Crack healing in silicon nitride due to oxidation

Conference · Tue Oct 01 04:00:00 EDT 1991 · Ceramic Engineering and Science Proceedings; (United States)

OSTI ID:6073943

Choi, S R; Tikare, V; Pawlik, R

The crack healing behavior of a commercial, MgO-containing, hot pressed Si3N4 was studied as a function of temperature in oxidizing and inert annealing environments. Crack healing occurred at a temperature 800 C or higher due to oxidation regardless of crack size, which ranged from 100 microns (indentation crack) to 1.7 mm (SEPB precrack). The resulting strength and apparent fracture toughness increased at crack healing temperature by 100 percent and 300 percent, respectively. The oxide layer present in the crack plane was found to be highly fatigue resistant, indicating that the oxide is not solely silicate glass, but a mixture of glass, enstatite, and/or cristobalite that was insensitive to fatigue in a room temperature water environment. 20 refs.

• OSTI ID: 6073943
• Report Number(s): CONF-910162--
• Conference Information: Journal Name: Ceramic Engineering and Science Proceedings; (United States) Journal Volume: 12
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALKALINE EARTH METAL COMPOUNDS
ANNEALING
CERAMICS
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
FATIGUE
FRACTURE PROPERTIES
HEAT TREATMENTS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
SILICON COMPOUNDS
SILICON NITRIDES
TEMPERATURE DEPENDENCE