Additive manufacturing (AM) is gaining popularity due to the increased demands for the production of complex geometries and difficult-to-machine components. The increasing trend of AM focuses more on high-temperature applications in the field of aerospace, automotive, power generation, etc. In high-temperature applications, the material often needs to be resistant to oxidation and corrosion. Alloy 718 is a promising material because of its better properties at elevated temperatures. Recently alloy 718 based parts have been manufactured by the electron beam powder bed fusion (EBPBF) process. Different post-processes such as shot peening (SP) and hot isostatic pressing (HIP) were used to improve the properties of the AM-built samples. As an alternative method to post-processing, NiCoCrAlY coating was thermal sprayed on the AM-built samples.

The present study explores the effect of the different processing methods on the mechanical and functional properties of the coatings . Post-processes help reduce the roughness of AM components due to the peening effect during SP and temperature and pressure during HIP. The shot peening was responsible for increasing the hardness near the coating-substrate interface while HIP reduces the hardness due to grain coarsening and dissolution of strengthening phases. The NiCoCrAlY coating was deposited on the sample by a high-velocity air fuel process. Coated AP, SP3 and HIP samples showed better adhesion strength because of mechanical interlocking between coating and substrate. The coating acts as a protective layer by forming oxide scale (Cr and Al oxides) and helps to protect the substrate from corrosion and oxidation. The shot peening was responsible for reducing the erosion rate in uncoated samples, while the coated sample showed similar behavior.

The present study explores the effect of post-process on the coating microstructure and other properties. The AM-produced sample does not require post processes before spraying a coating. Thermal spraying on AM parts is beneficial for improving properties.