Interactions between Ion-Beam-Modied SiC Films on a Ni-Based Superalloy with Intermediate Maxthal Layers

Interactions between Ion-Beam-Modied SiC Films on a Ni-Based Superalloy with Intermediate Maxthal Layers

Hastelloy X, one of the Ni-based superalloys, is a promising candidate in various structural applications for high-temperature and corrosive environments. However, it is prone to environmental degradation in the iodine-sulfur cycle for nuclear hydrogen generation systems where the threat spectrum includes high temperature and pressure and corrosive gases based on sulfuric acid decomposition. In order to increase its tolerance, use of suitable coating materials is one option. Herein, a study has been made of electron-beam evaporative-coated and of ion-beam-mixed (IBM) SiC films on Hastelloy X coupons with intermediate Maxthal 211 (T2AlC) films. Cross-sectional trans- mission electron microscopy (X-TEM), scanning electron microscopy (SEM) and X-ray elemental mapping were performed on the coated and IBM samples. Preliminary studies of as-deposited and IBM coupons indicate a uniform and sound interface with some recoil implantation effects near the interface. In the case of coupons annealed in air at 1000℃ after the coating/IBM processing, severe interdiflusion from some of the proactive species into the coating and towards the substrate were found. The surfaces and the interfaces of the as-deposited coupons were characterized by an oxidation that was found to increase as a result of annealing.

Hastelloy X, one of the Ni-based superalloys, is a promising candidate in various structural applications for high-temperature and corrosive environments. However, it is prone to environmental degradation in the iodine-sulfur cycle for nuclear hydrogen generation systems where the threat spectrum includes high temperature and pressure and corrosive gases based on sulfuric acid decomposition. In order to increase its tolerance, use of suitable coating materials is one option. Herein, a study has been made of electron-beam evaporative-coated and of ion-beam-mixed (IBM) SiC films on Hastelloy X coupons with intermediate Maxthal 211 (T2AlC) films. Cross-sectional trans- mission electron microscopy (X-TEM), scanning electron microscopy (SEM) and X-ray elemental mapping were performed on the coated and IBM samples. Preliminary studies of as-deposited and IBM coupons indicate a uniform and sound interface with some recoil implantation effects near the interface. In the case of coupons annealed in air at 1000℃ after the coating/IBM processing, severe interdiflusion from some of the proactive species into the coating and towards the substrate were found. The surfaces and the interfaces of the as-deposited coupons were characterized by an oxidation that was found to increase as a result of annealing.