Abstract
Particle bonding is crucial to coating quality in cold spray, but it has been a challenge to accurately quantify bonding even in single particle impacts. This paper uses FIB-SEM to explicitly map the particle-substrate interface for Cu-on-Cu single microparticle impacts in a full 3D rendering that spans a wide range of impact velocities. This approach permits a detailed quantification of the total bonding area and all of its associated components. In addition to revealing why prior 2D characterization efforts have missed important details about impact bonding, these data quantitatively reveal the evolution of bonding from its onset at the “critical velocity” Vcr (where bonding is generally poor, ∼6 %) to its peak at around 1.3‧Vcr (where almost 90 % of the particle bonds). Further increase in the velocity to 1.5‧Vcr and beyond finds the onset of hydrodynamic penetration and a decrease in bonding. These data then support the development of a simple analytical model based on oxide rarefication and extrusion of bare metal through gaps in the oxide layer as driving the development of bonding. The model reproduces the experiments and provides guidance on optimization of bonding as a function of material and process parameters.
Original language | English (US) |
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Article number | 120105 |
Journal | Acta Materialia |
Volume | 276 |
DOIs | |
State | Published - Sep 1 2024 |
Funding
This work was primarily supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under award no. DE-SC0018091. VP would like to thank the DOE NNSA Stewardship Science Graduate Fellowship (DOE NNSA SSGF) \u2014 DE-NA0003960 for financial support. FIB-SEM tomography work was performed at the Harvard University Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by the National Science Foundation under NSF award no. 1541959. SEM characterization was performed in part in the MIT.nano Characterization Facilities. We also thank Dr. Stephan Kraemer of Harvard University for support and guidance with FIB-SEM. VP further thanks Professor Ahmed A. Tiamiyu of University of Calgary and Mike Marsh of Dragonfly ORS for insightful discussions.
Keywords
- Analytical methods
- Bonding
- FIB-SEM tomography
- High-velocity impact
- LIPIT
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys