Innovative process combination for substrate bonding of thermally sprayed coatings

The existing substrate bonding mechanisms are important for the quality of thermally sprayed coatings. (Photo: IW)

IW | Corundum blasting used as a pre-treatment of coating surfaces is more and more replaced by machining processes. Researchers are developing an innovative combination of processes for the form-locked bonding of thermally sprayed coatings.

Scientists from the Institute of Materials Science (IW) and the Institute of Machining Technology (ISF) are designing novel surface structures which can reach the adhesive tensile strength required for thermally sprayed coatings without the need of a blasting process. For this purpose, a wave structure is applied to the surface of a steel shaft using a knurl milling process. Since the knurled wave structure alone cannot guarantee the required bonding quality, a rolling process is used afterwards to apply undercuts at the surface, thus improving the mechanical bonding of the coatings sprayed onto the substrate. Moreover, the spraying parameters and the post-treatments for the sprayed coatings are adapted to the new challenge.

by Manuel Rodriguez Diaz, Kai Möhwald, Florian Vogel, Dirk Biermann

Image gallery for this article

  • The existing substrate bonding mechanisms are important for the quality of thermally sprayed coatings. (Photo: IW)
  • The aim is to substitute corundum blasting, an established process for the pre-treatment of coating surfaces, by machining processes. (Photo: ISF, IW)
  • But knurled structures alone cannot provide the mechanical bonding required to compete against corundum blasting successfully. (Photo: ISF, IW)
  • Rolling of the wave structure produces undercuts on the surface, thus improving the adhesive tensile strength considerably. (Photo: ISF, IW)
  • Due to the symmetrical arrangement of the undercuts and the post-treatment of the coating by deep rolling, adhesive tensile strength measurements reach nearly the same level as with corundum-blasted specimens. (Photo: ISF, IW)
This website uses cookies to provide you with the best possible functionality. You agree to the use of cookies by using our website without changing your preferences. (Data Protection)