Particulate and whisker toughened alumina composites

Conference · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5985423

Tiegs, T N; Becher, P F

Two approaches have recently been examined for achieving an increase in K/sub Ic/ in a ceramic matrix composite system with Al/sub 2/O/sub 3/ as the matrix in both cases. In one approach, studies were conducted to determine if submicron metal particles distributed in the alumina matrix could effectively increase K/sub Ic/. Fracture surface and microstructural analyses of these composites indicated that the observed increases in K/sub Ic/ were due to a relatively large grain duplex microstructure developed in the Al/sub 2/O/sub 3/ during densification. This same duplex microstructure resulted in reduced fracture strength. For the other approach, the concept of utilizing SiC whiskers in a ceramic matrix has been studied and the results in the Al/sub 2/O/sub 3/-SiC whisker system have been particularly encouraging. For the initial experimental work, the composites were hot pressed to essentially theoretical density. In later work, some success has been achieved in pressureless sintering these composites. The SiC whisker reinforced alumina composites were shown to have improved fracture toughness and strength compared to conventional monolithic alumina. For example, at a 20 vol % whisker cencentration, fracture toughness (K/sub Ic/) and flexural strength were 8.3 MPa.m/sup 1/2/ and 650 MPa at room temperature, respectively. Equally important, is that these properties remain relatively constant up to temperatures of 1000/sup 0/C.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5985423
• Report Number(s): CONF-8410103-7; ON: DE85005239
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360303* -- Composite Materials-- Mechanical Properties-- (-1987)
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
CHROMIUM
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
CRYSTALS
DISPERSION HARDENING
ELEMENTS
FLEXURAL STRENGTH
FRACTURE PROPERTIES
GRAIN SIZE
HARDENING
MATERIALS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
MONOCRYSTALS
NICKEL
OXIDES
OXYGEN COMPOUNDS
REINFORCED MATERIALS
SILICON CARBIDES
SILICON COMPOUNDS
SIZE
SURFACES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
WHISKERS