Session BB9.3

4:00 PM BB9.3
PROCESSING EFFECTS ON MICROSTRUCTURE DEVELOPMENT DURING THERMAL SPRAYING. Sanjay Sampath, Center for Thermal Spray Research, State University of New York, Stony Brook, NY.

Thermal spraying is a highly dynamic process resulting from rapid heating/melting/accelerating of powder particles or wire in a flame, followed by impact and rapid solidification of the droplet (splat). The particles experience large thermal gradients in the flame during its heating/melting which can lead to phase decomposition, species volatilization and oxidation of metallic components. Due to the rapid solidification nature of the process, deposit evolution is complex, commonly leading to ultra-fine-grained and metastable microstructures. Thus, the non-equilibrium phenomena are common in the microstructure, with important implications for properties and performance. A splat resulting from the flattening of an individual droplet is the basic building block of the thermal spray microstructure. The phase and microstructure of the splats and the integration of the splats are both affected by processing. Furthermore, particle size and deposition temperature have been shown to influence the microstructure development. Thus, understanding and prediction of phase/microstructure evolution by examining rapid solidification provide insight into structure-property-performance triad. This presentation will cover the deposit formation dynamics, the evolution of the rapidly solidified microstructure, and provide case studies to illustrate the relationships between processing-microstructure. Implications of the effects on properties will also be discussed for select systems.