Titanium Separator Surface Layer for Press-Formed Fuel Cell Conductivity
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Solution Overview
Problem
Existing fuel cell separator materials face challenges in maintaining high conductivity and adhesion between the surface layer and substrate, especially when press molding is performed to form narrow grooves, leading to interfacial corrosion and decreased conductivity.
Innovation Solution
A surface-treated titanium material with a titanium substrate and a surface layer comprising a titanium oxide layer and carbon particles, where the carbon particles are dispersed within the titanium oxide layer, and the titanium oxide layer contains Ti2O3 and TiO2, with a total film thickness of 25 nm or more, and a specific ratio of Ti2O3 to TiO2 to enhance adhesion and toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If press molding is performed to form narrow grooves to increase power generation efficiency, then productivity and power generation efficiency are improved, but the mixture layer containing titanium oxide mainly composed of rutile peels off from the titanium substrate and numerous cracks are introduced, causing interfacial corrosion and decreased conductivity
Solution Approach 1:
The patent changes the crystal structure parameter of titanium oxide from mainly rutile to a mixture containing anatase and/or brookite, which fundamentally alters the mechanical properties of the surface layer. This parameter change in crystal structure enables the surface layer to withstand press molding forces without peeling or cracking, resolving the contradiction between forming narrow grooves and maintaining adhesion
Solution Approach 2:
The patent creates a composite surface layer structure consisting of titanium substrate, titanium oxide layer (with specific crystal phases), and carbon black particles. This composite structure combines the advantages of different materials: titanium oxide provides adhesion and toughness, while carbon black maintains conductivity. The composite nature allows the surface layer to resist peeling and cracking during press molding while maintaining electrical conductivity
2Productivity
If press molding is performed to form narrow grooves, then productivity and power generation efficiency are improved, but numerous cracks are introduced into the mixture layer, causing corrosive acidic solution to reach the interface and progress interfacial corrosion
Solution Approach 1:
The patent changes the crystal structure parameter of titanium oxide from mainly rutile to a mixture containing anatase and/or brookite, which fundamentally alters the mechanical properties of the surface layer. This parameter change in crystal structure enables the surface layer to withstand press molding forces without peeling or cracking, resolving the contradiction between forming narrow grooves and maintaining adhesion
Solution Approach 2:
The patent creates a composite surface layer structure consisting of titanium substrate, titanium oxide layer (with specific crystal phases), and carbon black particles. This composite structure combines the advantages of different materials: titanium oxide provides adhesion and toughness, while carbon black maintains conductivity. The composite nature allows the surface layer to resist peeling and cracking during press molding while maintaining electrical conductivity
3Reliability
If a mixture layer containing carbon black and titanium oxide mainly composed of rutile is formed to achieve high conductivity, then electrical conductivity is improved, but the mixture layer lacks sufficient toughness and peels off during press molding
Solution Approach 1:
The patent changes the crystal structure parameter of titanium oxide from mainly rutile to a mixture containing anatase and/or brookite, which fundamentally alters the mechanical properties of the surface layer. This parameter change in crystal structure enables the surface layer to withstand press molding forces without peeling or cracking, resolving the contradiction between forming narrow grooves and maintaining adhesion
Solution Approach 2:
The patent creates a composite surface layer structure consisting of titanium substrate, titanium oxide layer (with specific crystal phases), and carbon black particles. This composite structure combines the advantages of different materials: titanium oxide provides adhesion and toughness, while carbon black maintains conductivity. The composite nature allows the surface layer to resist peeling and cracking during press molding while maintaining 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 solution effectively maintains high conductivity for a long period, even under severe press molding conditions, by improving adhesion and toughness of the surface layer, thus preventing interfacial corrosion.
Implementation Method 1
improve adhesion between the surface layer and the substrate
Implementation Method 2
a titanium substrate having a passive film on a surface thereof
Data Source
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AI summary
Provided are: a surface treatment titanium material for a fuel cell separator, said surface treatment titanium material having good toughness and excellent adhesion between a surface layer and a base material even when press molding is performed in harsh conditions, and it being possible to maintain electroconductivity for a long period of time; and a method for manufacturing said surface treatment titanium material. The surface treatment titanium material for a fuel cell separator is provided with a titanium base material having a passivation film on the surface, and a surface layer formed on the titanium base material, the surface layer including a titanium oxide layer and carbon particles, the carbon particles being dispersed inside the titanium oxide layer. The total film thickness of the titanium oxide layer and the passivation film is 25 nm or more, and when peak separation is performed on the Raman spectrum combining the surface layer and the passivation film, the ratio (Ti2O3/TiO2) of the peak height indicating the Ti2O3 and the peak height indicating the TiO2 is 0.08-1.45, inclusive, and the void ratio found on the boundary of the titanium oxide layer and the titanium base material is 0.30 or less.