Sintering and grain/particle growth of composites in the system alumina-chromia/zirconia-hafnia

Thesis/Dissertation · Wed Jan 01 04:00:00 UTC 1986

OSTI ID:7078284

Li, A K

Sintering and grain/particle growth behaviors of the two phase system (Al/sub 1-x/Cr/sub x/)/sub 2/O/sub 3//(Zr/sub 1-y/Hf/sub y/)O/sub 2/ were studied. The starting powders were prepared by the coprecipitation method. The sinterability of Al/sub 2/O/sub 3//ZrO/sub 2/ composites is enhanced by increasing the amount of dispersed zirconia particles as well as by adding Cr/sub 2/O/sub 3/. The sintering kinetics of alumina/zirconia composites, with or without addition of hafnia, can be interpreted by the mechanism of grain boundary diffusion control. By adding chromia, the sintering mechanism is altered to volume diffusion control when the chromia content is low (2-10 M/O) and a concurrent volume diffusion and evaporation and condensation control when the chromia content is high (20-30 M/O). The grain growth and particle growth in the alumina/zirconia composites, with or without hafnia addition, have shown the same time dependence and obeyed a r approx. = t/sup 1/4/ law. The grain growth is controlled by the particle movement which is under volume diffusion control. The particle coarsening is dominantly controlled by coalescence. The chromia addition varies the grain growth as well as the particle growth kinetics. The grain size distribution skews toward large grain size and follows a log normal distribution. It is demonstrated that the matrix phase dominates the influence on the sintering and microstructure development behavior.

• Research Organization: Michigan Univ., Ann Arbor (USA)
• OSTI ID: 7078284
• 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
360601 -- Other Materials-- Preparation & Manufacture
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
FABRICATION
GRAIN GROWTH
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
MATERIALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
REFRACTORY METAL COMPOUNDS
SINTERING
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES