Effect of additive content on liquid-phase sintering on silicon carbide ceramics
Submicron silicon carbide (SiC) was sintered to about 98% of its theoretical density by using alumina and yttria as sintering additives. This densification was attributed to the liquid-phase sintering of a eutectic liquid formed between Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3} at sintering temperatures. Observation by scanning electron microscopy (SEM) revealed that SiC exhibited a uniformly distributed fine-grained microstructure and a highly intergranular fracture behavior. The maximum values of strength and toughness were as high as 650 MPa and 7.5 MPa{sm{underscore}bullet}m{sup 1/2}, respectively. The improved toughness is considered to be associated mainly with the deflection of cracks along interphase boundaries, due to a weak interface, as well as with the introduction of microcracks at the interface between SiC grains and the secondary phases, due to a residual tensile stress from thermal expansion mismatch.
- Research Organization:
- Osaka National Research Inst. (JP)
- OSTI ID:
- 20013375
- Journal Information:
- Materials Research Bulletin, Vol. 34, Issue 10-11; Other Information: PBD: Jul-Aug 1999; ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
Similar Records
Particulate and whisker toughened alumina composites
Microstructural design of silicon nitride with improved fracture toughness. 2: Effects of yttria and alumina additives