Dispersoid-toughened silicon nitride composites: Final report

Technical Report · Thu Sep 01 04:00:00 EDT 1988

OSTI ID:6726889

Buljan, S T; Baldoni, J G; Neil, J; Zilberstein, G

This report is a summary of results of a study aimed at the development of silicon nitride composites of enhanced fracture toughness and strength utilizing particulate and whisker dispersoids. Composited with 40% higher fracture toughness and 25% higher room-temperature fracture strength over that of the base silicon nitride ''monolith'' have been prepared using 30 v/o SiC whisker dispersoids. An increase in fracture toughness of 70% has been observed at 35 v/o whisker additions. Both fracture toughness and strength improvements persist over a wide range of temperatures (25-1200/degree/C). These composites exhibit excellent oxidation resistance and improved resistance to slow crack growth and creep at elevated temperatures. A process for fabrication of complex composite ceramic parts was developed and demonstrated. The present study has also provided extensive information regarding microstructure-property dependence in dispersoid-modified ceramics, which has been utilized to derive a formal theory of fracture toughness and microstructure relationship. 22 refs., 49 figs., 21 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA); GTE Labs., Inc., Waltham, MA (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6726889
• Report Number(s): ORNL/Sub-85-22011/1; ON: DE89001952
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CRACK PROPAGATION
CREEP
CRYSTAL STRUCTURE
CRYSTALS
DOCUMENT TYPES
EQUATIONS
FRACTURE PROPERTIES
GRAIN SIZE
MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MONOCRYSTALS
NITRIDES
NITROGEN COMPOUNDS
OXIDATION
PHYSICAL PROPERTIES
PNICTIDES
PROGRESS REPORT
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SIZE
THERMAL CONDUCTIVITY
THERMAL DIFFUSIVITY
THERMODYNAMIC PROPERTIES
WHISKERS