SEDL / STP / STP745-EB / STP28298S

Effect of Stable Crack Growth on Fracture Toughness Determination for Hot-Pressed Silicon Nitride at Elevated Temperatures

Munz, D
University of Karlsruhe,

Himsolt, G
Research engineers, Deutsche Forschungs-und Versuchsanstalt für Luft-und Raumfahrt, Cologne,

Eschweiler, J
Research engineers, Deutsche Forschungs-und Versuchsanstalt für Luft-und Raumfahrt, Cologne,

Pages: 16    Published: Jan 1981

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Abstract

Fracture toughness of hot-pressed silicon nitride was determined between room temperature and 1300°C using four-point bend specimens with straight-through and chevron notches. For T > 1100°C fracture toughness increases due to crack branching and secondary cracking caused by the viscous flow of the grain boundary phase. To determine correct K-values with the specimens having a straight-through notch the stable crack extension at T > 1100°C has to be taken into account.