Depositing plasma sprayed NiCoCrAlY coating on additively manufactured Inconel 718 surfaces: Is grit blasting always necessary?

• NiCoCrAlY coating directly deposited on additively manufactured Inconel 718 surface. • As-printed roughness did not significantly affect coating adhesion. • Coating adhesion strengths exceeding 60 MPa was achieved on as-printed surface. • Surface oxidation during heat treatment reduced adhesion strength to ∼24 MPa. Additive manufacturing (AM) often produces non-uniform surfaces with defects such as oxides, cracks and unmelted particles; yet their effect on coating deposition is not well investigated. This study demonstrates that plasma sprayed NiCoCrAlY coating can be directly deposited on AM Inconel 718 surfaces without any grit blasting. Coating adhesion strengths exceeding 60 MPa are achieved, and AM-induced roughness exhibits little influence on the overall coating integrity. However, heat treatment introduces ∼3–5 µm thick surface oxide layer that significantly reduces adhesion strength by hindering metallurgical bonding between the splats and the substrate. The findings highlight the feasibility for direct deposition of plasma sprayed coating on AM parts while emphasizing the need to control oxidation during post-processing.