Ion-plated Al–O–N and Cr–O–N films on Ni-base superalloys as diffusion barriers

Al–O–N and Cr–O–N films were deposited as diffusion barriers between NiCoCrAlY overlay coating and Ni-base superalloy DSM11 using arc ion plating (AIP) techniques. The efficiency of the diffusion barriers was investigated at 1050 and 900 °C. The results showed that the Al–O–N barrier could inhibit the interdiffusion of the alloying elements. Unfortunately, because of deterioration of the mechanical and oxidation properties of the whole system, it could not act as a successful barrier. The Cr–O–N film could act as an active diffusion barrier by changing into an Al-rich oxide layer in high temperature annealing. The achieved interface structure can offer both the barrier properties of a dense ceramic layer and strong bond strength of a reaction-bonding zone. In addition, Cr–O–N films could improve the oxidation properties of the NiCoCrAlY coatings by 18–37%, which were influenced by the original chemical compositions of the Cr–O–N films.