DCP Processing

1
Mechanisms of Incongruent Reduction (DMR-0341010)
K.
H. Sandhage, R. L. Snyder, Georgia Institute of
Technology
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 PIs 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.
2
Mechanisms of Incongruent Reduction (DMR-0341010)
K.
H. Sandhage, R. L. Snyder, Georgia Institute of
Technology

• 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
• l Principles of Materials Science and
  Engineering (MSE 605, Snyder/OSU)
• l Materials Characterization (MSE 715,
  Snyder/OSU)
• l High-Temperature Corrosion (MSE 736,
  Sandhage/OSU)
• l Introduction to Engineering (MSE 1001,
  Sandhage/GIT)
• l 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)
• l Ceramic body armor (Mr. Jason Zielsdorf,
  supervised by Sandhage/OSU)
• l Bulk metallic glass composites (Mr. Geoff
  Lofstrom, Mr. Alex Tsai, supervised by
  Sandhage/OSU)
• l Rocket nozzle composites (Ms. Erin Beatty,
  Ms. Wendy Fu, Mr. James Sinclair, supervised by
  Sandhage/GIT)