Cold Spray Metal Matrix Composite Coatings
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Solution Overview
Problem
Existing methods for producing metal matrix composite (MMC) coatings and freestanding bulk forms face issues such as oxidation, delamination, decomposition, and degradation during thermal spray techniques, leading to poor quality and performance characteristics due to improper particle size selection, blending techniques, and consolidation procedures.
Innovation Solution
The method involves blending metal and ceramic powders with predetermined particle sizes to create homogeneous MMC powders, which are then deposited using cold spray deposition with controlled spray parameters, employing a non-oxidizing carrier gas to ensure plastic deformation and bonding upon impact, avoiding metallurgical transformation and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal spray techniques are used to deposit MMC coatings, then coating deposition is achieved, but oxidation of metal powders occurs leading to unacceptable composite bulk form
Solution Approach 1:
The patent employs cold spray technology that operates in an inert or controlled atmosphere environment, preventing oxidation of metal powders during deposition. The process uses compressed gas to accelerate particles without thermal exposure to oxygen, thereby eliminating the harmful oxidation effect while maintaining high productivity in coating deposition.
2Productivity
If thermal spray techniques are used, then coating is deposited, but delamination and bond failure occur at matrix-particulate interface
Solution Approach 1:
The patent changes the fundamental parameters of the deposition process by transitioning from thermal spray to cold spray technology. This involves changing the temperature parameter from high-temperature thermal processes to ambient or low-temperature cold processes, and changing the particle acceleration mechanism from thermal expansion to compressed gas propulsion. These parameter changes prevent the thermal degradation and interface delamination problems while maintaining deposition efficiency.
3Ease of manufacture
If consolidation processing is performed, then MMC bulk form is formed, but decomposition and preferential evaporation of components occur
Solution Approach 1:
The patent utilizes the phase transition characteristics of the carrier gas (compression and expansion of gas phases) to accelerate and deposit particles without subjecting the MMC components to high-temperature consolidation processing. The compressed gas propels particles through phase transitions that enable deposition while preserving the chemical stability and preventing decomposition of ceramic and metal components.
4Productivity
If spray coating of tungsten carbide-cobalt powder is performed, then coating is deposited, but decarborization and matrix dissolution occur
Solution Approach 1:
The cold spray process operates in an inert or oxygen-controlled environment that prevents decarborization of tungsten carbide and dissolution of the cobalt matrix. By eliminating exposure to oxidizing atmospheres during deposition, the patent preserves the chemical integrity of the coating materials while maintaining efficient coating formation.
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 produces dense, strong, and well-bonded MMC coatings and freestanding bulk forms with enhanced mechanical and thermal properties, overcoming issues of oxidation and degradation, and achieving high-quality composite materials.
Implementation Method 1
depositing the metal matrix composite powder onto a surface of the substrate using a non-oxidizing carrier gas such that the metal matrix composite powder plastically deforms and bonds to the substrate and itself upon impact with the substrate surface
Implementation Method 2
the metal matrix composite powder plastically deforms and bonds to the substrate and itself upon impact
Implementation Method 3
a supersonic gas jet is formed by a converging/diverging nozzle which is used to accelerate the powder particles towards the substrate
Implementation Method 4
Thermal spray techniques such as flame, high velocity and plasma, that are performed in an open air environment lead to oxidation of the metal powders
Data Source
AI summary
A method of manufacturing homogenous metal matrix composite (MMC) powders and using the powders as the feedstock with cold spray deposition is described to produce composite coatings and freestanding bulk forms. Measured quantities of metal and ceramic powders having predetermined particle sizes are blended to produce homogeneous MMC powders. Spray parameters and procedures are controlled to produce dense, strong and well-bonded MMC coatings on any substrate.