Abstract
Processing and some properties of 28.6mass% Shirasu/71.4mass% alumina light weight composites were studied to develop the dielectric constant and hermeticity required high performance microelectronic ceramic substrates. Colloidal processing was applied to obtain homogeneous and dense compact of Shirasu (or Shirasuballoons) and alumina. Mixed suspension of pulverized Shirasu particles (diameter of 8.2μm) or Shirasuballoons (15μm), and alumina particles (0.5μm) were prepared by adding an appropriate amount of polyelectrolyte. The green compacts were sintered at 1800-1500°C for 1h in air. The flexural strength of Shirasu/alumina composites sintered at 1400°C showed maximum value. Relative dielectric constant of the Shirasu/alumina composites was lower than that of the sintered monolithic alumina, which was interpreted by a modified Maxwell's equation. Mullite formation was confirmed for the Shirasu/alumina composites sintered at 1500°C by X-ray diffractometer.
