Segmented Superconducting Filaments with Compliant Buffer
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Solution Overview
Problem
Second-generation high-temperature superconducting (HTS) tapes exhibit mechanical weakness due to debonding and delamination issues, particularly at the interface between the LaMnO3 top buffer layer and the REBa2Cu3Ox superconducting film, and are prone to coil degradation under transverse stresses, limiting their commercial deployment in energy and other applications.
Innovation Solution
A novel 2G HTS tape architecture featuring a plurality of superconducting filaments with a compliant material layer, such as silver, disposed between the filaments and extending between the substrate and overlayer, creating gaps less than 100 μm in width to redirect and mitigate transverse tensile stresses, thereby enhancing mechanical and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional 2G HTS tape architecture with multiple oxide films on metallic substrate is used, then the tape can be manufactured with standard processes, but the tape exhibits mechanical weakness due to debonding and delamination at interfaces
Solution Approach 1:
The superconducting layer is divided into multiple discrete filaments rather than a continuous layer. This segmentation prevents crack propagation across the entire tape width and reduces stress concentration at interfaces, thereby improving transverse tensile strength while maintaining manufacturability through established deposition processes
Solution Approach 2:
A compliant material layer is introduced as an intermediary between the substrate and the superconducting filaments. This intermediate layer accommodates thermal expansion mismatches and mechanical stresses, preventing debonding and delamination at the substrate-superconductor interface while allowing standard manufacturing processes to be used
2Reliability
If the tape structure uses multiple oxide films and metallic substrate with silver and copper overlayers, then the electrical properties can be maintained, but the complex composite structure is prone to delamination within the superconductor layer
Solution Approach 1:
The superconducting layer is segmented into multiple filaments, which simplifies the internal stress distribution within the composite structure. This segmentation reduces the complexity of managing multiple oxide films by creating discrete units that are less prone to delamination, while maintaining the necessary electrical properties through the filament configuration
Solution Approach 2:
Different regions of the tape are assigned different functions: the compliant material layer handles mechanical stress accommodation, the silver overlayer provides electrical conductivity and protection, and the segmented superconducting filaments provide the superconducting function. This local specialization reduces overall system complexity by optimizing each component for its specific function
3Ease of manufacture
If epoxy impregnation is used in coil fabrication, then the coils can be manufactured, but the difference in thermal expansion coefficients between tape and epoxy results in transverse stress on the tape causing coil degradation
Solution Approach 1:
The compliant material layer serves as a buffer between the superconducting filaments and the epoxy impregnation in coils. This intermediate layer absorbs thermal expansion differences between the tape and epoxy, reducing transverse stresses during thermal cycling while maintaining coil fabrication capability
Solution Approach 2:
The segmented filament structure allows for better stress distribution when epoxy is applied during coil fabrication. The gaps between filaments and the compliant material create stress relief zones that prevent crack propagation through the entire tape structure, maintaining transverse stress resistance during coil manufacturing and operation
Data Source
AI summary
A configuration and a method of constructing a high-temperature superconductor tape including a plurality superconducting filaments sandwiched between a substrate and an overlayer comprising compliant material extending to the substrate through gaps between each superconducting filament thereby isolating each superconducting filament.