Functionally Graded Electrical Contacts via Cold Spray Deposition
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Solution Overview
Problem
The existing metal powder sintering process for producing electrical contacts is time-consuming, requiring three vacuum sintering runs and extensive machining, making it inefficient and costly, and often results in a uniform composition that wastes expensive hard metals by dispersing them throughout the contact unnecessarily.
Innovation Solution
The method involves using cold spray additive manufacturing or friction stir additive manufacturing to deposit a first and second metal in a functionally graded manner, varying their composition throughout the contact to achieve high conductivity and arc erosion resistance, with the second metal only being present in necessary regions, thereby reducing production time and material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal powder sintering process is used to produce electrical contacts, then the contacts achieve sufficient density and metallurgical bonds, but the production time becomes excessively long (6-10 days) requiring three vacuum sintering runs
Solution Approach 1:
The patent changes the fundamental processing parameters from thermal sintering (6-10 days at elevated temperatures in vacuum) to cold spray deposition (minutes at ambient temperature in atmosphere). This parameter transformation achieves rapid solid-state bonding through high-velocity particle impact and plastic deformation, eliminating the need for multiple vacuum sintering runs while maintaining contact integrity
Solution Approach 2:
The patent replaces the thermal-metallurgical bonding mechanism of sintering with a mechanical bonding mechanism. Cold spray particles are accelerated to supersonic velocities and deform plastically upon impact with the substrate and each other, creating mechanically interlocked bonds that achieve sufficient contact strength without thermal processing
2Manufacturing precision
If metal powder sintering process is used, then electrical contacts are produced, but extensive machining is required to achieve specific configuration requirements
Solution Approach 1:
The patent performs preliminary shaping during the deposition process itself. The cold spray system deposits material in controlled layers that build up the contact geometry progressively, allowing configuration features to be formed during manufacturing rather than requiring post-production machining operations
3Ease of manufacture
If uniform composition is used in electrical contacts, then manufacturing is simplified, but expensive hard metals are wasted by dispersing them throughout the contact unnecessarily
Solution Approach 1:
The patent implements local quality by varying the composition of deposited material as a function of position within the contact. The cold spray system can change powder feed composition during deposition, creating regions with different metal ratios - for example, higher hard metal content at the contact surface for erosion resistance and lower content in the bulk for conductivity
Solution Approach 2:
The patent creates composite material structures with spatially varying composition. By depositing different metal powder combinations in different regions, the contact becomes a functionally graded composite material that optimizes both electrical conductivity and arc erosion resistance in their respective locations
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 significantly reduces production time to between 2 minutes and 25 minutes, enhances mechanical strength and arc erosion resistance, and optimizes the use of expensive hard metals by only incorporating them where needed, resulting in a more economical and efficient electrical contact.
Implementation Method 1
depositing the first metal and second metal on a substrate by applying a compressed gas to the metals to eject the metals toward the substrate, wherein the depositing is performed under a pressure sufficient to form a solid state bond between the first and second metals to yield a material column, while maintaining the material column at a temperature that is below the melting temperature of both the first and second metals
Implementation Method 2
operating a material feeder on a friction stir additive device to release a feed of a first solid state metal and a second solid state metal onto a substrate, yielding a material column
Data Source
AI summary
The presently disclosed subject matter relates to multi-material electrical contacts, and methods of making multi-material electrical contact comprising a functionally graded monolithic structure, having a first metal and a second metal, an amount of the second metal as compared to an amount of the first metal increases with distance in the structure from a first surface to a second opposing surface of the structure such that the second metal content increases continuously or incrementally throughout the height of the electrical contact.