Copper-Coated SOC Interconnect Contact Against Chromium Poisoning
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Solution Overview
Problem
In solid oxide cell stacks, chromium poisoning and mechanical instability at the contact points between interconnects and oxygen electrodes lead to performance degradation and potential failure due to chromium diffusion and thermal stress-induced gaps, respectively.
Innovation Solution
A ferritic stainless steel interconnect coated with a sintering aid, such as copper oxides, forms a strong bond with the oxygen electrode or contact layer, enhancing mechanical strength and reducing electrical resistance through sintering, thereby improving contact integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferritic stainless steel interconnect is used, then oxidation resistance is improved, but chromium diffusion to the oxygen electrode causes chromium poisoning and performance degradation
Solution Approach 1:
A coating layer comprising CuO and Fe2O3 is applied to the interconnect surface, serving as an intermediary barrier between the chromium-containing ferritic stainless steel and the oxygen electrode. This coating prevents chromium diffusion to the electrode while maintaining electrical conductivity and oxidation resistance, thereby eliminating chromium poisoning without sacrificing the benefits of ferritic stainless steel.
2Reliability
If the interconnect contacts the oxygen electrode directly, then electrical contact is established, but thermal stress induces gaps and mechanical instability at the contact points
Solution Approach 1:
The coating is formed as a composite material comprising CuO and Fe2O3 in specific proportions (CuO: 30-70 wt%, Fe2O3: 30-70 wt%). This composite structure provides both electrical conductivity (through CuO) and mechanical strength (through Fe2O3), while the composite nature allows for stress distribution that prevents gap formation under thermal cycling conditions.
3Object-generated harmful factors
If a coating is applied to prevent chromium diffusion, then chromium poisoning is reduced, but electrical resistance at the contact point increases
Solution Approach 1:
The coating composition is optimized by controlling the CuO to Fe2O3 ratio within specific ranges (CuO: 30-70 wt%, Fe2O3: 30-70 wt%). By adjusting these parameters, the coating achieves the right balance between chromium barrier properties and electrical conductivity. The specific composition ensures low electrical resistance while effectively preventing chromium diffusion.
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 copper-based coating acts as a sintering aid, improving the mechanical strength and electrical conductivity of the contact points, reducing chromium poisoning and thermal stress-induced failures, resulting in a more robust and efficient solid oxide cell stack operation.
Implementation Method 1
A ferritic stainless steel interconnect coated with a sintering aid, such as copper oxides, forms a strong bond with the oxygen electrode or contact layer, enhancing mechanical strength and reducing electrical resistance through sintering
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
Improved contact between interconnect and oxygen electrode material in solid oxide cell (SOC) stacks is achieved through a contact point between the oxygen electrode or an oxygen-side contact layer of the SOC and a coated ferritic stainless steel interconnect in the SOC stack, where the coating on the metallic interconnect comprises Cu.