Accession Number:

ADA310443

Title:

Creep of Carbon Yarns and Composites at High Temperatures.

Descriptive Note:

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS

Personal Author(s):

Report Date:

1988-09-30

Pagination or Media Count:

41.0

Abstract:

Creep was measured in unidirectional carbon-carbon composites P55, HM3000, and WCA fibers with A240 and 15V pitch matrices in tension 2-10 ksi in the high-temperature range between 2000 and 3000 deg C. The composites were analyzed by optical and scanning electron microscopy to identify creep-elongation-induced changes in microstructure and mechanical properties. Such changes include matrix microcracking, fiber-matrix debonding, and filament necking. Rate mechanisms were also derived from the measured creep rates. The activation energies for the composites range from 50 to 130 kcalmole. These values are smaller than activation energies for bulk graphites and indicate low-energy deformation mechanisms. Elastic modulus of the samples was measured before and after creep occurred. The observed increases or decreases are related to specific microstructural changes.

Subject Categories:

  • Laminates and Composite Materials
  • Physical Chemistry
  • Textiles
  • Mechanics
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE