Elastic Behavior of Carbons at High Temperatures

Abstract

Recent developments in high temperature technology require advanced knowledge of high temperature mechanical properties of graphite. Quite a lot of information has recently become available concerning the high temperature behavior of the mechanical properties of certain types of commercial graphites. However, there has been but little information available on the dependence of the elastic modulus on temperature for carbon materials made from various types of carbon and heat treated at various temperatures. In this paper, the following studies on static elastic modulus of carbons in bending at high temperatures have been carried out as follows; (1) dependence of Young's modulus on temperature for four basic types of carbons heat treated at 3000°C (soft filler-soft binder, soft filler-hard binder, hard filler-soft binder); (2) a complete system of temperature dependence for these four types of carbons and for glassy carbon and low density carbon has been obtained as these carbons progressively heat treated to higher temperature and then cooled back to room temperature; (3) the dependence of Young's modulus on temperature to 2500°C was measured for pyrolytic and ZTA graphite. It was found that for soft filler materials all the curves of Young's modulus vs. temperature shows a maximum below the heat-treatment temperature. Hard filler bodies show a continuous decrease in modulus with increase of temperature. The ZTA graphite, the low density carbon and the pyrolytic graphite behavior are respectively similar to that of soft filler bodies, whereas the glassy carbon behavior similar to that of hard filler materials.