Adarsh Kongani
(Advisor: Prof. Rosario Gerhardt)

will defend a master’s thesis entitled,

Characterization of LCM 3D-Printed and Spark Plasma Sintered Alumina Using Dielectric Spectroscopy
On
Thursday, August 20 at 12 p.m.
Love Room 210
Abstract
LCM (Lithographic-based Ceramic Manufacturing) is a 3D ceramic manufacturing technique developed by LITHOZ. A plethora of ceramic materials including alumina, zirconia, silicon nitride, and custom ceramic materials can be printed. Because of this LCM is used in many applications in addition to ceramic dielectrics. To understand how this processing technique affects the electronic properties of these printed dielectric ceramics, different print parameters – sintering temperature, layer height, and print orientation -- were changed. Alumina samples were printed by LITHOZ using their LCM printer. The alumina samples were sintered at either 1475°C or 1650°C with layer heights of 25 μm or 50 μm, and either the XY-orientation or the Z-orientation. The samples were characterized using SEM and optical imaging to look for voids and uniformity.  Impedance Spectroscopy was used to characterize the dielectric constant and dissipation factor. The permittivity gives an idea of the porosity due to the divergence from the dielectric constant of alumina which is expected to be 9.8. The higher sintering temperature and larger layer heights gave a higher dielectric constant (K) and higher densification. For the 50 μm layer sample with XY orientation, the 1475°C sample gave a K of 5.703 while the 1650°C sample gave a K of 8.6. The Z-orientation gave a lower K in all cases. In addition, the 1475 °C samples were heavily influenced by humidity. LCM was also compared to spark plasma sintering (SPS) to see how processing techniques affected electronic properties of alumina. SPS samples were made at 4 different sintering temperatures: 1400˚C, 1475˚C, 1500˚C, and 1650˚C using 0.3µm -alumina powder. The SPS samples had a much higher K compared to the LCM samples with values of 9.74 and 9.59 for 1475˚C and 1650˚C SPS samples respectively. However, there was carbon contamination in the samples during fabrication. The SPS samples were also denser compared to the LCM samples. Impedance and dielectric spectroscopy is a useful tool to monitor density and compositional variation.
Committee
• Prof. Rosario Gerhardt – School of Materials Science and Engineering (advisor)
• Prof. Aaron Stebner– School of Materials Science and Engineering
• Prof. Blair Brettmann – School of Materials Science and Engineering