Preparation and characterization of nanostructured siliconnitride based ceramic

Abstract

The high-energy milling with an acceleration of 28g or 50g was applied for the mechanical activation of the aluminium and ?-silicon nitrides mixture with yttria additive. The activated powders showed the significant damage of the crystal structure and amorphous areas were produced. Subsequent sintering of the activated precursor demonstrated higher ability for densification and started at 300 °C lower temperature in comparison to the standard mixture. Thus densification was possible below ??? transformation temperature while crystallization of amorphous areas in defective particles resulted in formation of ?-Si<inf>3</inf>N<inf>4</inf> nuclei. Because of the high viscosity of the oxy-nitride liquid at lower densification temperature the grain growth of secondary ?-Si<inf>3</inf>N<inf>4</inf> was preserved and nanocrystalline material was produced. As an alternative, the continuous growth of Al-O for Si-N substitution at rising temperature was observed. © 2013 Elsevier B.V., All rights reserved.