An experimental design matrix was set up in which carbon steel coatings were deposited with a twin wire arc spray gun (TAFA 9000 TM ), using either compressed air or nitrogen as spraying gas. The coating's mechanical properties were studied. Some correlations were made between these properties, spraying conditions and the microstructure of the deposits. Young's modulus was estimated by the single beam method using finite element modeling. Results show that direct relationships do exist between spray conditions, oxide content in the coating and microhardness. Young's modulus of the coatings depends on the lamella thickness and the oxide content. When increasing the compressed air flow rate, Young's modulus increases at first because smaller particles and finer lamellae were made and it decreases later because of a higher oxide content. The increase of nitrogen flow rate lowers the oxide content and increases Young's modulus. #
Twin wire arc spraying is widely used in industry due to its low cost and high rate of material deposition. Much has been learned about the process over the course of its use, most recently in regard to the correlation between spray parameters and coating microstructure. The aim of this study is to investigate the behavior of steel particles in nitrogen and air jets and show how in-flight particle characteristics affect coating properties. In the experiments, an optical sensing system is used to measure the velocity, temperature, and size of carbon steel particles fired from a wire arc spray gun set at 100 A and 30V for gas flow rates of 94, 110, 122, and 144 m3/h. The particle data obtained is presented and correlated with coating microstructure, hardness, and oxide content. Paper includes a German-language abstract.
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.
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