Sintering and Related Powder Processing Science and Technologies: Poster Session
Sponsored by: ACerS Basic Science Division, TMS Powder Materials Committee
Program Organizers: Wolfgang Rheinheimer, University of Stuttgart; Ricardo Castro, University of California, Davis; Zachary Cordero, Rice University; Eugene Olevsky, San Diego State University
Tuesday 4:45 PM
November 3, 2020
Room: Poster Hall
Location: MS&T Virtual
On the Bending of High-aspect Ratio Freestanding Aerosol Jet Printed Micropillar Arrays during Thermal Sintering: Sandra Ritchie1; Sasa Kovacevic2; Prithviraj Deshmukh1; Mohammad Saleh1; Sinisa Mesarovic2; Rahul Panat1; 1Carnegie Mellon University; 2Washington State University
High-aspect ratio free-standing micropillars have several technologically important applications such as neural probes, biosensors, and microelectronics. Freestanding micropillars with aspect ratios of 20:1 have been previously fabricated by our group. Increasing pillar length and aspect ratios to 60:1 has thus far been limited by the warping, which occurs during the post-printing thermal sintering of the nanoparticles. As such, it has become necessary to increase our understanding of the fundamental mechanisms of nanoparticle sintering and to develop effective control parameters to prevent or minimize warping. The use of optical and thermal in-situ imaging has allowed for the discovery and study of coordinated motion found in arrays of pillars. This motion results from temperature gradients present during sintering, which can cause differential sintering rates, hence the distortion. Based on these findings, successful engineering solutions have been developed which allows repeatable fabrication of long, straight pillars with aspect ratios as high as 60:1.
The Effect of Texturing by Applied Magnetic Field on Grain Growth of Alumina: Bryan Conry1; Michael Kesler2; Amanda Krause1; 1University of Florida; 2Oak Ridge National Laboratory
Grain growth is a critical mechanism to metals and ceramics processing, as grain size is critical to bulk properties. Abnormal grain growth (AGG) is a process by which a small fraction of grains grow faster than their neighbors, resulting in a bimodal grain size distribution and heterogeneous bulk properties. The cause and underlying mechanisms behind AGG are poorly understood, although it has been theorized that anisotropy of grain boundary energy is directly related to AGG. We employ magnetically induced texturing of Ca-doped alumina, a widely used ceramic in industry that is known to exhibit significant grain boundary energy anisotropy, to investigate this theory. We will compare the extent of AGG in samples with varying degrees of texturing cast in the magnetic field. By comparing samples cast in different fields, we can quantitatively determine the relationship between degree of texture, grain growth behavior, and distribution of grain boundary character anisotropy.