Cold spray is a promising process to coat polymers and carbon fiber-reinforced polymer (CFRP). The choice of the metal-polymer couple of materials, however, has a strong influence on coating build-up and properties. In the present work, we show that spraying mixtures of copper and polymer particles lead to composite coating. We observe that the polymer promotes coating build-up onto CFRP to the expense of the electrical conductivity of the coating as a result of its insulating properties. The present work investigates the influence of the coating microstructure on electrical conductivity. Various copper powders, with different morphologies, particle sizes and oxygen contents were mixed with a PEEK (Polyaryl-Ether-Ether-Ketone) powder. Cold spray of these powders resulted into composite coatings and we study the microstructures and electrical properties of such coatings as a function of powder characteristics and spraying parameters. A morphological model of the coating microstructure was developed to reproduce numerically microstructures in 3D. The conductivity of the coatings was measured experimentally for various copper powders. Careful selection of blends of copper and PEEK powders coupled with optimized spraying parameters led to metal-polymer coatings onto CFRP with a fairly high electrical conductivity.

In this article, we study the microstructure of cold sprayed films of copper particles deposited onto a carbon fiber reinforced polymer. The microstructure of the coating is made of a packing of seemingly round-shaped particles of varying sizes embedded in a polymer matrix. The copper particles are separated by thin interstices. The coating is designed to cover the body of recent commercial aircrafts. Its role is to protect the aircraft from lightning impact by ensuring that the surface is conductive enough to evacuate electrical charges. A high resistivity contrast is observed between the copper particles and the polymer matrix. Therefore, the global resistivity of the material is highly dependent on the microstructure geometry. Following an approach commonly used in materials science, to investigate its influence on the electrical properties of the global material at the macroscopic scale, we design a 3D multiscale stochastic model that enables us to simulate the microstructure. The model is based upon a generalization of the classical JohnsonMehl tessellation, which accounts for the interstices that appear between copper particles. The method is very general and could potentially be applied to model any microstructure exhibiting similar interstices between aggregates of particles.

In this work, copper and PEEK powder mixtures are cold sprayed onto carbon fiber-reinforced polymer (CFRP) substrates with the aim of producing a well-adhered conductive layer. The composite coatings were optimized through the study of the deposited mass and its dependence on process parameters and Cu powder morphology. A morphological model based on Cu phase data was developed to better understand coating microstructures. Coatings synthesized from irregular Cu particles were found to be electrically conductive, while those containing spherical Cu particles were insulating. These phenomena are explained using the developed simulation tools coupled with the investigation of coating build-up and microstructure.

No abstract