Abstract
Considerable effort has been made to translate the beneficial properties of bulk Ti(C,N)-based hardmetals to wear resistant thermal spray coatings. Such efforts have focused primarily on as-sprayed coatings. However, past work has shown that hardmetal coatings can undergo significant changes when operated at elevated temperature for extended periods. This work characterised the microstructural changes in a HVOF sprayed (Ti,Mo)(C,N)-Ni coating treated in air at 700°C for up to 30 days. The microstructural development of the carbonitride phase was very subtle. Image analysis indicated that the Mo-rich rim phase underwent the greatest degree of dissolution during spraying and precipitation with heat treatment. Dissolution of the carbonitride phases during spraying led to significant alloying of the Ni binder. Rapid recovery of the Ni binder composition occurred after one day of treatment, but it retained a higher steady state degree of alloying relative to the starting powder.
