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.
|Titolo:||Long term oxidation behaviour of liquid phase pressureless sintered SiC-AlN ceramics obtained without powder bed|
|Data di pubblicazione:||1-ott-2006|
|Appare nelle tipologie:||1.1 Articolo in rivista|