Cold Spray Composite Contact Assembly for Wear Resistance
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Solution Overview
Problem
Existing electrical contact assemblies face issues with wear and erosion due to defects in the interface between the contact and substrate, leading to degradation and separation, which affects their thermal, electrical, and mechanical performance.
Innovation Solution
A contact assembly is fabricated using a composite material with a refractory core and a ductile matrix material, deposited via a cold spray process, creating a dense, well-bonded layer with a core region rich in refractory material for strength and an outer region rich in ductile material for conductivity and heat dissipation, eliminating the need for brazing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a refractory material is used for the contact to provide wear and erosion resistance, then the durability is improved, but the ductility and electrical conductivity deteriorate
Solution Approach 1:
The patent applies composite materials by combining refractory material particles (for wear and erosion resistance) with a ductile matrix material (for conductivity and impact resistance). This creates a contact that exhibits both the hardness of refractory materials and the ductility of soft metals, resolving the contradiction between wear resistance and ductility.
Solution Approach 2:
The patent implements local quality by creating a composite structure where refractory material is distributed within a ductile matrix. The refractory particles provide localized wear and erosion resistance at the contact surface, while the ductile matrix provides overall structural integrity, conductivity, and impact absorption throughout the contact body.
2Ease of manufacture
If brazing is used to bond the contact to the substrate, then the assembly is achieved, but voids are created at the interface that degrade heat transfer and lead to separation
Solution Approach 1:
The patent extracts the harmful brazing process from the manufacturing sequence and replaces it with a cold spray deposition method. This eliminates the source of interface voids while achieving secure bonding between the composite contact material and the substrate through cold welding and mechanical interlocking.
Solution Approach 2:
The patent replaces the thermal brazing process with a mechanical cold spray deposition process. Instead of using heat and filler metal to create bonds, the process uses high-velocity particle impact to create metallurgical bonds without melting, thereby eliminating the void formation associated with brazing.
3Reliability
If a composite material with refractory particles is deposited via cold spray, then wear resistance is improved, but the deposition process complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the cold spray deposition parameters (gas pressure, temperature, particle velocity, feedstock composition) to achieve proper deposition of composite material. By controlling these parameters, the process successfully deposits refractory particles within a matrix material while maintaining a dense, void-free structure, making the complex process manageable and repeatable.
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 method results in a durable, conductive contact assembly with enhanced wear resistance and improved bonding, reducing manufacturing costs while maintaining high-quality electrical and mechanical properties.
Implementation Method 1
directing the gas stream and entrained feedstock through a nozzle onto a substrate to dispose the feedstock on the substrate in a continuous layer
Implementation Method 2
axially feeding a powder feedstock into a gas stream of a cold spray deposition apparatus
Implementation Method 3
a refractory material, such as tungsten, nickel, molybdenum, or tungsten carbide, to provide resistance to erosion and impact wear
Implementation Method 4
graphite to provide resistance to welding of contacts while maintaining low electrical resistance
Implementation Method 5
an outer region rich in ductile material for conductivity and heat dissipation
Data Source
AI summary
A contact assembly for an electrical device and a method for making such an assembly are presented. The contact assembly comprises a substrate and a contact material disposed on the substrate. The contact material comprises a composite material comprising a refractory material and a matrix material. The matrix material has a higher ductility than the refractory material. The composite material further comprises a core region and an outer region bounding the core region, the core region having a higher concentration of the refractory material than the outer region. The method applies cold spraying a blended feedstock to produce a layer that includes the composite material described above.