This study focuses on the development of thermally sprayed coatings for magnetic data storage. In the con-text of Industry 4.0 and the associated digitization of production, there is more demand than ever for suitable data storage on components in order to be able to automatically identify and process products. The resistance of certain sprayed coatings to harsh environmental conditions, make them a promising alternative compared to other solutions for dynamic data storage such as the RFID chips already available on the market. This area of application results in the requirement for a high stability of the written data against external influences such as temperature, wear or interference fields. These requirements can be met by the tailored choice of material including a sufficient magnetic anisotropy of the sprayed coatings. The influence of the spraying process on the formation of the magnetic material properties in the applied coatings is discussed with the aim of being able to change and optimize them in a targeted manner. The characterization of the produced samples is done by structural and magnetic analysis methods

In addition to the proper functional properties, the adhesive strength represents one of the key criteria for industrial use of thermally sprayed coatings. Since conventional thermal spraying processes are almost carried out exclusively in air atmosphere, this leads to the oxidation of the particles and of interfaces within the coatings. As a result, conventional thermally sprayed metallic and metal-ceramic coatings are characterized by heterogeneous microstructures with interlamellar oxide fringes at the interfaces between individual splats and also between the coating and the substrate. This has a decisive influence on the bond strength and on the wear and corrosion protection properties of thermally sprayed coatings. The aim of this study is to present the potentials of thermal spraying processes carried out in a mixture of monosiliane and an inert gas at ambient pressure as an alternative to the known vacuum spraying process in order to prevent oxidation during the coating process. Using the example of arcsprayed coatings, it is demonstrated that the extremely low oxygen partial pressure in the silane-doped medium leads to coatings free of oxide seams with a reduced porosity and substantially enhanced properties.

In the semiconductor industry, plasma etching processes are widely used. Process chamber parts that are located in the plasma etching system are also exposed to the harsh environmental conditions. Thus, parts located close to the process area are typically coated with yttria to increase service life, and thus process performance. However, such yttria coatings are usually porous, and thus can be attacked by fluorine containing plasma. In order to increase the lifetime of the components in the plasma etching system, this research project aimed to improve the protective yttria layer by reducing the porosity of the protective layer. Specifically, a design of experiment was employed in which the porosity was the target value. The main effects of the coating parameters and their interactions including the surface treatment before the coating process were determined. Furthermore, the bonding of the protective coating to the component to be protected, as well as the element distribution and the coating morphology were investigated. The results and their ramifications with respect to the envisaged application will be discussed.

Depending on the size and type defects of nickel-based alloy turbine blades two procedures are used mainly: cladding and high temperature brazing. The repair brazing of turbine blades is used to regenerate cracks and surface defects and is the focus of this work. In this contribution a two stage hybrid repair brazing process is presented which allows reducing the current process chain for repair brazing turbine blades. In the first stage of this process the filler metal (NiCrSi) then the hot gas corrosion protective coating (NiCoCrAlY) and finally the aluminium are applied in this order by atmospheric plasma spraying. In the second stage of this hybrid technology the applied coating system undergoes a heat treatment in which brazing and aluminising are combined. The temperature-time regime has an influence on the microstructure of the coating which is investigated in this work.

In this research project a hybrid technology is developed to repair turbine blades. This technology incorporates procedural and manufacturing aspects like raising the degree of automation or lowering the effort of machining and includes materials mechanisms (e.g. diffusion processes) as well. Taking into account these aspects it is possible to shorten the process chain for regenerating turbine blades. In this study the turbine blades of the high pressure turbine are considered and therefore nickel-based alloys are regarded. To repair or regenerate turbine blades the following methods are employed: welding and brazing and a subsequent aluminizing CVD-process. The focus in this work lies on the brazing method and the required filler-metal is applied together with the hot-gas corrosion protective coating by means of thermal spraying and represents the first stage of this hybrid technology. In the second stage of this hybrid technology the brazing process is integrated into the aluminizing CVD-process and a first effort is presented here.

The aim of the research project is to combine repair brazing with protective coating against hot-gas corrosion into a common integrated process. Both the braze-metal as well as the hot-gas corrosion protection coating is applied by means of thermal spraying. The material layout is to be realized as far as possible to the near net shape by using thermal spraying. The processes are to be performed in such a way that the brazing is integrated into the CVD diffusion annealing process as a transient liquid phase bonding (TLP bonding) process which, as a consequence, can then be eliminated as a separate processing step. The thermal spraying processes of atmospheric plasma spraying (APS), high velocity oxygen fuel spraying (HVOF) and cold gas spraying (CGS) are to be qualified for this purpose. Thus the project working hypothesis is to be able to transform thermal coating and joining processes into a common integrated hybrid process and, in doing so, obtain both high-quality and economic advantages. The importance of combining these processes lies in reducing the effort of grinding as well as economizing on the vacuum brazing, which is currently a separate process step, and consequently lowering the production costs.