High-Temperature Superconducting Tape Substrate Optimization
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Solution Overview
Problem
Conventional high-temperature superconducting tapes face issues with reduced critical current density and surface roughness due to metal substrate diffusion and thick buffer layers, leading to increased manufacturing costs and tape thickness.
Innovation Solution
A high-temperature superconducting tape using a SUS310s or stainless steel substrate with adjusted silicon and molybdenum composition and reduced crystal grain size, combined with a buffer layer of yttrium oxide, magnesia, or alumina, to enhance electropolishing and prevent metal diffusion, resulting in improved critical current characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional metal substrate (e.g., hastelloy or nickel-based alloy) is used, then the substrate provides good mechanical strength and flexibility, but metal components diffuse into the superconducting layer at high temperature, deteriorating superconducting characteristics
Solution Approach 1:
A buffer layer comprising multiple layers (seed layer, IBAD template, homogeneous epitaxial buffer layer, and lattice-matched buffer layer) is introduced as an intermediary between the metal substrate and the superconducting layer. This buffer layer prevents direct contact and diffusion between the substrate and superconducting materials while providing a suitable template for epitaxial growth of the superconducting layer.
2Reliability
If a buffer layer is formed to prevent metal diffusion, then superconducting characteristics are improved, but the buffer layer increases the total thickness of the superconducting tape and manufacturing complexity
Solution Approach 1:
The buffer layer is divided into multiple functional layers with specific thicknesses optimized for each function: seed layer (5-50 nm), IBAD template (50-200 nm), homogeneous epitaxial buffer layer (200-500 nm), and lattice-matched buffer layer (50-200 nm). This segmentation allows each layer to perform its specific function efficiently while minimizing total thickness.
3Manufacturing precision
If the buffer layer is made thick to ensure proper superconducting layer deposition, then superconducting characteristics are improved, but manufacturing time and cost increase significantly
Solution Approach 1:
The invention optimizes the thickness parameters of each buffer layer component to achieve the minimum necessary thickness for proper superconducting layer deposition. By precisely controlling the thickness of each layer within specific ranges, the invention achieves high manufacturing precision while minimizing total buffer layer thickness and manufacturing time.
4Reliability
If a diffusion barrier layer is formed to prevent metal diffusion, then superconducting characteristics are improved, but the surface roughness of the buffer layer increases, requiring a thicker template
Solution Approach 1:
The IBAD template layer acts as an intermediary that provides a smooth surface for subsequent buffer layers. This layer, formed by ion beam assisted deposition, creates a template with controlled surface morphology that enables smooth epitaxial growth of the homogeneous buffer layer, thereby maintaining surface smoothness while preventing metal diffusion.
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 significantly enhances the critical current density and surface smoothness of the superconducting tape, reducing manufacturing costs and improving overall tape performance by allowing a thinner buffer layer and higher-grade superconducting layer deposition.
Implementation Method 1
a stainless steel substrate, which is advantageous to electropolishing, is used
Implementation Method 2
it is required to form a buffer layer, serving as a diffusion barrier, between the YBCO superconducting layer and the metal substrate
Data Source
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AI summary
Disclosed herein is a high-temperature superconducting tape, including: a substrate; a buffer layer formed on the substrate; and a high-temperature superconducting layer formed on the buffer layer, wherein the substrate is made of SUS310s or stainless steel containing 0.01 - 1% of silicon (Si) and 1 - 5% of molybdenum (Mo) and has an average metal crystal grain size of 12 µm or less, and the high-temperature superconducting layer is made of a ReBCO (ReBa2Cu3O7, Re = Nd, Sm, Eu, Gd, Dy, Ho, Y)-based superconductive material. The high-temperature superconducting tape is advantageous in that a stainless steel substrate is inexpensive and easily electroplished, so that the surface roughness thereof is low and thus the thickness of a buffer layer can be reduced, with the result that a high-grade superconducting layer can be deposited on the thin buffer layer and thus the critical current density of the high-temperature superconducting tape can be improved, thereby remarkably improving the characteristics of the high-temperature superconducting tape.