Zhang Qitu
( Nanjing University of Chemical Technology)
Abstract: The oxidation behavior and the affect of a Si2N2O surface layer to the oxidation properties of Si3N4 have been investigated .The results indicate that the oxidation behavior in air for the samples is in good agreement with the parabola law .In addition, the existence of the Si2N2O layer has been confirmed by both XRD and XPS analyses .The formation of the surface layer of Si2N2O significantly decreases the oxidation weight -gaining of Si3N4 ceramics in 100h at 1300 ℃ from 0 .42mg/cm2 to 0 .24mg/cm2, and the oxidation resistance properties are significantly improved .The strength of Si3N4 ceramics is also improved by surface treatment .For example, the strength at room temperature grows from 621MPa to 662 MPa .
Key words: Si3N4, Si2N2O, surface treatment, oxidation, strength