Splats formed during a thermal spray process may be either highly fragmented or intact and disk-like. To predict this change in splat morphology, a dimensionless solidification parameter (Θ), which takes into account factors such as the substrate temperature, splat and substrate thermophysical properties, and thermal contact resistance between the two, has been defined. Θ is the ratio of the thickness of the solid layer formed in the splat while it is spreading, to the splat thickness. The value of Θ can be calculated from simple analytical models of splat solidification and spreading. If the solid layer growth is very slow (Θ << 1), the droplet spreads out to a large extent. Once it reaches maximum spread it becomes so thin that it ruptures, producing fragmented splats. If, however, the solid layer thickness is significant (Θ ~ 0.1 – 0.4), the droplet is restricted from spreading too far and does not become thin enough to rupture. Under such circumstances, disk-type splats are expected. When the solid layer growth is rapid (Θ~1), spreading of the droplet is significantly obstructed by the solid layer, producing splats with fingers around their periphery. Predictions from the model are compared with experimental data.

This content is only available as a PDF.
You do not currently have access to this content.