SiAlON ceramics from nanopowders

Different compositions of α- and α-/β-SiAlON materials have been prepared from two different starting powders (commercial and nanopowder). Separate nanopowders and their composites were used as nanocomponents: Si3N4, 90%Si3N4–10%AlN, 90%AlN–10%Y2O3, Si3N4–AlN–Al2O3–Y2O3 and Y2O3, produced by the method of plasma-chemical synthesis. Powder mixtures of the same composition from α-Si3N4 powder (Ube grade SN-E10) and additives (Y2O3, Al2O3 and AlN) produced by a conventional powder mixture process were used for comparing. Compositions have been pressure less sintered under nitrogen atmosphere until 1650 °C with a heating rate of 10 °C/min and holding time of 2 h. The densification behavior of the materials depends on the powder composition and the size of the particles used for starting powder. It is possible to obtain dense materials from nano-sized powder at relatively low temperatures (1500–1600 °C) with good mechanical room temperature properties in comparison with material made of a μm-sized starting powder.