Internal friction measurement of C/C composites by lateral vibration method

Recent advancement of CMCs and MMCs demads new and precise methods to evaluate mechanical properties at very high temperatures. A lateral vibration type internal friction measurement apparatus by electrostatic capacitance method with an advanced high temperature capability was developed and applied to 2D C/C composites. From temperature dependence of internal friction up to 800degC, three internal friction peaks have been observed. These peaks were related with desorption phenomena of gases from the C/C specimens which were simultaneously measured, during the internal friction measurements. The hysteresis and time dependent behaviors of internal friction suggest the gas desorption from closed pores together with that from open pores. (author)