Silicon nitride composites materials with an improved high temperature Oxidation Resistance

The oxidation resistance of Si3N4 based materials at 1500°C was studied. Si3N4/SiC- and Si3N4/MoSi2-composite materials were found to obey a less severe oxidation mechanism in comparison to the monolithic Si3N4 material, with the consequence of an improved microstructural and mechanical stability after high temperature oxidation. An oxidation mechanism based on the formation of Si2ON2 instead of SiO2 is proposed to be the main reason for the different oxidation behavior of the composite materials.