Fuel Cell Support Substrate Surface Roughness Control
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Solution Overview
Problem
Fuel cells experience cracks in the support substrate's gas flow paths during reducing treatment due to surface roughness issues, leading to reduced performance and reliability.
Innovation Solution
A fuel cell design with a porous support substrate having gas flow paths and a surface roughness of 0.16 μm to 5.2 μm, covered with a dense solid electrolyte film, to prevent cracks during reducing treatment, utilizing materials like nickel oxide and insulating ceramics with specific porosity and aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface roughness of the gas flow path wall surface is not controlled, then the manufacturing process is simpler, but cracks are generated in the support substrate during reducing treatment
Solution Approach 1:
The invention specifies a precise surface roughness range (Ra: 0.16 μm to 5.2 μm) for the gas flow path wall surface of the support substrate. By controlling this physical parameter within the defined range, the invention prevents crack generation during reducing treatment while maintaining manufacturing feasibility. This parameter optimization resolves the contradiction between reliability improvement and manufacturing precision requirements.
2Reliability
If the support substrate is made more dense to prevent cracks, then crack resistance improves, but gas flow performance deteriorates
Solution Approach 1:
The invention applies different structural characteristics to different regions of the support substrate. The gas flow path walls are designed with controlled surface roughness (Ra: 0.16 μm to 5.2 μm) to prevent cracks, while the bulk structure maintains appropriate porosity for gas flow. This local differentiation of structural properties resolves the contradiction between crack resistance and gas flow performance.
Solution Approach 2:
Instead of making the entire support substrate dense to prevent cracks (which would harm gas flow), the invention inverts the approach by controlling surface roughness specifically at the gas flow path walls. This surface-level control prevents cracks without compromising the internal porosity needed for gas flow, thus resolving the contradiction through reverse thinking.
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 prevents cracks in the fuel cell's support substrate, enhancing its durability and operational stability by maintaining the surface roughness within a critical range during temperature changes, ensuring reliable power generation.
Implementation Method 1
During the above-mentioned reducing treatment, cracks are generated across a wall surface of the gas flow path to the principal surface in the support substrate
Implementation Method 2
An outer periphery of the support substrate is covered with a dense film of the solid electrolyte
Implementation Method 3
a porous plate-like support substrate having a plurality of gas flow paths formed therein
Data Source
AI summary
Provided is a fuel cell as a fired body including a porous plate-like support substrate having a gas flow path formed therein, and a power generation element part provided on a principal surface of the support substrate, the power generation element part including at least a fuel electrode, a solid electrolyte, and an air electrode laminated in this order. The generation of cracks in the support substrate has a strong correlation with a “surface roughness of a wall surface of a gas flow” of the fuel cell in a state of a reductant. When the surface roughness of the wall surface of the gas flow path is 0.16 to 5.2 in terms of an arithmetic average roughness Ra in a state in which the fuel cell is a reductant that has been subjected to heat treatment in a reducing atmosphere, the generation of the cracks can be suppressed.