Metallic coatings can be produced easily with thermal spray and cold gas spray processes. However, when coating thicknesses below 50 μm are required for economical or technological reasons, the use of these well-established processes becomes more challenging. The company OBZ Innovation GmbH has developed spray processes that can produce metallic coatings with thicknesses of less than 20 μm. Such coatings are of interest for applications such as cold gas sprayed silver coatings with high purity and good electrical conductivity. Thinner sprayed coatings of such valuable materials have economic advantages, and the process may be competitive with commonly used thin film coating methods.

In order to meet the increased requirements for power electronics in the automotive sector, an effective utilization of difficult installation spaces is necessary. A new production concept to realize this 3D integration of electronic circuit boards directly on components is the combination of thermal spraying and cold gas spraying to create multilayer-coating systems consisting of conducting and insulating coatings. In this study two- and tree-dimensional demonstrators were developed, showing the flexible use of thermal spraying in mechatronics and power electronics. In contrast to past studies on this construction concept, the main focus of this study was on the optimization of the ceramic insulting coatings and bond strength of the metallization. The ceramic coatings showed a dielectric strength and electrical resistance, which was suitable for most applications. Additional post treatment improved the electrical resistance in humid conditions. Already 150 µm thick electrical insulation layers showed a breakdown voltage of more than 5 kV AC and a specific electrical resistance of 5.1011 Ω.m.

Electrically insulating coatings featuring high dielectric strength, high electrical resistance and high thermal conductivity are essential for applications in high power electronics. The capability of HVOF-sprayed coatings for high power electronic components based on 20 different powders was investigated in this study. The powders used are aluminum oxide ceramics containing additives of chromium oxide, titanium oxide and magnesium oxide. Key result of this study is that both, pure alumina (Al 2 O 3 ) and one class of spinel (Al 2 O 3 - 28MgO) meet the requirements for electrical insulation. In order to reach high resistivity, the insulation coatings should be sealed subsequently. The amount of impurities, such as Na 2 O or Fe 2 O 3 must be less than 0.1%.

In this study, nickel and Inconel coatings were deposited on aluminum and steel substrates by cold gas spraying. Fine, standard, and coarse nickel powders and two standard Inconel (625 and 718) powders were selected as feedstock materials and sprayed at different gas pressures and temperatures. A coaxial air-cooled nozzle was used in spray trials, except for the fine Ni powder, which required a water-cooled nozzle to prevent clogging at high temperatures. Coating microstructures were examined and various properties were measured including shear strength, adhesive tensile strength, hardness, and porosity. Cross-sectional images of different coating samples are presented and discussed along with test results.