Investigation of the interface of overlapping splats for a WC-based Cermet

Scientists working on thermal spraying applications often investigate the behavior of single splats after their impact on polished or roughened substrates. If splats do not overlap it is easy to distinguish between different morphologies of splats, but no information about the interface between two splats is provided.

In this investigation, the behavior of overlapping HVOF-sprayed Cermet splats is analyzed. Samples were sprayed in several steps with a low density of splats. The sample surfaces were analyzed after every step in a SEM. Therefore it is possible to sort overlapping splats according to their chronological order of impact. With this information, a cross section is made of areas with overlapping splats to see the microstructure, at the boundaries of the splats. An ion-polishing method was employed to avoid the corruption of small pores and structures by mechanical polishing.