AFFORDABLE MULTI-LAYER CERAMIC (MLC) MANUFACTURING FOR POWER SYSTEMS (AMPS)

McDermott Technology, Inc. (MTI) is attempting to develop high-performance, cost-competitive solid oxide fuel cell (SOFC) power systems. Recognizing the challenges and limitations facing the development of SOFC stacks comprised of electrode-supported cells and metallic interconnects, McDermott Technology, Inc. (MTI) has chosen to pursue an alternate path to commercialization. MTI is developing a multi-layer, co-fired, planar SOFC stack that will provide superior performance and reliability at reduced costs relative to competing designs. The MTI approach combines state-of-the-art SOFC materials with the manufacturing technology and infrastructure established for multi-layer ceramic (MLC) packages for the microelectronics industry. The rationale for using MLC packaging technology is that high quality, low-cost manufacturing has been demonstrated at high volumes. With the proper selection of SOFC materials, implementation of MLC fabrication methods offers unique designs for stacks (cells and interconnects) that are not possible through traditional fabrication methods. The MTI approach eliminates use of metal interconnects and ceramic-metal seals, which are primary sources of stack performance degradation. Co-fired cells are less susceptible to thermal cycling stresses by using material compositions that have closely matched coefficients of thermal expansion between the cell and the interconnect. The development of this SOFC stack technology was initiated in October 1999 under the DOE cosponsored program entitled ''Affordable Multi-layer Ceramic Manufacturing for Power Systems (AMPS)''. The AMPS Program was conducted as a two-phase program: Phase I--Feasibility Assessment (10/99--9/00); and Phase II--Process Development for Co-fired Stacks (10/00-3/02). This report provides a summary of the results from Phase I and a more detailed review of the results for Phase II. Phase I demonstrated the feasibility for fabricating multi-layer, co-fired cells and interconnects and resulted in selection of the most promising configuration for high-performance, low-cost SOFC stacks. During Phase II, the MTI Team successfully refined the fabrication processes and achieved low-rate production of cells and interconnects (about 100 per month). Short stacks (3-10 cells) using co-fired cells and interconnects were assembled and tested to validate the MTI multi-layer SOFC design. The team successfully demonstrated co-fired repeat units, comprised of a cell and the interconnect layers. Development of co-fired cells and multi-layer interconnects based on the new stack design was completed; all component fabrication and stack testing efforts were redirected to the new design toward the end of Phase II. Finally, low-cost alternate materials for the interconnect body and conductors within the interconnect were identified. At the end of Phase II, the MTI Team successfully transitioned the multi-layer SOFC stack development effort to the Solid State Energy Conversion Alliance (SECA) program