FWSWE congratulates Samantha (Sammy) Zellner on her recent award at #WE18. Zellner competed in the Graduate Collegiate Poster Competition and won First Place Overall! Zellner is a graduate student at the University of North Texas earning her Masters in Material Science and Engineering. She has served as UNT SWE’s Outreach Chair, Social Chair, and President. Additionally, Zellner was selected as a ’16-17 SWEFL at the Society level. She has been an active participant in FWSWE throughout her undergraduate career, and we are excited to celebrate her for her hard work! Congratulations Samantha!
Samantha’s Abstract: Design of a Corrosion Measurement System of SiC at High Temperatures
Silicon carbide has potential for use in high temperature semiconductor devices due to its
thermochemical stability and wide band gap. However, active oxidation of SiC at processing
temperatures ranging from 650 to 1000°C can prevent it from being used in these applications.
Silicon carbide oxidation at temperatures above 1100°C is well understood, but few have studied
at temperatures below this. As the need for wide band gap semiconductors increases, measuring
the corrosion of SiC becomes more important.
Silicon carbide coupons are created for semiconductor applications through chemical vapor
deposition (CVD). In this process, the orientation of silicon carbide can differ between samples,
where some samples grow in a textured, or preferred orientation, and other consists of mixed
orientations. The corrosion behavior of SiC based on the structural orientation is also not well
studied. In this project, my team and I constructed a vertical tube furnace and conducted a high
temperature corrosion analysis of a SiC coating on a graphite substrate at 750°C. In our analysis,
we measured the resulting properties and differences in corrosion behavior between textured
orientation sand mixed orientation specimens.
The first component of this project was to create a vertical tube furnace and an applied,
simulated corrosive environment. Our tube furnace was made from a mullite wrapped in Kanthal
A1 Furnace wire, encased in cement. The furnace was placed in a steel frame with a quartz tube
in the center. A scale was mounted on top, and the gas flow system was installed last. A
simulated corrosive environment was applied to the furnace, which consisted of temperatures up
to 750°C and argon gas with an oxygen partial pressure of 10^-5 atm. These conditions created
an oxidizing environment that would influence the corrosive behavior on the sample.
The second part of the project was a four-step corrosion experimentation process. First, we hung
the sample in the quartz tube and then flowed the gas through the quartz tube to purge the
system. Next, we then heated the furnace up to 750°C and held it for 40 hours. After 40 hours,
we turned the furnace off, cooled it until it was safe to handle, and then removed the samples for
further characterization. We then repeated the process for each test coupon.
For this project, we considered corrosion as any sign of mass loss or gain. To further analyze the
property changes in each sample, we performed scanning electron microscopy (SEM), x-ray
diffraction (XRD), and atomic force microscopy (AFM). Analysis of the results showed that
corrosion successfully occurred at the 750°C mark resulting in nearly ten grams of mass loss for
each sample. Through SEM, the surface on a larger scale (100 micron) showed no differences
before and after corrosion. However, AFM showed that the surface roughness increased on both
samples after they underwent the corrosion process. XRD showed little to no change in
composition of the sample. Overall, there was no discernable difference in corrosion or corrosion
rates and behavior between the (111) orientation and the mixed orientation.