Flash-sintering of Co2MnO4 spinel for solid oxide fuel cell applications

We show that cobalt manganese oxide (Co2MnO4) spinel can be sintered (without the application of external pressure) in a few seconds at about ∼325 °C by applying a DC electrical field of 12.5 V cm−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 Co2MnO4 point towards the generality of the process, since 3YSZ is an ionic conductor while the spinel is a predominantly electronic conductor. The Co2MnO4 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.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Cobalt manganese oxide, a coating applied to protect stainless steel interconnects in solid-oxide-fuel-cells (SOFCs) is shown to sinter by the application of weak electrical field of about 10 V per cm, at ∼350 °C, far lower than the nominal sintering temperature of 1100 °C. ▶ In addition to the low temperature sintering occurs in just a few seconds, by a process known as flash sintering. ▶ Incorporation of flash sintering can greatly reduce the time, and energy cost of SOFC manufacturing. The short time and low temperatures avoid the formation of undesirable phases during the manufacturing process.