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Ceramic whiskers are added to monolithic ceramics to improve resistance to cracking in the matrix and thereby to enhance toughness. The interaction between whiskers and matrix and the effectiveness of the reinforcement is dependent upon both the matrix whisker bond strength and the stress field generated in the surrounding matrix by, for example, differences in thermal expansion coefficient. Quantification of interphase stress states provides a measure for engineering the composite structure to optimise reinforcement. A methodology previously developed for determining residual stresses in machined ceramic surfaces was adapted to study residual stresses arising from thermal expansion mismatch during cooling in a silicon nitride-silicon carbide (whisker) composite. The composite samples were selected to compare the effects on interphase stress of whisker content, whisker length and whisker diameter. Early results have demonstrated that the technique gives a consistent indication of the size and nature of the residual stresses generated in whisker-matrix interfaces. The resolution of the technique allows the determination of stresses of 10 MPa difference, giving a powerful method for quantifying interface characteristics.

Additional information

Authors: PRADELL T, JRC Petten (NL);OLAGNON C, JRC Petten (NL);BULLOCK E, JRC Petten (NL)
Bibliographic Reference: Article: Journal of Materials Science Letters, Vol. 9 (1990) pp. 960-961
Record Number: 199110061 / Last updated on: 1994-12-02
Original language: en
Available languages: en