• 제목/요약/키워드: Ceramic dispersant

검색결과 68건 처리시간 0.026초

Preparation of Granule Powders for Thermal Spray Coating by Utilization of Pyrophyllite Minerals

  • Kim, Yong-Hyeon;Shin, Pyung-Woo;Lee, Sang-Jin
    • 한국세라믹학회지
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    • 제53권5호
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    • pp.557-562
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    • 2016
  • Pyrophyllite granule powders for thermal spray coating were successfully prepared through spray drying process. To produce a stable slurry, commercial pyrophyllite powder of $45{\mu}m$ in size was ball-milled for reduction of the size to $2{\sim}3{\mu}m$ and a dispersant was added to control the viscosity. Dense and spherical granules (average granule size : $59{\mu}m$) were prepared under conditions of 12,500 rpm for rotation velocity of the atomizer and 100 cps for slurry viscosity. The granules were then heat treated at $1,200^{\circ}C$ for proper handling strength and flow properties. The final granules had an apparent density of $0.725g/cm^3$ and a flow rate of 2.5 g/sec, which represent excellent properties to be used as the granule powder for thermal spray coatings.

잉크젯 프린팅을 이용한 연속 조성 세라믹 화합물 구조체 형성 (Additive Manufacturing of Various Ceramic Composition Using Inkjet Printing Process)

  • 박재현;최정훈;황광택;김진호
    • 한국재료학회지
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    • 제30권11호
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    • pp.627-635
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    • 2020
  • 3D printing technology is a processing technology in which 3D structures are formed by fabricating multiple 2D layers of materials based on 3D designed digital data and stacking them layer by layer. Although layers are stacked using inkjet printing to release various materials, it is still rare for research to successfully form a product as an additive manufacture of multi-materials. In this study, dispersion conditions are optimized by adding a dispersant to an acrylic monomer suitable for inkjet printing using Co3O4 and Al2O3. 3D structures having continuous composition composed of a different ceramic material are manufactured by printing using two UV curable ceramic inks whose optimization is advanced. After the heat treatment, the produced structure is checked for the formation and color of the desired crystals by comparing the crystalline analysis according to the characteristics of each part of the structure with ceramic pigments made by solid phase synthesis method.

SiAlON 원료분말제조를 위한 분무건조 과립분말의 형상과 크기에 미치는 공정변수효과 (Effect of Process Parameters on the Morphology and Size of Spray-Dried Granule Powder for Fabrication of SiAlON Raw Material)

  • 최재형;이소율;한윤수;이성민;남산;김성원
    • 한국재료학회지
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    • 제27권12호
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    • pp.716-721
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    • 2017
  • SiAlON-based ceramics are some of the most typical ceramic materials used as cutting tools for HRSA(Heat Resistant Super-Alloys). SiAlON can be fabricated using ceramic processing, such as mixing, granulation, compaction, and sintering. Spray drying is a widely-used method for producing a granular powder of controlled morphology and size with flowability. In this study, we report a systematic investigation aimed at optimizing spherical granule morphology by controlling spray-drying parameters such as gas flow and feed rate. Before spray drying, the viscosities of the raw material slurries were also optimized with the amount of dispersant added.

Fabrication of transparent dielectric mono layer green sheet for plasma display panel

  • Jeon, Young-Hwan;Hwang, Jong-Hee;Lee, Myung-Hyun;Hong, Kyung-Jun;Kim, Nam-Sok;Seo, Byung-Hwa;Moon, Won-Seok
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.898-901
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    • 2006
  • To fabricate mono layer green sheet (MLGS) of transparent dielectric for PDP front panel, dispersion of transparent dielectric slurry and various properties of green sheets were examined as a function of amount and kinds of organic additives. Sedimentation height and viscosity of slurry were measured to determine proper types and amount of dispersant in non-aqueous system transparent dielectric slurry. Many MLGS having various ratios of the transparent dielectric glass frit, binder and plasticizer were fabricated. Finally we got the transparent dielectric layer of high transparency and free from residual pore might be remained in the gap between the electrodes.

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LCP(Liquid Crystal Polymer)와 BaTiO3복합체의 제조 및 유전특성 (Preparation and Dielectric Properties of LCP and BaTiO3 Composites)

  • 윤기현;이승주;양병덕;김종희
    • 한국세라믹학회지
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    • 제40권12호
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    • pp.1183-1188
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    • 2003
  • LCP(Liquid Crystal Polymer)와 BT(BaTiO$_3$) 복합체를 LCP varnish와 BT 슬러리를 혼합하여 제조하고, BT 슬러리 내에서 BT 입자의 분산 특성과 LCP-BT 복합체의 조성 및 BT 분말 크기가 유전 특성에 미치는 영향에 대하여 연구하였다. 분말 크기가 다른 BT 분말에 대하여 분산제 GLYMO(3-glycidyloxypropyltrimethoxysilane) 첨가량에 따른 용매 ODBZ(o-dichlorobenzene) 내에서의 분산 특성을 측정한 결과, BT분말 크기가 증가할수록 비표면적의 감소로 인하여 소요되는 최적 분산제의 양이 감소하였다. 분산된 BT슬러리를 LCP와 혼합하고 테잎 케스팅법을 이용하여 LCP-BT복합체를 제조하였다. BT 입자의 크기가 100nm에서 500nm로 증가함에 따라 복합체의 유전 상수는 34.3에서 44.1로, 유전 손실은 0.05 에서 0.063으로 증가하였다.

콜로이드 계면화학을 이용한 저온형 고체전해질용 $CeO_2$계 복합 산화물의 소결체 제조 (The Preparation for Sintered Body of $CeO_2$ Based Complex Oxide in Low Temperature Solid Oxide Fuel Cells Using Colloidal Surface Chemistry)

  • 황용신;최성철
    • 한국세라믹학회지
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    • 제37권7호
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    • pp.705-712
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    • 2000
  • In this study, the dispersion stability of CeO2 based complex oxide was studied, and density, porosity, and microstructure of green body were investigated using colloid surface chemistry to manufacture the Gd2O3 doped CeO2 solid electrolyte in an aqueous system. To prepare the stable slurry for slip casting, the dispersion stability was examined as a function of pH using ESA(electrokinetic sonic anplitude) analysis. The dynamic mobility of particles was enhanced with anionic and cationic dispersant were added the amount of 0.5wt% respectively, but pH value in slurries didn't move to below 6.0 because of the influence of dopants. This phenomenon also appeared in the CeO2-Y2O3 and CeO2-Sm2O3 systems, so it could be inferred that rare earth dopants such as Gd2O3, Sm2O3 and Y2O3 not only have the similar motion with changing pH in an aqueous system but also can be dissolved in the range of pH 6.0∼6.5. In CeO2-Gd2O3 system, when the anionic dispersant was added the amount of 0.5wt% and pH value in slurries was fixed at 9.5, the green body density was 4.07g/㎤, and the relative density of sintered body was 95.2%. It could be inferred from XRD analysis that Gd3+ substituted into Ce4+ site because there was no free Gd2O3 peak.

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Viscosity Study to Optimize a Slurry of Alumina Mixed with Hollow Microspheres

  • Bukhari, Syed Zaighum Abbas;Ha, Jang-Hoon;Lee, Jongman;Song, In-Hyuck
    • 한국세라믹학회지
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    • 제52권6호
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    • pp.403-409
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    • 2015
  • Porous alumina ceramics are involved in many industrial applications due to the exceptional properties of these products. This study addresses the preparation of porous alumina ceramics using hollow microspheres as a pore-forming agent and slip casting as a green-body-forming technique. A uniform distribution of pores is a basic requirement of a porous material. This study investigates three different slurry systems, i.e., as-prepared alumina slurry, alumina slurry electrostatically dispersed by hydrochloric acid (HCl), and slurry dispersed by the commercial dispersant 'Darvan C-N'. At a low viscosity, the hollow microspheres in the slurry tend to float, which causes a non-uniform pore distribution. To avoid this phenomenon, the viscosity of the slurry was increased to the extent that the movement of hollow microspheres ceased in the slurry. As a result, a uniform pore distribution was achieved.

Gelcasting을 이용한 Mullite 세라믹스의 제조 (Fabrication of Complex-shaped mullite Ceamics by Gelcasting)

  • 최연규
    • 한국세라믹학회지
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    • 제36권7호
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    • pp.773-781
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    • 1999
  • A new technique to fabricate complex-shaped mullite has been developed through gelcasting without organic binder. The suspension of a commercial mullite powder and boehmite-SiO2 sol as binder was elecrtrosterically stabilized. Ammonium polymetharylyate was employed as a dispersant for the electrosteric stabilization. Complex-shaped bodies were made through casting and gelation at room temperature. The green bodies were dried at a temperature of 30$^{\circ}C$ and relative humidity of 98% without crack development. The dried bodies were then pressureless-sintered at 1650$^{\circ}C$ for 2 h to get a relative density of 98% The Vickers hardness and 4-point flexural strength of sintered parts were 11.0 GPa and 150MPa respectively which are similar to those of commercially available sintered mullite.

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구형의 단분산 Alumina 및 Mg-doped Alumina의 합성과 소결에 관한 연구 (Preparation of Monodispersed, Sheperical Al2O3 and Mg-doped Al2O3 Powder and Sintering Characterization of These Powders)

  • 이중윤;부재필;최상흘
    • 한국세라믹학회지
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    • 제31권1호
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    • pp.1-10
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    • 1994
  • Monodispersed alumina and Mg-doped alumina fine particles were prepared by controlled hydrolysis of alkoxides. Aluminium alkoxide and magnesium alkoxide were dissolved into complex solvent which was composed of hydrophobic n-octanol and hydrophilic acetonitrile. Hydroxypropyl cellulose(HPC) was used as a dispersant for the alumina particles. The size of these prepared powders was approximately 0.3 ${\mu}{\textrm}{m}$. In the case of sintering above 100$0^{\circ}C$, most of these prepared powders were transformed to $\alpha$-alumina. The relative density of the sintered body of these prepared powders at 1$600^{\circ}C$ was 98%. The sintered body of the Mg-doped alumina powder had more uniform grain size than that of the undoped alumina podwer.

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Gel-Casting 및 마이크로파 기상반응소결에 의한 질화규소 세라믹 제조에 대한 연구(I) : Gel-Casting에 의한 실리콘 성형체의 제조 (Fabrication of Silicon Nitride Ceramics by Gel-Casting and Microwave Gas Phase Reaction Sintering(I) : Silicon Gel-Casting)

  • 배강;우상국;한인섭;서두원
    • 한국세라믹학회지
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    • 제48권5호
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    • pp.348-353
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    • 2011
  • By gel-casting, the silicon-polymer green bodies were prepared for silicon nitride ceramics, sintered by microwave gas phase reaction. Considering the viscosity and the idle time of slurries, we decided the operational conditions of related processes, and the optimum concentrations of raw materials powders, organic monomers, cross-linker, dispersant, initiator, and catalyst. So we could get the machinable green bodies, having about 50 MPa of bending strength without cracks by selecting drying conditions carefully.