Ceramic materials on the basis of Si₃N₄ including sialons are characteristic with outstanding mechanical properties (hardness, bending strength etc.) at temperatures up to 1400 °C and good wear and corrosion resistance.

Because of low diffusion speed sintering processes of Si₃N₄-containg materials as well as microstructure and mechanical properties depend not only on the chemical composition of sialon, but also on the size of particles of the starting material. Therefore application of nanoparticles would be interesting for development of new materials.

The aim of this work was to find the dependence of sinterability, microstructure and properties of the mentioned α-sialons on the chemical composition of sialons by using nanopowder composites.

Investigation were made of 15 different Y-containing α- sialon composites corresponding to the formula Y_m/3Si_12-(m+n)Al_m+nO_nN_16-n or near it. Si₃N₄ – 27 wt. % AlN nanocomposite was used as a raw material with the addition of Al₂O₃, Y₂O₃ and Si₃N₄ nanopowders. Sialon composites were made by mechanical mixing of raw powders. Final specific surface area of composite was of 70-100 m²/g corresponding to the average particle size of 20-30 nm. Ceramic materials were obtained by sintering in nitrogen medium at 1400-1700 °С.

It was found that it is possible to obtain dense ceramic materials with relatively fine-grained structure (200-300 nm) from nanopowders beginning with 1500 °С and they differ from sialons obtained from traditional more coarse powders, because the density of them at such sintering temperatures does not exceed 60-70 %. Hardness of some sialon composites prepared at such sintering temperatures reaches even 23 GPa. Fracture toughness К_1с of samples obtained after sintering at 1600 °С is of 4-6 MPa·m^1/2 and grows with the increase of sintering temperature. If the sintering temperature is increased over 1700 °С, the concentration of needle-shaped crystals in material grows increasing the mechanical strength of material.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/15699 must be provided.

1. Metallic filler containing polymer nanocomposites