A thermal perspective of flash sintering: The effect of AC current ramp rate on microstructure evolution. Issue 4 (April 2021)

• Record Type: Journal Article
• Authors: Grimley, Carolyn A.; Funni, Stephen; Green, Christopher; Dickey, Elizabeth C.
• Is Part Of: Journal of the European Ceramic Society. Volume 41:Issue 4(2021)
• Page Start: 2807
• Page End: 2817
• Publication Date: 2021-04
• Subjects: Flash sintering -- Microstructure -- Grain growth -- Zirconia; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2020.11.040
• Languages: English
• ISSNs: 0955-2219

Abstract

Highlights: Novel controls system bridges gap between conventional and flash sintering. FEA and in-situ flash sintering IR measurements correlated with microstructure. Densification and grain growth trends follow classic dependency on thermal profile. Bulk conductivity depends on flash sintering thermal profile, including quench. Flash sintered samples consistently exhibit higher grain boundary conductivity. Abstract: In flash sintering experiments, the thermal history of the sample is key to understanding the mechanisms underlying densification rate and final properties. By combining robust temperature measurements with current-ramp-rate control, this study examined the effects of the thermal profile on the flash sintering of yttria-stabilized zirconia, with experiments ranging from a few seconds to several hours. The final density was maximized at slower heating rates, although processes slower than a certain threshold led to grain growth. The amount of grain growth observed was comparable to a similar conventional thermal process. The bulk electrical conductivity correlated with the maximum temperature and cooling rate. The only property that exhibited behavior that could not be attributed to solely the thermal profile was the grain boundary conductivity, which was consistently higher than conventional in flash sintered samples. These results suggest that, during flash sintering, athermal electric field effects are relegated to the grain boundary.