Oxidation Behavior of Inconel 625 Alloy through Aliminide Diffusion Method Using Y2O3 and ZrO2 Nanoparticles

Abstract

Nano Y 2 O 3 and ZrO 2 particles were used in diffusion coating by the single-step pack cementation process • Effects of Y 2 O 3 and ZrO 2 on mechanical properties and oxidation resistance of coated Inconel 625 superalloy were analyzed • Microstructure of coated IN625 superalloy consists of an outer layer, a transition layer, and an interdiffusion zone • Adding Y 2 O 3 and ZrO 2 to the Cr-Comodified aluminide coating might increase the oxidation resistance The pack cementation process was used to create a type of Y 2 O 3 +ZrO 2 doped Cr-Co-modified aluminide coating that takes advantage of the synergistic effects of nano Y 2 O 3 and ZrO 2 particles. A Ni-based superalloy (type IN625 type) was coated with pack powder containing: Al as a source of aluminum; Cr as a source of chromium, Co as a source of cobalt, NH 4 Cl as a source of activator; nano Y 2 O 3 -ZrO 2 as a source of reactive element oxide; and Al 2 O 3 as a source of filler metal. The process was carried out for 6 hours at 1100 o C temperature. The microstructure characterization of the coating was performed by SEM, EDS, and XRD. It was found that the cross-section of the coating obtained was uniform and free from cracking. The maximum hardness value was found at the outer layer (997H.V.) and decreased toward the core sample core (366H.V.). The coating's microstructure consists of an outer layer, a transition layer, and an IDZ. The average coating thickness is 132.37, 36.11, and 37.65µm for the outer layer, transition layer, and IDZ, respectively. The XRD analysis of the coating system after 6 hours at 1100 o C revealed phases formed by AlNi 3 , CoO, Al-Cr-Co, and Cr 4 NiZr. The n (growth rate time constant) and Kp (parabolic rate constant) values increase with increased oxidation temperature. It was found that adding Zr and Y to the Cr-Co-modified aluminide coating might increase the oxidation resistance.

Investigation and evaluation of high-temperature lead-bismuth eutectic (LBE) corrosion resistance and compression performance of the FeCrAl-based coatings

“…Among them, surface coating technology is regarded as one of the most effective methods, because it can significantly improve the corrosion resistance while maintaining the outstanding mechanical properties of the cladding tube [10,11]. Up to now, the corrosion resistance of metal coating [5,12,13] and ceramic coating [14][15][16] has been investigated. Especially, FeCrAl-based coatings have been regarded as one of the most promising candidates due to their excellent LBE corrosion resistance and outstanding bonding strength with the steel cladding tube [17].…”