Mechanical properties of hot isostatically pressed Si[sub 3]N[sub 4] and Si[sub 3]N[sub 4]/SiC composites

Journal Article · Mon Mar 01 04:00:00 EST 1993 · Journal of Materials Research; (United States)

DOI:https://doi.org/10.1557/JMR.1993.0626· OSTI ID:6710718

Unal, O ^[1]; Petrovic, J J ^[2]; Mitchell, T E ^[1]

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1. Center for Materials Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2. Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

The mechanical properties of hot isostatically pressed monolithic Si[sub 3]N[sub 4] and Si[sub 3]N[sub 4]--20 vol. % SiC composites have been studied by microindentation at temperatures up to 1400 [degree]C. Indentation crack patterns and microstructures have been examined by optical microscopy, scanning electron microscopy, and transmission electron microscopy. It is shown that dense Si[sub 3]N[sub 4] base materials can be synthesized by HIPing without densification aids. Both the monolithic Si[sub 3]N[sub 4] and the Si[sub 3]N[sub 4]/SiC composites exhibit high hardness values which gradually decrease with increasing temperature. Both types of material show low fracture toughness values apparently because of strong interfacial bonding. On the other hand, the fracture toughness of the composite is about 40% higher than that of the monolithic material, due to the presence of the 20 vol. % SiC whiskers. A crack deflection/debonding mechanism is likely to be responsible for the higher toughness observed in the composite. High resolution electron microscopy shows that the grain boundaries in both samples contain a thin SiO[sub 2] layer.

• OSTI ID: 6710718
• Journal Information: Journal of Materials Research; (United States), Journal Name: Journal of Materials Research; (United States) Vol. 8:3; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
CRYSTALS
FABRICATION
FRACTURE PROPERTIES
GRAIN BOUNDARIES
HOT PRESSING
MATERIALS
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
MONOCRYSTALS
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
PRESSING
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SILICON OXIDES
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
WHISKERS