Improved Ceramic Manufacturability With Electric Field Assisted Sintering: Developing Underlying Principles
Abstract
This is approved for public release Project Title: Improved ceramic manufacturability with electric field assisted sintering: Developing underlying principles High density ceramics maximize strength, translucency, thermal conductivity and provide gas tight environments, features key to applications ranging from armor, IR missile domes, integrated circuit substrates and solid oxide fuel cell electrolytes, respectively. To achieve desired high densities, sintering must be performed at temperatures often in excess of 1500¡C for extended periods of time, leading to high costs, need for specialized facilities and incompatibility with less refractory materials. Electric field assisted sintering has recently demonstrated great potential in reducing temperature constraints imposed on ceramic materials during sintering. Application of electrical fields during sintering can reduce densification temperatures from above 1300¡C to 800¡C, to times as short as seconds, the latter via Flash Sintering (FS). While there have been many phenomenological observations and demonstrations of Field Assisted Sintering (FAST), reliable micro and nanoscale descriptions remain lacking. Here, our goal is to quantitatively reveal the dominant mechanisms governing field assisted sintering as a function of material electrical properties, microstructure evolution and environmental conditions. We propose to address this challenge by investigating model titania based ceramics in which we plan to 1) systematically vary the ionic and electronic defects and thereby the underlying factors controlling both densification and electrical properties, 2) monitor the development of conductive pathways and thereby microstructure by in-situ frequency dependent complex impedance spectra during densification both with and without applied fields and 3) support the analysis of experiments by performing atomistic modeling to understand and predict how defect formation and transport are modified under applied external fields and in the vicinity of space charge fields accompanying grain boundaries. Progress along these lines should provide considerable insights into the factors contributing to and controlling FAST processes, thereby allowing for more detailed analysis of results and projections for other conditions and materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1710223
Entities
People
- Harry L Tuller
Organizations
- Army Contracting Command
- Massachusetts Institute of Technology
- United States Army