Self-healing effects by the Ce-rich precipitations on completing defective boundaries to manage microstructures and oxidation resistance of Ni-CeO2 coatings

This paper presented an effective approach for electroplating of coatings on the activated surface of pure Ti substrate using pulsed electro deposition. Regarding the ceramic-like TiO 2 barrier layer on its surface of Ti substrate to inhibit surface activity, a novel activating solution that composed of HF, HCl, Ce(NO 3 ) 2 , TiCl 3 , and bal. DMF dissolvent was applied for surface modifications of Ti substrate in order to increase interfacial bonding strength of surface Ni coatings. Besides a comparative study of Ni nanocrystalline coatings without and with CeO 2 addition was carried out for disclosing the role of the Ce-rich phase on managing microstructure and high-temperature oxidation resistance during oxidation at 800 or 1000   °C. Results indicated that Ce-rich precipitations, where dispersed along grain boundaries (GBs), were favorable for completing the spalling oxide-layers on Ni-CeO 2 nanocomposite coatings during oxidation at 800   °C. Furthermore, an analytical modeling was validated for better understanding of Ce-rich precipitations along GBs defects for monitoring oxidation mechanisms. Furthermore, this finding would be therefore leading to the guidelines for Ce-rich precipitations on the strengthening of Ni-based superalloys.