Ternary Molybdenum Chalcogenide Superconducting Wire Manufacturing
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Solution Overview
Problem
Current high field superconductors, such as NbTi and Nb3Sn, face limitations in achieving sufficient engineering critical current densities and mechanical strength, particularly at high magnetic fields, due to granular behavior and poor intergrain connectivity, which restricts their application in large-scale magnet systems like MRI and High Energy Physics.
Innovation Solution
The process involves hot plastic/superplastic deformation of 100% dense TMC bulk material using a molybdenum barrier and stainless steel jacket to enhance intergrain connectivity, eliminating granular behavior and achieving high engineering critical current densities, with the molybdenum barrier acting as both a stabilizer and diffusion barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Nb3Sn superconductors are used to achieve higher magnetic fields up to 24 Tesla, then the magnetic field strength is improved, but the material becomes brittle and requires complex assembly manufacturing processes, increasing cost and reducing ease of manufacture
Solution Approach 1:
The patent changes the material composition parameters by using ternary molybdenum chalcogenides (TMC) with specific stoichiometric ratios instead of conventional Nb3Sn, enabling high field performance with improved manufacturability through powder metallurgy and hot deformation processes
Solution Approach 2:
The patent employs composite material structures with TMC superconducting phase embedded in metal matrices (such as Mo, Nb, or Ta), combining the advantages of high field superconductivity with mechanical strength and ease of processing
2Ease of manufacture
If conventional powder metallurgy processes are used to manufacture TMC wires, then the manufacturing process is simplified, but poor intergrain connectivity and granular behavior result in insufficient engineering critical current densities
Solution Approach 1:
The patent changes the processing parameters by implementing hot plastic and superplastic deformation at elevated temperatures (500-1200°C) to achieve 100% dense bulk material with eliminated porosity and improved intergrain connectivity, transforming the material from granular to homogeneous structure
Solution Approach 2:
The patent applies localized hot deformation treatment to the TMC bulk material to achieve uniform density and connectivity throughout the wire cross-section, ensuring consistent superconducting properties along the entire conductor length
3Reliability
If heat treatment after magnet winding is applied to Nb3Sn superconductors to form the superconducting phase, then the superconducting properties are achieved, but the process complexity and cost increase significantly
Solution Approach 1:
The patent performs preliminary formation of the superconducting TMC phase during the wire manufacturing process itself, rather than requiring post-winding heat treatment. The hot deformation process simultaneously densifies the material and establishes the superconducting phase, eliminating subsequent processing steps
4Stability of the object's composition
If barrier materials such as tantalum or niobium are used to prevent intergrain diffusion, then diffusion protection is improved, but granular behavior is favored due to sulfur diffusion along grain boundaries at higher temperatures
Solution Approach 1:
The patent changes the temperature parameter profile by conducting hot deformation at optimized temperature ranges and durations that achieve sufficient densification without excessive sulfur diffusion, thereby maintaining barrier effectiveness while avoiding granular behavior
Solution Approach 2:
The patent uses molybdenum as an intermediary barrier material between the TMC core and external environment, providing effective diffusion protection while maintaining compatibility with the superconducting phase and preventing granular behavior
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 results in TMC superconducting wires with uniform engineering critical current densities exceeding 100 A/mm2 at magnetic fields above 22 Tesla, enabling the construction of high field magnets without the need for heat treatment after winding, and offering improved mechanical strength and cost efficiency.
Implementation Method 1
molybdenum barrier with a residual resistivity ratio (RRR) of at least 100... preventing intergrain diffusion
Implementation Method 2
hot plastic/superplastic deformation of 100% dense TMC bulk material... to enhance intergrain connectivity
Implementation Method 3
hot plastic/superplastic deformation... followed by hot extrusion and hot wire drawing
Implementation Method 4
hot isostatic pressing (HIP) to form 100% dense TMC bulk material
Implementation Method 5
molybdenum barrier... acting as both a stabilizer and diffusion barrier... with a residual resistivity ratio (RRR) of at least 100
Implementation Method 6
high purity molybdenum with a residual resistivity ratio (RRR) of at least 100... serves as a stabilizer
Data Source
AI summary
The present invention concerns a process for the manufacturing of single or multifilamentary superconducting wires of ternary molybdenum chalcogenide (TMC), in particular of SnMo6S8 or PbMo6S8. 100% dense bulk material formed by hot isostatic pressing (HIP) of TMC powder is inserted into a molybdenum/stainless steel can and deformed by hot extrusion and hot wire drawing, thereby allowing for perfect TMC grain boundaries essential for an increase of the critical current density above 100 A/mm2 at high magnetic fields.