In this work, thermally sprayed sustainable coatings with spray additives recycled from dry alkaline batteries and solid-oxide fuel cells are developed to allow the growth of drought-resistant plants like moss, microclover and chamomile. It is assumed that these plants anchor to the coating with their rhizoids and hence can be grown without the presence of soil. Preliminary tests of a thermally sprayed Yttrium Stabilized Zirconia (YSZ) ceramic coating on sheet metal confirms the growth of chamomile plant.

Previous own works revealed that novel partially amorphous Fe-based alloys have a combination of proper-ties that are beneficial for the application in liquid hydrogen (LH2) tanks, viz low thermal diffusivity, little porosity, and good adhesion. The influence of cryogenic temperatures or hydrogen on coating tensile strength, on the other hand, has not been investigated yet for this material. However, this is crucial for the long-term durability of the coatings under hydrogen and other alternative fuels. Thus, in this work, tubular coating tensile (TCT) tests were performed at room temperature and cryogenic temperatures. In addition, hydrogen charging was carried out to identify a possible regime that is sufficient for TCT tests under the influence of hydrogen. Subsequently, the fracture surfaces were evaluated analytically, optically and profilometrically. Under cryogenic conditions, a significant increase in tensile strength and a finer structure of the fracture surfaces was observed.

Whenever farming tools are used, the focus is on wear resistance. As the wear rate differs with local soil conditions, the progress of wear and thus the time for tool change is difficult to identify. Hence, component failure and breakage as well as the unknown retention of components or parts thereof in the field are possible undesirable consequences. This demands not only a better wear-resistant coating, but also a wear limit indicator to determine the time for tool change more precisely. This helps in reducing the fuel consumption and increasing the quality of soil. Therefore, the aim of this study is the development and application of a coating system with increased wear resistance compared to original OEM parts (Original Equipment Manufacturer) and integrated optical wear indication. Preliminary own tests demonstrated that arc-sprayed hard-facing coatings can increase the wear limit. Thus, in the current work two different types of thermal sprayed coatings are analyzed with regard to their wear resistance behavior. After positive wear test results, field testing on farmland was carried out. Further investigations concerned microstructure, optical as well as profilometry surface analyzes.

In the current work, a typical NiCrAlY alloy and, moreover, amorphous Fe-based alloys are arc-sprayed for the desired application in cryogenic environments. Nitrogen is used as process gas, while the stand-off distance and number of passes were varied. The results demonstrate coatings with low, but varying porosity and oxide content and mostly high electrical conductivity. Especially the amorphous Fe-based coatings reveal homogeneous coating structures and promising properties. Further investigations regarded the deposition efficiency, tensile adhesive strength, hardness, durability under cryogenic conditions and the thermal diffusivity.

The present study compares needed prerequisites for the application of cavitation resistant bronzes by applying different coating techniques, such as cold spraying, HVOF spraying, warm spraying and arc spraying. By optimization to optimum cavitation resistance, the deposited coatings can increase the service life of ship rudders significantly and even serve as repair processes for ship propellers. The given overview aims to support the selection of processes when specifying the target properties to be set with regard to cavitation protection. By using high-pressure warm spraying and cold spraying, properties similar to those of cast nickel aluminum bronze were achieved, however at relatively high costs. In contrast, coatings produced by using HVOF and arc spraying have erosion rates that are only about four respectively three times higher as compared to cast nickel aluminum bronze, while far outperforming bulk shipbuilding steel. Hence, their properties should be sufficient for acceptable service life or docking intervals for ship rudder applications. Propeller repair might demand for better coating properties as obtained by cold spraying. With respect to costs, HVOF and arc spraying in summary might represent a good compromise to reach coating properties needed in application.

This study assesses the quality of flame-sprayed alumina coatings produced from recently developed alumina cord using argon and compressed air as atomizing gases. Coatings of different thicknesses were deposited on aluminum substrates and then analyzed using optical microscopy, X-ray diffraction, and resistivity measurements. The coatings, particularly those sprayed with argon, had fine microstructure and higher surface and volume resistivity than flame-spray coatings made from alumina cord in the past. They were also found to have higher alpha phase content than plasma-sprayed coatings, regardless of the atomizing gas used. The effect of humidity and the possible formation of aluminum hydroxides are also addressed.

In this study, NiCr alloy coatings were deposited by arc spraying using different combinations and mixtures of pressurizing gases and other process modifications. Coating properties were examined mainly by SEM, EDS, and conductivity measurements. The results show significantly reduced oxygen contents and improved coating morphologies compared to reference coatings produced using current plasma processes. Improved microstructure is shown to have a positive effect on surface quality and specific resistivity, making it possible to texture arc-sprayed coatings just as successfully as the plasma-sprayed reference layers. Moreover, the temperature coefficients and resistivities of arc-sprayed NiCr were found to be superior to those of conventionally manufactured coatings.

The alloys CuAl9Ni5Fe4Mn and CuMn13Al8Fe3Ni2 were arc-sprayed with a spiral-shaped pattern in this work, using both pressurized air and a mixture of nitrogen and hydrogen. Process temperatures were recorded by thermographic imaging and residual stresses were measured by modified hole-drilling method. Moreover, analyses of the cavitation erosion behavior and other properties were carried out. It was found that a change in the spray pattern can strongly reduce residual stresses and material loss by cavitation erosion.

The highly cavitation erosion resistant propeller alloys CuAl9Ni5Fe4Mn and CuMn13Al8Fe3Ni2 were arc sprayed with different traverse speeds by using a mixture of nitrogen and 2 % of hydrogen as atomising gas. Residual stresses were measured by the modified hole-drilling method using ESPI. Microstructural, chemical and mechanical analyses were realised to examine adhesive and cohesive properties. Additionally, the cavitation erosion behaviour was investigated. In comparison to coatings sprayed with pressurised air, the results of the study show superior coating qualities with regard to microstructure, cavitation erosion resistance and residual stresses.

Within the scope of a current research project, aluminum bronze alloy wires were arc sprayed at different traverse speeds in order to influence heat transfer and hence the stress state of the coating. Microstructural, chemical, and mechanical analyses were conducted to evaluate adhesive and cohesive properties. The materials used are highly cavitation erosion resistant propeller alloys, CuAl9Ni5Fe4Mn and CuMn13Al8Fe3Ni2. Cavitation erosion tests were carried out and residual stress distribution was measured using a modified hole-drilling method.