The use of suspensions in the thermal spraying process, makes it possible to apply sufficiently thin (<30 μm), metallic coatings made of nickel-chromium alloy 2.4869 (NiCr8020). High velocity oxy-fuel suspension flame spraying (HVSFS) is used to manufacture these thin metallic coatings in order to be able to effectively use them as electric panel heaters. Area heating capacities of 25 W cm -2 are possible with them and heating rates of 15 K s -1 even outperform many ceramic heating elements. In addition, it provides a flexible way to apply the heating coatings directly to the components to be heated. The use of fine powders in the micron and sub-micron ranges allows a more precise adjustment of the coating thickness, compared to conventional thermal spraying techniques, even in the thickness range below 10 μm. Therefore, an adaption to customer needs is possible regarding the electric panel heater characteristics, like electric resistance, applied voltages and current range and heating rates.

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.

This paper presents developments in the field of induction capable coatings, mainly used for induction cookware on aluminum or copper base material, based on work by OBZ Innovation GmbH. The aim was to develop a new type of “intelligent” induction coating that influences the magnetic susceptibility depending on its temperature. This not only allows to limit the maximum reachable temperature, but also supports the uniform heat distribution over the bottom of the cookware. Thus, this new type of “intelligent” induction coating regulates such important boundary conditions, independently of undesirable or even unsafe settings of an end-user. Finally, this makes cooking easier, healthier and more durable as it prevents damaged PTFE sealings and safer by reducing the danger of fire because of overheating and burning. Additionally, such coatings can be used in further applications, whenever a passively limited or uniform heat distribution is advantageous, for example when the temperatures are too high or in general an electronic control system is for technical or economical reasons not suitable.

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.

The shear test developed within a European research project has important advantages compared to the coating strength test mainly in use today, the adhesion strength test according to DIN EN 582 or ASTM C 633. One of the main advantages is that no glue is used avoiding any possible influences of the glue. Furthermore the test is a rapid process compared to the adhesion strength test as there is no gluing procedure. However a number of very important directions have to be obeyed in order to make sure that the shear test is correct and comparable results can be reached. This is very important as in many cases it is not possible to control after the test if the directions had not been correctly obeyed. A number of further rules need to be followed to make sure the test results are correct. Within this presentation these direction will be summarized and essential hints will be given to make sure the test is carried out in the correct way. Finally a comparison will be given between the tensile adhesive test and the shear test from the practical and economical point of view of obz innovation gmbh, a thermal and cold spray job shop.

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%.

This paper deals with some of the latest developments and serial production applications at OBZ innovation GMBH. With three serial production cold gas systems and one for the R&D department, obz innovation gmbh is the leading supplier of cold sprayed coatings. The development of the well-known serial production process of a sinusoidal copper coating for hybrid cars is explained. Furthermore our ferritic chromium steel induction coating and our newly developed product, an immanent temperature limiting function for safety critical reasons, will be addressed. As an example for a current field of research currently examined at obz within a public funded project will be discussed insulating ceramics for power electronics with cold sprayed circuit paths for a potential use in fields like automotive and others. Last but not least, the latest product, “obz fingerprint” and “obz sensor” coatings that can be used against plagiarism and as a sensory element are presented for the first time.

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.

This work investigates the properties of insulating coatings deposited by HVOF and atmospheric plasma spraying and the effects of various sealants. It is shown that adhesive tensile strength depends strongly on surface roughness and that the dielectric strength of a material is normally higher in the unsealed state. In the case of a new sealant, however, the dielectric strength of HVOF sprayed alumina coatings is shown to be higher in the sealed state, which potentially opens new applications in high-performance electronics.

For the development and quality control of highly electrically conductive coatings, a device is required by which the electric conductivity can be measured. For this purpose a handheld device for measuring the electric conductivity of nonferrous metals in a nondestructive manner was tested. The measurement principle is based on an eddy current sensor which allows determining the electric conductivity within seconds. The method fulfills the demands for using it in the environment of a job shop for thermal spraying. Coatings applied with different thermal spraying methods like cold gas, HVOF, electric arc or flame spraying have been examined. Thus, it will be presented a comparison of the electric conductivity dependent on different spraying methods. Additionally, important edge conditions for spraying and measuring the conductivity of highly electrically conductive coatings like the influence of the oxygen content of the powder, the minimal coating thickness measurable with the device and the influence of the surface roughness onto the measurement were analyzed.

Since the first installation of a cold spray system at OBZ Innovation GMBH in 2002 the application areas of cold spraying have increased greatly. Cold spraying has developed into a safe and reliable process that is used successfully in various areas of industry. In this presentation current applications and new project developments at OBZ Innovation GMBH are demonstrated. Furthermore within an outlook the new possibilities with the latest cold spray technology, the KINETICS-8000-HP, are demonstrated. With this unit it is possible to increase the deposition rate compared to previous cold spray systems and expand the material spectrum usable for cold spraying to include higher refraction materials – all while cutting costs, increasing quality and maintaining excellent process reliability.

The shear test in accordance with DIN EN 15.340 is a method to test the bond between substrate and coating in thermal spraying. It has been developed in order to avoid the disadvantages of the test mainly in use, the adhesion test (DIN EN 582). In quality management in a thermal spraying job shop often results of coating analyses are necessary within a very limited time frame; very important is a low number of necessary specimens and a fast and reliable test method. It is described how the shear test can be implemented into the practice of a job shop and the experiences of the OBZ innovation GMBH, which has used the shear test for more than four years, are explained.

The shear test in accordance with EN 15340 is a new test method for testing the bond between substrate and thermally sprayed coatings. It has been developed in order to enable a test method without the disadvantages of the method currently in use, the adhesion test. In the adhesion test the adhesives influence the test results; therefore in the shear test no adhesives are used. The adhesives are among others the reason for a large deviation of the test results using the pull-off test. Using the shear test the mode of the test results depend on the ratio between adhesion and cohesion; this ratio causes three different fracture modes. In order to investigate the deviation depending on the fracture mode samples have been coated by wire flame spraying, arc, plasma and HVOF spraying. Different ceramics, carbides and metals have been used as thermal spraying materials. For each material-process combination between 30 and 120 samples have been coated. This report describes the interpretation of the results of the shear test depending on the fracture mode and the coating materials applied by different thermal spraying processes. The deviation of the results depending on the fracture mode has been investigated using a shear test device by which the shear force is recorded over the displacement of the coating. The knowledge of the deviation and the distribution of the results is necessary to decide on the required number of samples to reach a result with a defined reliability.

Anilox rolls are ink-metering rolls used in the printing industry to transfer an exact amount of ink to the printing cylinder. The importance of high quality anilox rolls has increased with the demand for higher quality printing. Improvements of the characteristics of anilox rolls have been achieved mainly by using laser-engraved, ceramic-coated rolls rather than the common chrome-plated and mechanically engraved rolls. The best results concerning the ceramic coating of anilox rolls were achieved by Cr 2 O 3 coatings. These coatings require a bond coat for good corrosion resistance. By far the most-used technology to produce this bond coat is high velocity oxygen fuel (HVOF) spraying using NiCr material. In order to lower the cost of the anilox roll coating it has been investigated if NiCr can be replaced by the chromium steel 316L as bondcoat material. 316L was applied to the surface by HVOF. The characteristics of 316L / Cr 2 O 3 layers were compared with respect to the required quality of the coating. The results were 316L / Cr 2 O 3 coatings with good mechanical characteristics compared to NiCr / Cr 2 O 3 layers. In particular, the metallographic sections showed compact coatings having a tensile adhesive strength slightly higher than and a corrosion resistance similar to the coatings with a NiCr bond coat.

This article gives an overview of thermal spraying of polymers with respect to the different spraying processes, the polymer materials in use for thermal spraying and new trends of using polymers as separate spraying material and in combination with plastic and non-plastic materials. Flame spraying is by far the most common process used for thermal spraying of plastic materials. In addition in the past years two other processes have been used to produce thermal sprayed plastic coatings: plasma spraying and high-velocity oxy fuel spraying (HVOF). The areas where the different processes are used as well as the modifications to conventional plasma and HVOF devices and the advantages and disadvantages using these two processes to produce plastic coatings will be described. In addition to the common materials used for flame spraying (e.g., PA 11, PA 12 or EVAL), other materials giving new opportunities of application of thermal sprayed coatings have been used like PEEK and LCPs. The areas where these materials are used are described as well as the special features of these materials. Furthermore there are new trends in using plastic materials for thermal spraying. Thermal sprayed polymer materials are for example combined with plastic as well as non-plastic materials or pigments giving special effects to the coatings, e.g, reflective or anti-skidding coatings. It is described how coatings with the mentioned effects can be produced.

The improvement of the tribologic characteristics of surfaces is an important application of thermal sprayed coatings. Also various ranges of application demand good antiadhesive characteristics. The tribologic and antiadhesive characteristics of fluorine containing polymers are very good. Since furthermore those polymers have the highest thermal resistance of all plastics it has been investigated if those polymers can be integrated in thermal sprayed oxide and carbide coatings. The aim was to improve the tribologic and antiadhesive characteristics. The processes Plasma- and HVOF-spraying have been used to apply the coatings. The polymers in the coatings were detected by examinations with the light-optical and the scanning electron microscope. To heighten the contrast for the light microscopy examinations the metallographic sections of the specimens were physically contrasted. To clearly identify the different phases with the scanning electron microscope EDX-analyses have been carried out. Samples have been tested to investigate the mechanical characteristics of the coatings. Paper text in German.