Deposition and Bonding Mechanism of Multiparticle Impacts in Cold Spraying: A Molecular Dynamics Simulation

Area of Science:

• Materials Science
• Surface Engineering
• Computational Physics

Background:

• Cold spraying is a coating process where particles impact a substrate at high velocities.
• Understanding particle deformation and bonding is crucial for coating quality.
• Experimental investigation of nanoscale phenomena during cold spraying is challenging.

Purpose of the Study:

• To investigate the deformation and structural evolution of particles during sequential impacts in cold spraying.
• To analyze the influence of particle velocity on these phenomena.
• To elucidate the mechanisms of bonding and material modification at the atomic scale.

Main Methods:

• Development of a multiparticle impact model using Molecular Dynamics (MD) simulation.
• Simulation of titanium (Ti) particle deposition.
• Analysis of atomic-scale deformation, intermixing, stress evolution, and structural transformations.

Main Results:

• Sequential impacts induce continuous deformation in bottommost particles and the substrate.
• Significant atomic intermixing occurs between deposited layers and the substrate.
• Repeated impacts lead to stress accumulation, driving crystal amorphization and dislocation generation.
• Higher particle velocities accelerate amorphization.
• The effect of successive impacts attenuates after the fourth layer.

Conclusions:

• Successive particle impacts enhance deformation and bonding in cold spraying through persistent stress transmission.
• MD simulations provide critical insights into atomic-scale mechanisms governing cold spray deposition.
• The findings are valuable for understanding and optimizing the cold spray process for difficult-to-deform metals.