Fuel Cell Alloy Cr Diffusion Suppression Layer
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Solution Overview
Problem
Current fuel cell technologies face issues with chromium (Cr) poisoning due to Cr diffusion from Cr-containing alloys, leading to increased electric resistance and reduced power generation performance, as well as potential cracks in oxide coatings that can further facilitate Cr diffusion and electrical connection degradation.
Innovation Solution
A heat-resistant alloy with a Cr-diffusion suppression layer composed of laminated ZnMn2O4 and MnCo2O4, followed by a (La, Sr)MnO3-based perovskite oxide layer, which suppresses Cr diffusion and crack formation, enhancing long-term reliability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Cr-containing alloy is used for the current collecting member, then ease of manufacture and heat resistance are improved, but Cr diffusion to the air-side electrode occurs over time, increasing electric resistance and degrading power generation performance
Solution Approach 1:
The coating structure is segmented into multiple functional layers: a Cr diffusion prevention layer (first layer) that blocks Cr diffusion, and a protective oxide layer (second layer) that provides environmental stability. This segmentation allows each layer to perform its specific function independently, preventing Cr poisoning while maintaining manufacturing feasibility
Solution Approach 2:
The invention uses composite material structures both in the alloy composition (Fe-Cr-Al-Si-Ni composite) and in the coating system (multiple oxide layers with different functions). The composite structure combines materials with complementary properties to achieve both ease of manufacture and long-term reliability by preventing Cr diffusion
2Object-affected harmful factors
If a single-layer oxide coating is applied to suppress Cr diffusion, then Cr diffusion is partially suppressed, but cracks may form due to thermal expansion differences, facilitating Cr diffusion and electrical connection degradation
Solution Approach 1:
The coating is divided into two layers with different functions: the first layer (Cr diffusion prevention layer) directly contacts the alloy and blocks Cr diffusion, while the second layer (protective oxide layer) provides environmental protection and mechanical stability. This segmentation prevents crack formation by distributing thermal stress across layers with different mechanical properties
Solution Approach 2:
Each layer is designed with specific local properties: the first layer has high Cr diffusion barrier properties with specific composition ratios, while the second layer has properties optimized for environmental resistance and thermal stress management. This local quality optimization ensures both Cr diffusion suppression and crack prevention
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 reduces Cr diffusion and crack generation, maintaining high conductivity and power generation efficiency over time, thereby improving the reliability of fuel cell stack devices and modules.
Implementation Method 1
a Cr-diffusion suppression layer which is made by laminating a first layer that contains ZnMn2O4 and MnCo2O4 and a second layer that does not contain ZnO but contains an (La, Sr)MnO3-based perovskite oxide
Implementation Method 2
due to a difference between the coefficients of thermal expansion of the perovskite composite oxide containing La together with Fe or Mn, and the oxide of Zn, there is concern that cracks may be generated in the second layer
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
The invention provides a heat-resistant alloy capable of effectively suppressing diffusion of Cr, as well as an alloy member for a fuel cell, a fuel cell stack device, a fuel cell module and a fuel cell device. A heat-resistant alloy according to the invention includes a Cr-containing alloy, and a Cr-diffusion suppression layer located on at least a part of a surface of the Cr-containing alloy, the Cr-diffusion suppression layer being made by laminating a first layer that contains a Zn-containing oxide and a second layer that does not contain ZnO but contains an (La, Sr)MnO3-based perovskite oxide in that order, so that it is possible to effectively suppress diffusion of Cr. By using the heat-resistant alloy for an alloy member for a fuel cell, a fuel cell stack device, a fuel cell module and a fuel cell device each having improved reliability can be obtained.