Adhesion of rough cold sprayed metal coatings on polymers

ABSTRACT The adhesion strength from the cold-spray coating requires assessing multiple flaws and property distributions. Two approaches have been proposed for determining the adhesion strength of the cold spray-coated substrate. The interfacial shear strength approach combines the fragmentation test with a modified Weibull model. Fragmentation testing can examine materials with geometrical (roughness) and property (strength) variations for cold spray-coated specimens. The results give an insight into local strength and the coating strength distribution. The fracture toughness approach uses an electrical four-point probe to identify crack initiation and calculate the energy release rate of the coating. Sn coatings between 74 and 120 μm show an interfacial shear strength between 25 and 53 MPa and an energy release rate between 15 and 32 J m–2. The measured interfacial shear strength was independent of the coating thickness, while the energy release rate depends on the coating thickness.