도예용 소지 및 유에 석탄재 적용 연구

이세우,박성,정윤중,Ri, Se-W,Park, Sung,Chung, Yun-Joong 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6

This study is on the application of ceramic body and art glaze by using coal ash according to each wt%. Body color was turned red and dark as increasing coal ash contents in the body and art glaze because of the effect of noncombustible carbon in $Fe_2O_3$ and coal ash. Not only pore and black core were generated but also absorptance and shrinkage were increased as increasing coal ash contents. The glaze of coal ash 20 wt% showed blue absorption band, turned red band as increasing coal ash contents, $Al_2O_3\;to\;SiO_2$ ratio got lower and became mat because glaze is estranged from $Al_2O_3\;to\;SiO_2$ mol ratio 1:10 of transparent glaze as increasing coal ash contents. Glaze showed unstable dissolving condition in the more coal ash contents.

SiC의 Precursor Polycarbosilane의 합성 (II)

한철,이형복,정윤중,Han, Chul,Lee, Hyung-Bock,Chung, Yun-Joong 한국세라믹학회 1988 한국세라믹학회지 Vol.25 No.5

Polycarbosilane was synthesized from polydimethylsilane at 42$0^{\circ}C$, pyrolysis temperature with various times And IR, NMR, UV, and GPC were detected. Average molecular weight Mn was increased proportionally with the reaction time. Average molecular weight of polycarbosilane was about 700(n=20), which has chain structure and the product yield was 72%.

저가 탄소섬유를 이용한 악취제거 기술 개발

임연수,유기상,김희석,정윤중,Lim, Yun-Soo,Yoo, Ki-Sang,Kim, Hee-Seok,Chung, Yun-Joong 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.10

In this study, two kinds of activated carbon fibers were prepared from PAN-based stabilized fibers by physical activation with steam. The variations in specific surface area, amount of iodine adsorption and pore size distribution of the activated carbon fibers after the activation process were discussed. The activated carbon fibers were prepared by two different methods, namely a 1- and 2-step method. For the 2-step method, carbonization of fibers in $N_2$ atmosphere was carried out to make carbon fibers and then activated by steam. In normal two step steam activation, BET surface area of about $1019m^2/g$ was obtained in the study. In the 1-step steam activation process, the carbonization and activation were simultaneously carried out. In the one step steam activation, BET surface area of $1635m^2/g$ was obtained after heat-treatment at $990^{\circ}C$. However, nitrogen adsorption isotherms for oxidized PAN based activated carbon fibers that were prepared by both methods were type I in the Brunauer-Deming-Deming-Teller (BDDT) classification even though they have different BET surface areas, amounts of iodine adsorption and pore size distributions. 본 연구에서는 PAN계 안정화섬유를 원료로 하여 수증기를 이용한 물리적 활성화에 의해 여러 등급의 활성탄소섬유를 제조하고, 비표면적, 요오드 흡착량, 미세구조, 세공구조 등을 측정하여 제조조건에 따른 그 특성변화를 고찰하였다. 수증기를 이용한 물리적 활성화에서 기존의 탄화과정과 활성화과정의 2단계를 이용한 공정과, 탄화공정과 활성화 공정을 동시에 수행하는 1단계 활성화과정을 비교함으로써 저가로 활성탄소섬유를 제조할 수 있는 제조방법을 연구하였다. 2단계 법에서는 안정화 섬유를 $900^{\circ}C$에서 탄화한 후 이를 다시 $900^{\circ}C$에서 활성화하는 방법으로 $1019m^2/g$의 비표면적을 갖는 활성탄소섬유를 얻었으나 1단계 방법에서는 $900^{\circ}C$에서 $1636m^2/g$의 비표면적을 갖는 활성탄소섬유를 제조하였다. 이들 활성탄소섬유 사이에는 비표면적, 요오드 흡착력, 기공분포 등이 서로 차이가 있음에도 불구하고, Brunauer-Deming-Deming-Teller(BDDT)에 의한 분류에서는 제I형을 나타내는 공통점도 가지고 있었다.

폐도자기를 골재로 이용한 콘크리트의 특성

강성구,이완조,황인동,박성,정윤중,Kang, Sung-Gu,Lee, Wan-Jo,Hwang, In-Dong,Park, Sung,Chung, Yun-Joong 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2

Nowadays, large amount of waste pottery and porcelain annually are produced. It is needed that they are used as recycled materials in order to prevent environmental pollution and gain economic profits. Therefore, the purpose of this study is to present the method of utilizing the recycled aggregates that are obtained from waste pottery and porcelain as the concrete aggregate. The qualities of the recycled aggregate were compared with those of the crushed aggregate through measuring their physical properties. The test results showed that the replacement of crushed aggregate by recycled aggregate at the levels $10\%,\;20\%$, and $30\%$ had little effect on the compressive strength of the concretes, but higher levels of replacement reduced the compressive strength. Increment of the replacement of recycled aggregate caused increase in absorption ratio. As a conclusion, norman strength recycled aggregate concretes can be produced using less than $30\%$ of recycled aggregate. 현재 국내에서 많은 양의 도자기 폐기물이 발생하고 있으며, 이들 폐기물은 경제적 이득과 환경 보전의 차원에서 재활용하는 방안이 모색되어져야 한다. 따라서, 본 연구에서는 도자기 폐기물을 콘크리트용 골재로 이용하여 폐도자기의 재활용성을 검증하고자 하였다. 폐도자기 재활용 골재(recycled aggregate)의 품질을 부순 골재(crushed aggregate)와 비교 분석하였으며, 부순 골재 단독 콘크리트와 재활용 골재가 비례대로 치환된 콘크리트의 물리적 특성을 비교 분석하였다. 실험 결과 재활용 폐도자기의 비율이 $10\%,\;20\%$, 그리고 $30\%$까지는 압축강도에 작은 영향을 미쳤지만, 재활용 폐도자기의 비율이 $30\%$ 이상 증가할수록 압축강도는 급격히 감소하였으며, 홉수율은 증가하였다. 실험 결과에 따르면, 일정한 압축강도를 지니는 폐도자기 재활용 콘크리트의 제조를 위해서 대체 가능한 재활용 골재의 최대 함량은 $30\%$임을 확인 할 수 있었다.

SiC의 Pricursor Polycarbosilan의 합성

한철,한인섭,이형복,정윤중,Han, Chul,Han, In-Seop,Lee, Hyung-Bock,Chung, Yun-Joong 한국세라믹학회 1988 한국세라믹학회지 Vol.25 No.1

Polycarbosilane was synthesized from the pyrolysis of polydimethylsilane, which is dechlorinated from dimethyldichlorosilane. The pyrolysis temperature was varied at 280-480$^{\circ}C$ for 2 hours. FT-IR, FT-NMR and GPC measurement were studied on the residue inside the reaction crucible and viscous solution inside the cooling zone respectively. From the viscous solution in the cooling zone at 420$^{\circ}C$, the synthesis of polycarbosilane wa well detected.

Ceramic 재질을 이용한 자동차용 대형 디젤 엔진 Valve Lifter 연구 -Ⅰ. Brazing Process에 의한 Ceramic-Metal 접합체 개발

윤호욱(Ho Wook Yun),한인섭(In Sup Han),임연수(Yun Soo Lim),정윤중(Yun Joong Chung) 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.2

Camshaft와 계속되는 접촉을 갖는 valve lifter는 주철제로 엔진이 고출력화되면서 증가되는 valve train system에서의 가혹한 면압(load) 때문에 face면은 편마모 및 조기마모 되어지고 이러한 비정상적 마모현상은 valve lifting시 over clearance라는 결함이 되어 연소실내 engine valve의 여닫음을 불일치 시켜 연료를 불완전 연소시킨다. 불완전연소는 결국 엔진 출력저하 및 환경오염의 주요 원인이 되기 때문에 비정상적 마모현상을 방지하기 위하여 face면을 내마모 특성이 높은 세라믹계의 초경합금으로 제조하여 SCM435H 합금강 몸체와 브레이징 접합하는 valve lifter를 개발하고자 하였다. Valve train system에서의 가혹한 면압을 견딜 수 있는 Vickers hardness 1100-1200 정도의 우수한 표면경도 값을 갖는 초경합금(텅스텐 카바이드) 소결체(face면)를 제조하였으며, 여러 조성의 브레이징 합금으로 실험한 결과 150MPa 정도의 우수한 인장전단강도 값을 갖는 접합체를 얻을 수 있었다. SEM & EDS, Optical microscope를 이용하여 초경합금의 미세조직과 접합체에서의 계면을 분석을 하였다. 또한 주철제인 valve lifter와 개발된 세라믹/금속 접합체 valve lifter에 대하여 2500시간 고속(3000-4000 rpm)연속(1step 12hr) 엔진 동력 내구시험을 동시에 실시하면 편마모 및 조기마모와 같은 마모현상과 마모량 등에 대하여 비교 평가하였다. Continuously contacting with camshaft, the face of Valve Lifter, made of cast iron, brings about abnormal wear such as unfairwear or earlywear because it is heavily loaded in the valve train system as the engine gets more powered. This abnormal wear becomes a defect namely over-clearance when the valve is lifting so that the fuel gas imperfectly combusted by unsuitable open or close action of the engine valve in the combustion chamber. The imperfect combustion, in the end, results in the major causes of air pollution and decrease of the engine output. Consequently, to prevent this wear, this study was to develop the valve lifter which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened ceramics alloy which has high wear resistance. Having the excellent surface hardness with Hv1100-1200, the sintered body developed with superhardened alloy(WC) can endure the severe face loading in the valve train system. We experienced with various brazing alloys and obtained the excellent joining strength to the joint had 150MPa shear strength. Interface analysis and microstructure in a joint were examined thorough SEM & EDS, Optical microscope. Also, 2,500 hours, high speed(3,000-4000 rpm) and continuous (1step 12hr) engine dynamo testing was carried out to the casting valve lifter and ceramics-metal joint valve lifter so that the abnormal wears were compared and evaluated.

상변화 물질을 이용한 저발열 콘크리트 개발에 관한 연구

손명수(Shon, Myung-Soo),이완조(Lee, Wan-Jo),정윤중(Chung, Yun-Joong),김진근(Kim, Jin-Keun),황인동(Hwang, In-Dong) 한국콘크리트학회 2006 한국콘크리트학회 학술대회 논문집 Vol.2006 No.11

환원분위기중에서 크로ㆍ마그내화물의 고온안정성

정윤중,이형복 明知大學校 産業技術硏究所 1987 産業技術硏究所論文集 Vol.6 No.2

The reaction mechanism and the Vaporization of CaO·CrO₃ Compound were studied over the temperature range of 600 to 1200 in Hydrogen atmosphere. The Obtained results are as follows; The reaction of CaCrO₄under the hydrogen atmosphere is assumed to be controlled by the interface chemical reaction and the activation energy is 1 Kcal/mole. When the sintering atmosphere of CaO·CrO₃was changed to the reducing atmosphere, the CaO·CrO₃ compound was prohibited to from which causes pollution and corrosion of products.

TiO₂및 SnO₂계 Spinel 안료의 구성

정윤중,이희수 연세대학교 산업기술연구소 1982 논문집 Vol.14 No.2

For the fabrication of the 2 AO ·BO₂ spinel pigment, each 1 mole of TiO₂, SnO₂and each 2 mole of ZnO, CoO, MgO, MnO, NiO and Fe₂O₃were fired at the temperature ranges from 700˚to 1.300℃ for 2 hours respectively. Analysing the X-ray diffraction, the following results were obtained. ⑴ In case of TiO₂, the spinel structures were formed with ZnO, CoO and in case of SnO₂, the spinel structures were formed with ZnO, CoO and MgO. ⑵ The other 2 valence metal oxides NiO, MnO, CuO and Fe₂O₃made geikielite structures with TiO₂, and SnO₂. ⑶ In order to form the spinel or geikielite structures, SnO₂series required higher firing temperature than TiO₂series. ⑷ Borax decreased the firing temperature in any series, having the spinel or geikielite structure.

Cusil/SiC 접합의 계면 현상

오세철,윤호욱,최성민,정윤중 明知大學校 産業技術硏究所 1997 産業技術硏究所論文集 Vol.16 No.-

To detect the interfacial phenomena on Ceramic/metal. SiC and Cusil were joined in N₂ or Ar gas atmosphere at various reaction temperature and the cross section were observed. Ag, which was separated from Cusil infiltrated into SiC side and separated it to Si and C. As a matrix, Ag transfered free Si to Cusil side and helped to form (Cu, Si) eutectic phase in Cusil side. the (Cu, Si) eutectic phase was transfered and precipitated into CuxSiy silicide in SiC side. The remaining SiC, not separated, was growing by the process of Ostwald ripenning in Ag matrix. (Cu, Si) eutectic phase had a dendrite type crystal phase in Ag molten matrix at N₂ gas atmosphere. This phenomena were appeared explicitly with the increased reaction temperature from 850, 900 to 950℃. But at the Ar gas atmosphere, the shapes of (Cu, Si) eutectic phase were aggromerated, and the transfer phenomenon to ceramic side was less compare to N₂ gas atmosphere.