A numerical model is presented for the computation of heat transfers during the APS thermal spray process. This model includes the contributions of both the impinging plasma jet and that of the particle flux on the substrate heating. The contribution of the impinging plasma jet is taken into account using a computational fluid dynamic model describing the impact of the plasma jet on the substrate. For this part of the work, a two-layer extension to the Chen-Kim k-s model was used allowing the description of both the turbulent plasma jet and that of the flow in the viscous sub-layer formed on the substrate surface. The contribution of the sprayed particles is taken into account considering their distribution in the spray jet. Since this is an important parameter that could affect the model accuracy, measurements of the deposit thickness profiles were first performed using the non-destructive acoustic microscopy method and the corresponding particle flux distribution was then deduced. Heat transfers inside the substrate were then computed using a three dimensional in-house code based on a finite volume approach. In the case studied, the results show that the contribution of the sprayed particles forming the coating is much more focalized than that of the plasma flow itself whereas the substrate nature has a strong influence on the thermal flux dissipation (not presented in the following). These elements are expected to provide useful information concerning the coating adhesion mechanisms and the formation of residual stresses during the coating elaboration.

In view of its advantages (simplicity, low cost, high deposition rate), the wire arc spray process has become a widely used technology for the spraying of metals. Nevertheless, numerous parameters (gun design, atomizing gas nature, velocities, pressures, ...) may have a significant influence on the quality of the produced coatings. One of the major problems related in the literature concerns the poor control over the spray pattern; the understanding of this phenomenon has thus become essential for further improvements. In the present study, a special feature of the PHOENICS commercial code (from CAD to CFD ) was used to produce a 3D simulation of the flow within the gun and outside. This method was especially useful in view of the complex geometry of the TAFA 9000 gun, which was investigated. The results show the presence of a highly asymmetric external jet.

Thermal spraying is an efficient process for producing surface coatings that have improved corrosion and wear properties. In modern injection processes, robots are used, which enable higher productivity and piece quality. However, there are some difficulties with robot programming when the part geometry becomes very complex. In order to improve the robot programming procedure and accordingly increase the quality and economy of the process, a research program was set up in which the thermal spray process was simulated. The off-line simulation of the trajectories of the spray guns, the thickness distribution of the layer and the temperature distribution on the substrate were included. This paper presents the simulation procedure. It also presents some examples with numerical results that showed an improvement in the coating procedure. Paper includes a German-language abstract.