Fabio Greco

Development of High Temperature Mechanical Rig for Characterizing the Viscoplastic Properties of Alloys Used in Solid Oxide Cells

Analyzing the thermomechanical reliability of the solid oxide cell (SOC) stack requires precise measurement of the mechanical properties of the different components in the stack at operating conditions of the SOC. It is challenging to precisely characterize the time-dependent deformational properties of metallic components in the SOC stacks at the required level of stress and operational conditions (high temperature and controlled atmosphere). This work presents an improved methodology for characterizing the time-dependent, or viscoplastic, properties of metallic alloys used in the SOC stacks at a high temperature and in a controlled atmosphere. The methodology uses a mechanical loading rig designed to apply variable and constant loads on samples within a gas-tight high temperature furnace. In addition, a unique, remotely installed length measuring setup involving a laser micrometer is used to monitor deformations in the sample. Application of the methodology is exemplified by measurement of stress relaxation, creep, and constant strain rate behaviors of a high-temperature alloy used in the construction of SOC metallic interconnects at different temperatures. Furthermore, measurements using the proposed methodology are also verified by the literature and experiments conducted using other machines.

Chapter 7 – Lifetime Issues for Solid Oxide Fuel Cell Interconnects

Abstract The manuscript aims to introduce the reader to the main drawbacks interconnects face in SOFC environments, giving the basis to understand the problem and the literature references to deepen the knowledge on each specific topic.The chapter is divided in two parts: a theoretical description of the degradation phenomena affecting the interconnects (notably corrosion and mechanical stresses) and a table presenting its behaviour in operating conditions, at the end of the chapter. In the first part, influence of oxygen, fuel and water partial pressure on scale growth process are taken in consideration, with the latter being the most influent. A paragraph is dedicated to the corrosion behaviour of sealants too, while the mechanical degradation part is focused on the model methodology currently used to forecast stress-strain behaviour in SOFC metal interconnects. A paragraph describing solutions to mitigate interconnect lifetime issues is provided at the end of this section. In the table are presented results of interconnects coupled with different types of SOFC cell: anode, electrolyte and metal supported and tested in operating conditions. From the analysis of the data collected in the table, it can be said that current solutions to extend lifetime are already reasonably effective

Lifetime Issues for Solid Oxide Fuel Cell Interconnects, Solid Oxide Fuel Cell Lifetime and Reliability

Abstract The manuscript aims to introduce the reader to the main drawbacks interconnects face in SOFC environments, giving the basis to understand the problem and the literature references to deepen the knowledge on each specific topic.The chapter is divided in two parts: a theoretical description of the degradation phenomena affecting the interconnects (notably corrosion and mechanical stresses) and a table presenting its behaviour in operating conditions, at the end of the chapter. In the first part, influence of oxygen, fuel and water partial pressure on scale growth process are taken in consideration, with the latter being the most influent. A paragraph is dedicated to the corrosion behaviour of sealants too, while the mechanical degradation part is focused on the model methodology currently used to forecast stress-strain behaviour in SOFC metal interconnects. A paragraph describing solutions to mitigate interconnect lifetime issues is provided at the end of this section. In the table are presented results of interconnects coupled with different types of SOFC cell: anode, electrolyte and metal supported and tested in operating conditions. From the analysis of the data collected in the table, it can be said that current solutions to extend lifetime are already reasonably effective

Lifetime Issues for Solid Oxide Fuel Cell Interconnects

Abstract The manuscript aims to introduce the reader to the main drawbacks interconnects face in SOFC environments, giving the basis to understand the problem and the literature references to deepen the knowledge on each specific topic.The chapter is divided in two parts: a theoretical description of the degradation phenomena affecting the interconnects (notably corrosion and mechanical stresses) and a table presenting its behaviour in operating conditions, at the end of the chapter. In the first part, influence of oxygen, fuel and water partial pressure on scale growth process are taken in consideration, with the latter being the most influent. A paragraph is dedicated to the corrosion behaviour of sealants too, while the mechanical degradation part is focused on the model methodology currently used to forecast stress-strain behaviour in SOFC metal interconnects. A paragraph describing solutions to mitigate interconnect lifetime issues is provided at the end of this section. In the table are presented results of interconnects coupled with different types of SOFC cell: anode, electrolyte and metal supported and tested in operating conditions. From the analysis of the data collected in the table, it can be said that current solutions to extend lifetime are already reasonably effective