Cold Spray Deposition of Brittle Functional Materials
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Solution Overview
Problem
The existing supersonic cold spray technology is limited in depositing brittle functional materials with feature sizes smaller than the typical nozzle exit area, making it difficult to achieve micro-scale features and thin layers, especially for materials like semiconductors, magnetic materials, and optical materials, which require smaller particle sizes and non-uniform shapes.
Innovation Solution
The use of a supersonic cold-spray process with controlled particle sizes, shapes, and distributions, combined with specific nozzle designs and masking techniques, allows for the deposition of brittle functional materials with feature sizes as small as 10 microns, achieving near theoretical density layers and micro-thin features on various surfaces, including metals, glass, and ceramics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cold spray technology is used with standard nozzle exit areas, then deposition of metallic materials is achieved, but deposition of micro-scale features and thin layers of brittle functional materials is not possible
Solution Approach 1:
The patent applies local quality by using masking techniques to selectively deposit material only in specific micro-scale regions of the substrate. The mask defines precise deposition areas, enabling micro-scale feature creation while maintaining the ability to deposit various brittle functional materials. This resolves the contradiction by making the deposition process adaptable to both small features and diverse material types through localized control.
Solution Approach 2:
The patent changes key process parameters including reducing particle size to sub-micron ranges, optimizing gas pressure and temperature, and adjusting nozzle geometry to achieve supersonic velocities. These parameter changes enable the deposition of brittle functional materials with micro-scale precision, resolving the contradiction between manufacturing precision and material versatility.
2Manufacturing precision
If particle size is reduced to achieve micro-scale features, then feature size precision is improved, but particle deformation capability deteriorates
Solution Approach 1:
The patent utilizes phase transitions by heating the gas stream to elevated temperatures (but below material melt points) before supersonic expansion. This thermal energy enables sub-micron brittle particles to deform plastically upon impact without melting, resolving the contradiction between achieving micro-scale features through particle size reduction and maintaining particle deformation capability for strong bonding.
Solution Approach 2:
The patent employs pneumatic acceleration through a de Laval nozzle to achieve supersonic velocities of particles. The gas dynamics and pressure gradients provide the necessary kinetic energy for particle deformation and bonding, enabling micro-scale feature deposition while maintaining particle deformation capability through optimized gas-particle interaction.
3Manufacturing precision
If nozzle exit area is reduced to deposit micro-scale features, then feature size is improved, but deposition rate and productivity deteriorate
Solution Approach 1:
The patent applies segmentation by using masking techniques to divide the deposition process into multiple targeted steps. The mask is applied to the substrate, and material is deposited only in the exposed regions. This allows micro-scale feature deposition with high precision while maintaining productivity by avoiding unnecessary deposition in masked areas and enabling efficient material utilization.
4Quantity of substance
If brittle materials are used without ductile binders, then material purity and functional properties are improved, but adhesion between particles and substrate deteriorates
Solution Approach 1:
The patent utilizes phase transitions by controlling the thermal state of the gas stream and particles during supersonic expansion. The heated gas provides thermal energy that enables brittle particles to undergo plastic deformation upon impact, creating strong mechanical interlocking and metallurgical bonding without requiring ductile binders. This maintains material purity while achieving strong adhesion through controlled phase transition effects.
Solution Approach 2:
The patent changes process parameters including gas temperature, pressure, and particle velocity to optimize adhesion of brittle materials. By adjusting these parameters, the kinetic energy and thermal energy are balanced to enable particle deformation and strong bonding without adding ductile materials, resolving the contradiction between material purity and adhesion strength.
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 enables the successful deposition of fine and micro features of brittle materials, such as semiconductors and magnetic materials, with feature sizes down to 10 microns, maintaining the materials' functional properties and expanding the application of cold spray technology to complex components and devices.
Implementation Method 1
A helium, nitrogen or other gas stream under pressure is accelerated to supersonic velocity by expansion through a de Laval type converging-diverging nozzle
Implementation Method 2
accelerated to supersonic velocity by expansion through a de Laval type converging-diverging nozzle
Implementation Method 3
The metal particles in the size range from 5-80 micrometers become entrained within the gas and are directed towards the surface where they deform and knit together on impact forming a strong bond with the surface and with each other without melting
Data Source
AI summary
An apparatus and methods to make a product using supersonic cold-spray deposition of brittle functional materials in fine and micro features down to 10 μm in minimum dimension. The process may use semiconductors such as bismuth and antimony telluride formulations, and hard magnetic materials such as neodymium iron boride and strontium ferrite, and soft magnetic materials such as manganese zinc ferrite, and manganese ferrite materials. In addition, the methods and processes have been demonstrated for materials as soft as graphite and as hard as boron carbide. Micro components have been deposited in square, tapered and elongated shaped features with feature sizes as small as 10 μm in minimum dimensions and applied to flat and highly complex shaped surfaces. This process when combined with other cold spray manufacturing processes allows the total additive manufacturing of complete electronic, magnetic and other complex devices including multiple type of brittle functional materials.