SOFC Interconnect Refurbishing with Selective Pulsed Laser Reflow
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Solution Overview
Problem
Current methods for refurbishing solid oxide fuel cell (SOFC) stack interconnects are time-consuming and prone to damaging due to mechanical singulation and costly grit blasting, which fails to efficiently remove coke deposits and seal materials without damaging the metal oxide layer.
Innovation Solution
A method using pulsed laser beams to vaporize seal and corrosion barrier residue on the air side of interconnects without damaging the metal oxide layer, and reflowing the metal oxide layer to maintain its integrity, while also forming microcavities for improved corrosion barrier layer adhesion and seal material deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical prying is used to separate interconnects from the stack, then singulation is achieved, but the interconnects are damaged by chipping, cracking, or inducing camber
Solution Approach 1:
The patent replaces mechanical prying with a combination of thermal treatment and chemical dissolution. The interconnects are heated to a specific temperature range (400-600°C) to soften the seal material, then immersed in a chemical solution that dissolves the softened seal material, enabling separation without mechanical contact and thus preventing damage to the interconnects
Solution Approach 2:
The patent changes the temperature parameter of the seal material from its normal solid state to a softened state by heating to 400-600°C. This parameter change allows the seal material to become more pliable and susceptible to chemical dissolution, enabling damage-free separation of the interconnects from the stack
2Manufacturing precision
If grit blasting is used to remove seal material and metal oxide, then clean surfaces are achieved, but the process is costly, time consuming, and causes damage by inducing camber and excessive erosion
Solution Approach 1:
The patent replaces mechanical grit blasting with a chemical dissolution process using a tailored solution that selectively removes seal material and metal oxide layers. This chemical approach eliminates the need for high-energy particle bombardment, preventing camber induction and excessive erosion while achieving clean surfaces
Solution Approach 2:
The patent changes the removal mechanism from mechanical (grit blasting) to chemical (dissolution). The chemical solution parameters (composition, temperature, concentration) are optimized to selectively remove unwanted materials at controlled rates, achieving surface cleanliness without the damaging effects of mechanical erosion
3Manufacturing precision
If grit blasting is used to remove metal oxide layer, then seal and oxide removal is achieved, but the metal oxide layer is damaged or removed entirely
Solution Approach 1:
The patent changes the removal mechanism from mechanical to chemical, using a solution with specific pH and composition that selectively dissolves seal material while being gentler on the metal oxide layer. The chemical parameters are tuned to achieve differential removal rates, preserving the metal oxide layer's integrity
Solution Approach 2:
The patent applies local quality by creating selective chemical reactivity - the dissolution solution has different reactivity toward seal material versus metal oxide layer. The solution is formulated to aggressively attack seal material while having minimal effect on the metal oxide layer, achieving selective removal without compromising the protective oxide layer
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
This approach enables efficient and damage-free removal of residues, maintaining the metal oxide layer's integrity and improving the adhesion of the corrosion barrier layer, thus enhancing the refurbishment process's efficiency and reducing costs.
Implementation Method 1
scanning a pulsed laser beam on an air side of the interconnect to vaporize seal and corrosion barrier layer residue without vaporizing a metal oxide layer located on the air side of the interconnect below the corrosion barrier layer residue
Implementation Method 2
scanning a second pulsed laser beam which is different from the first pulsed laser beam on the exposed metal oxide layer on the air side of the interconnect to reflow the metal oxide layer without removing the metal oxide layer
Implementation Method 3
forming microcavities through the metal oxide layer in the seal ring regions by laser drilling
Data Source
AI summary
A method of refurbishing a singulated fuel cell stack interconnect includes scanning a first pulsed laser beam on an air side of the interconnect to vaporize seal and corrosion barrier layer residue without vaporizing a metal oxide layer located on the air side of the interconnect below the corrosion barrier layer residue, and scanning a second pulsed laser beam which is different from the first pulsed laser beam on the exposed metal oxide layer on the air side of the interconnect to reflow the metal oxide layer without removing the metal oxide layer.