수계 테이프 케스팅 법에 의한 봉상 γ-LiAlO₂ 입자 강화 MCFC 매트릭스 제조 공정의 최적화

최현종,신미영,현상훈,임희천,Choi, Hyun-Jong,Shin, Mi-Young,Hyun, Sang-Hoon,Lim, Hee-Chun 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.3

Rod-shaped particle reinforced $LiAlO_2$ matrices for MCFC were fabricated by an aqueous tape-casting technique. The hydrolysis reaction and agglomeration of $\gamma-LiAlO_2$ particles in aqueous slurries were inhibited by additions of $LiOH{\cdot}H_2O$ and glycerin to the aqueous $\gamma-LiAlO_2$ slurry. The tape-casting, performed using the aqueous slurry containing protein albumin, was fast and led to an effective drying at casting temperature range of $60{\sim}65^{\circ}C$. The strength of the particle reinforced matrix was improved about 4 times compared to that of matrix without reinforcement. Pore size distribution ($0.1{\sim}0.4{\mu}m$) and porosity ($50{\sim}60%$) of the reinforced matrices were determined to be appropriate for the MCFC matrix. The aqueous tape casting process is not only environmental-friendly but also efficient for fabricating MCFC matrices compared to non-aqueous tape casting.

수계 테이프 케스팅 법에 의한 봉상 γ-LiAlO₂ 입자 강화 MCFC 매트릭스 제조 공정의 최적화

최현종,현상훈,신미영,임희천 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.3

Rod-shaped particle reinforced LiAlO₂ matrices for MCFC were fabricated by an aqueous tape-casting technique. The hydrolysis reaction and agglomeration of γ-LiAlO₂ particles in aqueous slurries were inhibited by additions of LiOH·H₂O and glycerin to the aqueous γ-LiAlO₂ slurry. The tape-casting, performed using the aqueous slurry containing protein albumin, was fast and led to an effective drying at casting temperature range of 60~65℃. The strength of the particle reinforced matrix was improved about 4 times compared to that of matrix without reinforcement. Pore size distribution (0.1~0.4 µm) and porosity (50~60%) of the reinforced matrices were determined to be appropriate for the MCFC matrix. The aqueous tape casting process is not only environmental-friendly but also efficient for fabricating MCFC matrices compared to non-aqueous tape casting.

저온소성 마이크로파 유전체 세라믹스 복합체의 Tape Casting특성

이우석,김창환,하문수,정순종,송재성,류봉기,Lee, Woo-Suk,Kim, Chang-Hwan,Ha, Mun-Su,Jeong, Soon-Jong,Song, Jae-Sung,Ryu, Bong-Ki 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2

마이크로파 유전체 세라믹스 $BaO-Nd_{2}O_3-TiO_{2}(BNT)$계 상용분말과 PbO-base의 결정화 유리프릿 복합체를 출발원료로 하여 테입 케스팅법으로 그린시트를 제초하기 위해 첨가유기물의 조성 변화에 따른 슬러리의 분산특성 및 유동특성 그리고 최종그린시트의 그린/소결밀도 변화를 연구하였다. 분산제량의 증가는 분산에 유효하였으나, 일정량 이상이 첨가되면 분산을 저해하는 요인으로 작용하였으며 복합체 분말에 1.75 wt$\%$의 fish oil을 첨가하였을 때 분산특성이 가장 우수하였다 준비된 모든 조성의 슬러리에서 의가소성거동(shear thinning)이 나타났고 파우더, 바인더 그리고 유기물의 전체 함량이 증가할수록 상대점도는 증가하는 경향을 나타내었다. 복합체 분말과 용매의 비율 65 : 35, 결합제는 6 wt$\%$, 가소제는 3 wt$\%$에서 테이프의 특성이 가장 우수하였다. 이때 슬러리의 점도는 677cps, 그린/소결밀도는 $3.3g/cm^3,\;5.56g/cm^3$로 각각 나타났다. Sintering behavior of $BaO-Nd_{2}O_3-TiO_2$ with a Pb-based glassceramics frit were investigated in order to understand an effect of glassceramics as a low temperature sintering agent on dielectric ceramics. A green sheet form was fabricated through tape casting method with the glassceramic fut added $BaO-Nd_{2}O_3-TiO_2$. The dispersion properties, rheological properties and final density of dielectric composit slurry as a function of amount and composition of organic additives was examined. The dispersants' addition was effective in controlling dispersion of the ceramics in solution. The addition of excessive dispersant showed adverse effect on dispersion. The prepared slurries, containing ceramic : powders, glass-ceramics and various kinds of organic viechles, exhibited typical shear thinning behavior. The best properties of tape casting appeared powder to solvent ratio 65 : 35 and amount of the binder 6 wt$\%$ and plasticizer 3 wt$\%$. The viscosity of the slurry was 677 cps and green/sintered density in the tape was $3.3 g/cm^3,\;5.56 g/cm^3$ respectively.

Effects of Suspension Composition on Defects in Aqueous Tape Casting of Alumina Ceramics: A Rheological Study

Shin, Hyo-Soon The Korean Ceramic Society 2005 한국세라믹학회지 Vol.42 No.1

In aqueous alumina tape casting, the effects of altering the composition of the suspensions, the binders and the casting thickness were studied. The rheological behavior of the suspensions and the defects of the dried tapes were examined and the relationships between them are discussed. The changes in the defect regions reported in the previous paper were related with the rheological properties with variations of the binder, the composition and the casting thickness. The shear thinning factor increased with the organic content and the solid content (the decrease of water content). The apparent viscosity increased with the shear thinning factor. The relation between the shear thinning factor and the log apparent viscosity was similar for all binder types. In the relation between the defect free region and the rheological properties, the defect free region became narrower with increasing casting thickness. The defect free region is independent of binder type. Therefore, the thicker tape is more difficult to produce in aqueous alumina tape casting. Knowledge of the rheological properties of the suspensions could help Predict the defect type and the possibility of defect free dried tapes.

빅데이터 구축을 위한 알루미나 테이프 캐스팅 공정 최적화

김동하,김시연,이주성,여동훈,신효순,윤상옥 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.6

For machine learning techniques, a large amount of high-quality material property data should be accumulated. In this study, several data for an alumina tape casting process were produced with the variables of slurry viscosity, gap size, and coating speed. The alumina tapes were manufactured in the range of 1,000~6,000 cps for slurry viscosity, 300~1,000 ㎛ for gap size, and 0.5~2.0 m/min for coating speed. As a result, the lower the viscosity, coating speed, and gap size, the more pore-free tapes could be manufactured. The viscosity of the slurry limited the minimum thickness of the tape. Green sheets with high packing density were manufactured from the slurry of 100~6,000 cps slurry viscosity, coating speed of 0.5 m/min, and a 300~500 ㎛ gap size. 머신 러닝 기법에 표준화 된 빅데이터를 구축하기 위해서는 경향성을 갖춘 양질의 데이터가 지도학습되어야 한다. 본 연구에서는 테이프 캐스팅 방법으로 알루미나 테잎을 제작하였으며, 슬러리 점도, 갭 높이, 코팅속도에 따른 최적화를 진행하였다. 슬러리 점도 1000-6000 cps, 갭 높이 300-1000 ㎛, 코팅속도는 0.5-2.0 m/s 범위에서 알루미나 테잎을 제조하였다. 그 결과, 코팅속도가 늦을수록 그리고 슬러리 점도와 갭 높이가 낮을수록 기공이 없고 충진밀도가 높은 테잎을 제조할 수 있었다. 그리고 슬러리 점도 대역에 따라 구현 가능한 테잎 두께에는 한계가 있었다. 점도가 1000~6000 cps인 슬러리에서 코팅속도가 0.5 m/min, 갭 높이 300-500㎛ 일 때 충진밀도가 높은 우수한 테잎을 제작할 수 있었다. 슬러리 점도 1000 cps 경우에는 갭 300-700 ㎛ 범위에서 약 64%, 점도 3300 cps 경우에는 갭 300-500 ㎛에서 약 61%, 그리고 점도 6000 cps 경우에는 갭 300-500 ㎛에서 약 64%의 높은 충진밀도를 나타내었다.

Optimization of Barium Titanate Slip for Tape Casting Using Design of Experiments

Kwon, Sung-Wook,Darsono, Nono,Yoon, Dang-Hyok The Korean Ceramic Society 2006 한국세라믹학회지 Vol.43 No.9

A full-factorial design of experiments with three input factors and two levels for each factor including center points was utilized for the preparation and characterization of twelve types of $BaTiO_3$ slips for tape casting. Ceramic powders with different particle sizes, different milling methods such as high energy milling and conventional ball milling, and two types of dispersant with different polymeric species were chosen as input factors in order to investigate their effects on slip and on green tape properties. Tape casting, a small rectangular-shaped K-square preparation, characterization and quantitative data analysis using statistical software were followed. Ceramic powder was the most significant among three input factors for the output responses of slip viscosity and green tape density, showing more favorable results with large particles than with very fine ones. In addition, high energy milling for only 30 min was more efficient than 24h of conventional ball milling in terms of powder dispersion and milling. The optimum condition based on the experimental results was a slip exposed to high energy milling with large ceramic particles along with a methylethyl acetate dispersant.

Si$_3$N$_4$ Whisker의 첨가량과 배열방향이 Si$_3$N$_4$ 복합 소결체의 기계적 특성에 미치는 영향

김창원,박동수,박찬,Kim, Chang-Won,Park, Dong-Soo,Park, Chan 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.1

0~5 wt%의 $\beta$-Si3N4 whisker를 첨가한 질화규소 가스압 소결체를 제작하였다. 첨가된 whisker들은 tape casting을 응용하여 tape 내에서 일방향으로 배열하였으며, 제작된 tape로부터 절취된 sheet들의 적층 과정을 변화하여 다양한 미세구조를 갖는 성형체를 제작하였다. 가스압 소결을 통하여 치밀화된 소결체의 조대결정립은 성형체의 whisker와 같은 방향성을 가졌으며, 소결수축률과 기계적 특성 등도 이러한 다양한 미세구조상의 특징과 일관된 결과를 나타내었다. Whisker를 일방향으로 배열하였을 경우, 소결수축률은 whisker 배열 방향과 평행한 방향보다 수직한 방향으로 크게 일어났을 때, whisker 함량이 증가함에 따라 수축률의 차이가 증가하였다. Indentationi crack length는 whisker 함량이 증가함에 따라 whisker 배열 방향과 수직한 방향의 균열 길이는 더 짧아졌고, 그와 평행한 방향의 균열 길이는 길어졌다. Whisker 첨가에 의해 결정립이 더 크게 성장하였으나 강도는 whisker를 첨가하지 않을을때보다 낮지 않았다. Whisker 배열 방향을 90$^{\circ}$ 및 45$^{\circ}$ 간격으로 엇갈리게 적층하였을 경우에는 특성의 이방성이 나타나지 않았다. Gas pressure sintered silicon nitride based composites with 0~5wt% $\beta$-Si3N4 whiskers were prepared. The whiskers were unidirectionally oriented by a modified tape casting technqiue and green bodies with various microstructure were formed by changing stacking sequences of sheets cut from the tape. Orientations of the large elongated grains of the sample after gas pressure sintering were the same as the those of the whiskers of green body, and the sintering shrinkage and mechanical properties of sintered sample were consistent with the microstructural characteristics. In case of unidirectional samples, the sintering shrinkage normal to whisker alignment direction was larger than that parallel to the direction. The shrinkage difference inceaed as the whiskercontent increaed. As whisker content increaed, the crack length normal to and parallel to tape casting direction became shorter and larger, respectively. Although the grain size increased by th whisker addition, the flexural strength of unidirectional samples was not lower than that of smaple without the whisker. In case of crossplied and 45$^{\circ}$rotated samples, the anisotropy of mechanical preoperties disappeared.

Tape Casting법을 이용한 W-Cu, Mo-Cu 박판소재 제조

박치완 ( Chi Wan Park ),장건익 ( Gun Eik Jang ),김태형 ( Tae Hyoung Kim ),우용원 ( Yong Won Woo ) 한국열처리공학회 2004 熱處理工學會誌 Vol.17 No.5

N/A For the application of heat sink device, the green sheets of powder of W-XCu and Mo-XCu composites were fabricated by tape casting technique. The mixing ratio of powder and binder was 6 : 4. The green sheet was shrinked up to 10~20% after sintering and the maximum relative density was above 95%. Thermal conductivity and Thermal expansion systematically increased with increasing Cu contents. The maximum thermal conductivity of W-20wt.%Cu was about 206[W/mK].

테이프캐스팅법에 의한 화이버 강화 $\gamma-LiAlO_2$ 메트릭스의 제조

현상훈,백계현,홍성안 한국세라믹학회 1997 한국세라믹학회지 Vol.34 No.3

용융탄산염 연료전지(Molten Carbonate Fuel Cell) 메트릭스의 성형성 및 강도 증진을 위한 알루미나/${\gamma}$-LiAlO2 화이버 강화 매트릭스에 대하여 연구하였다. ${\gamma}$-LiAlO2 입자에 10~30wt%의 화이버를 첨가한 슬러리를 테이프캐스팅 한 후 $650^{\circ}C$까지 열처리하여 두께가 500~600$\mu\textrm{m}$인 MCFC 매트릭스를 제조하였다. 화이버의 첨가량이 증가할수록 매트릭스의 기공율은 감소하였으나 입자크기가 대략 50$\mu\textrm{m}$인 ${\gamma}$-LiAlO2 분체의 첨가비를 50wt%까지 증가시킴으로써 MCFC 매트릭스에 적합한 기공율(50~60%)을 얻을 수 있었다. 알루미나 화이버의 첨가량이 20wt% 이고 길이가 250$\mu\textrm{m}$이하인 화이버를 사용하였을 때 매트릭스내의 분산성 및 강도 증진 효과가 가장 우수하였다. 반면에 본 연구에서 제조한 ${\gamma}$-LiAlO2 화이버를 이용한 강화 매트릭스의 강도(156 gf/$\textrm{mm}^2$)는 알루미나 화이버 강화 매트릭스에 비해 20~40% 정도 증진되었다. 또한 알루미나 화이버 강화 매트릭스는 용융탄산염에 의하여 부식되지만 ${\gamma}$-LiAlO2 화이버 강화 매트릭스는 전혀 부식되지 않음을 알 수 있었다. To enhance the strength and formability of MCFC matrixes, alumina/${\gamma}$-LiAlO2 fiber-reinforced ${\gamma}$-LiAlO2 ma-trixes have been investigated. The MCFC matrixes with the thickness of 500~600 ${\mu}{\textrm}{m}$ were prepared by tape-casting of the slurry containing 10~30wt% fibers, followed by heat-treating up to $650^{\circ}C$. The porosity of fi-ber-reinforced matrixes decreased with the content of fibers, while the appropriate porosity(50~60%) for MCFC matrixes could be attained by adding larger ${\gamma}$-LiAlO2 particles with the diameter of about 50${\mu}{\textrm}{m}$ up to 50 wt%. The optimum length and content of the alumina fiber, both in the alignment of fibers and the enhancement of the strength, were found to be below 250${\mu}{\textrm}{m}$ and 20 wt%, respectively. On the other hand, the strength(156 gf/$\textrm{mm}^2$) of the ${\gamma}$-LiAlO2 matrix reinforced with ${\gamma}$-LiAlO2 fibers prepared in this study was improved by 20~40% in comparison with the alumina-fiber-reinforced matrix. It was also found that the alu-mina-fiber-reinforced matrix was completely corroded in molten carbonates but the ${\gamma}$-LiAlO2 was not.

Acrylate를 결합제로 사용한 수계 테이프 캐스팅에서 알루미나 슬러리의 분산 및 점성 특성

조유정,박일석,문주호,김대준,Cho, Yu-Jeong,Park, Il-Seok,Moon, Joo-Ho,Kim, Dae-Joon 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.2

Acrylate 수계 결합제를 사용한 알루미나 테이프 캐스팅용 슬러리의 완전분산을 위한 최적의 분산제와 분산제량을 결정하기 위해 침강실험, 분말 함유량 실험, 점도 및 zeta 전위 측정을 행하였다. 알루미나 슬러리의 완전분산은 분산제를 polycarboxylic acid로 했을 때 얻어졌으며, 최적의 첨가량은 알루미나 100에 대하여 0.23∼0.24g 이었다. 분말에 대한 분산제량이 증가할수록 분산은 잘 이루어졌으나, 일정량 이상이 첨가되면 분산제가 용매 안에 과잉으로 존재하여 분산을 저해하는 요인으로 작용하였다. 테이프 캐스팅용 슬러리는 100g의 알루미나 분말에 0.2g의 polycarboxylic acid를 첨가하였을 때 분산 및 테이프 특성이 가장 우수하였고, 이 때 혼합한 결합제는 acrylate였고, 가소제는 Benzoflex를 사용하였다. 이 때 슬러리 최적 점도는 약 570 cps였고, 테이프 내 알루미나 량은 57 vol%이었다. Measurements of sedimentation, solid loading, zeta potential, and viscosity were employed to determine a proper dispersant and its amount for a well dispersed alumina powders in aqueous alumina tape casting using acrylate as a binder. Polycarboxylic acid was the most effective one among various dispersants considered in the present study and its amount was 0.23∼0.24 g per 100 g alumina for a dispersion. Better dispersion was obtained as an increase of dispersant addition. However, the dispersion was hindered as the amount of dispersant was higher than the optimum amount because of bridging or tangling of polymer chains. Excellent aqueous alumina tapes were prepared from the slurry containing the optimum amount of the polycarboxylic acid (0.2g), alumina powders(100 g), acrylate and Benzoflex as binder and plasticizer, respectively. The viscosity of the slurry was 570 cps and the alumina loading in the tape was 57 vol%.