Improvement of Oxidation Resistance of Inconel 600 Alloy by Pack Cementation Process

Abstract

The aim of this paper is to improve the oxidation resistance of Inconel 600 alloy by diffusion coating. In this study, (Si and Al) and (Al, Si and Y2 O3 ) were simultaneously deposited by cementation process into Inconel 600 alloy at 1120°C for the different times (2,4,6,8)hours. The pack powder mixture consists of 18Al-8Si-2NH4 Cl-72Al2 O3 (wt.%) for silicon modified aluminide diffusion coating and replaced 1% from Al2 O3 by Y2 O3 for yttria doped silicon modified aluminide diffusion coating. Cyclic oxidation was carried out at 50 hours at 900°C, 5 hours for each cycle. The results showed that the coatings microstructure consists of two layers: outer layer and inter-diffusion zone. The best oxidation resistance was found for the deposition by yttria-doped silicon modified aluminide diffusion coating from 6-8 hours of coating time. The phases formed after cyclic oxidation for both coated type and uncoated of Inconel 600 alloy are Ni, NiO, NiFe2 O4 , (Cr,Fe)2 O3 , AlNi, CrO3 , α-Al2 O3 , and Y4 Al2 O9