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).

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.

알루미늄 판재의 센딩조건에 따른 도장특성 평가

윤한기(Han-Ki Yoon),최석인(Seok-In Choi),이종호(Jong-Ho Lee) 한국해양공학회 2011 韓國海洋工學會誌 Vol.25 No.1

Researchers suggested painted coating characteristics if aluminum sheet by various sending condition. Painted coating is used to protect the surface of the blocks from the interior and exterior. It is also used to enhance the value of automobiles and ship materials. This process makes the materials surface for protection and elegance. Although analysis of the roughness and critical scratch load of painted coating is important, the effects of this material have not progressed much. In this study, the characteristics of painted coating in the other conditions of the polished aluminum sheet were investigated. The results of both various conditions and initial roughness values were almost similar to final values after painted coating.

나노인덴테이션기법을 이용한 ZnO/Si 박막의 기계적 특성

윤한기(Han-Ki Yoon),정헌채(Hun-Chae Jung),손종윤(Jong-Yoon Sohn),유윤식(Yun-Sik Yu) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

Recently there has been a great world-wide interest in developing and characterizing new nano-structured materials. These newly developed materials are often prepared in limited quantities and shapes unsuitable for the extensive mechanical testing. The development of depth sensing indentation methods have introduced the advantage of load and depth measurement during the indentation cycle. In the present work, ZnO thin films are prepared on Si(111), Si(100) substrates at different temperatures by pulsed laser deposition(PLD) method. Because the potential energy in c-axis is low, the films always show c-axis orientation at the optimized conditions in spite of the different substrates. Thin films are investigated by X-ray diffractometer and Nano indentation equipment. From these measurements it is possible to get elastic modulus and hardness of ZnO thin films on Si substrates.

핵융합로 디버터 대면재의 W 접합부 미세조직과 마이크로경도 측정

윤한기(Han-Ki Yoon),한흥남(Heung Nam Han),박준수(Joon-Soo Park) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.12

본 연구는 신뢰성 있는 W접합 SiC/SiC복합재료 대면제 제조를 위한 제조조건 검토를 목적으로, 분말 또는 판재형태의 W와 SiC을 핫프레스로 접합하고, 접합층의 형성상태 및 물성에 대하여 조사하였다. 그리고, 동일 조건에서 SiC/SiC복합재료표면에 W을 접합시켰을 경우의 접합성과 SiC/SiC재료의 미세조직변화를 TEM을 이용하여 평가하였다. 마이크로기공이 관찰되지 않은 W판재를 이용한 접합법을 채용하여 W-SiC/SiC복합재료의 접합에 성공하였다. To develop the joining technology for the W-SiC/SiC joining materials as plasma facing materials, W layers were formed on monolithic SiC and SiC/SiC composites. W layers were produced from W powder or W plate by hot pressing method. Their microstructure and mechanical properties were evaluated through various microstructural observation and nano-indentation methods. It seems that the diffusion of carbon from SiC to W was one of the reasons of the formation of reaction phases. Thin oxide layer and micropores were observed in the W-SiC interface, which was prepared using W powders. Because of the existence of the micropores and because the reaction phases exhibited different hardness values, the hardness values measured by nano-indentation varied considerably. W-SiC/SiC composites were successfully prepared using a W plate-joining method, which was adopted to avoid the formation of micropores in the interface.

고온용 SiC<SUB>f</SUB>/SiC 복합재료개발 기술과 활용방향

윤한기(Han Ki Yoon),이영주(Young Ju Lee),박이현(Yi Hyun Park) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.11

The development of the first wall whose major function is to withstand high neutron and heat fluxes is a critical path to fusion power. The materials database and the fabrication technology are being developed for design, construction and safety operation of the fusion reactor. The first wall was designed to consist of the plasma facing armor, the heat sink layer and the supporting plates. and Porous materials are of significant interest due to their wide applications in catalysis, separation, lightweight structural materials. In this study, the characteristics of the sintering process of SiC ceramic, SiCf/SiC composite and porous Cf/SiC composite have been introduced order to study of the fusion blanket materials and heat-exchange pannel.

Inject ion-molded Bamboo/PBS 복합재료의 섬유길이에 따른 기계적 특성

윤한기(Han-Ki Yoon),이연희(Yeon-Hee Lee),Hitoshi Takagi,Kazuya Ohkita 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

In this paper we studied the effects of fiber length on mechanical properties of injection-molded bamboo/PBS composites. We carried out tensile test and Izod tests for evaluating the mechanical properties of bamboo/PBS composites. The fiber length of the composites consisted of the range from -75㎛, +75㎛ to -180㎛, +180㎛ to -250㎛, and +250㎛ to -500㎛. Also we examined fracture surface of the bamboo/PBS composites by SEM. The results of evaluated tensile strength of the composites with bamboo fiber ranging from +75㎛ to -180㎛ and from +180㎛ to -250㎛ were higher than those ranging from -75㎛ and from +250㎛ to -500㎛. Izod impact strength of the bamboo/PBS composites decreased in the case of the composites with shorter fiber length. In particular, the shortest fiber length in range of -75㎛, we observed sharply dropped strength. The fracture surface of the bamboo/PBS composites showed the formation of pull-out fibers.

알루미늄 판재의 센딩조건에 따른 도장 특성

윤한기(Han-Ki Yoon),이종호(Jong-Ho Lee),유덕생(Duck-Seng Ryu),최석인(Seok-In Choi) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

Painted coating is a work to cover the surface of the blocks from the interior and exterior. It is used for raising qualities and values of automobiles. This process makes protection and elegance to the material surfaces. A lot of researches about the composition of aluminum or plastic and the process of making steel sheet materials of automobiles were studied. However painted coating studies were insufficient. It is important that researching about characteristics of the roughness and critical scratch load by the effect of painted coating because the roughness was expected to cause a low effect to the painted coating. In this study, the characteristics of painted coating on polished aluminum sheets with different conditions were investigated to develop the work condition and process of painted coating on aluminum sheet in automobile manufacture line. The results showed the roughness after final painted coating was similar to the first roughness of sheet. The high surface roughness and force of the specimen polished by sandpapers was obtained.

투명전도성 박막기술과 특성평가

윤한기(Han-Ki Yoon),Ri-ichi Murakami 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

The development of electromagnetic wave shielding materials are strongly required because the malfunction of electronic equipment, mobile phone and EMI. ITO and IZO films of transparent conducting thin films were produced onto plastic and glass substrates at room temperature by the inclination opposite target type DC magnetron equipment, which a metallic In2O3+SnO2 and In2O3+ZnO alloy target was used. The effects of electric properties, electromagnetic wave shielding effectiveness, gas barrier deposited SiO and SiON were investigated. In the result, the ITO thin films deposited at room temperature showed the most electromagnetic shielding effectiveness and we found that effect of the gas barrier deposited SiO and SiON in IZO thin film is very important parameter.

SiC-SiC세라믹스 동종재 접합재의 전단강도 특성 평가

윤한기(Han Ki Yoon),정헌채(Hun Chea Jung),T.Hinoki,A.Kohyama 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 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 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 1400-1900℃ 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).