Cold spray is a solid-state particle deposition technique with a wide range of applications for coating, repair and additive manufacturing. Cold spray parameters are normally tuned to obtain deposits with minimal porosity and thus highest strength. However, there are specific applications such as biomedical prostheses, heat sinks and energy absorbing products, where a higher exposed surface area can lead to enhanced performance, rendering porosity a desirable feature. Few recent studies have experimentally evaluated the potential of cold spray technology for obtaining porous deposits. To enhance the efficiency of these approaches, here we developed a detailed numerical framework that can determine the topological and mechanical features of cold spray porous deposits. A series of combined Eulerian-Lagrangian finite element models were developed considering a multi-material feedstock, one constituent of which served as a porogen. Different powder blends of pure Ti mixed with either Al or Cu, as the sacrificial powder, with varying volumetric fractions were analysed. A novel post-processing approach was developed to remove the sacrificial powder and extract distinct characteristic indicators from the simulations' output; these indices include porosity and structural connectivity of the remaining Ti structure. Equivalent plastic strain was considered as an index to assess the strength of the resultant deposit. The obtained data regarding particle deformation were in agreement with preliminary experimental tests. The numerical results revealed that Ti-Cu combinations can yield deposits with higher Ti particle deformation compared to the Ti-Al blend and hence, lead to a better inter-particle bonding. This study presents a robust numerical approach for selection of cold spray process parameters towards obtaining coatings and freestanding porous metal parts with modulated porosity, connectivity and strength.

A numerical Approach to design and develop freestanding porous structures through cold spray multi-material deposition

Terrone M.;Ardeshiri Lordejani A.;Kondas J.;Bagherifard S.
2021-01-01

Abstract

Cold spray is a solid-state particle deposition technique with a wide range of applications for coating, repair and additive manufacturing. Cold spray parameters are normally tuned to obtain deposits with minimal porosity and thus highest strength. However, there are specific applications such as biomedical prostheses, heat sinks and energy absorbing products, where a higher exposed surface area can lead to enhanced performance, rendering porosity a desirable feature. Few recent studies have experimentally evaluated the potential of cold spray technology for obtaining porous deposits. To enhance the efficiency of these approaches, here we developed a detailed numerical framework that can determine the topological and mechanical features of cold spray porous deposits. A series of combined Eulerian-Lagrangian finite element models were developed considering a multi-material feedstock, one constituent of which served as a porogen. Different powder blends of pure Ti mixed with either Al or Cu, as the sacrificial powder, with varying volumetric fractions were analysed. A novel post-processing approach was developed to remove the sacrificial powder and extract distinct characteristic indicators from the simulations' output; these indices include porosity and structural connectivity of the remaining Ti structure. Equivalent plastic strain was considered as an index to assess the strength of the resultant deposit. The obtained data regarding particle deformation were in agreement with preliminary experimental tests. The numerical results revealed that Ti-Cu combinations can yield deposits with higher Ti particle deformation compared to the Ti-Al blend and hence, lead to a better inter-particle bonding. This study presents a robust numerical approach for selection of cold spray process parameters towards obtaining coatings and freestanding porous metal parts with modulated porosity, connectivity and strength.
2021
Additive manufacturing
Cold spray
Connectivity
Coupled Eulerian Lagrangian
Finite element method
Porogen
Porosity
Sacrificial powder
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1203900
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