Influence of Grain Size on Ionic Conductivity of Pure and Dense alpha-Al2O3 in the Temperature Range 400-1000 degrees C
2004 (English)In: High Temperature Corrosion And Protection Of Materials 6, Prt 1 And 2, Proceedings, 2004, Vol. 461-464, no II, 865-872 p.Conference paper (Refereed)
Ionic transport in alpha-Al2O3 at high temperatures is important for oxidation/corrosion resistance of Al2O3-forming heat resistant alloys. Whereas most of previous studies were performed at temperatures above 1000degreesC, this work concerns the temperature range 400 to 1000degreesC. Electrical proper-ties of polycrystalline and single crystal alpha-Al2O3 were measured in air by using impedance spectroscopy in order to study the ionic transport in Al2O3. The influence of grain size was investigated by measurements on a series of highly pure and dense samples with well-defined grain size ranging from 0.5 to 15 mum, produced by the spark plasma sintering technique. The results show that the grain size has a certain influence on the conductivity in the temperature range between 650 and 1000degreesC, where the activation energy for conductivity decrease from 2.4 to 1.6 eV with increasing grain size. At lower temperatures the activation energy is about 1.0 eV and independent of the grain size, indicating a different conduction mechanism.
Place, publisher, year, edition, pages
2004. Vol. 461-464, no II, 865-872 p.
, Materials Science Forum, ISSN 0255-5476 ; 461-464
Alumina; Electrical conductivity; Grain size; Impedance spectroscopy; Charge transport; Impedance spectroscopy; Ionic transport; Low conductivity; Activation energy; Corrosion resistance; Diffusion; Electric conductivity; Grain size and shape; Ionic conduction; Leakage currents; Oxidation; Single crystals; Sintering; Superalloys; Thermal effects; Transport properties; alumina
IdentifiersURN: urn:nbn:se:kth:diva-6900ISI: 000223339700103ScopusID: 2-s2.0-8744239371ISBN: 0-87849-945-8OAI: oai:DiVA.org:kth-6900DiVA: diva2:11744
6th International Symposium on High Temperature Corrosion and Protection of Materials Les Embiez, FRANCE, MAY 16-21, 2004
QC 201412082007-03-152007-03-152014-12-08Bibliographically approved