Fabrication of Al2O3-W functionally graded materials by slipcasting method

Tomoyuki Katayama, Sohei Sukenaga, Noritaka Saito, Hajime Kagata, Kunihiko Nakashima

研究成果: ジャーナルへの寄稿Conference article

4 引用 (Scopus)

抄録

We have successfully fabricated a functionally graded material (FGM) from tungsten and alumina powders by a slip-casting method. This FGM has applications as a sealing and conducting component for high-intensity discharge lamps (HiDLs) that have a translucent alumina envelope. Two types of W powder, with different oxidizing properties, were used as the raw powders for the Al2O3-W FGM. "Oxidized W" was prepared by heat-treatment at 200 °C for 180 min in air. Alumina and each of the W powders were mixed in ultrapure water by ultrasonic stirring. The slurry was then cast into a cylindrical acrylic mold, which had a base of porous alumina, under controlled pressure. The green compacts were subsequently dried, and then sintered using a vacuum furnace at 1600 °C for a fixed time. The microstructures of the FGMs were observed by scanning electron microscopy (SEM) of the polished section. The Al2O3-W FGM with the "oxidized W" powder resulted in a microscopic compositional gradient. However, the FGM with "as-received W" showed no compositional gradient. This result was mainly attributed to the difference between the ζ-potentials of the W powders with the different oxidizing conditions; basically "oxidized W" powder tends to disperse because of the larger ζ-potential of the oxide layer coated on the W powder core.

元の言語英語
記事番号202023
ジャーナルIOP Conference Series: Materials Science and Engineering
18
発行部数SYMPOSIUM 14
DOI
出版物ステータス出版済み - 1 1 2011
イベント3rd International Congress on Ceramics, ICC 2011 - Osaka, 日本
継続期間: 11 14 201011 18 2010

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Functionally graded materials
Powders
Fabrication
Aluminum Oxide
Alumina
Discharge lamps
Vacuum furnaces
Tungsten
Oxides
Acrylics
Casting
Ultrasonics
Heat treatment
Microstructure
Scanning electron microscopy
Water
Air

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)

これを引用

Fabrication of Al2O3-W functionally graded materials by slipcasting method. / Katayama, Tomoyuki; Sukenaga, Sohei; Saito, Noritaka; Kagata, Hajime; Nakashima, Kunihiko.

:: IOP Conference Series: Materials Science and Engineering, 巻 18, 番号 SYMPOSIUM 14, 202023, 01.01.2011.

研究成果: ジャーナルへの寄稿Conference article

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abstract = "We have successfully fabricated a functionally graded material (FGM) from tungsten and alumina powders by a slip-casting method. This FGM has applications as a sealing and conducting component for high-intensity discharge lamps (HiDLs) that have a translucent alumina envelope. Two types of W powder, with different oxidizing properties, were used as the raw powders for the Al2O3-W FGM. {"}Oxidized W{"} was prepared by heat-treatment at 200 °C for 180 min in air. Alumina and each of the W powders were mixed in ultrapure water by ultrasonic stirring. The slurry was then cast into a cylindrical acrylic mold, which had a base of porous alumina, under controlled pressure. The green compacts were subsequently dried, and then sintered using a vacuum furnace at 1600 °C for a fixed time. The microstructures of the FGMs were observed by scanning electron microscopy (SEM) of the polished section. The Al2O3-W FGM with the {"}oxidized W{"} powder resulted in a microscopic compositional gradient. However, the FGM with {"}as-received W{"} showed no compositional gradient. This result was mainly attributed to the difference between the ζ-potentials of the W powders with the different oxidizing conditions; basically {"}oxidized W{"} powder tends to disperse because of the larger ζ-potential of the oxide layer coated on the W powder core.",
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