Superconducting Wire Substrate Asymmetric Surface Roughness
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Solution Overview
Problem
The challenge in manufacturing high-performance superconductive wire materials lies in achieving high crystalline orientation and epitaxial growth of oxide layers on substrates, where surface roughness defects and fluctuations can lead to reduced critical current values and manufacturing issues, particularly with the back side surface roughness of substrates not being adequately controlled during the formation of intermediate layers.
Innovation Solution
A superconductive wire material substrate is developed with specific surface roughness profiles for both sides, where one surface has a roughness of 10 nm or less and the other surface has a roughness of 8 nm to 15 nm, achieved through a method involving cold-rolling with rolls of different surface roughnesses and subsequent heat treatment, ensuring optimal orientation and minimizing damage during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness Ra of both surfaces is reduced to a few nm by mechanical polishing, then the crystalline orientation and epitaxial growth are improved, but the substrate and susceptor are easily damaged during contact
Solution Approach 1:
The patent applies different surface roughness treatments to different surfaces of the substrate. The front surface (to be coated) is polished to Ra ≤ 10 nm for high crystalline orientation, while the back surface is controlled to have Ra between 3 nm and 10 nm to prevent damage during contact with the susceptor. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
Solution Approach 2:
The patent creates an asymmetric surface roughness profile where the front and back surfaces have different roughness characteristics. The front surface has Ra ≤ 10 nm for optimal coating adhesion and crystalline growth, while the back surface has Ra between 3-10 nm to provide mechanical protection during handling and contact. This asymmetry allows each surface to serve its specific purpose without compromising the other.
2Reliability
If the surface roughness Ra is controlled to a few nm, then the critical current value property is improved, but the manufacturing complexity increases due to additional polishing processes
Solution Approach 1:
The patent specifies precise surface roughness parameter ranges (Ra ≤ 10 nm for front surface, Ra between 3-10 nm for back surface) that can be achieved through controlled rolling and heat treatment processes. By defining these specific parameter ranges, the patent enables optimization of critical current value while maintaining manageable manufacturing complexity through standardized process control.
Solution Approach 2:
The patent performs surface roughness control during the rolling and heat treatment stages before the coating process. By establishing the appropriate surface roughness characteristics in advance, before intermediate layer formation, the patent ensures optimal conditions for epitaxial growth and high critical current values without requiring complex post-processing steps.
3Manufacturing precision
If the back side surface roughness Ra is reduced to match the front side, then the substrate-susceptor contact is improved, but the manufacturing yield decreases due to increased damage risk
Solution Approach 1:
The patent applies different surface roughness specifications to the front and back surfaces based on their respective functions. The front surface requires Ra ≤ 10 nm for uniform contact during coating, while the back surface is optimized with Ra between 3-10 nm to reduce damage risk during handling and contact with the susceptor. This localized optimization maintains contact uniformity where needed while preserving manufacturing yield.
Solution Approach 2:
The patent defines specific surface roughness parameter ranges for each surface to balance contact quality and damage prevention. By controlling the back surface roughness to Ra between 3-10 nm (not excessively smooth), the patent reduces the risk of damage during susceptor contact while still providing adequate contact uniformity for the coating process, thereby maintaining high manufacturing yield.
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
This approach enables the production of high-performance, long superconductive wire material substrates with improved superconductivity and reduced defects, allowing for efficient manufacturing of high-strength and high-orientation superconductive wire materials.
Implementation Method 1
a step of cold-rolling of a metal body
Implementation Method 2
a step of heat-treating of the cold-rolled metal body
Data Source
Figure 1
Figure 2
AI summary
Provided is a less expensive and high-performance superconductive wire material substrate, a method of manufacturing the less expensive and high-performance superconductive wire material substrate, and a superconductive wire material using the less expensive and high-performance superconductive wire material substrate. A superconductive wire material substrate 1 is formed such that a surface roughness Ra of one surface is 10 nm or less, and a surface roughness Ra of an other surface is larger than the surface roughness Ra of the one surface, and is 8 nm or more and less than 15 nm, between the surface roughnesses Ra of both surfaces of the superconductive wire material substrate 1.