| Redox Processing of Al20 3/Al Composite Materials |
R. BHAT, D. D. UPADHYAYA, S. RAMANATHAN AND S. K. RoY
Pages : 234-236
DOI : 10.1080/0371750X.1995.10804731 |
| Abstract |
| The co-continuous alumina/aluminium based composites
show immense potential for high performance engineering
applications where alumina offers superior stability to oxidation
at elevated temperatures. In this paper preliminary
results on fabrication of AI20/AI composites by a metathesis
reaction between silicon dioxide preforms and molten
aluminium are reported. The reaction ingredients
employed were pure aluminium (commercial grade-IS)
and optical grade silica glass. The transformation kinetics
were studied in the temperature regimes of 900°-1300°C in
1 00°C steps and the various reaction times between 5.0
mins and 18.0 hrs. The composite growth took place
through the formation of an intermediate phase and
followed a linear rate behaviour. The width of the reaction
interface decreased with the increase/decrease in temperature
of the reaction. Typical growth rate~ of about 1.0 and
5.0 mm.h-1 were obtained at 1000° and 1200°C respectively.
Bulk density of these composites was estimated to be
3.2 gm.cm-3
• Optical microscopy 1·evcalcd a continuous
network of alumina phase interpenetrated by the tortuous
microscopic channels of residual metallic phase. |
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