• Title, Summary, Keyword: ceramic granule powder

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

  • Kim, Yong-Hyeon;Shin, Pyung-Woo;Lee, Sang-Jin
    • Journal of the Korean Ceramic Society
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    • v.53 no.5
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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.

Study on Test Method for Strength of Ceramic Spray Dried Powder (분무 건조된 세라믹 과립의 강도 측정방법에 대한연구)

  • 엄우식;이희수;이세훈;김덕희;이인식
    • Journal of the Korean Ceramic Society
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    • v.33 no.6
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    • pp.660-664
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    • 1996
  • We have studied the test method for strength of spray dried ceramic powder using manual press and UTM. which is one of the important to influence forming process. We could observe the compaction behavior using manual press. However the measurement of granule strength was only possible with UTM capable of providing the condition of a constant pressing rate. The strength of granule can be measured from the slope change of compaction curve and agrees with the value which is obtained from the combination of saturated tap density and compaction curve. So we proposed the accurate method to measure the strength of granule from the results of this study.

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

  • Choi, Jae-Hyeong;Lee, Soyul;Han, Yoonsoo;Lee, Sung-Min;Nahm, Sahn;Kim, Seongwon
    • Korean Journal of Materials Research
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    • v.27 no.12
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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.

Effect of Hydrophobic Surface Coating on Flowability of Ceramic Tile Granule Powders (표면 소수화 처리를 통한 도자타일 과립 분말의 유동 특성)

  • Kim, Jin-Ho;Kim, Ung-Soo;Han, Kyu-Sung;Hwang, Kwang-Take
    • Korean Journal of Materials Research
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    • v.29 no.7
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    • pp.425-431
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    • 2019
  • Generally, ceramic tiles for building construction are manufactured by dry forming process using granular powders prepared by spray drying process after mixing and grinding of mineral raw materials. In recent years, as the demand for large ceramic tiles with natural texture has increased, the development of granule powders with high packing ratio and excellent flowability has become more important. In this study, ceramic tile granule powders are coated with hydrophobically treated silica nanoparticles. The effects of hydrophobic silica coating on the flowability of granule powders and the strength of the green body are investigated in detail. Silica nanoparticles are hydrophobically treated with GPTMS(3-glycidoxypropyl trimethoxy silane), which is an epoxy-based silane coupling agent. As the coating concentration increases, the angle of repose and the compressibility decrease. The tap density and flowability index increase after silica coating treatment. These results indicate that hydrophobic treatment can improve the flowability of the granular powder, and prevent cracking of green body at high pressure molding.

Effect of Suspension Property on Granule Characteristics and Compaction Behavior of Fine Si3Na4 Powder (분산계 특성이 질화규소 미분의 과립특성 및 충진거동에 미치는 영향)

  • 이해원;오성록
    • Journal of the Korean Ceramic Society
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    • v.32 no.4
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    • pp.462-470
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    • 1995
  • The characteristics of spray-dried granules are important for dry pressing operation since they have great influences on die-filling, compaction ratio, and resulting green microstructure. An attempt was made to control granule morphology and the packing structure of fine Si3N4 particles in granules by adjusting suspension property. Mercury porosimetry was used to characterize the pore structures of both granules and green compacts. Finally, the effects of particle packing structure in granules and green microstructure on sintering behavior were investigated.

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Influence of Solid Loading on the Granulation of 3Y-TZP Powder by Two-Fluid Spray Drying

  • Jeong, Hyeongdo;Lee, Jong Kook
    • Journal of the Korean Ceramic Society
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    • v.55 no.4
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    • pp.337-343
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    • 2018
  • The influence of solid loading in the slurry composition on the morphology of 3Y-TZP granules fabricated by two-fluid spray drying was investigated for solid contents varying between 30 wt% and 50 wt%. The resulting 3Y-TZP granules showed a sphere-like shape with diameters of $40-70{\mu}m$. However, a donut-like shape and a few cracks were observed on the granule surfaces fabricated using the slurry with 50 wt% solid content. The green density after cold isostatic pressing at 200 MPa was $2.1-2.2g/cm^3$, and a homogeneous fracture surface was obtained by complete destruction of granules. After sintering at $1500^{\circ}C$ for 2 h, all specimens had relative densities of 96.2 - 98.3%. With increasing solid content, the relative density decreased from 98.3% to 96.2%, but the grain size increased from $0.3{\mu}m$ to $0.6{\mu}m$. Highly sinterable zirconia granule powder could be obtained by controlling the slurry composition.

Spray Drying of Zirconia/Alumina Composite Powder Using PVP as a Binder (PVP 결합제를 이용한 지르코니아/알루미나 복합분말의 분무건조)

  • Shim, Hyung-Bo;Moon, Joo-Ho;Kim, Dae-Joon
    • Journal of the Korean Ceramic Society
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    • v.39 no.5
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    • pp.446-451
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    • 2002
  • Zirconia/alumina mixture powder was spray-dried various degree of dispersion, type of dispersants and powder content in the slurry. The quality of the granule was determined by observation of the granule shapes after spray drying and fracture of intergranular boundaries during pressing. Defect-free granules were obtained from the powders that formed weak flocs in the slurry. The granules, spray-dried from the slurry containing 32.5 vol% powder mixture and PVP as binder, were fractured completely during shaping and the sintered specimens showed a density of 99.7% and a flexural strength of 850 MPa.

Study on the Granulation Behavior of TiO2-PVA Composite Powders Prepared Via Spray Drying Technique

  • Avcioglu, Celal;Ozkal, Burak
    • Journal of the Korean Ceramic Society
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    • v.56 no.5
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    • pp.443-452
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    • 2019
  • In this study, TiO2-polyvinyl alcohol (PVA) composite granules were prepared via spray drying technique. To investigate the effects of solid content and binder/powder ratio in the slurry on the granulation behavior of TiO2 powders, the feed compositions were designed to vary over a wide range. The morphology, actual densities, and average granule size and size distribution of the TiO2-PVA composite granules were characterized by using scanning electron microscopy technique, a gas pycnometer, and an image analyzing program (Image-J), respectively. The results indicate that solid content and the amount of PVA in the feedstock slurry are the dominant factors determining the granule morphology, size, and size distribution of TiO2-PVA composite. Moreover, it was observed that increasing the solid content and the amount of PVA in the slurry improved the granulation process and reduced the granule defects. For the preparation of spherical TiO2-PVA composite granules with the minimum amount of non-granulated powders, the optimized composition of the feedstock slurry was found to be 35 wt.% solid and 3 wt.% PVA.

A Case Study on Sintering Characteristics of Yttria Stabilized Zirconia Powder Prepared by Two-Fluid Spray Drying

  • Choi, Jin Sam;Kong, Young-Min
    • Journal of the Korean Ceramic Society
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    • v.53 no.3
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    • pp.332-337
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    • 2016
  • As a case study on yttria stabilized zirconia ceramics, the sintering characteristics of submicron powders and the granulation prepared by two-fluid spray drying of submicron particles were investigated. As-received powders of yttria stabilized zirconia particles were reduced to a uniform size of less than about 200 nm by repeated milling. Granulation size obtained by the two-fluid spray drying was affected by the organic matter and the primary particle size. Sintering behavior such as porosity, water absorption ratio, density, and transparency was influenced by processing conditions of the powder, and the discontinuous interfaces in a green body were reduced.

Characterization of Lightweight Earthenware Tiles using Foaming Agents

  • Lee, Won-Jun;Cho, Woo-Suk;Hwang, Kwang-Taek;Kim, Jin-Ho;Hwang, Hae-Jin;Lee, Yong-Ouk
    • Journal of the Korean Ceramic Society
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    • v.52 no.6
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    • pp.473-478
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    • 2015
  • Green bodies of earthenware tile were prepared from a mixture of earthenware tile powder and SiC as forming agents by applying a conventional process. Granule powder for tile samples was prepared using the spray drying method with commercial earthenware raw material with a quantity of SiC of 0.3 wt%. The applied pressure was $250kg{\cdot}f/m^2$ and the firing temperature was $1050-1200^{\circ}C$. The effects of the SiC particle size and sintering temperature on the open porosity and total porosity were investigated and the correlative mechanism was also discussed. While total porosity was not significantly changed by decreasing the SiC particle size, the open porosity showed a gradual decrease, which represents an increase of the closed porosity. As the sintering temperature increased, coarsening was made among the pores due to excessive oxidation. The volume shrinkage and bending strength were demonstrated for the sintered tile samples. The sintered bulk density was also measured to determine the weight reduction value.