Publication Date:
2012-07-10
Description:
This work studies reactive mechanisms involved in liquid Al infiltration of green preforms containing tailored amounts of Al 2 O 3 and CuO . Infiltration reactions involving Al and copper oxides are expected to produce Al 2 O 3 , 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 P O 2 , copper oxides are reduced to Cu , blocking the opportunity for reactive infiltration. Also, the Al - Cu / Al 2 O 3 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 Al 2 O 3 . At 1100°C, CuO reduces to Cu 2 O and infiltration is triggered, although the process is incomplete due to formation of a compact Al 2 O 3 layer which inhibits metal supply to the reaction front. At or behind the halted infiltration front consumption of starting Al 2 O 3 particles and formation of CuAlO 2 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 Al 2 O 3 / CuO greens is possible at 1100°C, in air, due to destabilization of the Al 2 O 3 enveloping film and reactive infiltration, promoted by the redox reaction between Al and copper oxide.
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
