Stainless Steel Sheet Electrolytic Etching for Fuel Cell Separators
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Solution Overview
Problem
The production of stainless steel sheets for fuel cell separators using hydrofluoric acid-containing treatment solutions faces challenges in achieving stable contact resistance reduction and poses safety concerns due to high chemical activity and disposal issues.
Innovation Solution
A method involving electrolytic etching treatment in the active region of stainless steel sheets, followed by surface stabilizing treatment, using sulfuric acid or mixed acid solutions to reduce contact resistance without hydrofluoric acid, thereby enhancing productivity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrofluoric acid-containing treatment solution is used for etching, then contact resistance is reduced, but safety concerns arise due to high chemical activity and disposal issues
Solution Approach 1:
The patent replaces the hazardous hydrofluoric acid treatment solution with a safer, inexpensive sulfuric acid-based treatment solution. This substitution eliminates the safety concerns associated with hydrofluoric acid while maintaining the etching function needed to reduce contact resistance, effectively using a disposable, safe alternative to the hazardous chemical process.
Solution Approach 2:
The patent converts the naturally formed oxide layer on stainless steel, which typically increases contact resistance, into a beneficial component by controlling its removal and regeneration. Through electrolytic etching in sulfuric acid solution, the oxide layer is selectively removed to reduce contact resistance, then a controlled passive film is formed to provide corrosion resistance, turning a harmful factor into a beneficial one.
2Duration of action of stationary object
If stainless steel is used as separator material, then durability is enhanced, but contact resistance increases due to passive film formation
Solution Approach 1:
The patent applies local quality by creating a non-uniform surface structure on the stainless steel separator. Through electrolytic etching, specific regions develop micro-roughness and localized active sites that reduce contact resistance, while the overall passive film structure is maintained to preserve corrosion resistance. This local modification allows different regions to serve different functions.
Solution Approach 2:
The patent applies preliminary action by performing electrolytic etching treatment before the separator is assembled into the fuel cell. This pre-treatment creates the optimal surface condition for low contact resistance, ensuring that when the separator is installed, the desired electrical conductivity is already achieved without requiring additional in-situ treatment.
3Reliability
If graphite is used as separator material, then contact resistance is low and corrosion does not occur, but the material easily breaks on impact and processing cost is high
Solution Approach 1:
The patent applies parameter changes by modifying the surface parameters of stainless steel rather than changing the bulk material. Through electrolytic etching, the surface roughness and chemical composition are altered to achieve low contact resistance, while the bulk stainless steel material retains its high strength and impact resistance properties, combining the advantages of both graphite and metal materials.
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 method effectively achieves low contact resistance in stainless steel sheets, maintaining performance even under heat treatment conditions, thus improving the practical use of stainless steel sheets as fuel cell separators.
Implementation Method 1
subjecting the stainless steel sheet to electrolytic etching treatment
Implementation Method 2
thereafter removing an oxide layer at a surface of the stainless steel sheet
Data Source
AI summary
A production method for a stainless steel sheet for fuel cell separators comprises: preparing a stainless steel sheet as a material; thereafter removing an oxide layer at a surface of the stainless steel sheet; and thereafter subjecting the stainless steel sheet to electrolytic etching treatment in an active region of the stainless steel sheet.