Accession Number:

ADA303864

Title:

Heat Treatment Effects on the Tensile Properties and Microstructures of a SiC/RBSN Composite in Nitrogen.

Descriptive Note:

Technical memo.,

Corporate Author:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s):

Report Date:

1995-09-01

Pagination or Media Count:

9.0

Abstract:

The room-temperature tensile properties and constituent microstructures of a unidirectionally reinforced SiCRBSN composite have been investigated after heat treatments at 1400, 1600, or 1800 deg C in nitrogen for up to 100 hr. The composite consisted of approx. 24 vol of aligned 140 micrometers diameter, continuous length, chemically vapor deposited SiC fibers in a approx. 40 porous silicon nitride matrix. The composites heat treated at 1400 deg C for up to 100 hr showed elastic modulus, first matrix cracking strength, and ultimate tensile strength values similar to those of the as-fabricated composites, but those heat treated for 1 hr beyond this temperature displayed losses in all three properties. Recrystallization of the SiC fibers, reaction between the carbon-rich interface coating on the fibers and the RBSN matrix, and dissociation of the RBSN matrix are the reasons for the loss of mechanical properties. jg p2

Subject Categories:

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

Distribution Statement:

APPROVED FOR PUBLIC RELEASE