Interfacial studies of chemical-vapor-infiltrated (CVI) ceramic matrix composites. Final report

Technical Report · Sat Mar 31 04:00:00 EST 1990

OSTI ID:6669038

Brennan, J J

The objective of this program was to investigate the fiber/matrix interfacial chemistry in CVI SiC matrix composites utilizing Nicalon SiC and Nextel 440 mullite fibers and to determine how this interface influences composite properties such as strength, toughness, and environmental stability. The SiC matrix was deposited using three different reactants; methyldichlorosilane (MDS), methyltrichlorosilane (MTS), and dimethyldichlorosilane (DMDS). The fiber/matrix interface was tailored by means of introducing a carbon, BN, or carbon rich SiC interfacial layer. It was found that applying a carbon interfacial layer to either NICALON or Nextel 440 fibers prior to deposition of SiC resulted in a weakly bonded interface that imparted toughness to CVI matrix composite through its ability to deflect matrix cracks. This carbon layer can be applied either deliberately by the decomposition of methane or by utilizing an argon flushing gas in the reactor that apparently interrupted the normal deposition of SiC from silane precursors and instead allowed carbon to deposit. It was found that this carbon interfacial layer, no matter how it was deposited, was not oxidatively stable at elevated temperatures, leading to severe degradation of composite properties.

• Research Organization: United Technologies Research Center, East Hartford, CT (USA)
• OSTI ID: 6669038
• Report Number(s): AD-A-221867/5/XAB; UTRC/R--90-917779-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360601 -- Other Materials-- Preparation & Manufacture
360603 -- Materials-- Properties
360604 -- Materials-- Corrosion
Erosion
& Degradation
ALKANES
ALKYL RADICALS
ARGON
BORON COMPOUNDS
BORON NITRIDES
CARBIDES
CARBON
CARBON COMPOUNDS
CERAMICS
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CORROSION RESISTANCE
DEPOSITION
DOCUMENT TYPES
ELEMENTS
ENVIRONMENT
FABRICATION
FLUIDS
FRACTURE PROPERTIES
GASES
HIGH TEMPERATURE
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INTERFACES
JOINTS
LAYERS
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
METHANE
METHYL RADICALS
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
OXIDATION
PNICTIDES
PRECURSOR
PROGRESS REPORT
RADICALS
RARE GASES
SILANES
SILICON CARBIDES
SILICON COMPOUNDS
STABILITY
VAPORS