Cold Spray Preform Production via Rotating Substrate
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Solution Overview
Problem
Conventional cold spray deposition methods face challenges in producing solid shapes like rods or bars due to thermal stresses and oxidation issues, which lead to defects and inefficiencies in depositing materials like titanium alloys, especially when trying to create large deposits without a starter substrate.
Innovation Solution
A process involving a starter substrate rotated about a preform axis with controlled movement of the cold spray applicator in a plane perpendicular to the axis, allowing for axial movement to form a preform of desired length while maintaining a uniform microstructure and avoiding thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If preheating is used to achieve high particle velocities and thermal softening, then deposition quality improves, but thermal stresses cause cracking and separation
Solution Approach 1:
The patent changes the temperature parameter from high (preheating to melting point) to low (below melting point, typically -50°C to +50°C), fundamentally altering the deposition mechanism from thermal softening to kinetic energy-driven plastic deformation. This resolves the contradiction by achieving both high deposition quality and structural integrity through cold spray technology.
Solution Approach 2:
The patent replaces the thermal field (heating) with a mechanical field (supersonic particle acceleration). Instead of using heat to soften particles for deposition, the invention uses mechanically accelerated particles at supersonic velocities to achieve bonding through plastic deformation upon impact, eliminating thermal stress-related defects.
2Productivity
If high gas temperatures are used to accelerate particles, then deposition rate increases, but oxidation occurs on the substrate surface
Solution Approach 1:
The patent employs an inert or controlled atmosphere during the cold spray deposition process to prevent oxidation of the substrate and deposited material. By maintaining the substrate temperature below the melting point and using controlled gas composition, the invention achieves high deposition rates without oxidation hazards.
Solution Approach 2:
The patent replaces thermal acceleration with mechanical acceleration of particles. Instead of heating the gas to high temperatures to accelerate particles (which causes oxidation), the invention uses a supersonic nozzle to mechanically accelerate particles to high velocities while keeping the gas temperature low, thus preventing oxidation.
3Strength
If rapid nozzle scanning is used to dissipate heat, then thermal stress cracking is reduced, but surface irregularities increase requiring frequent machining
Solution Approach 1:
The patent replaces thermal management strategies (rapid scanning to dissipate heat) with a fundamentally different approach: cold spray deposition that doesn't generate significant heat in the first place. By using supersonic particle acceleration instead of thermal softening, the process avoids thermal stress cracking without requiring rapid scanning, thereby maintaining surface flatness and reducing machining requirements.
4Productivity
If robot arm moves cold spray gun at high velocity, then deposition speed increases, but vibrations affect uniformity of deposit
Solution Approach 1:
The patent segments the deposition process into controlled passes over a rotating substrate, allowing the spray gun to remain relatively stationary or move slowly while the substrate provides the relative motion. This eliminates the vibrations associated with high-velocity robot arm movement while maintaining high deposition speeds through efficient material utilization.
Solution Approach 2:
The patent inverts the conventional approach by keeping the spray gun relatively stable and rotating the substrate instead. This reversal eliminates the problem of robot arm vibrations affecting deposit uniformity, as the substrate rotation provides smooth, controlled relative motion between the spray and substrate surfaces.
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 method enables the production of solid preforms with uniform microstructure and reduced defects, allowing for the creation of large, solid titanium or titanium alloy preforms without the need for a starter substrate, improving efficiency and reducing thermal stress-related issues.
Implementation Method 1
In cold spray processes, small particles in the solid state are accelerated to high velocities (normally above 500 m/s) in a supersonic gas jet and deposited on a substrate material. The kinetic energy of the particles is utilised to achieve bonding through plastic deformation upon impact with the substrate.
Implementation Method 2
The kinetic energy of the particles is utilised to achieve bonding through plastic deformation upon impact with the substrate.
Implementation Method 3
The kinetic energy of the particles is utilised to achieve bonding through plastic deformation upon impact with the substrate.
Implementation Method 4
providing a starter substrate about a preform axis of rotation... rotating the starter substrate about the preform axis of rotation
Implementation Method 5
depositing material onto the deposition surface of the starter substrate using cold spray deposition to form a product deposition surface
Data Source
AI summary
A process for producing a preform by cold spray deposition, the process comprising: providing a starter substrate about a preform axis of rotation, the starter substrate having at least one axial end having a substantially flat deposition surface; rotating the starter substrate about the preform axis of rotation; depositing material onto the deposition surface of the starter substrate using cold spray deposition to form a product deposition surface, the cold spray deposition process including a cold spray applicator through which the material is sprayed onto the deposition surface; successively depositing material onto a respective top product deposition surface using cold spray deposition to form successive deposition layers of the material; and moving at least one of: the cold spray applicator; or the starter substrate and preform product, relative to the other in an axial direction along the preform axis of rotation to maintain a constant distance between the cold spray applicator and the top product deposition surface, thereby forming a preform product of a selected length, wherein the cold spray applicator is moved in a plane perpendicular to the preform axis of rotation so as to deposit material as a substantially flat surface on each respective deposition surface of the starter substrate or product deposition surface of the preform product.