In-Situ Observation Of Laves Phase Precipitation And Oxidation Of HVOF Deposited TribaloyTM T-800 (CoMoCrSi alloy) Coatings

The deposition of T-800/CoMoCrSi alloys via HVOF has seen widespread deployment as a wear resistant surface, particularly in turbine applications, where high service temperature requirements need to be met. The powder’s sensitivity to processing can lead to the coating being hardened either by the intermetallic Laves phase or oxides formed during spraying, and even further altered by heat treatment, making production of targeted coating properties difficult. This paper describes how the use of In-Situ bi-layer curvature measurements during coating deposition and heat treatment can be used to observe the processing influence on the coating formation dynamics of stress, Laves phase precipitation, in-flight particle oxidation, and coating crystallization. Comparisons to traditional methods such as XRD, EDS, and property measurements are used to further validate in-situ observations and give insight into the mechanisms responsible for the properties of HVOF sprayed T-800/CoMoCrSi, providing a clearer path to produce targeted coating requirements.