Cold Spray Repair of Engine Alloys While Preserving Microstructure
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Solution Overview
Problem
Existing methods for repairing high-temperature metal alloy components in gas turbine engines, such as arc welding and thermal spray, alter the metallurgical microstructure of the material, making them unsuitable for maintaining the structural integrity of the components.
Innovation Solution
A cold spray process that uses a cold spray system to deposit metal powders onto the components, maintaining the material's properties by operating at specific temperature and pressure conditions to ensure the deposited material has at least 50% of the parent material's property values, thereby preserving the structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If traditional welding or thermal spray methods are used to add material to high temperature metal alloy components, then material can be added to repair worn or corroded areas, but the metallurgical microstructure of the added material is altered, compromising structural integrity
Solution Approach 1:
The invention changes the temperature parameter of the spray process from high temperature (thermal spray) to low temperature (cold spray), specifically maintaining substrate temperature below 100°F (37.8°C) during deposition. This parameter change prevents metallurgical microstructure alteration while still enabling material addition for repair purposes
Solution Approach 2:
The invention replaces the thermal field (heat-based welding and thermal spray) with a kinetic field (cold spray using high-velocity particles). Material is deposited through kinetic energy impact rather than thermal fusion, eliminating microstructure alteration while achieving successful repair
2Reliability
If cold spray is used to add material without altering microstructure, then metallurgical integrity is maintained, but achieving sufficient material deposition is difficult
Solution Approach 1:
The invention introduces dynamic elements to the cold spray process by using high-velocity gas flow (supersonic or near-supersonic speeds) to accelerate powder particles. This dynamic approach enables sufficient material deposition by increasing particle kinetic energy and impact frequency, overcoming the low deposition efficiency limitation of traditional cold spray
3Productivity
If high velocity powder is used in cold spray to improve deposition, then material can be added effectively, but the complexity of the spray system increases
Solution Approach 1:
The invention uses pneumatic principles to generate high-velocity gas flow through carefully designed nozzle geometries. By utilizing compressed gas expansion and converging-diverging nozzle design, the system achieves supersonic particle velocities without requiring complex mechanical acceleration systems, thus maintaining relative system simplicity while improving deposition efficiency
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 cold spray process effectively repairs high-temperature metal alloy components without altering their metallurgical microstructure, ensuring the repaired components retain similar mechanical properties to the original materials, thus maintaining the structural integrity and operational efficiency of the gas turbine engines.
Implementation Method 1
cold spraying a powder towards a region of the component to form a deposit on the region of the component
Implementation Method 2
the cold spray system defines a gas temperature at an inlet of the cold spray nozzle greater than 650 degrees Celsius and less than 1500 degrees Celsius
Data Source
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AI summary
A method is provided for adding material to a turbine engine component. The method includes cold spraying a powder towards a region of the component to form a deposit on the region of the component, the component being formed of a parent material, the parent material being a superalloy or a titanium alloy and defining a parent material property value, and the deposit defining a deposit material property value equal to at least fifty percent of the parent material property.