Densification behavior and properties of Y{sub 2}O{sub 3}-containing {alpha}-SiAlON-based composites

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1996.tb08762.x· OSTI ID:271668

Bandyopadhyay, S; Hoffmann, M J; Petzow, G ^[1]

---

1. Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

Different SiAlON composites based on {alpha}{prime}-SiAlON are investigated, with respect to the phase relationships, densification behavior, and mechanical properties. The compositions are located on a phase-diagram line parallel to the Si{sub 3}N{sub 4}-Y{sub 2}O{sub 3}{center_dot}9AlN compound in the Si{sub 3}N{sub 4}-SiO{sub 2}-AlN-Al{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-YN system. Analysis of the reaction sequences shows that the formation of the composites is associated with the transient appearance of Y{sub 4}Al{sub 2}O{sub 9} (YAM), yttrium-aluminum-garnet (YAG), melilite, and a nitrogen-rich liquid phase. The small shift of compositions on the Si{sub 3}N{sub 4}-Y{sub 2}O{sub 3}{center_dot}9AlN compound phase-diagram line toward the Al{sub 2}O{sub 3}-rich side offers the advantage of a higher sinterability and the removal of the melilite phase from a wide range of compositions containing {alpha}{prime}-SiAlON and polytypes. The {alpha}{prime}/{beta}{prime}-SiAlON composites show better mechanical properties in comparison to pure {alpha}{prime}-SiAlON and composites of {alpha}{prime}-SiAlON and polytypes. A post-heat-treatment causes the crystallization of YAG as a grain-boundary phase and leads to excellent strength retention up to temperatures of 1,350 C.

• Sponsoring Organization: USDOE
• OSTI ID: 271668
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 6 Vol. 79; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
CHEMICAL COMPOSITION
COMPOSITE MATERIALS
CRYSTALLIZATION
FERRITE GARNETS
GRAIN BOUNDARIES
HEAT TREATMENTS
HOT PRESSING
LIQUIDS
MECHANICAL PROPERTIES
PHASE DIAGRAMS
SILICON NITRIDES
SILICON OXIDES
SINTERING
SOLID SOLUTIONS
YTTRIUM NITRIDES
YTTRIUM OXIDES