Self-Strengthening of the Adhesion of HVOF Sprayed MCrAlY Coatings

This paper assesses the effect of different annealing treatments on the adhesion strength of NiCrAlY coatings. The coatings were HVOF sprayed on superalloy substrates using widely available powders. It was found that the annealing atmosphere has no significant influence on adhesion, indicating that the coatings self-reinforce when subjected to high temperatures. The observed effect is due to the diffusion of elements, forming a metallurgical bonding layer at the coating-substrate interface. Test results show that, in an ambient atmosphere at 1000 °C, this bonding layer becomes stronger with time, more than doubling the adhesion strength of HVOF NiCrAlY coatings on Inconel 738 substrates. Paper includes a German-language abstract.