Oxidation resistance of NiCrAlHf-YSZ as a thermal barrier coating system for nickel-based superalloy applications
Nurul Latifah (a,b), Eni Sugiarti (a*), Djoko Triyono (b), Safitry Ramandhany (a,b), Kurotun Aini (a,b), Risma Yulita Sundawa (c), Muhamad Sar^i (a), Budi Prawara (a), Endro Junianto (a), Tubagus Suryaman (d), and Adhitya Trenggono (d)

a) Research Center for Energy Materials, National Research and Innovation Agency (BRIN), Serpong, Indonesia
*enis006[at]brin.go.id
b) Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, Indonesia
c) Department of Material Science and Engineering, Faculty of Mechanical and Aerospace Engineering, Institut Teknologi Bandung, Bandung, Indonesia
d) Department of Metallurgical Engineering, Faculty of Engineering, Universitas Sultan Ageng Tirtayasa, Banten, Indonesia

Abstract

Thermal barrier coating (TBC) systems are widely employed to improve the oxidation resistance of nickel-based superalloys operating at high temperatures. This study examines the oxidation resistance of NiCrAlHf-YSZ coatings applied to Inconel 625 and Hastelloy C-276 substrates during isothermal oxidation at 1000 C for 100 hours. The bond coat material, Ni-24Cr-7Al-0.4HfO2 (wt.%), was produced by mechanical milling, whereas 8 wt.% yttria-stabilized zirconia (8YSZ) served as the top coat. The bond coat and top coat were applied via high velocity oxygen fuel (HVOF) and air plasma spraying (APS), respectively. Microstructural and phase analyses were conducted using field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The results showed that the NiCrAlHf-YSZ coating applied to Inconel 625 exhibited enhanced oxidation resistance compared to Hastelloy C-276, as evidenced by the reduced mass change and oxidation rate values of 1.06987 mg/cm2 and 2.48 x 10-9 g2cm4/s, respectively. The thermally grown oxide (TGO) layer between the bond coat and top coat was assessed to comprehend the oxidation behavior during high-temperature exposure. The enhanced oxidation resistance was associated with the formation of a stable and protective oxide layer.

Keywords: Hastelloy C-276- Inconel 625- Oxidation- Thermal barrier coating

Topic: Material Physics