Titanium Separator Surface Layer for Press-Formed Fuel Cell Grooves
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Solution Overview
Problem
Fuel cell separators with narrow grooves face issues of peeling and cracking during press molding, leading to decreased conductivity due to insufficient adhesion and toughness of the surface layer, and susceptibility to interfacial corrosion in corrosive acidic environments.
Innovation Solution
A surface-treated titanium material with a titanium substrate and a surface layer comprising a titanium oxide layer and carbon particles, where carbon particles are dispersed within the titanium oxide layer, and the total film thickness is 25 nm or more, with a specific Raman spectrum peak ratio and void interface ratio to ensure adhesion and toughness, manufactured through annealing, oxidation, and reduction treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a separator with narrow flow path grooves is manufactured by press molding, then power generation efficiency increases, but the mixture layer peels off from the substrate and cracks form due to insufficient adhesion and toughness
Solution Approach 1:
The invention changes the chemical composition parameters of the surface layer by incorporating specific metal elements (Al, Si, Mn, Zn, Ni, Cu, Co, Fe) in controlled amounts (0.1-10 at%). This compositional modification enhances both the adhesion to substrate and toughness of the mixture layer, enabling it to withstand press molding stresses while maintaining narrow groove geometry for high power generation efficiency
Solution Approach 2:
The invention creates a composite surface layer by combining carbon black (0.1-10 mass%) with titanium oxide and specific metal elements. This composite structure provides improved mechanical properties including enhanced adhesion to the titanium substrate and increased toughness, preventing peeling and cracking during press molding while maintaining electrical conductivity
2Strength
If the mixture layer does not have sufficient toughness, then numerous cracks are introduced during press molding, but increasing toughness may compromise conductivity
Solution Approach 1:
The invention optimizes the concentration parameters of carbon black (0.1-10 mass%) and metal elements (0.1-10 at%) to achieve the right balance between toughness and conductivity. The carbon black provides toughness and crack resistance, while the metal elements bridge the carbon particles to maintain electrical conductivity pathways even in the tougher, more crack-resistant matrix
3Object-affected harmful factors
If cracks are introduced into the mixture layer during press molding, then corrosive acidic solution reaches the interface and interfacial corrosion progresses, but preventing corrosion may require thicker protective layers
Solution Approach 1:
The invention applies preliminary protective action by incorporating corrosion-resistant metal elements (Al, Si, Mn, Zn, Ni, Cu, Co, Fe) into the surface layer composition before the fuel cell operates. This pre-engineered corrosion resistance prevents acidic solution penetration and interfacial corrosion without requiring thicker protective layers, thus maintaining the narrow groove geometry and manufacturing precision
Solution Approach 2:
The composite structure of titanium oxide, carbon black, and corrosion-resistant metal elements creates a chemically resistant surface layer that blocks corrosive acidic solutions from reaching the substrate interface. This composite material provides both mechanical integrity (preventing crack formation) and chemical resistance (preventing corrosion) while maintaining the required narrow groove dimensions
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 surface-treated titanium material maintains high conductivity and adhesion between the surface layer and substrate, even under severe press molding conditions, effectively preventing corrosion and ensuring long-term conductivity.
Implementation Method 1
a titanium substrate having a passive film on a surface thereof
Implementation Method 2
an oxidation treatment step of thermally treating the titanium substrate coated with the carbon particles in an oxidizing atmosphere to form a titanium oxide layer including the carbon particles
Implementation Method 3
a reduction treatment step of heat-treating the titanium substrate having the titanium oxide layer formed thereon in a vacuum or in an inert gas atmosphere to form a surface layer
Data Source
AI summary
A surface-treated titanium material for a fuel cell separator, including a titanium substrate having a passive film on a surface of the titanium substrate and a surface layer formed on the titanium substrate. The surface layer includes a titanium oxide layer and carbon particles, the carbon particles are dispersed in an inside of the titanium oxide layer, and a total film thickness of the titanium oxide layer and the passive film is 25 nm or more.