ISSN: 0884-6804
CODEN: JCTRER
Page Count: 6

Dynamic Elastic Modulus and Vibrational Damping in Nicalon SiC^xO^y Fiber/Borosilicate Glass Composites: Effects of Thermal Cycling
Boccaccini, AR
Technische Universität Ilmenau,

Wolfenden, A
Texas A & M University, TX

Anthony, DL
Texas A & M University, TX

Chawla, KK
University of Alabama at Birmingham, AL

Abstract

Measurements of dynamic elastic modulus and vibrational damping were made at room temperature for DURAN (a borosilicate glass) and SiC^xO^y Nicalon™/DURAN (a glass matrix composite). Both sets of materials had been thermal cycled to 500 and 700°C which are below and above the glass transition temperature (T^g = 530°C), respectively. The piezoelectric ultrasonic composite oscillator technique (PUCOT) was used to determine the values of the Young’s modulus and damping. Archimedes’ method was used to find the density of the specimens, and the impulse excitation technique was used to find the flexural modulus. Microstructural examinations were made on selected specimens. The experimental results showed that thermal cycling of the composites below T^g had no distinguishable effect on the density, dynamic Young’s modulus or flexural modulus values; however, an increase in damping of 56% was observed. For thermal cycling above T^g, the density decreased by about 0.5%, the Young’s modulus decreased by 8%, the flexural modulus decreased by 15% and the damping increased by 608%. The simultaneous decrease of elastic modulus and density, and increase of damping in the composites with increasing thermal cycling temperature were analyzed in terms of microstructural degradation due to thermal effects on the matrix, fibers and interfaces.

Keywords:
elastic modulus, damping, glass matrix composites, borosilicate glass, Nicalon™ fibers, thermal cycling

Paper ID: CTR10629J
DOI: 10.1520/CTR10629J
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