Premium
Effect of Aqueous Processing Conditions on the Microstructure and Transformation Behavior in Al 2 O 3 ─ZrO 2 (CeO 2 ) Composites
Author(s) -
Bleier Alan,
Becher Paul F.,
Alexander Kathleen B.,
Westmoreland C. Gary
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb05484.x
Subject(s) - materials science , microstructure , grain size , sintering , composite material , tetragonal crystal system , monoclinic crystal system , toughness , grain growth , fracture toughness , cubic zirconia , diffusionless transformation , martensite , ceramic , mineralogy , crystallography , crystal structure , chemistry
Aqueous processing of Al 2 O 3 ─ZrO 2 (123 mol% CeO 2 ) composites, combined with sintering conditions, was used to control the microstructure and its influence on the martensitic transformation temperature of t ‐ZrO 2 and the transformation‐toughening contribution at room temperature. The resultant ZrO 2 grain sizes in the dense composites were related to the transformation‐toughening behavior of t ‐ZrO 2 . The data show that (1) the best processing conditions exist when the electrophoretic mobilities of the two solids are positive, adequately high to ensure colloidal stability, efficient packing,and uniform ZrO 2 distribution but differ greatly in magnitude, (2) the colloidal stability of ZrO 2 controls the overall stability and the rheological and processing behavior of this mixture, (3) the grain size distribution in dense pieces sintered for 1 h at 1500°C is comparable to the particle size distribution of the powders, (4) the martensite start temperature for the tetragonal to‐monoclinic transformation in Al 2 O 3 containing 20 and 40 vol% ZrO 2 increases and can approach 0°C with increasing average ZrO 2 grain size, and as a result, (5) the fracture toughness values at room temperature are raised from 4–5 MPa.m 1/2 to 9–12 MPa.m 1/2 for these two compositions.