Current-ramp assisted sintering of 3YSZ: Electrochemical and microstructural comparison to flash and thermal sintering. Issue 2 (February 2020)

• Record Type: Journal Article
• Authors: Christian, Kent Harrison; Charalambous, Harry; Jha, Shikhar Krishn; Tsakalakos, Thomas
• Is Part Of: Journal of the European Ceramic Society. Volume 40:Issue 2(2020)
• Page Start: 436
• Page End: 443
• Publication Date: 2020-02
• Subjects: Flash sintering -- Current assisted sintering -- Yttria-stabilized zirconia -- Impedance spectroscopy -- Space charge layer; 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.2019.09.036
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Flash sintering features an unoptimized and uncontrolled rise in current density and sample conductivity. By using a controlled current-ramp technique with a predetermined ramp function, microstructure and electrochemical properties can be improved. This current-ramp method is investigated through use of test functions that follow square-root, linear, and parabolic time dependence with comparison to conventional flash sintering and thermal sintering. Steeper ramp functions during the sintering result in higher activation energy, suggesting a change in the vacancy concentration for both the bulk and grain boundary regions. Estimation of the grain boundary domain width suggests a grain size dependence of the unique space charge contribution to conduction independent of sintering method. Contrary to conventional wisdom, flash sintering can actually result in enhanced grain growth compared to controlled current-ramps and conventional sintering, implying that uncontrolled rise in current to a set cutoff may not be the optimal method for densification.