High-temperature characterization of reaction-sintered mullite-zirconia composites

Journal Article · Tue Oct 01 04:00:00 EDT 1991 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1991.tb06788.x· OSTI ID:5930914

Descamps, P; Sakaquchi, S; Poorteman, M; Cambier, F ^[1]

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1. Research Center of the Belgian Ceramic Industry, B-7000 Mons (BE)

In this paper mullite-zirconia composites are prepared by reaction sintering of zircon and alumina, either using reaction and sintering additives (titania (T-MZ) or magnesia (M-MZ)) or starting from highly reactive powder mixtures obtained by an ultra-rapid-quenching technique (URQ-MZ). In the latter case, the presence of large amounts of an amorphous phase in the quenched powders enables sintering without the use of additives. The various composites differ mainly by their microstructure-i.e., the mullite grains aspect ratio and grain size-and by the quantity and nature of impurities or additives. Within this work, the modulus of rupture and critical stress intensity factor of each material are measured from room temperature to 1200{degrees} C. Bending creep is also investigated for various temperature and stress ranges. For the three materials, the fracture toughness (K{sub IC}) decreases with temperature, according to tetragonal zirconia stabilization, up to 600{degrees} to 700{degrees} C, above which a significant increase occurs. This toughening effect is attributed to plastic relaxation ahead of the crack tip associated with a glassy phase at the grain boundaries. The reinforcement is more efficient for T-MZ because of the higher viscosity of the glassy phase. For the same material, strength does not follow the K{sub IC} curve because of subcritical crack growth. Creep data are explained on the basis of two distinct mechanisms, depending on stress and temperature range. At high stresses and/or low temperatures, creep is associated with micro-crack formation, whereas, at low stresses and/or high temperatures, data are in agreement with a solution-precipitation mechanism accommodating grain-boundary sliding with interface reaction as the limiting stage.

• OSTI ID: 5930914
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 74:10; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ADDITIVES
AMORPHOUS STATE
CERAMICS
CHALCOGENIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CREEP
CRYSTAL STRUCTURE
DISPERSIONS
FABRICATION
FAILURES
FRACTURES
GRAIN SIZE
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MINERALS
MIXTURES
MULLITE
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POWDERS
QUENCHING
SINTERING
SIZE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES