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Powder chemistry effects on the sintering of MgO‐doped specialty Al 2 O 3
Author(s) -
Frueh Tobias,
Marker Cassie,
Kupp Elizabeth R.,
Compson Charles,
Atria Joe,
Gray Jennifer L.,
Liu ZiKui,
Messing Gary L.
Publication year - 2018
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/jace.15427
Subject(s) - sintering , dissolution , materials science , grain boundary , doping , solubility , chemical engineering , grain growth , mineralogy , grain size , metallurgy , microstructure , chemistry , optoelectronics , engineering
In this work, we investigate the effects of powder chemistry on the sintering of MgO‐doped specialty alumina. The stages at which MgO influences densification of Al 2 O 3 were identified by comparing dilatometry measurements and the sintering kinetics of MgO‐free and MgO‐doped specialty alumina powders. MgO is observed to reduce the grain boundary thickness during densification using TEM . We show that MgO increases the solubility of SiO 2 in alumina grains near the boundaries using EDS . First‐principles DFT calculations demonstrate that the co‐dissolution of MgO and SiO 2 in alumina is thermodynamically favored over the dissolution of MgO or SiO 2 individually in alumina. This study experimentally demonstrates for the first time that removal of SiO 2 from the grain boundaries is a key process by which MgO enhances the sintering of alumina.