Superconducting Wire Insulation Coating Surface Roughness Control
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Solution Overview
Problem
Rare earth element-based superconductor wires with a laminated structure face peeling issues due to thermal expansion differences between the epoxy resin and metal substrate, leading to potential delamination of the intermediate and superconductor layers during coil processing and cooling.
Innovation Solution
A superconductor wire with a laminated structure featuring a substrate, intermediate layer, superconductor layer, and metal stabilization layers, coated with an insulation layer that maintains a maximum height roughness of 890 nm or less, ensuring appropriate adhesion and reducing peeling stress, and a surface roughness of 80 nm or less to prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick resin layer is applied and baked to form insulation coating on rare earth element-based superconductor wire, then electrical insulation is ensured, but peeling stress increases due to thermal expansion difference between resin and metal substrate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness of the metal substrate within 0.03 to 0.2 micrometers and the resin layer thickness to 10-50 micrometers. These parameter optimizations ensure adequate electrical insulation while minimizing peeling stress caused by thermal expansion differences between the resin and metal substrate.
Solution Approach 2:
The patent implements local quality by creating specific surface roughness characteristics on the metal substrate surface. The controlled roughness provides localized anchoring points for the resin layer, enhancing adhesion in critical areas without requiring a uniformly thick resin coating, thereby reducing overall peeling stress.
2Reliability
If insulating tapes are wound to overlap each other for insulation coating, then electrical insulation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the mechanical winding system with a chemical deposition system. Instead of mechanically winding insulating tapes, the invention uses a resin coating process where liquid resin is applied and then baked to form a solid insulation layer. This substitution eliminates the complexity of tape winding while ensuring uniform electrical insulation.
3Strength
If the surface roughness of metal substrate is increased to improve resin adhesion, then bonding strength increases, but peeling stress concentration increases leading to layer delamination
Solution Approach 1:
The patent resolves this contradiction through precise parameter control, specifying surface roughness within the optimal range of 0.03 to 0.2 micrometers. This parameter optimization ensures sufficient bonding strength for resin adhesion while preventing excessive roughness that would concentrate peeling stress and cause layer delamination during thermal cycling.
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 prevents peeling of the intermediate and superconductor layers, maintaining the structural integrity of the superconducting coil and ensuring stable superconducting characteristics even under thermal stress.
Implementation Method 1
an insulation coating layer that covers an outer surface of the superconducting laminate and is formed by baking a resin material
Implementation Method 2
peeling stress is applied in the vertical direction of the superconductor wire 200 during the cooling of the superconducting coil due to a difference in thermal expansion between the epoxy resin, which is an impregnating material, and the metal substrate 201
Data Source
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AI summary
A superconductor wire includes: a superconducting laminate that includes: a substrate and an intermediate layer; a superconductor layer, and a metal stabilization layer which are laminated on the substrate; and an insulation coating layer that covers an outer surface of the superconducting laminate and is formed by baking a resin material. Further, a maximum height Rz of at least a part of the outer surface of the superconducting laminate covered with the insulation coating layer is 890 nm or less.