Research And Development On Advanced Graphite Materials. Vol V - Analysis Of Creep And Recovery Curves For ATJ Graphite

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Report Number: WADD TR 61-72 Volume V
Author(s): Seldin, E. J., Draper, R. N.
Corporate Author(s): National Carbon Company, Inc.
Laboratory: Directorate of Materials and Processes
Date of Publication: 1961-09
Pages: 44
Contract: AF 33(616)-6915
DoD Project: 7350
DoD Task: 73503
Identifier: AD0270536

Flexural creep tests were made on specimens of ATJ graphite at temperatures ranging from 2300° to 3000°C. The creep curves have been fitted by graphical and analytical means to four equations. Fairly good fits have been obtained with all of the equations which were used. Attempts were made to determine the stress and temperature dependence of several of the parameters in the equations Of the four equations which were used, one could be related to simple rheological models having some physical significance. A model was found useful not only in describing the creep curves, but also in describing the recovery after creep and relating the behavior in recovery to the behavior during creep. Generally good agreement was found between the qualitative predictions of the models and the observed behavior. Using a model, an activation energy for the steady state creep rate was determined to lie between 70 and 76 kcal/mole. Some deviations were detected between the actual behavior of the material and that predicted by the simple models which suggest some modifications that may be made to obtain a better model. The value of a model is discussed, and several additional experiments are suggested to supplement the information given by creep experiments.

Provenance: Lockheed Martin Missiles & Fire Control

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