Spinel Oxide Bonding Member for SOFC Interconnector
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Solution Overview
Problem
The bonding between the air electrode and the interconnector in solid oxide fuel cells (SOFCs) requires a more cost-effective and high-strength solution than traditional Pt materials, while maintaining electrical connectivity and withstanding high-temperature environments.
Innovation Solution
A bonding member using a ferritic stainless steel interconnector and a transition metal oxide with a spinel type crystal structure, such as MnCo2O4 or CuMn2O4, is employed, with a chromia layer and a co-continuous structure to enhance bonding strength and conductivity, and optionally incorporating noble metals like Pt or Ag to reduce electric resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Pt material is used as the bonding agent, then bonding strength and electrical connectivity are improved, but material cost increases
Solution Approach 1:
The patent replaces expensive Pt material with cheaper conductive ceramic materials (such as La-Sr-Co-Fe perovskite complex material or Mn-Co spinel material) that can achieve sufficient bonding strength and electrical conductivity without requiring noble metals, thereby reducing material cost while maintaining functional performance
Solution Approach 2:
The patent uses composite ceramic materials combining multiple elements (La, Sr, Co, Fe, Mn) to create bonding agents with optimized electrical conductivity, sintering performance, and bonding strength, replacing single-element Pt materials with multi-element ceramic composites that offer comparable or superior performance at lower cost
2Quantity of substance
If conductive ceramic material is used as bonding agent, then material cost is reduced, but sintering performance and bonding strength deteriorate
Solution Approach 1:
The patent optimizes sintering parameters (temperature, time, atmosphere) and material composition (element ratios, particle size distribution) to enhance the sintering performance of conductive ceramic materials, enabling them to achieve adequate bonding strength without requiring Pt material, thus resolving the contradiction between cost reduction and bonding strength maintenance
3Ease of manufacture
If spinel type oxide is used as bonding agent, then sintering performance is improved, but electrical conductivity decreases
Solution Approach 1:
The patent creates a multi-layer structure at the bonding interface with different material compositions and properties: a chromia layer for chemical bonding and stability, a spinel layer for sintering performance and mechanical strength, and conductive ceramic materials for electrical conductivity. Each layer performs its specific function locally, achieving overall system optimization that balances sintering performance and electrical conductivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bonding member achieves high bonding strength and electrical connectivity between the metal interconnector and the air electrode, even at elevated temperatures, with improved sintering performance and reduced material costs compared to traditional Pt-based solutions.
Implementation Method 1
a paste, which is a precursor of the bonding agent, is interposed between the air electrode (the bonding portion of the air electrode) and the interconnector (the bonding portion of the interconnector), and with this state, the paste is sintered
Implementation Method 2
a bonding member that is made of a transition metal oxide having a spinel type crystal structure... and that electrically connects the first and second conductive connection members
Data Source
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AI summary
Powders of respective metal elements (Mn, Co) constituting a transition metal oxide (MnCo2O4) having a spinel type crystal structure are used as a starting material. A paste containing the mixture of the powders is interposed between an air electrode and an interconnector, and with this state, a sintering is performed, whereby a bonding agent (sintered body) is formed to obtain the bonding member according to the present invention. In the bonding member, a chromia layer including Cr2O3, a first layer including elements of Mn, Co, Fe, Cr, and O, and a second layer including elements of Mn, Co, Fe, and O are provided in this order from the side close to the interconnector at the bonding portion between the bonding agent and the interconnector. The bonding member has sufficiently great bonding strength between the interconnector and the bonding agent.