Studies of young's modulus of carbons at high temperature

Abstract

Preliminary results of measurements of the static Young's modulus for carbons at high temperature were reported previously. Since that time the apparatus was improved in reliability and in reproducibility. As previously the deflection of a specimen heated in a graphite tube furnace is obtained from deflections measured at three points using Linear Variable Differential Transformers; however in the new equipment the corresponding electronic circuits are greatly modified. The forcedeflection curves are directly obtained on an X–Y recorder. With this improved apparatus the following studies were carried out as follows; 1. (1) dependence of Young's modulus on temperature for four basic types of carbons heat treated to 3000°C (soft filler-soft binder, soft filler-hard binder, hard filler-soft binder and hard filler-hard binder); 2. (2) complete systems of temperature dependence curves for these four types of carbons and for glassy carbon (Tokai Electrode Co.) were obtained as these carbons are progressively heat treated to higher temperatures and then cooled back to room temperature; 3. (3) dependence of Young's modulus on temperature was measured for pyrolytic graphite (General Electric Co.) and ZTA graphite (National Carbon Co.). It has been found that for soft filler materials all curves of Young's modulus vs. temperature show a maximum below the heat-treatment temperature. Hard filler bodies show a continuous decrease in modulus with increase of temperature. ZTA and pyrolytic graphite behavior is similar to that of soft filler bodies, whereas glassy carbon is similar to hard filler materials.