Studies on Young's Modulus of Graphites (II)

Abstract

Further studies of the in-vacuum Young's modulus as a function of temperature ranging from room temperature up to 1000®C have been examined on various artificial and natural graphites. The modulus (E) vs. temperature (T) relationship when temperature is elevated up has been found to satisfy the following empirical formular;ET/E50=a+bT+cT2, where E50 denotes the modulus at 50®C. The minimum value of Young's modulus for porous graphites is indicated at about 400®C, while that for dense specimens appears around 250®C. Also in the increasing rate of modulus, the porous ones definitely predominate the dense ones. As to the effect of heat treatment temperature (HT), the characteristic hysteresis in the E vs. T curve tends to diminish with decreasing HT. The coefficient c in the above formular is found to increase as HT is elevated. The temperature dependency of E for natural graphite compacts is strongly affected by the apparent density as well as by the presence of binder materials.