Contactless Flash Sintering to Address Emerging Needs in the Fabrication of Technical Ceramics.
Abstract
Sintering the densification of a powder compact is the most energy consumptive step in the fabrication of ceramics. Yet it is al,so one of the most important because it determines a materials microstructure, which controls its final properties. The conventiona,l approach to sintering uses high temperatures and long times, limiting productivity and efficiency. These long cycles produce fully,final properties of ceramics requires a new approach which reduces both the temperature and time required by the process.Applying an,time required from hours down to minutes. This process is called flash sintering, named after the abrupt increase in sample conduc,tivity and current observed at a critical combination of process parameters. The current rapidly heats the sample, which accelerates, the densification rate. Usually, the kinetics of external heat transfer limit similar rapid rate sintering approaches to small comp,onents; however, the internal nature of the heat dissipation which drives the flash event makes flash sintering uniquely and funda,mentally friendlier to commercial scale-up.Contactless flash sintering is an innovative implementation of flash sintering which appl,ies field and current to a ceramic via a mobile plasma electrode. This form of current transfer eliminates the complications associa,ted with the electrical, mechanical, and thermal interface of a physical electrode. Lucideon developed contactless flash sintering f,or ceramic electrolyte coatings, but we hypothesize that the approach is appropriate for thicker and more functionally diverse mater,ials.We have identified three objectives which would test this hypothesis: 1. Identify concrete dimensional limitations of contactle,ss flash sintering as a function of kinetic parameters and depth prof, Link changes in underlying material properties to the identified dimension limitations.3. Troubleshoot contactless flash sintering,when scaled to geometric complexity; identify engineering difficulties or fundamental limitations.We propose three types of investig,ations to fulfill the above objectives: single-track, optimization, and complex features. Single-track experiments provide the therm,al and microstructural profile generated locally for a given set of flash sintering conditions. A Lucideon partner will model the he,at flow of this profile using finite element analysis, validated by these results. The way these profiles vary with the sample dimen,sions and material properties informs the kinetics of heat dissipation and sintering which underpin the fundamental question of larg,e-scale feasibility.Optimization experiments establish conditions for contactlessly flash sintering previously untested materials an,d thicknesses over larger lateral areas and to the highest quality possible. These results provide proof-of-concept for sample size,scale-up and produce samples appropriate for property characterization. Complex feature experiments then investigate the effect of s,urface features on heat flow, elucidating and troubleshooting complications present in real-world products.Successful completion of,the proposed work would position flash sintering for scale-up with an engineering partner for the most promising applications identi,fied during the program. The data generated would provide a framework which de-risks the flash sintering of new materials, smoothing, the way for discussions with a broad range of potential early adopters. The successful commercialization of flash sintering would b,enefit many end-users, including the Navy and its suppliers, who seek more sustainable and higher performing ceramics.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 16, 2022
- Source ID
- N000142212132
Entities
People
- Carolyn Grimley
Organizations
- Office of Naval Research
- United States Navy