Cold spray deposition of various powders on CFRC structures: a numerical study

ZHANG Teng1, PADAYODI Essolé1, SAGOT Jean-Claude1, RAOELISON Rija Nirina2

1 Université de Technologie de Belfort-Montbéliard, ELLIADD, F-90010 Belfort cedex, France

2 Université de Technologie de Belfort-Montbéliard, CNRS, ICB, F-90010 Belfort cedex, France

Abstract: Based on experimental results from our recent work, this study aims to explore the deposition mechanisms of cold spraying of various powders on a Carbon Fiber Reinforced Composite (CFRC) structure, using a compatibilizing metal-based polymeric (Cu_epoxy or Al_epoxy) sublayer. Such a sublayer consists of Cu or Al micron-sized powders mixed with an epoxy phase that are embedded onto the CFRC surface by means of a vacuum molding process.

A finite element computational analysis is performed to investigate the cold spray deposition of diverse powders (Al, Sn and Zn powders) and the response of the Cu_epoxy and Al_epoxy substrates due to the high-speed collision. The damage behavior of the sublayer along with the decohesion between the epoxy zone and the embedded powders of the sublayer is considered using cohesive elements. This computational approach enables to explain the issue of coating formation due to the fragmentation within the sublayer. It was found that the high brittleness of the thermoset epoxy and the plastic deformation of the metallic particles govern the coating formation or the erosion of the sublayer. During the high-speed collision, the Sn powders are locally melted at the contact zone, that led to the occurrence of material jetting, but also to a plastic deformation and thus, a bonding onto the substrates. The Al powders didn’t achieve its melting point, and thus, they were less deformed and individually scattered on the substrate surface. Although Zn powders have the highest value of particle velocity upon impact, the absence of thermal softening and the presence of epoxy fragments prevented the effective particle-substrate bonding formation. As conclusion, among the different sprayed powders, the Sn powders are prone to form a coating due to a better thermomechanical softening process during the collision onto both Cu_epoxy and Al_epoxy substrates. Together, these results provide further insight into ways of optimizing the cold spray metallization of CFRC structures via suitable surface conditions along suitable cold spray deposition.

Keywords: Finite element analysis; CFRCs; Powders; Deposition mechanisms; Cold Spraying.