Enhanced Interfacial Reaction of SiC Films Deposited onto Hastelloy X Substrates by Ion-Beam Mixing

A surface modification of Hastelloly X by a SiC coating and an ion-beam mixing has been studied. The deposited SiC film is easily peeled off during heating at elevated temperatures; however, the SiC coating on Hastelloy X with ion-beam mixing (IBM) is sustained at elevated temperatures above 900 degrees C. The mechanism of good adhesion at the interface seems to be an interfacial reaction induced by ion-beam mixing, as revealed by cross-sectional transmission electron microscopy (X-TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), cross-sectional scanning electron microscopy (X-SEM) and Energy dispersive X-ray fluorescent spectroscopy (EDS). IBM plays a role of fastening the SiC film onto the Hastelloy X substrate until an interfacial reaction takes place. This study has been motivated by a SiC protective coating on a Hastelloy X (a Ni-Cr based alloy) substrate, which has potential applications in an extremely corrosive environment, such as an SO2/SO3 ambience, at temperatures higher than 900 degrees C.