Most of the very limited tensile creep information on monolithic ceramics has been generated using the four point bend test. Where data on ceramics under uniaxial tension do exist, it is invariably the case that lifetimes are much longer under flexure when, as is usual, the maximum principal tensile stress is used as the correlating parameter. In this paper, creep lifetime data for hot pressed silicon nitride are used to demonstrate that a geometry dependent ‘reference stress’ is a much superior correlating parameter and that its successful usage leads to important deductions about the process of fracture in this class of materials, under the stress and temperature regime studied.
MST/1668
Get full access to this article
View all access options for this article.
References
1.
GOVILAR. K.: J. Am. Ceram. Soc.,1982, 65, 15.
2.
QUINNG. D.: in‘Fracture mechanics of ceramics’, (ed. BradtR. C..), Vol. 8, 319; 1986, New York, Plenum.
3.
ANDERSONR. A., GARDNERL. R. T., and HODGKINSW. R.: J. Mech. Eng. Scl.,1963, 5, 238.
4.
MARRIOTTD. L. and LECKIEF. A.: PLOC. Conf. on ‘Thermal loading and creep in structures and components’, Vol. 4, 5; 1964, London, Institution of Mechanical Engineers.
5.
MACKENZIEA. C.: Inst. J. Mech. Sci., 1968, 10, 441.
6.
COHRTH., GRATHWOHLG., and THÜMMLERF.: Res. Mech. Lett.,1981, 1, 159.
7.
PENNYR. K. and MARRIOTTD. L.: ‘Design for creep’; 1971, New York, McGraw-Hill.
8.
CARROLLD. F. and WIEDERIIORNS. M.: in ‘Mechnical testing of engineering ceramics at high temperatures’, (ed. DysonB. F. et al.), 135; 1989, Amsterdam, Elsevier Applied Science.
9.
FETTT. and MUNZD.: in ‘Mechnical testing of engineering ceramics at high temperatures’, (ed. DysonB. F. et al.), 189; 1989, Amsterdam, Elsevier Applied Science.
10.
COHRTH., GRATHWOHLG., and THUMMLERF.: Res. Mech.,1984, 10, 55.
11.
ASIIBYM. F. and DYSONB. F.: in‘Advances in fracture research’, (ed. ValluriS. R..), Vol. 1, 3; 1984, Oxford, Pergamon Press.
