A novel Multi‐Phase Flash Sintering (MPFS) technique for 3D complex‐shaped ceramics

Sandra Molina-Molina,Eva Gil-González,Francisco José Durán-Olivencia,José Manuel Valverde,Antonio Perejón,Pedro E Sánchez-Jiménez,Luis A Pérez-Maqueda

doi:10.1016/j.apmt.2021.101274

Sandra Molina-Molina, Eva Gil-González + Show 5 more

Open Access

https://doi.org/10.1016/j.apmt.2021.101274

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Abstract

This work demonstrates the first proof-of-concept of Multi-Phase Flash Sintering (MPFS). This novel technique essentially consists of applying a rotating electric field to the sample by means of a multi-phase voltage source as furnace temperature increases. Several ceramic materials with different types of electrical conductivities are sintered within seconds at furnace temperatures much lower than those used for traditional DC flash sintering due to the higher power densities administered by a multi-phase power supply. Thus, ceramic materials are flashed at relatively lower applied voltages which minimizes undesired phenomena such as localization and preferential current pathways. Furthermore, MPFS allows diverse electrode configurations to promote a more uniform electric field distribution, enhancing the sintering of 3D complex-shaped specimens. MPFS could be a true breakthrough in materials processing, as 3D complex-shaped specimens are homogeneously sintered at reduced temperatures, while keeping all the advantages of conventional flash sintering.

Highlights

Since its inception in 2010, Flash Sintering (FS) has become one of the most exciting of the Field-Assisted Sintering Techniques (FAST) [1]
It is shown that 3D complex-shaped specimens are homogeneously sintered within seconds at furnace temperatures much lower than those used in conventional DC-FS
During the incubation period there is a linear increase of electrical conductivity with temperature, which leads to a rise of the dissipated power

Summary

Introduction

Since its inception in 2010, Flash Sintering (FS) has become one of the most exciting of the Field-Assisted Sintering Techniques (FAST) [1]. The electrical conductivity of the ceramic rises with temperature which leads to an amplification of the current intensity traversing the specimen. The sample enters the so-called “flash” stage, revealed by a sudden drop in the electrical resistivity and a surge in the power density dissipated by the sample. At this critical point, the current intensity must be quickly controlled to the preset value, which is maintained for a given period of time. It is accepted that the flash onset temperature is inversely related to the amplitude of the applied electric field [4]. FS has been demonstrated for many ceramic materials, exhibiting different electrical conductivities, and all of them characterized by a negative temperature coefficient of resistivity [5,6]

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