022 Composites research Vol.35 No.3
SiC 섬유강화 복합체는 경수형 원자로의 안전성을 획기적으로 향상시킬 수 있는 사고저항성 핵연료 피복관 소재이다. 지르코늄 합금 피복관 및 금속기반 사고저항성 핵연료 피복관에 비해, 중대 사고 환경에서도 우수한 구조적 안정성을 가지고 부식 속도가 매우 낮아, 사고 시 원자로의 온도를 낮추고 사고 진행을 늦출 수 있다. 본 논문에서는 현재 개발되고 있는 사고저항성 SiC 복합체 핵연료 피복관의 개념 및 가동/사고환경에서의 다양한 특성, 상용화를 위해 해결해야 할 다양한 이슈에 대해서 소개하고자 한다.
저압 화학기상증착법을 이용한 β-SiC의 증착 및 결정 성장 방위에 따른 기계적 특성 변화
김대종,이종민,김원주,윤순길,박지연,Kim, Daejong,Lee, Jongmin,Kim, Weon-Ju,Yoon, Soon Gil,Park, Ji Yeon 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.1
${\beta}$-SiC was deposited onto a graphite substrate by a LPCVD method and the effect of the crystallographic orientation on mechanical properties of the deposited SiC was investigated. The deposition was performed at $1300^{\circ}C$ in a cylindrical hot-wall LPCVD system by varying the deposition pressure and total flow rate. The texture and crystallographic orientation of the SiC were evaluated by XRD. The deposition rate increased linearly with the gas flow rate from 800 sccm to 1600 sccm. It also increased with the pressure but became saturated above a total pressure of 3.3 kPa. In the range of 3.3 - 10 kPa, the preferred orientation changed from the (220) and (311) planes to the (111) plane. The hardness and elastic modulus showed maximum values when the SiC had the (111) preferred orientation, though it gradually decreased upon a change to the (220) and (311) preferred orientations.
유리탄소의 동시증착에 의한 TRISO 피복입자의 ZrC 코팅층 미세구조와 화학양론비 제어
고명진,김대종,박지연,조문성,김원주,Ko, Myung-Jin,Kim, Daejong,Park, Ji Yeon,Cho, Moon Sung,Kim, Weon-Ju 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.6
TRISO coated particles with a ZrC barrier layer were fabricated by a fluidized-bed chemical vapor deposition (FBCVD) method for a use in a very high temperature gas-cooled reactor (VHTR). The ZrC layer was deposited by the reaction between $ZrCl_4$ and $CH_4$ gases at $1500^{\circ}C$ in an $Ar+H_2$ mixture gas. The amount of free carbon codeposited with in ZrC was changed by controlling the dilution gas ratio. Near-stoichiometric ZrC phase was also deposited when an impeller was employed to a $ZrCl_4$ vaporizer which effectively inhibited the agglomeration of $ZrCl_4$ powders during the deposition process. A near-stoichiometric ZrC coating layer had smooth surface while ZrC containing the free carbon had rough surface with tumulose structure. Surface roughness of ZrC increased further as the amount of free carbon increased.
핵연료 피복관용 다중층 SiC 복합체 튜브의 Hoop Stress 전산모사 연구
이현근,김대종,박지연,김원주,Lee, Hyeon-Geun,Kim, Daejong,Park, Ji Yeon,Kim, Weon-Ju 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
Silicon carbide-based ceramics and their composites have been studied for application to fusion and advanced fission energy systems. For fission reactors, $SiC_f$/SiC composites can be applied to core structural materials. Multilayered SiC composite fuel cladding, owing to its superior high temperature strength and low hydrogen generation under severe accident conditions, is a candidate for the replacement of zirconium alloy cladding. The SiC composite cladding has to retain its mechanical properties and original structure under the inner pressure caused by fission products; as such it can be applied as a cladding in fission reactor. A hoop strength test using an expandable polyurethane plug was designed in order to evaluate the mechanical properties of the fuel cladding. In this paper, a hoop strength test of the multilayered SiC composite tube for nuclear fuel cladding was simulated using FEA. The stress caused by the plug was distributed nonuniformly because of the friction coefficient difference between the inner surface of the tube and the plug. Hoop stress and shear stress at the tube was evaluated and the relationship between the concentrated stress at the inner layer of the tube and the fracture behavior of the tube was investigated.