Oxide Superconducting Wire Copper Stabilization Layer
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Solution Overview
Problem
Superconducting wires used in coils face deterioration and breakage due to repeated tensile stress, especially when the stabilization layer's surface roughness is too high, leading to compromised superconducting characteristics.
Innovation Solution
A superconducting wire configuration with a copper plating stabilization layer having a thickness of 2 to 100 μm and an arithmetic mean roughness ratio of 0.005 to 0.05, along with an intermediate layer between the substrate and oxide superconducting layer, ensures the wire's stability under repeated tensile stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface roughness of the stabilization layer is increased to prevent swelling and peeling, then the adhesion to resin coat is improved, but the superconducting characteristics deteriorate and wire breakage occurs due to excessive roughness under repeated tensile stress
Solution Approach 1:
The invention changes the parameters of surface roughness (Ra) and thickness (d) of the stabilization layer to resolve the contradiction. By specifying that Ra/d ratio should be 0.03 or less and Ra should be 0.5 μm or less, the invention finds an optimal parameter range that provides sufficient adhesion to resin coat while preventing superconducting characteristic deterioration and wire breakage under repeated tensile stress.
Solution Approach 2:
The invention uses a composite structure with multiple layers including the stabilization layer (copper plating), superconducting layer, and substrate. This composite material approach allows the stabilization layer to provide both mechanical support (preventing swelling and peeling) and electrical stability, while the controlled surface properties ensure proper adhesion to resin coat without compromising superconducting performance.
2Strength
If the surface roughness of the stabilization layer is increased to improve adhesion, then the resin coat bonding is enhanced, but the wire breaks due to surface roughness under repeated tensile stress
Solution Approach 1:
The invention resolves this contradiction by establishing specific parameter ranges: Ra/d ≤ 0.03 and Ra ≤ 0.5 μm. These parameter changes ensure that the stabilization layer has sufficient surface roughness for resin coat adhesion while maintaining smoothness and structural integrity to withstand repeated tensile stress without wire breakage.
3Object-affected harmful factors
If the stabilization layer is made smoother to maintain superconducting characteristics, then wire breakage is prevented, but adhesion to resin coat deteriorates
Solution Approach 1:
The invention resolves this contradiction by optimizing the Ra and d parameters. By setting Ra/d ≤ 0.03 and Ra ≤ 0.5 μm, the invention achieves a balance where the stabilization layer maintains sufficient smoothness to preserve superconducting characteristics while having adequate surface roughness for reliable adhesion to the resin coat.
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 wire's characteristics remain intact even after 100,000 cycles of tensile testing, maintaining a critical current ratio of 0.99 or more, thereby preventing deterioration and breakage.
Implementation Method 1
a stabilization layer made of copper plating formed around the superconducting laminate
Implementation Method 2
an oxide superconducting layer laminated on a substrate
Data Source
AI summary
A superconducting coil comprising an oxide superconducting wire includes: a superconducting laminate comprising a substrate and an oxide superconducting layer; and a stabilization layer made of copper plating formed around the superconducting laminate. A thickness d of the stabilization layer is in the range of 10 to 40 μm. A ratio Ra/d of the thickness d of the stabilization layer and an arithmetic mean roughness Ra of an outer surface of the stabilization layer is in the range of 0.005 to 0.03. An intermediate layer is arranged between the substrate and the oxide superconducting layer. When a tensile test of pulling the oxide superconducting wire in a longitudinal direction within a stress range of 180 to 600 MPa in liquid nitrogen is performed, a ratio of a critical current when a repeated pulling number reaches 100,000 times and an initial critical current measured before the tensile test is 0.99 or more.