Oxide Superconducting Wire Dual Stabilizing Layer
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Solution Overview
Problem
The existing techniques for forming oxide superconducting wires face challenges in achieving uniform moisture resistance and cost-effectiveness due to the high cost of silver (Ag) used in stabilizing layers and issues with adhesion and pinhole formation, leading to increased interface resistance and potential degradation of superconducting characteristics.
Innovation Solution
The oxide superconducting wire incorporates a dual stabilizing layer structure, where a thin Ag or Ag alloy first layer is covered by a Cu, Ni, Pb, or Bi-based second layer, reducing Ag usage and enhancing adhesion, thereby forming a plating layer with uniform thickness and high air-tightness, and preventing moisture infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thin Ag undercoat stabilizing layer is formed to reduce cost, then Ag usage is reduced, but moisture resistance becomes insufficient and pinholes form during heat treatment
Solution Approach 1:
The patent applies composite materials by forming a multi-layer undercoat stabilizing layer structure consisting of Ag, Cu, and Ni layers. The Ag layer provides moisture resistance, the Cu layer prevents Ag aggregation during heat treatment, and the Ni layer enhances adhesion. This composite structure resolves the contradiction by maintaining moisture resistance with reduced Ag thickness while preventing pinhole formation through the Cu layer's protective function.
Solution Approach 2:
The undercoat stabilizing layer is segmented into multiple functional layers (Ag layer, Cu layer, Ni layer) rather than using a single thick Ag layer. Each segment performs a specific function: Ag for moisture barrier, Cu for preventing aggregation, and Ni for adhesion. This segmentation allows reduction of Ag thickness while maintaining overall reliability through the coordinated function of all layers.
2Reliability
If a thick Ag undercoat stabilizing layer is formed to ensure moisture resistance, then moisture protection is improved, but Ag usage and cost increase
Solution Approach 1:
The patent replaces a single thick Ag layer with a composite multi-layer structure where Ag, Cu, and Ni layers work together. The Ag layer can be thinner since the Cu and Ni layers provide complementary protective functions, thereby reducing total Ag usage while maintaining or improving moisture resistance.
Solution Approach 2:
The patent introduces Cu and Ni layers that can serve as sacrificial or protective layers, allowing the Ag layer to be thinner. The Cu layer specifically prevents Ag aggregation during heat treatment, enabling the system to use less Ag while maintaining reliability through the combined functionality of all layers.
3Ease of manufacture
If a Cu plating layer is formed on Ni-based alloy substrate to create stabilizing layer, then adhesion is poor and plating layer may peel off
Solution Approach 1:
The patent introduces a Ni layer as part of the undercoat stabilizing layer structure that specifically addresses the adhesion problem between Cu plating and Ni-based alloy substrates. This Ni intermediate layer creates a metallurgical bond that prevents peeling, while still allowing Cu plating to be formed on top for electrical stability.
Solution Approach 2:
The Ni layer acts as an intermediary between the Ni-based alloy substrate and the Cu plating layer. It provides a compatible interface that ensures strong adhesion, preventing the Cu plating layer from peeling off while maintaining the electrical stability function of the Cu layer.
4Quantity of substance
If the undercoat stabilizing layer is made thin to reduce cost, then Ag usage decreases, but interface resistance increases due to pinhole formation
Solution Approach 1:
The patent uses a composite multi-layer structure (Ag-Cu-Ni) where the Cu layer specifically prevents Ag aggregation and pinhole formation during heat treatment. This ensures uniform interface resistance across the conductor, while the overall structure allows reduced Ag thickness to lower cost.
Solution Approach 2:
The Cu layer is positioned to prevent Ag aggregation and pinhole formation before they can occur during subsequent heat treatment processes. This proactive protective layer ensures uniform interface resistance from the outset, preventing defects that would increase resistance.
Data Source
AI summary
An oxide superconducting wire wherein an outer periphery of an oxide superconductor is covered with a plating layer (stabilizing layer). In addition, the oxide superconductor includes: an oxide superconducting laminate that is formed by a tape-shaped substrate, an interlayer, and an oxide superconducting layer, in which the interlayer and the oxide superconducting layer are laminated on a main surface of the substrate; and an undercoat stabilizing layer that is laminated on an outer periphery of the oxide superconducting laminate. The undercoat stabilizing layer includes: a first undercoat stabilizing layer formed of Ag or an Ag alloy; and a second undercoat stabilizing layer formed of one of Cu, Ni, Pb, Bi, and an alloy containing Cu, Ni, Pb or Bi as a major component.