Cold Spray Preform Recrystallization Under Lateral Compression
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Solution Overview
Problem
Existing methods for producing wrought structures from cold spray deposition face challenges such as thermal stresses, oxidation, and the need for energy-intensive processes like HIPing, which are costly, time-consuming, and can result in defects like large tunnel defects and gas pockets.
Innovation Solution
A method involving simultaneous application of heat and compressive load laterally to a cold spray deposition preform, transforming the consolidated particle structure into a wrought structure by recrystallization without melting, using rapid heating techniques and rollers to apply compressive force perpendicular to the application area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cold spray methods are used to produce low porosity deposits, then particle consolidation is achieved, but thermal stresses cause cracking and separation due to heat transfer from the heated spray gas
Solution Approach 1:
The patent replaces the conventional thermal spray process with a cold spray process that uses mechanically accelerated particles instead of thermally heated particles. The particles are accelerated to supersonic velocities (greater than 500 m/s) using a gas dynamic nozzle system, eliminating the need for thermal softening and avoiding thermal stress cracking while achieving particle consolidation through plastic deformation upon impact
Solution Approach 2:
The patent fundamentally changes the temperature parameter from conventional thermal spray (typically 700-1100°C) to cold spray conditions where particles remain below the melting point of the substrate material. This parameter change eliminates thermal stress cracking while maintaining particle consolidation through high-velocity impact and plastic deformation
2Reliability
If HIPing process is used to form wrought structure from cold spray deposition, then porosity is reduced and density is improved, but the process is energy-intensive, costly, and time-consuming
Solution Approach 1:
The patent performs preliminary consolidation during the deposition process itself by controlling particle velocity, mass flux, and layer-by-layer accumulation to achieve near-net-shape parts with low porosity. This preliminary action eliminates the need for subsequent energy-intensive HIPing processes while maintaining high material density and structural integrity
Solution Approach 2:
The patent skips the intermediate HIPing step entirely by directly producing dense, low-porosity cold spray deposits through optimized deposition parameters. The process rushes through the consolidation stage during deposition itself, achieving wrought-like structures without the time-consuming and energy-intensive intermediate heat treatment step
3Reliability
If HIPing process is used to consolidate cold spray deposition, then fully dense materials are created, but large tunnel defects and gas pockets form as defects
Solution Approach 1:
The patent replaces thermal consolidation (HIPing) with mechanical consolidation through high-velocity particle impact. The supersonic particle stream mechanically densifies the deposit layer-by-layer during deposition, eliminating trapped gases and preventing tunnel defects before they form, rather than attempting to consolidate them afterward through heat and pressure
4Speed
If preheating of cold spray gas is used to achieve high velocities, then particle deposition is facilitated, but oxidation occurs if surface temperature is high enough
Solution Approach 1:
The patent replaces thermal heating with mechanical acceleration using a gas dynamic nozzle system that converts gas pressure into supersonic particle velocities without heating the substrate. The particles are accelerated to greater than 500 m/s through pressure differential and nozzle geometry, not thermal energy, keeping substrate temperature below oxidation thresholds while achieving high deposition rates
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 process enables the rapid conversion of cold spray deposited materials into wrought structures with high density and uniform microstructure, avoiding defects and reducing energy consumption, while allowing for the production of oxygen-sensitive materials like titanium at lower costs.
Implementation Method 1
rapid heating techniques and rollers to apply compressive force
Implementation Method 2
transforming the consolidated particle structure into a wrought structure by recrystallization without melting
Implementation Method 3
rollers to apply compressive force perpendicular to the application area
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(B)
Figure 3(a)~3(b)
AI summary
A process and apparatus of producing a product having a wrought structure. The process comprises the step of: applying heat and a compressive load simultaneously to an application area of a cold spray deposition preform to transform the comprising consolidated particle structure into a wrought structure, the compressive load being applied laterally to the application area. The application of compressive load and heat to the application area raises the temperature of the material of the preform in the application area to between the recrystallisation temperature and the melting point of the material.