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Mechanism of Alumina‐Enhanced Sintering of Fine Zirconia Powder: Influence of Alumina Concentration on the Initial Stage Sintering
Author(s) -
Matsui Koji,
Yamakawa Takanori,
Uehara Masato,
Enomoto Naoya,
Hojo Junichi
Publication year - 2008
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.1551-2916.2008.02350.x
Subject(s) - sintering , materials science , grain boundary diffusion coefficient , activation energy , isothermal process , shrinkage , diffusion , atmospheric temperature range , grain boundary , chemical engineering , analytical chemistry (journal) , mineralogy , metallurgy , composite material , thermodynamics , microstructure , chemistry , chromatography , physics , engineering
The isothermal shrinkage behavior of 2.9 mol% Y 2 O 3 ‐doped ZrO 2 powders with 0–1 mass% Al 2 O 3 was investigated to clarify the effect of Al 2 O 3 concentration on the initial sintering stage. The shrinkage of the powder compact was measured at constant temperatures in the range of 950°–1050°C. The Al 2 O 3 addition increased the densification rate with increasing temperature. The values of apparent activation energy ( nQ ) and apparent frequency‐factor term (β 0 n ), where n is the order depending on the diffusion mechanism, were estimated at the initial sintering stage by applying a sintering‐rate equation to the isothermal shrinkage data. The diffusion mechanism changed from grain‐boundary diffusion (GBD) to volume diffusion (VD) by Al 2 O 3 addition and both nQ and β 0 n increased with increasing Al 2 O 3 concentration. The kinetic analysis of the sintering mechanism suggested that the increase of densification rate by Al 2 O 3 addition largely depends on the increase of β 0 n , that is, the increases of n with GBD→VD change and β 0 with an increase in Al 2 O 3 content, although the nQ also increases with Al 2 O 3 addition. This enhanced sintering mechanism is reasonably interpreted by the segregated dissolution of Al 2 O 3 at ZrO 2 grain boundaries.