Influence of the forming method on flash sintering of ZnO ceramics

Author(s)

Storion, Ana Gabriela ^[1] ; Ferreira, Julieta Adriana ^[1] ; Maestrelli, Sylma Carvalho ^[2] ; de Jesus Agnolon Pallone, Eliria Maria ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Biosys Engn, 225 Duque Caxias Norte Ave, BR-13635900 Pirassununga, SP - Brazil

^[2] Univ Fed Alfenas, Jose Aurelio Vilela 11999, Cidade Univ, BR 267, BR-37715400 Pocos De Caldas, MG - Brazil

• Document type: Journal article
• Source: CERAMICS INTERNATIONAL; v. 47, n. 1, p. 965-972, JAN 1 2021.
• Web of Science Citations: 4

Abstract

This work aimed to investigate different forming techniques used in the ceramic industry when applied to flash sintering. The way the density gradient interferes with the final densification and microstructural heterogeneity development of ZnO specimens was studied. For this purpose, ZnO cylindrical specimens were formed by uni-axial pressing, isostatic pressing, and slip casting. All experiments were conducted isothermally at 800 degrees C in an adapted tube furnace, with an applied electric field of 60 V/cm and maximum current density of 200 mA/mm2. Samples formed by isostatic pressing showed better control in the development of microstructural homogeneity. The ones formed by slip casting had lower apparent densities and longer incubation times among all the forming methods. Also, slip casting samples showed the largest detachment of average grain size in the central region compared to the other regions. One outstanding result is related to differences between the regions close to the upper and lower electrodes in the samples formed by uniaxial pressing, even when using alternating current mode. These results showed that the density distribution along the green specimen should be considered a decisive factor when evaluating flash sintered samples. The chosen forming technique causes significant differences in incubation time, densification, and the development of microstructural heterogeneity. (AU)

• FAPESP's process: 18/11143-0 - Influence of flash sintering parameters on ZnO densification and microstructure
• Grantee: Ana Gabriela Storion
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 15/07319-8 - Study ultra rapid sintering and low energy consumption: flash Sintering
• Grantee: Eliria Maria de Jesus Agnolon Pallone
• Support Opportunities: Regular Research Grants