Fuel Cell Separator TiOx Binder Layer Adhesion Corrosion
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Solution Overview
Problem
Conventional fuel cell separators with a Ti/TiC/C structure face adhesion and corrosion issues due to the oxidation of the TiC adhesion layer in fuel cell environments, leading to poor corrosion resistance.
Innovation Solution
A method involving the formation of a TiOx (1<x<2) layer on a titanium base substrate followed by a carbon film using plasma CVD, creating a binder layer with Ti, O, and C that enhances adhesion and provides corrosion resistance, with a thickness of 0.1 nm to 5 nm to maintain conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a TiC adhesion layer is formed between titanium base substrate and carbon film, then adhesion is improved, but corrosion resistance deteriorates due to easy oxidation of TiC in fuel cell environment
Solution Approach 1:
A TiOx layer (where 1 < x < 2) is introduced as an intermediary layer between the titanium base substrate and the carbon film. This TiOx layer serves as a mediator that binds with carbon components to form a Ti-O-C binder layer, providing adhesion while maintaining corrosion resistance. The TiOx layer is more corrosion-resistant than TiC and prevents the carbon film from directly contacting the titanium substrate, thus solving the contradiction between adhesion and corrosion resistance.
Solution Approach 2:
The oxidation state of titanium is changed from Ti(IV) in TiO2 to a non-stoichiometric TiOx (1 < x < 2) state. This parameter change in the titanium oxide layer creates a material with intermediate properties: it has sufficient reactivity to form binder layers with carbon for adhesion, while maintaining adequate corrosion resistance. The controlled oxygen deficiency in TiOx allows it to bind with carbon components without being as easily oxidized as TiC.
2Strength
If TiO2 layer is removed by etching to improve adhesion, then adhesion is improved, but corrosion resistance deteriorates due to loss of protective oxide layer
Solution Approach 1:
Instead of removing the TiO2 layer to improve adhesion (conventional approach), the invention inverts the approach by utilizing and modifying the TiO2 layer. The TiO2 layer is transformed into a TiOx layer (1 < x < 2) through controlled reduction, which then serves as the adhesion-promoting layer. This inversion allows the oxide layer to be retained and utilized for adhesion rather than being removed, thus maintaining corrosion resistance while achieving good adhesion.
3Strength
If binder layer thickness is increased to improve adhesion, then adhesion is improved, but conductivity deteriorates due to oxidation and insulating properties
Solution Approach 1:
The thickness of the binder layer is precisely controlled within the range of 0.1 nm to 5 nm. This parameter control ensures that the layer is thick enough to provide adhesion through Ti-O-C bonding but thin enough to maintain conductivity through quantum tunneling effects. The binder layer is gradually oxidized under oxidative conditions, which would normally result in insulating properties, but the thin thickness (5 nm or less) allows it to maintain certain level of conductivity due to the tunneling effect.
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 significantly improves the adhesion of the carbon film to the titanium substrate and provides favorable corrosion resistance, maintaining conductivity and ensuring the separator's performance in fuel cell conditions.
Implementation Method 1
the TiOx layer binds with the carbon (C) components of the carbon film to form a binder layer including Ti, O and C between the TiO layer and the carbon film
Implementation Method 2
a carbon film is then formed on the TiOx layer by plasma CVD
Implementation Method 3
the binder layer, if it is as thin as 5 nm or less, can maintain a certain level of conductivity due to the tunneling effect, etc.
Data Source
AI summary
A manufacturing method of a fuel cell separator is provided, whereby the adhesion of a carbon film against a titanium base substrate can be improved and favorable corrosion resistance can be obtained at the same time. A fuel cell separator having such improved adhesion and favorable corrosion resistance is also provided. The method for manufacturing a fuel cell separator according to an embodiment of the invention includes the steps of: forming a TiOx (1<x<2) layer 42 on a titanium base substrate 40; and forming a carbon film 44 on the TiOx layer 42 by plasma CVD so that a binder layer 43 including Ti, O and C is formed between the TiOx layer 42 and the carbon film 44.