Fabrication of Al2O3-W functionally graded materials by slipcasting method

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

    Research output: Contribution to journalConference article

    6 Citations (Scopus)

    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.

    Original languageEnglish
    Article number202023
    JournalIOP Conference Series: Materials Science and Engineering
    Volume18
    Issue numberSYMPOSIUM 14
    DOIs
    Publication statusPublished - 2011
    Event3rd International Congress on Ceramics, ICC 2011 - Osaka, Japan
    Duration: 2010 Nov 142010 Nov 18

    ASJC Scopus subject areas

    • Materials Science(all)
    • Engineering(all)

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