Low temperature aluminising of Inconel 718 alloy by pack cementation(ICCESEN 2017)

Abstract

A novel pack-aluminizing diffusion coating has been conducted on -Inconel 718 alloy at 600 and 650 degrees C for 2 and 4 h. The aluminising powder packs have been prepared using Al powder as a source for depositing aluminium, Al2O3 powder as an inert filler and ammonium chloride NH4Cl as an activator. The microstructures of the coatings formed on the alloy surface are characterized by means of SEM/EDS and XRD analysis. Optical microscope and SEM analysis reveal that coating layers are homogenous, compact and nonporous and there is a good bonding at the interface of the coating and matrix. Layer thickness variation is measured from the surface to the matrix and changed from 10 to 40 mu m which is increased with increasing process time and temperature. The hardness of the coating layer increased to 1174 HVN with the increasing process time and the temperature while the hardness of the matrix is 300 HVN.