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- Title
Microstructural Evolution of a Nickel Ferrite-Copper Alloy Cermet During Sintering and High-Temperature Oxidation.
- Authors
Tao, Yuqiang; Li, Zhiyou; Zhang, Dou; Xiong, Huiwen; Zhou, Kechao; Joy, P.
- Abstract
The microstructural evolution during sintering and high-temperature oxidation of a cermet comprised of (wt%) a 40/60 ratio of an alloy of composition 80% Cu/20% Ni and a ceramic of composition 90% NiFe2 O4/10% NiO has been studied as a function of processing temperature. The porosity of the cermet reduced significantly without undue coarsening of the microstructure during sintering up to the melting temperature of the alloy phase ( Tm ≈ 1160°C), whereas at sintering temperatures higher than Tm, the ferrite rapidly coarsened with little additional reduction in porosity, and the alloy phase formed a continuous interconnected network while partially extruding from the composite. Upon oxidation in air at temperatures between 850°C and 1000°C, the cermet developed a multilayered oxidized scale, comprising a thin copper-rich outer oxide layer formed via external oxidation and a thicker zone of internal oxidation. The external oxide scale transformed from CuO to Cu2 O with increasing oxidation temperature. Out-diffusion of the copper to the externally oxidized layer led to significant porosity at the internal interface between oxide and unoxidized cermet.
- Subjects
NICKEL ferrite; SINTERING; COPPER alloys; CERAMIC metals; OXIDES
- Publication
Journal of the American Ceramic Society, 2012, Vol 95, Issue 10, p3031
- ISSN
0002-7820
- Publication type
Article
- DOI
10.1111/j.1551-2916.2012.05305.x