Determination of Fracture Toughness of SiC-Whiskers Reinforced Si3N4 by Two Different Techniques
In this work the fracture toughness of a Si3N4-SiCW composite was measured at temperatures up to 1000°C by two different techniques. In a first case, K Ic , was evaluated from the analysis of the stable growth of indentation cracks upon bending. In the second approach, long through-thickness cracks were obtained by a novel technique and the fracture toughness was determined from the bending strength of these samples. At room temperature values of K Ic equal to ≈4 MPa m1/2 and ≈7 MPa m1/2 were obtained by the indentation technique and by the notched specimens, respectively. The difference between K Ic values was related to the smaller crack opening which accounts for a higher toughening effect in long through-thickness cracks. Fracture toughness was observed to decrease at temperatures higher than 800°C, this effect being stronger in the notched samples.
KeywordsFracture Toughness Crack Length Crack Open Displacement Sandwich Beam Indentation Technique
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- 1.P.B. Becher and T.N. Tiegs, Adv. Ceram. Mat., 4, 2, 143 (1988).Google Scholar
- 2.J.B. Watchman, in: Mechanical properties of Ceramics, J. Wiley Sons, New York, USA, 221–234 (1996).Google Scholar
- 6.P. Pancheri, P. Bosettl, R. Dal Maschio and V.M. Sglavo, to be published on Eng. Frac. Mech. Google Scholar
- 7.V.M. Sglavo, P. Bosetti, E. Trentini and M. Ceschini, to be published on J. Am. Ceram. Soc. Google Scholar
- 10.B. Lawn, in: Fracture of Brittle Solids, Second Edition, Cambridge University Press, Cambridge, Great Britain, 249–306 (1993).Google Scholar
- 12.R.W. Steinbrech, F. Deuerler, A. Reichl and W. Schaarwächter, Sci. Ceram., 14, 695–64 (1988).Google Scholar
- 16.P.F. Becher, C. Hsueh, K.B. Alexander and E.Y. Sun, J. Am. Ceram. Soc., 79, 2, 298304 (1996).Google Scholar