MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
Strontium Doping Effect on High-Temperature Oxidation of Nano-Ni Dispersed Alumina Composites
Hai Vu PhamMakoto Nanko
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2018 Volume 59 Issue 6 Pages 939-943

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Abstract

Two sets of 0.1 mol% Sr-doped 5 vol% Ni/Al2O3 and undoped 5 vol% Ni/Al2O3 samples were fabricated by the pulsed electric current sintering technique to investigate the influence of Sr-doping effects on the high-temperature oxidation. Oxidation tests were conducted in air at temperature ranges of 1200–1400°C for 1–10 d. Oxidation of Ni within the matrix at high temperatures induced formations of the top surface layer and the oxidized zone. The top surface layer was composed of the oxidation product-NiAl2O4, while the oxidized zone consisted of Al2O3 matrix and NiAl2O4. Formation of the oxidized zone of undoped and Sr-doped samples followed the parabolic law. The parabolic rate constant of Sr-doped samples was approximately two times smaller than that of undoped samples. The apparent activation energies on the growth of the oxidized zone were determined to be 479 and 476 kJ/mol for undoped and Sr-doped 5Ni/Al2O3, respectively. Sr-doping reduced oxygen transport along Al2O3 grain boundaries and enhanced the high-temperature oxidation resistance of Ni/Al2O3.

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© 2018 The Japan Institute of Metals and Materials
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