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) : Bhatt, R. T.

PDF Url : ADA303864

Report Date : SEP 1995

Pagination or Media Count : 9

Abstract : The room-temperature tensile properties and constituent microstructures of a unidirectionally reinforced SiC/RBSN 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

Descriptors :   *MICROSTRUCTURE, *COMPOSITE MATERIALS, *TENSILE PROPERTIES, *NITROGEN, *HEAT TREATMENT, *SILICON CARBIDES, MECHANICAL PROPERTIES, TENSILE STRENGTH, CHEMICALS, CRACKING(FRACTURING), MODULUS OF ELASTICITY, CHEMICAL VAPOR DEPOSITION, MATRIX MATERIALS, STRENGTH(MECHANICS), DISPLAY SYSTEMS, ROOM TEMPERATURE, LOSSES, HEAT, DISSOCIATION, RECRYSTALLIZATION, SILICON NITRIDES, UNIDIRECTIONAL.

Subject Categories : Laminates and Composite Materials
      Inorganic Chemistry
      Physical Chemistry
      Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE