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Reaction Mechanisms in Al2O3/CuO Infiltration by Liquid Al
Article first published online: 9 JUL 2012
© 2012 The American Ceramic Society
Journal of the American Ceramic Society
Volume 95, Issue 10, pages 3064–3070, October 2012
How to Cite
Guedes, M., Ferreira, J. M. F., Ferro, A. C. (2012), Reaction Mechanisms in Al2O3/CuO Infiltration by Liquid Al. Journal of the American Ceramic Society, 95: 3064–3070. doi: 10.1111/j.1551-2916.2012.05334.x
- Issue published online: 2 OCT 2012
- Article first published online: 9 JUL 2012
- Manuscript Accepted: 26 MAY 2012
- Manuscript Received: 20 OCT 2011
- Portuguese Foundation for Science and Technology. Grant Number: SFRH/BD/25711/2005
This work studies reactive mechanisms involved in liquid Al infiltration of green preforms containing tailored amounts of Al2O3 and CuO. Infiltration reactions involving Al and copper oxides are expected to produce Al2O3, as fine particulate reinforcements, and Cu, as Al-matrix strengthener. Preforms with 75 mol%-CuO were infiltrated with Al at 1000°C and 1100°C in air. Under low PO2, copper oxides are reduced to Cu, blocking the opportunity for reactive infiltration. Also, the Al-Cu/Al2O3 contact angle is insufficiently low to drive spontaneous infiltration. At 1000°C, infiltration is incipient, indicating that CuO reaction with Al is not sufficiently vigorous to destabilize enveloping Al2O3. At 1100°C, CuO reduces to Cu2O and infiltration is triggered, although the process is incomplete due to formation of a compact Al2O3 layer which inhibits metal supply to the reaction front. At or behind the halted infiltration front consumption of starting Al2O3 particles and formation of CuAlO2 occur. The space among these phases is occupied by a Cu-rich matrix, rendering an almost totally densified microstructure. This study shows that liquid Al infiltration of Al2O3/CuO greens is possible at 1100°C, in air, due to destabilization of the Al2O3 enveloping film and reactive infiltration, promoted by the redox reaction between Al and copper oxide.