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Dispersion and Consolidation of the Colloidal Suspension in the Al2O3 Powder – Si3N4 Whisker System
Published online by Cambridge University Press: 21 February 2011
Abstract
Whisker-reinforced ceramics have high potential for structural materials application due to their high fracture toughness and high mechanical strength. In this paper, rheological property and consolidation of the colloidal suspension in the alumina powder-silicon nitride whisker system were studied to control the microstructure and density of the green and hot-pressed composite. A12O3 particles of average diameter 0.15 μm and Si3N4 whisker of average size 0.4 μm × 3.7 μm were electrostatically dispersed in water in pH range 1–11 and consolidated by filtration. A welldispersed state of the composite suspension was achieved at low pH. Decreasing the viscosity while increasing the solid content of the suspension at the same time is the key step in making green compact with higher density and a narrower pore size distribution. These compacts were densified to relative density 98.4–99.4% by hot-pressing at 1500°C at a pressure of 39 MPa in N2 atmosphere.
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- Copyright © Materials Research Society 1989
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