A new process called in-mold metal spraying (IMMS) shows good potential for producing metallized plastic parts quickly and inexpensively. A zinc layer is deposited on mold cavity inserts using wire arc spraying and subsequently transferred to a plastic carrier via injection molding. Finely adjusted bonding strength between the carrier body and coating is essential for successful coating transfer. To that end, this study evaluates the influence of carrier body surface pretreatments on the transferability and bonding strength of zinc coating. Carrier bodies made of different types of steel pretreated by glass bead blasting and EDM were tested and their surface topography examined. In the initial experiments, the hardness and surface topography of carrier bodies were identified as factors that can influence coating transferability. Further experiments focusing on the adhesion strength of zinc on hardened and annealed carrier bodies were conducted to verify the influence of hardness on bonding strength.

This study investigates the tribological properties of two HVOF-sprayed tungsten carbide coatings, each with a different content of cobalt, which were subjected to electrical discharge machining (EDM). It was found that the electrospark deposition of WC8Co over the HVOF-sprayed WC12Co and WC17Co coatingsresults in the formation of a homogeneous layer of tungsten carbide with a low cobalt content. The EDM layer is well bonded with the HVOF-sprayed coating as confirmed by the gradual change in the content of the elements in the coating and layer. The friction coefficients obtained for the two coatings with the EDM layer are very similar as their composition, microstructure, hardness, and surface roughness are approximately the same.

In this work, the microstructure of silver coatings obtained by cold spraying with a fine and a rather coarse powder were investigated. Cold-sprayed microstructures strongly depend on the deposition process parameters. These parameters have an influence on porosity, plastic strain, particle-to-particle bonding mechanisms. The originality of this study rests on the use of X-ray microtomography, which is shown to be a very powerful technique to investigate into cold-sprayed coatings. Several samples were machined from coatings by electro-discharge machining (EDM) then scanned using microtomography. Porosity fraction was determined by three-dimensional image analysis and compared to classical two-dimensional analysis of micrographs. A difference between the two methods was exhibited, which showed sample preparation effects. Consequently, X-ray microtomography seems to be well adapted to study cold-sprayed coatings thoroughly. Another result from this work was the characterization of the morphology of pores and deformed particles. Bonding mechanisms in cold spray could therefore be discussed. In addition, the knowledge on deformed particles allowed to simulate cold-sprayed coatings with build-up models. This will be done in a further work