Debonding behavior between [beta]-Si[sub 3]N[sub 4] whiskers and oxynitride glasses with or without an epitaxial [beta]-SiAlON interfacial layer
- Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
- Univ. of Karlsruhe (Germany). Inst. of Ceramics in Mechanical Engineering
In order to gain insight on the influence of intergranular glass on the fracture toughness of silicon nitride, the debonding behavior of the interface between the prismatic faces of [beta]-Si[sub 3]N[sub 4] whiskers and oxynitride glasses was investigated in model systems based on various Si-(Al)-Y(Ln)-O-N (Ln: rare-earth) oxynitride glasses. It was found that while the interfacial debonding strength increased when an epitaxial [beta][prime]-SiAlON layer grew on the [beta]-Si[sub 3]N[sub 4] whiskers, the critical angle for debonding was lowered with increasing Al and O concentrations in the SiAlON layer. Only in the absence of a SiAlON epitaxial layer, were debonding conditions altered by residual stresses imposed on the interface due to thermal-mechanical mismatch. A possible explanation for the effect of SiAlON formation and its composition on the debonding behavior is suggested by first-principles atomic cluster calculations. It is concluded that by tailoring the densification additives and hence the chemistry of the intergranular glass, it is possible to improve the fracture resistance of silicon nitride.
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 6332048
- Journal Information:
- Acta Materialia, Vol. 47:9; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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