Insights into the Development of WC-10Co-4Cr and MCrAlX Protective Coatings Using an ID-HVOF System

Inner diameter high velocity oxygen fuel (ID-HVOF) thermal spraying is intensely pursued as it offers unique solutions for coating space restricted industrial parts where access with conventional HVOF torches is not feasible. Yet, challenges associated with using these newly developed torches need to be addressed for successful transitioning of ID-HVOF from an R&D spray technology to an industrially viable process. Some of the challenges are related to the compact size and low combustion powers of the ID-torches as well as spraying small size feedstocks at short standoff distances while properly controlling parts’ thermal load.

This presentation will feature an in-depth study on the development of cermet and metallic coatings using a kerosene-fuelled ID-HVOF system. WC-10Co-4Cr feedstock composition was selected in the context of spraying wear and corrosion resistant protective coatings on inner cylinders of landing gears. MCrAlX (M=Ni, Co and X=Y, HfSi) feedstock compositions were also investigated for high temperature protection of small and complex parts of gas turbine engines. The development of coatings deposition parameters space for each composition will be discussed. Consequently, the effect of spray parameters and the correlated particle temperatures and velocities on the coatings microstructure and properties will be assessed through structural and mechanical characterizations.