DOE OSTI2018
Pacific Northwest National Laboratory (PNNL) has extensive experience in the development, fabrication, and evaluation of surface treatments and protective coatings for metallic solid oxide fuel cell (SOFC) components. For example, modified (Mn,Co)3O4 spinel coatings and coating/metal interfaces have been shown to substantially improve oxidation resistance, electrical performance, and oxide scale adhesion of ferritic stainless steel interconnects in planar SOFC stacks. At the time of the establishment of this CRADA, Protonex Technology Corporation had been working in the field of SOFC development for over 12 years and had demonstrated more than 250 thermal cycles with a less than 15 minutes start time and more than 2000 hours of continuous operation on a 250W tubular solid oxide hot zone module as part of a program for the Office of the Secretary of Defense (OSD). An industrial version of the military system, denoted P200i, had been developed that was launched at the 2015 Fuel Cell Expo in Tokyo. Feedback during beta testing of this unit was very positive. However, Protonex recognized that to transition from military markets, the commercial system would require longer life time and higher power. Leveraging their novel thermal management strategy from the tubular hot zone that allowed for rapid and repeated thermal cycling, Protonex developed a planar 1kW module aimed at the industrial and commercial market. However, more robust interconnect coatings were needed to bring the system into the 1000+ hour life time requested by customers. Therefore, PNNL’s experience and technology were engaged to enable the 1kw system to transition from military applications to commercial and industrial applications. In this CRADA, PNNL teamed with Protonex to leverage PNNL’s expertise in protective coating techniques for solid oxide fuel cell (SOFC) applications. As the first step in the collaboration, protective spinel coatings were fabricated at PNNL onto ten AISI 440 stainless steel bus bars provided by Protonex. A precursor slurry containing spinel powder was applied to the steel surfaces via an ultrasonic spray process. The coated bars were then subjected to a reducing atmosphere heat treatment (i.e., heated to 850°C at 3°C/min in a hydrogen atmosphere and held at that temperature for five hours). Five of the bars were left in this reduced condition; the other five bars were subjected to an oxidizing heat treatment (i.e., heated to 1000°C at 3°C/min in air and held at that temperature for one hour). The bars were then sent to Protonex for testing. Subsequently, Protonex decided to discontinue their SOFC development activities, so they had no further interest in continuing the collaboration with PNNL, and the CRADA activities were terminated.
30 DIRECT ENERGY CONVERSION↗