• 제목/요약/키워드: 세라믹엔지니어링

검색결과 45건 처리시간 0.022초

DLP 3D 프린팅으로 제작된 고순도 알루미나 세라믹 탈지 공정 연구 (A Study on the Debinding Process of High Purity Alumina Ceramic Fabricated by DLP 3D Printing)

  • 이현빈;이혜지;김경호;류성수;한윤수
    • 한국분말재료학회지
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    • 제27권6호
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    • pp.490-497
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    • 2020
  • The 3D printing process provides a higher degree of freedom when designing ceramic parts than the conventional press forming process. However, the generation and growth of the microcracks induced during heat treatment is thought to be due to the occurrence of local tensile stress caused by the thermal decomposition of the binder inside the green body. In this study, an alumina columnar specimen, which is a representative ceramic material, is fabricated using the digital light process (DLP) 3D printing method. DTG analysis is performed to investigate the cause of the occurrence of microcracks by analyzing the debinding process in which microcracks are mainly generated. HDDA of epoxy acrylates, which is the main binder, rapidly debinded in the range of 200 to 500℃, and microcracks are observed because of real-time microscopic image observation. For mitigating the rapid debinding process of HDDA, other types of acrylates PETA, PUA, and MMA are added, and the effect of these additives on the debinding rate is investigated. By analyzing the DTG in the 25 to 300℃ region, it is confirmed that the PETA monomer and the PUA monomer can suppress the rapid decomposition rate of HDDA in this temperature range.

볼밀 공정 중 점도와 음향 데이터의 실시간 수집 및 상관관계 분석 (Real-time Collection and Correlation of Viscosity and Acoustic Data During Ball Milling Process)

  • 정현덕;김영범;류성수;김세기
    • 한국분말재료학회지
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    • 제27권6호
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    • pp.484-489
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    • 2020
  • In this study, acoustic and viscosity data are collected in real time during the ball milling process and analyzed for correlation. After fast Fourier transformation (FFT) of the acoustic data, changes in the signals are observed as a function of the milling time. To analyze this quantitatively, the frequency band is divided into 1 kHz ranges to obtain an integral value. The integrated values in the 2-3 kHz range of the frequency band decrease linearly, confirming that they have a high correlation with changes in viscosity. The experiment is repeated four times to ensure the reproducibility of the data. The results of this study show that it is possible to estimate changes in slurry properties, such as viscosity and particle size, during the ball milling process using an acoustic signal.

광개시제 함량과 노광 시간이 DLP기반 알루미나 3D 프린팅 공정에 미치는 영향 (Effect of Photo Initiator Content and Light Exposure Time on the Fabrication of Al2O3 Ceramic by DLP-3D Printing Method)

  • 김경민;정현덕;한윤수;백수현;김영도;류성수
    • 한국분말재료학회지
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    • 제26권4호
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    • pp.327-333
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    • 2019
  • In this study, a process is developed for 3D printing with alumina ($Al_2O_3$). First, a photocurable slurry made from nanoparticle $Al_2O_3$ powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of $Al_2O_3$ is determined by measuring the rheological properties of the slurry. Then, green bodies of $Al_2O_3$ with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed $Al_2O_3$ green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that $Al_2O_3$ products of various sizes and shapes can be fabricated by DLP 3D printing.

엔지니어링 세라믹스에 대한 최근의 기술동향과 응용

  • 정석주
    • 기계저널
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    • 제30권3호
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    • pp.258-266
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    • 1990
  • 그간 화인세라믹에 대한 기대는 점점 더해졌으며 신소재붐의 최고의 지위를 확보했다고도 할 수 있다. 더욱이 최근에 있어서 실소온도이상의 높은 임계온도를 갖는 세라믹 초전도체가 발견되 었으며 새로운 재료의 개발은 신기술을 창성할 뿐만 아니라 산업 및 국민생활에도 변혁을 가져올 가능성이 확인되어 신소재로의 기대가 더한층 높아졌다. 각종 기술부품등으로서의 화인세라믹은 자동차용 엔진연구를 시작으로 발전되어 최근에는 점차로 그 제품개발의 단계에 도달하고 있다. 이와 같이 하나의 소재가, 말하자면 공업재료로서 정착하기에는 엄격한 개발경쟁과 그에 따른 시간이 요하게 된다. 본 글에서는 엔지니어링 세라믹의 개발경과를 살펴보고 최근의 동향 및 응용의 현상에 관하여 기술하고자 한다.

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Li2O-Bi2O3 첨가가 Pb(Mg1/3Nb2/3)0.65Ti0.35O3 세라믹의 압전 특성에 미치는 영향 (Effect of Li2O-Bi2O3 Addition on the Piezoelectric Properties of Pb(Mg1/3Nb2/3)0.65Ti0.35O3 Ceramics)

  • 김재혁;김시연;최정식;여동훈;신효순;남산
    • 한국분말재료학회지
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    • 제26권5호
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    • pp.405-409
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    • 2019
  • Piezoelectric ceramic specimens with the $Pb(Mg_{1/3}Nb_{2/3})_{0.65}Ti_{0.35}O_3$ (PMN-PT) composition are prepared by the solid state reaction method known as the "columbite precursor" method. Moreover, the effects of the $Li_2O-Bi_2O_3$ additive on the microstructure, crystal structure, and piezoelectric properties of sintered PMN-PT ceramic samples are investigated. The addition of $Li_2O-Bi_2O_3$ lowers the sintering temperature from $1,200^{\circ}C$ to $950^{\circ}C$. Moreover, with the addition of >5 wt.% additive, the crystal structure changes from tetragonal to rhombohedral. Notably, the sample with 3 wt.% additive exhibits excellent piezoelectric properties ($d_{33}=596pC/N$ and Kp = 57%) and a sintered density of $7.92g/cm^3$ after sintering at $950^{\circ}C$. In addition, the sample exhibits a curie temperature of $138.6^{\circ}C$ at 1 kHz. Finally, the compatibility of the sample with a Cu electrode is examined, because the energy-dispersive X-ray spectroscopy data indicate the absence of interdiffusion between Cu and the ceramic material.

빅데이터 구축을 위한 알루미나 테이프 캐스팅 공정 최적화 (Optimization of Alumina Tape Casting Process for Building Big Data)

  • 김동하;김시연;이주성;여동훈;신효순;윤상옥
    • 한국전기전자재료학회논문지
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    • 제32권6호
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    • pp.483-489
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    • 2019
  • 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, $300{\sim}1,000{\mu}m$ 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 $300{\sim}500{\mu}m$ gap size.

ZrO2가 코디어라이트-뮬라이트 세라믹스의 기계적 강도 및 내열충격성에 미치는 영향 (Effects of ZrO2 Addition on Mechanical Strength and Thermal Shock Resistance of Cordierite-Mullite Ceramics)

  • 임진현;김시연;여동훈;신효순;정대용
    • 한국재료학회지
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    • 제28권12호
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    • pp.719-724
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    • 2018
  • Cordierite composed of an alumina-silica-magnesia compound has a low coefficient of thermal expansion(CTE) and excellent thermal shock resistance. It also has a low dielectric constant and high electrical insulation. However, due to low mechanical strength, it is limited for use in a ceramic heater. In this study, $ZrO_2$ is added to an 80 wt% cordierite-20 wt% mullite composition, and the effect of $ZrO_2$ addition on the mechanical strength and thermal shock resistance is investigated. With an increasing addition of $ZrO_2$, cordierite-mullite formed $ZrO_2$, $ZrSiO_4$ and spinel phases. With sintering conducted at $1400^{\circ}C$ with the addition of 5 wt% $ZrO_2$ to 80 wt% cordierite-20 wt% mullite, the most dense microstructure forms along with an excellent mechanical strength with a 3-point flexural strength of 238MPa. When this composition is quenched in water at ${\Delta}T=400^{\circ}C$, the 3-point flexural strength is maintained. Moreover, when this composition is cooled from $800^{\circ}C$ to air, the 3-point flexural strength is maintained even after 100 cycles. In addition, the CTE is measured as $3.00{\times}10^{-6}{\cdot}K^{-1}$ at $1000^{\circ}C$. Therefore, 80 wt% cordierite-20 wt% mullite with 5 wt% $ZrO_2$ is considered to be appropriate as material for a ceramic heater.

SiAlON의 절삭성능에 미치는 소결조제와 조성의 영향에 대한 연구 (Effect of Sintering Additive and Composition on Cutting Performance of SiAlON)

  • 최재형;이성민;남산;김성원
    • 한국분말재료학회지
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    • 제26권5호
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    • pp.415-420
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    • 2019
  • SiAlON ceramics are used as ceramic cutting tools for heat-resistant super alloys (HRSAs) due to their excellent fracture toughness and thermal properties. They are manufactured from nitride and oxide raw materials. Mixtures of nitrides and oxides are densified via liquid phase sintering by using gas pressure sintering. Rare earth oxides, when used as sintering additives, affect the color and mechanical properties of SiAlON. Moreover, these sintering additives influence the cutting performance. In this study, we have prepared $Yb_{m/3}Si_{12-(m+n)}Al_{m+n}O_nN_{16-n}$ (m = 0.5; n = 0.5, 1.0) ceramics and manufactured SiAlON ceramics, which resulted in different colors. In addition, the characteristics of the sintered SiAlON ceramics such as fracture toughness and microstructure have been investigated and results of the cutting test have been analyzed.

고온가압소결을 이용한 YSZ-TiC 세라믹스 복합체의 제조와 특성 (Fabrication and Characteristics of YSZ-TiC Ceramics Composite by Using Hot Pressing)

  • 최재형;최지영;김성원
    • 한국분말재료학회지
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    • 제28권5호
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    • pp.381-388
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    • 2021
  • Zirconia has excellent mechanical properties, such as high fracture toughness, wear resistance, and flexural strength, which make it a candidate for application in bead mills as milling media as well as a variety of components. In addition, enhanced mechanical properties can be attained by adding oxide or non-oxide dispersing particles to zirconia ceramics. In this study, the densification and mechanical properties of YSZ-TiC ceramic composites with different TiC contents and sintering temperatures are investigated. YSZ - x vol.% TiC (x=10, 20, 30) system is selected as compositions of interest. The mixed powders are sintered using hot pressing (HP) at different temperatures of 1300, 1400, and 1500℃. The densification behavior and mechanical properties of sintered ceramics, such as hardness and fracture toughness, are examined.

알루미늄 보레이트 나노휘스커를 이용한 향상된 절연성 및 기계적 특성을 가지는 고분자 복합체 제작 (Fabrication of Polymer Composite with Enhanced Insulation and Mechanical Properties using Aluminum Borate Nanowhiskers)

  • 최준혁;이상인;송기호;김태경;안창의
    • 한국분말재료학회지
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    • 제30권4호
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    • pp.356-362
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    • 2023
  • Inorganic-organic composites find extensive application in various fields, including electronic devices and light-emitting diodes. Notably, encapsulation technologies are employed to shield electronic devices (such as printed circuit boards and batteries) from stress and moisture exposure while maintaining electrical insulation. Polymer composites can be used as encapsulation materials because of their controllable mechanical and electrical properties. In this study, we propose a polymer composite that provides good electrical insulation and enhanced mechanical properties. This is achieved by using aluminum borate nanowhiskers (ABOw), which are fabricated using a facile synthesis method. The ABOw fillers are created via a hydrothermal method using aluminum chloride and boric acid. We confirm that the synthesis occurs in various morphologies based on the molar ratio. Specifically, nanowhiskers are synthesized at a molar ratio of 1:3 and used as fillers in the composite. The fabricated ABOw/epoxy composites exhibit a 48.5% enhancement in mechanical properties, similar to those of pure epoxy, while maintaining good electrical insulation.