Effect of chemical composition of intergranular glass on superplastic compressive deformation of β-silicon nitride

• Published in: Journal of the European Ceramic Society Vol. 26; no. 6; pp. 1069 - 1074
• Main Authors: Narimatsu, E., Shinoda, Y., Akatsu, T., Wakai, F.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2006; Elsevier
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Glass; Si 3N 4; Structural ceramics; Superplasticity; Technical ceramics; Si 3N 4; Superplasticity; Glass; Scanning electron microscopy; Si3N4; Property composition relationship; Silicon nitride; Mechanical properties; Composition effect; Experimental study; Non oxide ceramics; Structural ceramic; Additive; Superplastic deformation; Aluminosilicate glass; Manufacturing; Microstructure
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2004.11.016

The effect of chemical composition of Y 2O 3–Al 2O 3–SiO 2-based intergranular glass on superplastic deformation of β-Si 3N 4 was studied by compression tests at 1873 K. All hot isostatically pressed Si 3N 4 materials had essentially the same microstructure and the same amount of glass phase, which was different in composition only. The relation between flow stress and glass composition qualitatively corresponded to the effect of chemical composition on viscosity of Y 2O 3–Al 2O 3–SiO 2 glass. However, the flow stress was not proportional to the viscosity of Y 2O 3–Al 2O 3–SiO 2 glass, probably because the composition of intergranular glass phase had changed by dissolving Si 3N 4. The strain hardening (increase of flow stress with deformation) was dependent on the chemical composition of intergranular glass. Actually, the apparent strain hardening was not proportional to the strain but was proportional to time. The crystallization of Si 2N 2O was also proportional to time, and was dependent on the chemical composition of the intergranular glass in a similar way to the strain hardening. Thus, it was suggested that the crystallization of Si 2N 2O reduced the amount of the intergranular glass, thereby increasing flow stress.