Atomic Oxygen Oxidation for Fuel Cell Interconnects
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Solution Overview
Problem
In high temperature solid oxide fuel cell systems, the oxidation of interconnects using molecular oxygen can lead to undesirable chromium nitridation, which blocks pores and inhibits uniform oxide formation, affecting the performance of the fuel cell stack.
Innovation Solution
Generating atomic oxygen through thermal decomposition, catalytic decomposition, or microwave discharge of nitrous oxide to form a controlled oxide layer on interconnects, reducing nitridation and enhancing oxide formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molecular oxygen is used for oxidation of interconnects, then oxidation process can be performed, but chromium nitridation occurs which blocks pores and inhibits uniform oxide formation
Solution Approach 1:
The patent changes the chemical state parameter of oxygen from molecular (O2) to atomic (O) form. Atomic oxygen is generated by thermal decomposition of nitrous oxide at temperatures of 700-950°C, or by catalytic decomposition using metals like platinum, palladium, or nickel. This parameter change in oxygen's chemical state enables oxidation without chromium nitridation, resolving the contradiction between achieving oxidation and preventing harmful nitridation.
Solution Approach 2:
The patent employs atomic oxygen as a strong oxidant that is more reactive than molecular oxygen. Atomic oxygen, generated through thermal or catalytic decomposition of nitrous oxide, provides accelerated oxidation that forms uniform oxide layers on interconnect surfaces without causing chromium nitridation. This strong oxidant approach directly addresses the contradiction by enabling effective oxidation while preventing the harmful side effect.
2Manufacturing precision
If conventional oxidation is performed, then oxide layer forms on interconnects, but non-uniform oxide formation occurs due to pore blocking by nitrides
Solution Approach 1:
The patent changes the oxidation mechanism by using atomic oxygen instead of molecular oxygen. This parameter change in the oxidizing agent's chemical state enables uniform oxide formation throughout the interconnect structure, including within pores, without the formation of chromium nitrides that would block pores and create non-uniform oxide layers. The atomic oxygen's higher reactivity ensures consistent oxidation across all surfaces.
Solution Approach 2:
The patent converts the potential harm of nitrous oxide decomposition into a benefit. While thermal or catalytic decomposition of nitrous oxide could potentially cause nitridation, the patent utilizes this decomposition to generate atomic oxygen, which provides oxidation without chromium nitride formation. The process temperature control (700-950°C) and atomic oxygen mechanism transform what could be harmful into a beneficial oxidation process that maintains pore structure integrity.
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 use of atomic oxygen decreases nitride formation, promotes uniform oxide layer formation, and reduces stress on fuel cell components, improving the operational efficiency and longevity of the fuel cell stack.
Implementation Method 1
the atomic oxygen may be generated by thermally decomposing nitrous oxide gas into molecular nitrogen and atomic oxygen
Implementation Method 2
the atomic oxygen may be generated by catalytically decomposing nitrous oxide gas into molecular nitrogen and atomic oxygen
Implementation Method 3
the atomic oxygen may be generated using microwave discharge
Implementation Method 4
forming an oxide layer on exposed surfaces of at least one interconnect using the atomic oxygen
Data Source
AI summary
Embodiments include methods and systems for oxidizing an interconnect for a fuel cell stack that include generating atomic oxygen, and forming an oxide layer on exposed surfaces of at least one interconnect using the atomic oxygen. In various embodiments, the atomic oxygen may be generated by thermally decomposing nitrous oxide gas into molecular nitrogen and atomic oxygen. In further embodiments, the atomic oxygen may be generated by catalytically decomposing nitrous oxide gas into molecular nitrogen and atomic oxygen. In further embodiments, the atomic oxygen may be generated using microwave discharge. In the various embodiments, the oxidation of the interconnect may be a controlled oxidation that is performed prior to incorporating the interconnect into a fuel cell stack.