Processing of concentrated aqueous Si3N4 slips stabilized with tetramethylammonium hydroxide

  • M. P. Albano
  • L. B. Garrido
Article
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Abstract

The optimization of the dispersion of 43 vol% aqueous Si3N4/sintering aid slurries with tetramethylammonium hydroxide to achieve high packing slipcast compacts and subsequent high sintered densities was investigated. Slips containing 43 vol% solids were obtained by dispersing most of the solid (35 vol%) at high pH values (9.7 to 12.3) with different amounts of tetramethylammonium hydroxide and with subsequent addition of the remaining solid up to 43 vol%. The influence of pH on the viscosity and on the amount of tetramethylammonium ions adsorbed, and in solution, of 43 vol% slips was studied. The minimum viscosity was observed in the 9.7 to 10.2 pH range. This pH range seemed to be an intermediate situation between high ionic strength (pH higher than 10.2) and low electrostatic repulsion (pH lower than 9.7). The maximum sintered density at 1650 °C, 97.5% of theoretical density (TD), was obtained from bars of green density, 55.6% TD, prepared from slips with the minimum viscosity (44 mPa/s).

Keywords

processing Si3N4 slips 
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Copyright information

© ASM International 1999

Authors and Affiliations

  • M. P. Albano
    • 1
  • L. B. Garrido
    • 1
  1. 1.Centro de Tecnología de Recursos Minerales y Cerámica (CETMIC)Provincia de Buenos AiresArgentina

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