원자력플랜트 고온구조용 SiC<SUB>f</SUB>/SiC 복합재료의 기계적 특성 평가

윤한기(Han-Ki Yoon),조호준(Ho-Jun Cho),박원조(Won Jo Park) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4

SiC<SUB>f</SUB>/SiC composites are well-known materials for high temperature structural applications because of their intrinsic properties using fusion power reactors such as shield and divertor coolant channel. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. For these reasons, SiC<SUB>f</SUB>/SiC composite can be considered as a promising for structural materials because of their good fracture toughness compared with monolithic SiC ceramics. But, high temperature and pressure lead to the degradation of the fiber. Therefore, an improvement of the coating fiber is key requirements for fabrication of SiC<SUB>f</SUB>/SiC composites by LPS method. In this paper, The SiC<SUB>f</SUB>/SiC composites were fabricated by the LPS method and investigated effects of SiC fiber coating. The SiC<SUB>f</SUB>/SiC composites were fabricated with coated and uncoated Tyranno-SA fibers. The thickness of the coating fiber was 0.25 ㎛ and 0.5 ㎛. In order to investigate effects of coating, the flexural strength were carried out at room temperature, respectively. The densification and microstructure of LPS-SiC<SUB>f</SUB>/SiC composites were observed by FE-SEM.

차세대 원자력 구조용 고온 SiC<SUB>f</SUB>/SiC 복합재료의 기계적 특성

조호준(Ho-Jun Cho),윤한기(Han-Ki Yoon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

SiC<SUB>f</SUB>/SiC composites are well-known materials for high temperature structural applications because of their intrinsic properties using fusion power reactors such as shield and divertor coolant channel. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. For these reasons, SiC<SUB>f</SUB>/SiC composite can be considered as a promising for structural materials because of their good fracture toughness compared with monolithic SiC ceramics. But, high temperature and pressure lead to the degradation of the fiber. Therefore, an improvement of the coating fiber is key requirements for fabrication of SiC<SUB>f</SUB>/SiC composites by LPS method. In this paper, The SiC<SUB>f</SUB>/SiC composites were fabricated by the LPS method and investigated effects of SiC fiber coating. The SiC<SUB>f</SUB>/SiC composites were fabricated with coated and uncoated Tyranno-SA fibers. The thickness of the coating fiber was 0.25 ㎛ and 0.5 ㎛. In order to investigate effects of coating, the flexural strength were carried out at room temperature, respectively. The densification and microstructure of LPS-SiC<SUB>f</SUB>/SiC composites were observed by FE-SEM.

폴리카보실란 전구체로부터 고온 산화성분위기서 기계적물성이 우수한 파이롯-규모의 탄화규소섬유 제조공정 개발

윤병일 ( B. I. Yoon ),최우철 ( W. C. Choi ),김정일 ( J. I. Kim ),김재성 ( J. S. Kim ),강홍구 ( H. G. Kang ),김명주 ( M. J. Kim ) 한국복합재료학회 2017 Composites research Vol.30 No.2

본 연구의 목적은 고온 산화성 분위기하에서 기계적물성이 우수한 탄화규소섬유(SiC Fiber)를 파일롯-규모로의 생산 제조공정을 개발하는 것이다. 프리세라믹 전구체로서 폴리카보실란(PCS)을 사용하여 탄화규소섬유를 제조하였다. 연속성의 PCS 섬유는 300~350℃에서 PCS를 용융한 후에 용융방사로부터 얻었다. 열처리 전에 섬유의 불융화를 위하여 공기 분위기하에서 경화를 하였다. 경화 전, 후에 측정한 FT-IR 스펙트라 피크로부터 경화도를 계산하였다. 탄화규소섬유의 물성은 경화도에 따라 크게 영향을 받았다. 본 개발에서 열처리 중 섬유의 장력 조절로 우수한 물성을 갖는 탄화규소섬유를 얻었다. 탄화규소섬유의 화학조성과 기계적물성은 안정화섬유의 열처리시의 이송속도에 영향을 받았다. 탄화규소섬유를 공기분위기하 1000℃에서 1분부터 50시간까지 노출한 후에 인장시험을 수행하였다. 그 결과 인장강도는 약 60%까지 감소함을 보여주었다. 장시간 노출시험시 낮은 인장 강도값을 나타내는 섬유는 화학성분 분석시 섬유의 표면에 많은 탄소량을 함유하고 있었다. The purpose of this study is to develop silicon carbide fiber showing an excellent mechanical properties under highly oxidative conditions at high temperature. Polycarbosilane(PCS) as a preceramic precursor was used for making the SiC fiber. PCS fiber was taken by melt spinning method followed by melting the PCS at 300~350℃ in N2 gas. The Curing of PCS fiber was carried out in air oxygen chamber, prior to high temperature pyrolysis. Degree of cure was calculated by characteristic peak`s ratio of Si-H to Si-CH₃ in FT-IR spectra before and after curing of PCS fiber. The properties of SiC fiber was affected greatly by the degree of cure. The SiC fiber produced by controlling fiber tension during heat treatment showed good properties. The SiC fiber exposed to 1000℃ at air from 1 min. up to maximum 50 hrs showed around 60% reduction in tensile strength. We found that large amount of carbon content on the fiber surface after long-term exposure has resulted in lower tensile strength.

LPS법에 의한 카본코팅 Tyranno-SA 섬유 보강한 복합재료의 굽힘 강도 특성

조호준(Ho-Jun Cho),문승현(Seung-Hyun Moon),윤한기(Han-Ki Yoon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

A recently developed SiC fiber, Tyranno-SA (2D plain-woven), was used as the reinforcemnet in several SiC<SUB>f</SUB>/SiC composites. The composites were fabricated by liquid phase sintering (LPS) process. The mechanical properties and fracture behaviors of LPS-SiC<SUB>f</SUB>/SiC composites, with the fiber volume fraction, were investigated in conjunction with a detailed analysis of their microstructure. The fiber preforms were prepared to keep a fiber volume fraction of about 20%, 30% and 40%, respectively. The flexural strength of LPS-SiC<SUB>f</SUB>/SiC composites were also carried out at room temperature thought three point bending test. A decrease in the fiber volume fraction led to an increase in the flexural strength of the LPS-SiC<SUB>f</SUB>/SiC composites, accompanying nearly full-density and a highly dense matrix with fiber bundle.

탄화규소섬유와 탄소섬유 하이브리드 직물을 강화재로 한 SiC 매트릭스 세라믹복합재의 기계적물성, 산화 및 삭마 저항성 개선 연구

윤병일,김명주,김재성,권향주,윤성태,김정일 한국복합재료학회 2019 Composites research Vol.32 No.3

In this study, Cf/SiC, SiCf/SiC and Cf-SiCf/SiC ceramic composites reinforcing carbon fiber, SiC fiber and hybrid fiber were fabricated by hybrid TGCVI and PIP process. After the thermal shock cycle, 3-point bending and Oxy-Acetylene torch test, their mechanical behavior, oxidation and erosion resistance were evaluated. The Cf/SiC composite showed a decrease in mechanical property along with increasing temperature, a pseudo-ductile fracture mode and a large quantity of erosion. The SiCf/SiC composite exhibited stronger mechanical property and lower erosion rate compared to the Cf/SiC, but brittle fracture mode. On the other hand, hybrid type of Cf-SiCf/SiC composite gave the best mechanical property, more ductile failure mode than the SiCf/SiC, and lower erosion rate than the Cf/SiC. During the Oxy-Acetylene torch test, the SiO2 formed by reaction of the SiC matrix with oxygen prevented further oxidation or erosion of the fibers for Cf-SiCf/SiC and SiCf/SiC composites particularly . In conclusion, if a hybrid composite with low porosity is prepared, this material is expected to have high applicability as a high temperature thermo-structural composite under high temperature oxidation atmosphere by improving low mechanical property due to the oxidation of Cf/SiC and brittle fracture mode of SiCf/SiC composite. 본 연구에서는 탄소섬유, 탄화규소섬유 그리고 하이브리드섬유를 강화재로 하여 TGCVI와 PIP 혼합 공정으로 Cf/SiC, SiCf/SiC, Cf-SiCf/SiC의 세라믹복합재를 제조하였다. 열충격싸이클시험, 3-점 굴곡험과 Oxy-Acetylene토취 시험후에 그들의 기계적물성, 산화저항성과 내삭마성을 평가하였다. Cf/SiC복합재는 온도 증가에 따라서 기계적물성의 감소와 준 연성의 파단모드, 그리고 높은 삭마량을 보였다. SiCf/SiC복합재는 Cf/SiC 복합재에 비하여 강한 기계적물성, 낮은 삭마량을 그리고 취성의 파단모드를 나타냈다. 한편 하이브리드 복합재는 가장 우수한 기계적물성과 SiCf/SiC보다는 연성의 파단모드 그리고 Cf /SiC 보다 낮은 삭마량의 결과를 나타냈다. Oxy-Acetylene토취 시험 중에 SiC매트릭스는 산화되어 SiO2층을 형성하였으며, 특히 이 층은 Cf-SiCf/SiC 와 SiCf/SiC 복합재에서 섬유의 추가적인 삭마를 막는 역할을 하는 것으로 나타났다. 결론적으로 낮은 기공율을 갖는 하이브리드 복합재를 제조한다면, Cf/SiC의 산화로 인한 기계적물성의 감소와 SiCf/SiC 복합재의 취성 파단모드의 개선으로 고온 산화분위기에서 고온열구조재로의 적용이 높을 것으로 기대한다.

비정질 SiC 섬유를 강화재로 한 SiC<SUB>f</SUB>/SiC 세라믹 복합재의 엔진 적용 가능성 연구

김재성(Jae Sung Kim),김명주(Myeongju Kim),김정일(Jungil Kim),윤병일(Byungil Yoon) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5

본 연구의 목적은 비정질의 SiC 섬유로 제조한 SiCf/SiC 세라믹 복합재에 대한 가스터빈엔진 적용성에 관한 연구이다. 본 실험에서는 Tyranno ZMI 섬유를 강화재로 한 RMI 공정으로 시편을 제조하였다. 평직의 SiC 섬유 직물을 적층한 후, z축 방향으로 스티칭하여 프리폼을 제작하였다. 프리폼은 I-CVD로 PyC와 SiC코팅을 하였다. RMI공정 시 ZMI 섬유의 손상을 방지하기 위해 PCS 세라믹 프리커서로 함침, 탄화 하였다. 밀도화는 SiC분말과 Carbon Black분말로 슬러리를 제조하여 진공함침 후 RMI 공정을 하였다. 상온과 고온에서 기계적 및 열적 물성을 측정으로 ZMI 섬유의 엔진 적용성을 살펴보았다. The purpose of this study is to investigate the applicability of SiCf/SiC ceramic composites reinforced with amorphous SiC fiber for gas turbine engine. In this study SiCf/SiC ceramic composites were fabricated by RMI process using Tyranno ZMI fiber as reinforcement. The preform was coated with PyC and SiC by I-CVD. Additionally PIP process using PCS precursor was used to prevent fiber damage exposed at high temperature during the process. The preform was impregnated with SiC powder and carbonblack slurry and siliconized finally to get SiCf/SiC plate. The applicability of SiCf/SiC to engine components was discussed with Mechanical and thermal property measurement.

고온내산화성 실리콘카바이드 섬유의 국내·외 기술개발 동향

윤병일(B. I, Yoon),최우철(W. C, Choi),김재성(J. S, Kim),김정일(J. I, Kim) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

초고온에서 단시간 혹은 장시간 사용할 수 있는 내열성과 구조성을 갖춘 소재는 오늘날 우주항공, 국방, 원자력발전소 및 일반산업분야에 까지 대단히 매력적이고 중요한 위치를 차지하고 있다. 특히 산화성이 강한 분위기하에서 작동하는 각종 엔진은 고온성과 내산화성을 갖춘 소재가 요구된다. 이의 하나가 실리콘카바이드섬유(SiC fiber)에 실리콘카바이드(SiC)를 매트릭스로 한 SiC/SiC 세라믹복합재이다. 또한 SiC 섬유는 전자기파 흡수력이 우수하여 항공기 등의 스텔스 소재로서 유망하다. 본 논문에서는 SiC/SiC를 구성하고 있는 SiC 섬유의 국내외에서의 기술 개발과, 그리고 SiC/SiC 복합재의 특성과 적용분야 현황을 실펴보고자 한다. The high temperature resistant thermal structural materials which are able to be used during a short or long time are very attractive and also hold key position in the area of aerospace, defense, nuclear power plant and general industry. All sorts of engines working particularly at highly oxidative environment require extremely oxidative resistant materials. One of them is SiC/SiC ceramic composite. It is also gretely promising material in the future due to thr excellent microwave absorbing feature. In this paper the technology development status of silicone carbide fiber at home and abroad and the characteristics and applications of SiC/SiC composite are introduced.

The Frequency Characteristics of Elastic Wave by Crack Propagation of SiC/SiC Composites

J.W. Kim,K.W. Nam 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.10

We studied on the nondestructive evaluation of the elastic wave signal of SiC ceramics and SiC/SiC composite ceramics under monotonic tensile loading. The elastic wave signal of cross and unidirectional SiC/SiC composite ceramics were obtained by pencil lead method and bending test. It was applied for the time-frequency method which used by the discrete wavelet analysis algorithm. The time-frequency analysis provides time variation of each frequency component involved in a waveform, which makes it possible to evaluate the contribution of SiC fiber frequency. The results were compared with the characteristic of frequency group from SiC slurry and fiber. Based on the results, if it is possible to shift up and design as a higher frequency group, we will can make the superior material better than those of exiting SiC/SiC composites.

SiC 장섬유 강화 탄화규소 복합재료의 제조 및 특성

신윤석(Yun-Seok Shin),이상필(Sang-Pill Lee),이진경(Jin-Kyung Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

The mechanical properties of SiC<SUB>f</SUB> / SiC composites reinforced with continuous SiC fiber have been investigated in conjunction with the detailed analysis of their microstructure. The effect of heat treatment on the characterization of monolithic SiC materials was also examined. SiC<SUB>f</SUB> / SiC composites was fabricated by the reaction sintering process using a braiding Hi - Nicalon SiC fiber. The complex matrix slurry was prepared by different composition ratios of SiC and C particles. The characterization of RS-SiC and RS - SiC<SUB>f</SUB> / SiC composites materials was investigated by means of SEM, EDS and three point bending test. Based on the of mechanical property-microstructure correlation, the high temperature properties of RS - SiC<SUB>f</SUB> / SiC composites was discussed for the applicability of structural material in the fusion power plant.

표면 균열을 가지는 SiC/SiC 복합재의 강도 특성

서임술(I. S. Seo),안석환(S. H. Ahn),남기우(K. W. Nam) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

SiC/SiC composites are among the most promising structural materials for fusion because of their potential application for high performance reactors and superior safety characteristics compared to metallic materials. And a recently developed SiC fiber, Tyranno-SA, was also used as the reinforcement in several SiC/SiC composites. In this study, we examined the relationship between various crack size and bending strength in order to analyze the mechanical properties under the room temperature. The mechanical properties and fracture behaviors were investigated using three-point bending test. The test results showed that a difference of the orientation of SiC fiber causes the variation of bending strength and crack propagation behavior. In order to clarify the cause of these phenomena, we observed an aspect of crack growth regarding both unidirectional composite specimen and cross ply composite specimen using a scanning electron microscope. And it was showed that crack healing effect by coating SiO₂ nano colloidal on SiC/SiC composite ceramics was not confirmed clearly.