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이상진,윤존도,권혁보,전병세,Lee, Sang-Jin,Yun, Jon-Do,Gwon, Hyeok-Bo,Jeon, Byeong-Se 한국재료학회 2001 한국재료학회지 Vol.11 No.9
In this study, the solution combustion method was employed to synthesize stoichiometric mullite, and hence the attrition process was employed to prepare ultrafine mullite particles with nano size. The thermal decomposition behavior and partial pressure of equilibrium species of both oxidizer and fuel were considered during solution combustion process. The synthesized product was mullite phase with 40 nm crystalline size, and the alumina contents of the product by TEM/EDS quantity analysis was 3.12$\pm$04 mole. The result showed that the synthesized mullite was almost close to the it's stoichiometric composition. For attrition process, the dispersion behavior of the mullite suspension was controlled and was comminuted with the condition of 800 rpm for 4 hours using 0.3 mm zirconia ball media. As a result of comminution, the mean particle size was 80 nm.
나노인덴테이션과 주사탐침현미경을 이용한 박막 재료의 특성평가
김봉섭,윤존도,김종국,Kim, Bong-seob,Yun, Jon-do,Kim, Jong-kuk 한국재료학회 2003 한국재료학회지 Vol.13 No.9
Surface and mechanical properties of thin films with submicron thickness was characterized by nanoindentation with Berkovich and Vickers tips, and scanning probe microscopy. Nanoindention was made in a depth range of 15 to 200 nm from the surface by applying tiny force in a range from 150 to $9,000 \mu$N. Stiffness, contact area, hardness, and elastic modulus were determined from the force-displacement curve obtained. Reliability was first tested by using fused quartz, a standard sample. Elastic modulus and hardness values of fused quartz measured were the same as those reported in the literature within two percent of error. Mechanical properties of ITO thin film were characterized in a depth range of 15∼200nm. As indentation depth increased, elastic modulus and hardness decreased by substrate effect. Ion beam deposited DLC thin films were indented in a depth range of 40∼50 nm. The results showed that the DLC thin film using benzene and bias voltage 0∼-50 V has elastic modulus and hardness value of 132 and 18 GPa respectively. Pure DLC thin films showed roughnesses lower than 0.25 nm, but silicon-added DLC thin films showed much higher roughness values, and the wavy surface morphology.
자전연소합성법에 의한 여러 가지 섬유상 및 입상 탄화물의 제조
방환철,윤존도,Bang, Hwan-Cheol,Yun, Jon-Do 한국재료학회 2000 한국재료학회지 Vol.10 No.5
Fabrication of various carbide fibers from carbon fibers and elementary powders of Ti, Zr, Nb, Zi, W, B, and Mo by self-propagating high temperature synthesis was attempted. It was found the almost pure phase of TiC, ZrC, NbC, SiC, $B_4$C, and $Mo_2$C carbides were successfully produced. The three types of morphologies were ob-served, TiC, ZrC, NbC, and $B_4$C had a hollow-type fibrous shape. SiC had fiber shape consisting of smaller particles and fine whiskers. WC and $Mo_2$C had non-fibrous shapes. The reason for the different morphologies was explained. The formation mechanism of hollow fibers was suggested. 자전연소합성(SHS)법을 이용하여 탄소섬유와 티타늄, 지르코늄, 니오븀, 규소, 붕소, 중석, 몰리브덴의 분말로부터 여러 가지 섬유상 탄화물의 합성을 시도하였다. 티타늄과 지르코늄은 예열없이, 그 이외의 경우는 전기로 또는 화학로를 사용하여 예열하여 반응을일으킨 결과, TiC, ZrC, NbC, SiC, $B_4$C, WC,$ Mo_2$C 의 순수한 탄화물의 형성되었다. TiC, ZrC, NbC 및 $B_4$C 탄화물의 형상은 속의 빈 섬유상이었고, SiC는 보다 작은 입자와 미세 휘스커로 이루어진 섬유상을 하고 있었고 WC와 $Mo_2$C 는 비섬유상을 하고 있었다. 여러 가지 형상의 원인에 대하여 합리적 설명을 시도하였으며 정성적 메카니즘을 제안하였다.
김지수,양현윤,윤존도,조상봉,Kim Ji-soo,Yang Hyeon-yun,Yun Jon-do,Cho Sang-bong 한국재료학회 2004 한국재료학회지 Vol.14 No.6
Elastic and plastic deformation behaviors of the high purity aluminum and the silica glass were studied using nanoindentation and finite element analysis(FEA) techniques. Berkovich- and cone-type indenters were used for the nanoindentation test. Deformation behaviors and nanoindent profiles of elastic, elastic-plastic or plastic materials were clearly visualized by FEA simulation. Effects of the penetration depth and strain hardening on the deformation behavior were examined. Pile-up and sink-in behaviors were studied by using FEA technique. Degree of pile-up or sink-in was found to be a function of the ratio of elastic modulus to yield strength of materials. FEA was found to be an effective method to study deformation behaviors of materials under nanoindentation, especially in the case when pile-up or sink-in phenomena occurred.
정아롱,김준수,윤존도,Jeong, A-Rong,Kim, Jun-Su,Yun, Jon-Do 한국재료학회 2012 한국재료학회지 Vol.22 No.8
Recently nanoscience and nanotechnology have been studied intensively, and many plants, insects, and animals in nature have been found to have nanostructures in their bodies. Among them, lotus leaves have a unique nanostructure and microstructure in combination and show superhydrophobicity and a self-cleaning function to wipe and clean impurities on their surfaces. Coating films with combined nanostructures and microstructures resembling those of lotus leaves may also have superhydrophobicity and self-cleaning functions; as a result, they could be used in various applications, such as in outfits, tents, building walls, or exterior surfaces of transportation vehicles like cars, ships, or airplanes. In this study, coating films were prepared by dip coating method using polypropylene polymers dissolved in a mixture of solvent, xylene and non-solvent, methylethylketon, and ethanol. Additionally, attempts were made to prepare nanostructures on top of microstructures by coating with the same coating solution with an addition of carbon nanotubes, or by applying a carbon nanotube over-coat on polymer coating films. Coating films prepared without carbon nanotubes were found to have superhydrophobicity, with a water contact angle of $152^{\circ}$ and sliding angle less than $2^{\circ}$. Coating films prepared with carbon nanotubes were also found to have a similar degree of superhydrophobicity, with a water contact angle of 150 degrees and a sliding angle of 3 degrees.
전병세 ( Byung Sei Jun ),윤존도 ( Jon Do Yun ),고철호 ( Cheol Ho Go ),조상봉 ( Sang Bong Jo ),곽동현 ( Dong Hyeon Kwak ) 경남대학교 신소재연구소 2009 신소재연구 Vol.21 No.-
본 연구에서는 스택형 고체산화물 연료전지의 전극과 전해질에 대한 특성평가를 실시하였고, 전산 모사하였다. 나노인덴테이션 기법을 이용하여 구성물의 기계적 특성인 경도, 탄성계수를 측정하였고 스택형 고체 산화물 연료전지 실형상에 대하여 모델링을 실행하여 상온에서 750℃까지 승온시의 연료전지내에 형성되는 응력 분포를 전산모사하였다. 그 결과 전해질과 기밀소재 그리고 기밀소재와 연결재의 접합부 끝과 모서리에서 열응력이 최고 200 MPa까지 집중하는 것으로 나타났다. Stack-type solid oxide fuel cell was characterized and simulated by finite element analysis method. The mechanical properties such as hardness and elastic modulus of the fuel cell components were measured by nanoindentation technique. The fuel cell shape was modeled and thermal stress was simulated while heating from the room temperature to 750 degree C. The distribution of thermal stress in the single or stack cell was obtained by the simulation. It was found that the maximum stress was as high as 200 MPa at the joint of the sealant and connector.
김행만,김준수,이홍림,안영철,윤존도,Kim, Haeng-Man,Kim, Jun-Su,Lee, Hong-Rim,Ahn, Young-Cheol,Yun, Jon-Do 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.1
Silicon carbide ceramics are used for oxidation resistive coating films due to their excellent properties like high strength, good oxidation resistance, and good abrasion resistance, but they have poor formability and are prepared by vapor process which is complicated, costly, and sometimes hazardous. In this study, preparation of silicon carbide coating film by liquid process using polymer precursor was attempted. Coating film was prepared by dip coating on substrate followed by heat treatment in argon at $1200^{\circ}C$. By changing the dipping speed, the thickness was controlled. The effects of plasticizer, binder, or fiber addition on suppression of crack generation in the polymer and ceramic films were examined. It was found that fiber additives was effective for suppressing crack generation.