Stainless Steel Fuel Cell Separator Surface Treatment
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Solution Overview
Problem
Stainless steel separators for fuel cells face challenges in achieving high electrical conductivity and corrosion resistance while maintaining durability, as existing surface treatment methods are costly, prone to defects, and can lead to metal ion elution, contaminating the electrolyte and reducing long-term performance.
Innovation Solution
A method involving surface treatment of stainless steel sheets with a mixed etching solution of nitric acid and sulfuric acid, or with oxalic acid and hydrogen peroxide, to selectively reduce iron content in the passive film, enhancing the atomic ratio of chrome and nickel, thereby improving conductivity and corrosion resistance without the need for expensive coatings or vacuum processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a noble metal such as gold is plated on the surface of a metal separator, then corrosion resistance and electrical conductivity are improved, but manufacturing costs increase significantly
Solution Approach 1:
The invention changes the chemical composition parameters of the passive film by controlling the ratio of chromium to iron atoms. By increasing the chromium content and decreasing the iron content in the passive film through specific heat treatment processes, the material achieves enhanced corrosion resistance and electrical conductivity without requiring expensive noble metal plating.
2Reliability
If a noble metal such as gold is plated on the surface of a metal separator, then electrical conductivity is improved, but manufacturing costs increase significantly
Solution Approach 1:
The invention changes the chemical composition parameters of the passive film by controlling the ratio of chromium to iron atoms. By increasing the chromium content and decreasing the iron content in the passive film through specific heat treatment processes, the material achieves enhanced corrosion resistance and electrical conductivity without requiring expensive noble metal plating.
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 reduces manufacturing costs and time, enhances the stainless steel separator's performance by improving electrical conductivity and corrosion resistance, and minimizes metal ion elution, ensuring long-term fuel cell reliability and reduced contamination of the electrolyte membrane.
Implementation Method 1
dipping the stainless steel sheet into a mixed etching solution of nitric acid (HNO3) and sulfuric acid (H2SO4) at a temperature of 50∼70 °C for 30 seconds to 30 minutes to selectively lower an amount of Fe in the passive film
Implementation Method 2
dipping the stainless steel sheet into a mixed etching solution of nitric acid (HNO3) and sulfuric acid (H2SO4) at a temperature of 50∼70 °C for 30 seconds to 30 minutes to selectively lower an amount of Fe in the passive film
Implementation Method 3
dipping the stainless steel sheet into an etching solution formed by mixing one of oxalic acid (C2H2O4) and hydrogen peroxide (H2O2) with a solution of nitric acid (HNO3) and sulfuric acid (H2SO4)
Data Source
Figure 1~2(C)
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AI summary
A method for surface treatment of a stainless steel separator for a fuel cell comprises preparing a stainless steel sheet containing nickel, chrome and iron, and having a passive film on a surface of the stainless steel sheet, and dipping the stainless steel sheet into a mixed etching solution of nitric acid (HNO3) and sulfuric acid (H2SO4) at a temperature of 50-70 °C for 30 seconds to 30 minutes to selectively lower an amount of Fe in the passive film formed on the surface of the stainless steel sheet.