Fuel Cell Separator Adhesion via Iron Hydrous Oxide
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Solution Overview
Problem
Conventional separators for fuel cells made of stainless steel suffer from low adhesion of water-soluble resins due to passive chromium oxide films, leading to peeling issues under shear stress and thermal expansion, compromising durability and seal effectiveness.
Innovation Solution
Formation of an iron-based hydrous oxide film on the stainless steel separator substrates through cathodic electrolysis in an alkaline solution, followed by electrodeposition of an amine-based water-soluble resin, which forms a strong bond with the hydrous oxide film and enhances adhesion, preventing peeling and improving seal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive chromium oxide film is formed on the stainless steel separator substrate, then anticorrosive properties are improved, but adhesion of water-soluble resin is worsened
Solution Approach 1:
An iron-based hydrous oxide film is introduced as an intermediary layer between the chromium oxide passive film and the water-soluble resin. This intermediate layer has high affinity for both the chromium oxide substrate and the hydrophilic resin, enabling strong adhesion while preserving the underlying corrosion-resistant structure
Solution Approach 2:
The separator substrate is transformed into a composite structure consisting of multiple layers: the stainless steel base metal, the chromium oxide passive film, and the iron-based hydrous oxide intermediate layer. This composite structure combines the anticorrosive properties of chromium oxide with the adhesion-promoting properties of iron hydrous oxide
2Object-affected harmful factors
If water-soluble resin is used as adhesive or sealant, then environmental friendliness is improved, but adhesion to separator substrate is worsened due to peeling under shear stress and thermal expansion
Solution Approach 1:
The iron-based hydrous oxide film serves as a mediator that bridges the hydrophilic resin and the hydrophobic chromium oxide surface. The hydrous oxide's amphoteric nature allows it to bond with both hydrophilic and hydrophobic materials, preventing resin peeling under operational stresses
Solution Approach 2:
The surface chemistry parameters of the separator substrate are changed by forming the iron-based hydrous oxide film, which modifies the surface energy and chemical composition to be more compatible with water-soluble resins, thereby improving adhesion without sacrificing environmental friendliness
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 solution provides superior adhesion between the resin layer and the separator substrate, enhancing the durability and seal effect of the fuel cell by preventing resin detachment and improving anticorrosive properties, even with thinner resin layers.
Implementation Method 1
an iron-based hydrous oxide film formed on each peripheral surface of the pair of separator substrates by cathodic electrolysis treatment of the separator substrates
Implementation Method 2
a resin layer of an electrodeposited water-soluble resin formed on the iron-based hydrous oxide film
Data Source
AI summary
A separator for use in a fuel cell has an iron-based hydrous oxide film formed on a passive film of a peripheral surface except a gas channel of a separator substrates of SUS by cathodic electrolysis treatment in an alkaline solution and further a resin layer of an electrodeposited water-soluble resin formed on the iron-based hydrous oxide film.