자전연소 반응에 의한 섬유상 TiC의 제조

방환철,윤존도 경남대학교 신소재연구소 1997 論文集 Vol.8 No.-

자전연소 합성법(SHS)을 이용하여 섬유상 TiC를 합성하였다. 섬유상 TiC가 형성되기 위한 최적조건을 구하였는데, 회석제로 TiC분말을 30무게% 첨가하였을 때 섬유상 TiC가 가장 잘 형성되었다. 합성된 TiC섬유는 내부에 속이 비어 있었는데 이는 TiC 내에서의 C와 Ti의 확산속도 차이와 C가 TiC로 변화할 때의 몰부피의 증가로 설명되었다. Titanium Carbide fibers were prepared by the self-propagating high temperature synthesis method in air from the mixture of metallic titanium powders and carbon fibers. Fibrous TiC was well formed with an addition of diluent. while it was not completely formed without diluent. Optimum amount of diluent was determined to be 30wt% for the formation of fibers. Microstructural analysis by SEM showed that fibers had hollow shapes. Fiber formation mechanism was suggested and discussed.

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.

고압 자전연소 소결법을 이용한 섬유강화 복합체의 제조

방환철,고철호,임동원,김봉섭,최태현,윤존도 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.5

Dense composites of titanium matrix and Al2O3 matrix with reinforcements of carbon or titanium carbide fibers were successfully fabricated by high-pressure self-combustion sintering method or combustion reacton under 30 MPa of uniaxial pressure with an aid of external heating in vaccum. It was found that the fibers were uniformly distributed in the matrix, and aligned in a phase perpendicular to the pressure axis. As a moel ratio of Ti/C or reaction time increased, the density of Ti-matrix composite increased Micro pores around fibers could be removed by using clean carbon fibers without sizing agent on their surface. The evolution of carbide fibers from carbon fibers was observed. The composition of the various phases around fibers were analyzed.

가압하의 SHS 반응에 의한 섬유강화 복합체의 제조

방환철,김봉섭,임동원,고철호,윤존도 경남대학교 신소재연구소 1999 論文集 Vol.11 No.-

고압연소소결법으로 TiC 섬유강화 금속 Ti 매트릭스와 Al2O3 매트릭스의 치밀 복합체를 제조하였다. 합성된 시편의 미세구조 관찰 결과 복합체는 대부분의 탄소섬유가 배향된 상태로 잘 분산되어 있었다. 합성된 TiC 치밀체는 반응시간이 증가할수록 첨가된 Ti의 몰 비가 증가할수록 밀도가 증가하였다. 섬유표면에 코팅되어 있는 사이징제를 제거한 섬유를 사용하였을 경우 탄소섬유와 매트릭스 사이에 존재하는 미세기공을 제거할 수 있었다. Dense composites of titanium matrix and A1203 matrix reinforced with fibrous Tic were successfully fabricated by combustion reaction under 30 MPa of uniaxial pressure with an aid of external heating in vacuum. Microstructural analyses by SEM showed that the fibers were found uniformly distributed, well-defind and aligned in the matrix. As a mole ratio of Ti/C or external heating time increased, the density of TiC composite increased. In case of using carbon fibers, from which the sizing agent was removed. micro pores around fibers disappeared.

자전연소 합성에 의한 섬유상 TiC의 형성 메카니즘

윤존도,방환철 慶南大學校 附設 工業技術硏究所 1998 硏究論文集 Vol.15 No.3

자전연소 합성법(SHS)을 이용하여 섬유상 TiC를 합성할 때 섬유형성 기구를 분석하였다. TiC-C공정온도인 2776℃를 임계로하여 공정온도 이상에서는 액상이 안정하여 탄소섬유가 녹고 TiC 섬유가 형성되지 않으나, 공정온도 이하에서는 고상 C와 TiC가 안정하여 TiC 섬유가 잘 형성되는 것으로 분석되었으며 이는 실험결과를 잘 설명하고 있다. 희석제로 TiC를 30무게% 첨가하였을 때 섬유상 TiC가 잘 형성되었다. 합성된 TiC 섬유는 내부에 속이 비어 있었는데 이는 TiC 내에서는 C와 Ti의 확산속도 차이와 C가 TiC로 변화할 때의 몰부피로 설명되었다. Forming mechanism of fibrous TiC during self-propagating high temperature synthetic reaction was analyzed and suggested. It was revealed that critical temperature for the stable fiber formation was not the melting point of TiC, but the eutectic reaction temperature of TiC and C. The explanation was consistent with the experimental results. Optimum amount of diluent addition was determined to be 30%. Synthesized fibers were found hollow tube-like. The morphology was explained by the diffusion rates of C and Ti in TiC, and by the molar volume change of C during the reaction.

자전연소 합성에 의한 섬유상 탄화물의 제조

윤존도,방환철 경남대학교 신소재연구소 1997 論文集 Vol.9 No.-

자전연소합성(SHS) 화학로법을 이용하여 탄소섬유와 규소, 붕소 및 중석 원료분말로부터 섬유상 탄화물의 합성을 시도하였다. 반응실험 결과, 세가지 경우 모두 SiC, B₄C, 또는 WC가 양호하게 합성된 것으로 나타났다. 합성된 시편의 미세구조관찰결과, SiC와 B₄C는 섬유상을 하고 있으나, WC는 섬유상을 하고 있지는 않았다. 합성된 SiCtjadb는 표면이 판상입자와 휘스커로 둘러싸여 있었고, 섬유상 B₄C는 섬유내부가 균일하게 형성되어 있지 않은 것으로 관찰되었다. WC섬유가 형성되지 않은 원인으로는 WC내에서의 W와 C의 확산 속도차이 때문인 것으로 분석되었다. Fabrication of fibrous carbides was attempted by self-propagating high temperature synthesis using chemical furnace. X-ray diffractometer analysis showed that SiC. B₄C, or WC were synthesized by the reaction when the samples were packed in the enough amount of chemical fuel powders. It was found that SiC and B₄C had fibrous forms but WC did not. Microstructural analyses by SEM showed that fibrous SiC was surrounded by whiskers and platelets, and unreacted C remained inside fibrous B₄C. The difference in the diffusion rates of W and C in WC was suggested to be the main reason why fibrous WC was not formed.

자전연소합성법으로 제조한 여러 가지 탄화물의 모폴로지 및 그 형성 메카니즘

윤존도,방환철 경남대학교 신소재연구소 1998 論文集 Vol.10 No.-

자전연소합성법(SHS)을 이용하여 탄소섬유와 지르코늄, 니오븀 및 몰리브데늄 원료분말로부터 섬유상 탄화물의 합성을 시도하였다. 합성된 탄화물의 미세구조관찰 결과 ZrC와 NbC는 속이 빈 섬유상이 Mo2C는 응융물층이 형성되었음을 알수 있었다. 자전연소 합성법으로 합성된 SiC, B4C, WC, ZrC, NbC 및 Mo2C 탄화물의 모폴로지 분석을 통하여, 탄화물의 형상을 크게 섬유상 과 비섬유상의 2가지로 분류하였다. 탄화물의 형상은 원료성분의 융점, 확산속도, 탄화물의 융점 및 단열온도와 관계가 있었으며, 각 섬유상 탄화물에 대한 형성 메카니즘을 제시하였다. Fabrication of fibrous carbides was attempted by self-propagating high temperature synthesis using carbon fibers and elementary powders(Zr. Nb. Mo). It was found that ZrC and NbC had fiber forms but Mo₂C did not. Synthesized carbides(SiC. B₄C. WC. ZrC. NbC. Mo₂C) were found to have two types of morphologies : ① fibrous shape(SiC. ZrC. NbC. B₄C). and ② non-fibrous shapet(WC. Mo₂C). It was suggested that shape of synthesized carbides were determined by the difference in the diffusion rates between metals and carbon in carbides, and existence of liquid phase during the reaction.

자전연소합성 반응중 속빈 TiC 섬유의 형성 기구

윤존도,방환철 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.4

Forming mechanism of fibrous TiC during self-propagating high temperature synthetic reaction was analyzed and suggested. It was revealed that critical temperature for the stable fiber formation was not the melting point of TiC, but the eutectic reaction temperature of TiC and C. Minimum amount of TiC diluent addition required to form fibers was calculated to be 25.6%, which was consistent with the experimental result. Synthesized fibers were found hollow tube-like. The morphology was explained by the diffusion rates of C and Ti in TiC, and by the molar volume chnage of C during the reaction. Expanding shell model was suggested for the hollow fiber formation mechanism.

저장탱크용 TMCP 강재의 대입열 용접 특성

류강묵(Kang-Mook Ryu),김대우(Dae-Woo Kim),이진우(Jin-Woo Lee),방환철(Hwan-Cheol Bang),박철규(Chul-Gyu Park),정홍철(Hongchul Jeong) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.6

Tensile strength, 485~550MPa grade of Quenching & Tempering or Normalizing heat-treated SA-537/A537 steels has been widely used as a steel for storage tanks. Since these steels have high crack sensitivity due to the relative high carbon equivalent, low heat input welding processes such as SMAW, GMAW or FCAW are commonly used for fabrication of storage tank. In this study, we have developed thermo-mechanical control process-type SA-841/A841 steels guaranteeing 1-pass high heat input EGW to increase welding productivity as well as superior quality of welded joints to normal low heat input welding processes. Besides, alloy design in base metal and TMCP process have been also optimized to obtain proper impact toughens in HAZ. As a result, excellent impact toughness at low temperature has been obtained in coarse grain HAZ (CGHAZ) under 340kJ/cm of heat input condition in 40mm thickness plates. Besides, more than 100J of absorbed energy at -10℃ have been achieved by optimizing welding consumables for A841 with high input welding.

SESSION 13 . 컴퓨터활용 Ⅰ ; 유연성있는 저가의 데이타수집장치 개발

장중순,양상식,임석철,정방환,오헌,민병도,김남하,인추식,안세영,조용대 대한산업공학회 1994 대한산업공학회 추계학술대회논문집 Vol.1994 No.-