Development of Machining Processes for the Use of Multilayer High-Performance Coatings

The development of corrosion- and wear-resistant high-performance coatings is important to improve components of mobile and stationary turbines, aerospace undercarriages, combustion engines, and hydraulic modules. New micro- and nanostructured coating materials and processes to machine these coatings are developed in order to increase the performance of workpieces and components, to enhance durability, and to reduce maintenance and manufacturing costs. At the Institute of Machining Technology (ISF), milling and grinding procedures have been developed for the preparation of the workpiece surface for the subsequent coating process. In contrast to conventional applications, the workpieces are not manufactured with the aim of achieving a minimized resulting surface roughness. Instead of this, a defined and adequate structure has to be generated, providing a good adhesion of the thermal sprayed coating on the workpiece surface. After first coating of the prepared substrates by a High-Velocity-Oxygen-Fuel (HVOF) coating process, the resulting surface topography does not have the required surface quality for a subsequent (Diamond Like Carbon) DLC coating process. In order to generate a more uniform surface structure, the deteriorated surface resulting from the HVOF coating process also has to be processed. Therefore, the application of an adapted grinding process with diamond wheels is used.