Temperature Dependence of Dynamic Young's Modulus and Mechanical Damping in a Nextel Fiber-Reinforced Glass Composite

Abstract

The piezoelectric ultrasonic composite oscillator technique (PUCOT), was used to measure the temperature dependence of dynamic Young's modulus and damping for a ceramic matrix composite (CMC) consisting of N51A glass as the matrix and Nextel 480 continuous fibers (volume fraction 0.29) as the reinforcement. The temperature range covered was 20 to 462°C. It was found that the Young's modulus decreased linearly with temperature, at a relatively low rate, and that the damping followed the form exp(-H/kT), where the value of the effective activation energy H was 0.07 ± 0.02 eV/atom, k is Boltzmann's constant, and T is temperature in Kelvin. Possible interpretations for this value of H are discussed. The glass transition temperature of the glass was found to be about 500°C.