Fig. 1. Rocket nozzle via IR process (U.S. Patent No. 6,598,656, Sandhage, et al.)
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Transcript of Fig. 1. Rocket nozzle via IR process (U.S. Patent No. 6,598,656, Sandhage, et al.)
“Incongruent Reduction (IR)” refers to a fluid/ solid reaction that results in the reduction of a solid compound via the formation of an inter-mediate solid product. IR reactions have been used by the PI’s to produce very high-melting, erosion-resistant, lightweight rocket nozzles (Fig. 1). Such novel processing is an attractive and cost-effective means of manufacturing advanced ceramic composites with complex 3-D shapes for aerospace, automotive, energy production, and defense industries.
This project is aimed at obtaining a basic understanding of the mechanism of IR in a model system: IR of Al2O3 by an Al-Mg melt,
which occurs via formation of spinel, MgAl2O4.
The spinel initially forms as oriented particles on an Al2O3 surface (Fig. 2). Further MgAl2O4
formation over time leads to a stack of continuous spinel layers on Al2O3 (Fig. 3). The
rate of layer thickening obeys a parabolic law (Fig. 4), which is consistent with solid-state diffusion as the rate-limiting step.
Mechanisms of Incongruent Reduction (DMR-0341010) K. H. Sandhage, R. L. Snyder, Georgia Institute of Technology
Fig. 1. Rocket nozzle via IR process (U.S. Patent No. 6,598,656, Sandhage, et al.)
Fig. 2. MgAl2O4 particles on an Al2O3 surface after immersion in Al-Mg(liq) for 0.5 h at 1100oC.
Fig. 3. MgAl2O4 layers on Al2O3 after immersion in Al-Mg(liq) for 168 h at 1000oC.
Fig. 4. MgAl2O4 thickness vs. reaction time at 1100oC.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0 5 10 15 20 25
Time (104 sec)
(Lay
er T
hick
ness
)2 (X
10-1
1 m
2 )
1100oC
Cross-sectionof MgAl2O4
layers
Al2O3
This research has been (Ohio State University, OSU) and is being (Georgia Institute of Technology, GIT) integrated with education via activities such as:
Integration into classroom lectures:
“Principles of Materials Science and Engineering” (MSE 605, Snyder/OSU)
“Materials Characterization” (MSE 715, Snyder/OSU)
”High-Temperature Corrosion” (MSE 736, Sandhage/OSU)
“Introduction to Engineering” (MSE 1001, Sandhage/GIT)
“Chemical and Environmental Properties of Materials” (MSE 8003J, Sandhage/GIT)
Integration into undergraduate research projects/senior theses on incongruent reduction-based processing (6 undergraduates have been involved to date):
“Ceramic body armor” (Mr. Jason Zielsdorf, supervised by Sandhage/OSU)
“Bulk metallic glass composites” (Mr. Geoff Lofstrom, Mr. Alex Tsai, supervised by Sandhage/OSU)
“Rocket nozzle composites” (Ms. Erin Beatty, Ms. Wendy Fu, Mr. James Sinclair, supervised by Sandhage/GIT)
Mechanisms of Incongruent Reduction (DMR-0341010) K. H. Sandhage, R. L. Snyder, Georgia Institute of Technology