Abstract
Novel apparatus and methodology have been developed for measuring the fracture toughness of ceramics using small disk-shaped samples 3 mm in diameter. The method involves the Vickers indentation of specimens ranging in thickness from 300 to 700 μm, and testing them in a ring-on-ring bending mode. Experiments on ZnS grown by chemical vapor deposition (CVD) have been used to evaluate the technique. The apparent fracture toughness of this material increases with crack length (R-curve behavior). This behavior is analyzed using established equations in conjunction with a new graphical method that obviates the need for measuring the apparent toughness of samples containing very large cracks. The fracture toughness at “infinite” crack length, 0.86 ± 0.08 MPa · m1/2, is in very good agreement with the values obtained by conventional methods. The effect of sample size on the accuracy of the results is thoroughly discussed. The thickness, t, of the sample should exceed by a factor of ten the initial crack length produced by the indentation. Also, since samples are tested at various indentation loads, P, the ratio of their thicknesses should be chosen to satisfy the condition t ∝ P 2/3. The importance of several parameters in the design of the apparatus is also discussed.
Similar content being viewed by others
References
G. R. Anstis, P. Chantikul, B. R. Lawn, and D. B. Marshall, J. Am. Ceram. Soc. 64, 533 (1981).
G. E. Lucas, Metall. Trans. 21A, 1105 (1990).
H. Li, F. C. Chen, and A. J. Ardell, Metall. Trans. A (1991, in press).
J. Zhang, W. W. Chen, and A. J. Ardell, in Window and Dome Technologies and Materials II, edited by P. Klocek (SPIE Proc., 1990), Vol. 1326, p. 93.
J. Zhang, W. W. Chen, A. J. Ardell, and B. Dunn, J. Am. Ceram. Soc. 73, 1544 (1990).
J. Zhang, W. W. Chen, B. Dunn, and A. J. Ardell, in Ceramics and Inorganic Crystals’ for Optics, Electro-Optics, and Nonlinear Conversion, edited by R. W. Schwartz (SPIE Proc., 1988), Vol. 968, p. 35.
P. Chantikul, G. R. Anstis, B. R. Lawn, and D. B. Marshall, J. Am. Ceram. Soc. 64, 539 (1981).
D. C. Harris, W. R. Compton, A. M. Harper, G. A. Hayes, M. E. Hills, N. A. Jaeger, L. D. Sawyer, R. C. Scheri, and J. L. Stokes, in Window and Dome Technologies and Materials II, edited by P. Klocek (SPIE Proc., 1990), Vol. 1326, p. 23.
R. J. Roarke and W. C. Young, Formulas for Stress and Strain, 5th ed. (McGraw-Hill Book Company, New York, 1975), p. 382.
R. F. Cook, C. J. Fairbanks, B. R. Lawn, and Y-W. Mai, J. Mater. Res. 2, 345 (1987).
R. F. Krause, Jr., J. Am. Ceram. Soc. 71, 338 (1988).
D. K. Shetty and J-S. Wang, J. Am. Ceram. Soc. 72, 1158 (1989).
R. F. Cook and D. R. Clarke, Acta Metall. 36, 555 (1988).
R. F. Cook, B. R. Lawn, and C. J. Fairbanks, J. Am. Ceram. Soc. 68, 604 (1985).
A. G. Evans, in Advances in Ceramics, Science and Technology of Zirconia II, edited by N. Claussen, M. Rühle, and A. H. Heuer (American Ceramic Society, Columbus, OH, 1984), Vol. 12, p. 193.
J. C. Newman and I. S. Raju, Engr. Fract. Mech. 15, 185 (1981).
W. F. Adler and S. V. Hooker, J. Mater. Sci. 13, 1015 (1978).
D. P. Williams and A. G. Evans, J. Test. and Eval. 1, 264 (1973).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Zhang, J., Ardell, A.J. Measurement of the fracture toughness of CVD-grown ZnS using a miniaturized disk-bend test. Journal of Materials Research 6, 1950–1957 (1991). https://doi.org/10.1557/JMR.1991.1950
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/JMR.1991.1950