Photoacoustic microscopy allows for ultrahigh resolution measurement of mechanical properties and is

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FRG Functionally Graded High-Al Mullite
Environmental Barrier Coatings PI Soumendra
Basu, Boston University, DMR-0233952
The thermodynamics and kinetics of the growth of
mullite coatings by chemical vapor deposition
have been studied. The effect of changing gas
phase composition on coating microstructure and
growth rate has been characterized. The effect of
the reactants and growth conditions on powder
formation has also been studied. This study
allows us to operate the CVD reactor under
optimal growth conditions for the best quality
coatings.
Photoacoustic microscopy allows for ultra-high
resolution measurement of mechanical properties
and is being used for spatially resolved
measurements in functionally graded materials. An
adaptive, holographic interferometry system has
been designed and fabricated. This system allows
for ultrasound inspection on specimens with high
surface roughness and eliminates the need for
surface preparation prior to inspection. The
system and representative waveforms measured on a
mullite coating are shown on the right. Depth
dependent mechanical property information is
obtained from the high frequency acoustic wave
dispersion characteristics.
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FRG Functionally Graded High-Al Mullite
Environmental Barrier Coatings PI Soumendra
Basu, Boston University, DMR-0233952
Outreach and Education One Post-doc, four
graduate students and one REU supported
undergraduate student have contributed to this
research. The group has presented several papers
on functionally graded CVD mullite coatings at
national and international conferences. The
PIs organized the second annual Science
Saturday event at Boston University in which
local high school students visited our labs.
Several hands on demonstrations were developed,
and the students explored several aspects of
Nondestructive Testing including ultrasonic
imaging using a medical ultrasound imaging
system, crack detection using a piezoelectric
transducer, and a study of the mechanical
properties of ceramics. The pictures on the right
show some of the high school students who
attended Science Saturday.