Correlations between operating conditions, microstructure and mechanical properties of twin wire arc sprayed steel coatings

An experimental design matrix was set up in which carbon steel coatings were deposited with a twin wire arc spray gun (TAFA 9000™), using either compressed air or nitrogen as spraying gas. The coatingʹs mechanical properties were studied. Some correlations were made between these properties, spraying conditions and the microstructure of the deposits. Youngʹs 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. Youngʹs modulus of the coatings depends on the lamella thickness and the oxide content. When increasing the compressed air flow rate, Youngʹs 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 Youngʹs modulus.