Flash-sintering of Co_2MnO_4 spinel for solid oxide fuel cell applications

摘要

We show that cobalt manganese oxide (Co_2MnO_4) spinel can be sintered (without the application of external pressure) in a few seconds at about ~325 ℃ by applying a DC electrical field of 12.5 Vcm~(-1), by a process known as flash-sintering. A transition from normal to flash-sintering occurs when the field is ≥7.5 V cm~(-1). The flash sintering phenomenon has also been observed in yttria-stabilized zirconia (3YSZ). Together, the results for 3YSZ and Co_2MnO_4 point towards the generality of the process, since 3YSZ is an ionic conductor while the spinel is a predominantly electronic conductor. The Co_2MnO_4 spinels are used to protect metals, such as stainless steels, in solid oxide fuel cells. The low temperatures employed in flash sintering can obviate interfacial interdiffusion with the metal substrate; in nominal sintering these interfacial reactions can produce deleterious interfacial phases.