Effects of Substrate Roughness and Spray Angle on Deposition Behavior of Cold Sprayed Inconel 718 for repair of aero engine components
Abstract In this study, Inconel 718 powder particles were successfully cold sprayed on Inconel 718 substrate by using nitrogen gas for a repair application of aero engine components. The effects of substrate roughness and spray angle on the deposition behavior of Inconel 718 particles were investigated. It has been found that the deposition behavior of Inconel 718 powder on Inconel 718 substrates is highly influenced by substrate surface roughness. Single powder particle interaction with substrates of different roughness showed that plastic deformation and interfacial material mixing is higher if powder particles interact with substrates of higher roughness. Consequently, substrates with lower roughness demonstrated many abnormalities (e.g. cracks, peeling off) during the deposition. Substrate roughness is limited to influence the deposition efficiency of the first few layers. Besides, it is also observed that particle deformation and coating quality are significantly affected by the spray angle because of asymmetric deformation of the particle due to additional tangential momentum. Moreover, it is observed that deposition efficiency is reduced with a decrease in spray angle, while the coating porosity and coating roughness show an inverse trend. Furthermore, the effects of three input parameters, namely substrate preparation, spray angle and stand off distance, on four outputs (responses) such as thickness, roughness, porosity and Vickers hardness of the coating were studied using non linear statistical regression analysis. The above mentioned four outputs were found to be significantly dependent on substrate preparation and spray angle.