Effect of substrate temperature on the oxidation behaviour of NiCrAlY coating

ABSTRACT

NiCrAlY coating was deposited on the IN-738LC Ni-based superalloy by cathodic arc deposition at the substrate temperatures of 400°C and 700°C. The effects of the substrate temperature on the microstructure and the isothermal oxidation behaviour of the coatings were then investigated. SEM image and XRD analysis were used to characterize the deposited coatings. It was found that when the substrate temperature was raised from 400°C to 700°C, the degree of coating crystallinity was increased from 23% to 58%. After the 20-hr oxidation at 1000°C in air, the γ′-depletion layer was formed in the substrate. The growth rate constants of the γ′-depletion layer after the 100-hr oxidation were 1.3$\times$10⁻⁴ μm (s^b)⁻¹ and 6.4$\times$10⁻⁵ μm (s^b)⁻¹ for the deposited coatings at 400°C and 700°C, respectively. The results, therefore, indicated that with increasing the substrate temperature from 400°C to 700°C, the oxidation resistance was improved.

KEYWORDS:

• Substrate temperature
• cathodic arc deposition
• NiCrAlY coating
• diffusion
• oxidation
• thermally grown oxide

Disclosure statement

No potential conflict of interest was reported by the authors.