Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1477377 | Journal of the European Ceramic Society | 2006 | 7 Pages |
This paper describes the results of the investigation of the oxidation behaviour of 50 wt.% SiC–50 wt.%AlN composites obtained by means of pressureless sintering with Y2O3 as sintering-aid and without using a powder bed to limit the weight loss. Sintered bodies show high density (>98%T.D.) and the microstructure reveals a matrix composed by SiC–AlN solid solution with Y10Al2Si3O18N4 as grain boundary phase. This material exhibits a parabolic oxidation kinetic in the temperature range 1200–1500 °C. Long term oxidation (200 h) induces the formation of a protective oxide scale, composed by mullite, cristobalite and yttrium disilicide, up to 1400 °C. At higher temperature (1500 °C), SiC oxidation behaviour changes from “passive” to “active” and the oxide layer consequently shows porosity due to the formation of gaseous species like SiO and CO.