Growth Rate and Microstructure of Al/Al2O3 Composite Body Obtained by Reaction between SiO2 and Molten Al

Noboru Yoshikawa, Yoshiyuki Watanabe, Zully Matamoros Veloza, Atsushi Kikuchi, Shoji Taniguchi

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Al/Al2O3 composite bodies are known to be obtained as reaction products between SiO2 and molten Al. In this study, quartz glass rods of 5 and 15 mm in diameter were dipped into molten Al at various temperatures between 973 and 1573 K in Ar atmosphere or in air. Growth rates of the reaction layers were measured and microstructures of the composite bodies were observed. Following results were obtained: According to the X-ray diffractometry and the wave dispersive X-ray microanalysis (WDX), the reaction products consisted of Al and Al2O3, and the concentration of Si was less than 5%. Volume fraction ratio of Al and Al2O3 phases in the composite bodies was almost 1 : 3. It was interpreted that the volume fraction of Al phase resulted from compensation of the molar volumes differences between SiO2 and Al2O3. In the temperature range between 973 and 1073 K, thickness of the reacted layer increased linearly with the time and the growth rate of the reacted layer (gradient of the time-thickness curve) increased with the temperature. However, in the temperature range between 1073 and 1273 K, the growth rate decreased with the temperature. Al2O3 phase produced by the reaction changed in this temperature range and this phase change is considered to be related to the decrease in growth rates. The thickness increased parabolically with the time above 1373 K, and the parabolic growth rate increased with the temperature. Coarsening of the composite microstructures occurred in this temperature range, remarkably. Transfer rate of molten Al in the composite body increased due to the increase in the width of Al channels. Therefore, growth rate of the reaction layer increased.

Original languageEnglish
Pages (from-to)312-318
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume63
Issue number3
DOIs
Publication statusPublished - 1999 Jan 1
Externally publishedYes

Keywords

  • Al/AlO
  • In-situ composite
  • Microstructure
  • Reaction mechanism
  • Reaction rate
  • SiO
  • Substitutional reaction

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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