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This paper reviews the new DIN EN ISO personnel qualification and quality management standards and EWF training guidelines for European thermal sprayers. EWF education and training programs run for a period of three weeks, filling critical gaps in knowledge and experience. The primary aim of the ISO standards is to facilitate a reproducible process for spraying coatings of a consistent quality. Paper text in German.

Working with qualified personnel means for each industrial company effectiveness and competitiveness. International standards and guidelines help to continue not only on the domestic market. In the recent years a considerable standardisation was made specially in the European Community. In the field of thermal spraying EN standards were and will be worked out, which fix the approval testing of thermal sprayers and the tasks and responsibilities of spraying co-ordinators. At the same time EWF guidelines were created to define the minimum requirements for training and educating spraying personnel. These standards and guidelines will be introduced, showing connections between them. Paper text in German.

More than 20 years the Institute of Technical Thermodynamics of the German Aerospace Center (DLR) in Stuttgart has been active in the field of plasma spray technology with improvements of spray equipment and their application. At the beginning the DC vacuum plasma spray method was in the center of interest and knowledge gained from rocket technology helped to develop supersonic nozzles for the plasma spray torches producing plasma jets with increased velocity and improved laminarity in order to get denser coatings with higher quality. In the meantime also nozzles for subsonic conditions with controlled expansion of the plasma jet leading to considerably increased deposition efficiency were developed as compatible parts for already existing equipment and made available on the market. In the next step also the DC plasma torches themselves have been improved. Recently a modern equipment for RF plasma technology could be developed and installed, where some new ideas could be realised. Paper text in German.

The aim of this work is to determine how to control the microstructure and tribological properties of HVOF-sprayed TiC composite coatings. The powders used in the study were made by the SHS process and contained a mixture of TiC and either FeCr20Ni10 or FeCr18Ni15Mo3, which serve as a binder and give the sprayed coatings additional corrosion resistance. The composites produced were assessed based on metallographic examination and wear testing. The results show how the structure of the SHS powder changes due to the injection molding process and how the tribological properties of the HVOF layers are influenced by spraying conditions and the formation of mixed carbides. Paper text in German.

The aim of this investigation is to increase the corrosion and wear resistance of magnesium (Mg) alloys. This paper explains how various coatings applied via plasma powder (PTA) and laser deposition welding processes affect the wear properties of two Mg alloys. It is shown that coating quality depends on the type of Mg used, the composition of the filler materials (matrix and carbides), and welding parameters. The best results for Mg alloys AM50 and AZ31 were obtained with a coating consisting of a composite matrix (AlSi 12 ) with boron carbide additions. Paper text in German.

This paper shows how thermal spraying, with an additional thermal treatment, can be used to join metal parts and fill surface defects. The joining and surface repair methods demonstrated in this work involve a wide range of materials and processes, and the results are characterized based on microstructural and elemental analysis and various property measurements. Paper text in German.

The development and introduction of more advanced spray systems continues to drive the thermal spray market. Most of these developments benefit from an increase in particle velocities. The latest generation of HVOF systems can spray cermet coatings of higher density and higher hardness, wear resistance and corrosion resistance than HVOF systems introduced previously, due to an 30 to 50 % increase in particle velocity. HVAF systems are offered as an cost-effective alternative to HVOF systems. A further increase in particle velocity and the introduction of cold gas spraying can be seen as a transition from thermal to kinetic spraying and may open a wide field of new applications for coatings and structures of oxidation sensitive materials. Advances are also reported for wire spraying. New arc spray systems are capable to increase the density of metal and alloy coatings considerably and to reduce the oxide content of these coatings. Similar improvements but at lower spray rates may be achieved with newly developed HVOF wire systems. Paper text in German.

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.

Meanwhile thermal spray shops may apply a comprehensive works of application and qualification standards, e.g. in the case of building up a spray shop, qualifying thermal spraying personnel, defining requirements for spraying constructions or parts and testing thermally sprayed coatings. High and reproducible quality of products and services are required by the customer. Concerning national and international competition, also pressure on prices by keeping high and reproducible quality of the sprayed coatings will be in store for spray companies. In the following, actual quality management and personnel qualifying standards are described, which are now available. Experiences of a certifying institution and a spray company made by installing a QM- System and certifying audit may serve to orientation for those who will aim at QM certification. Paper text in German.

For quality control in the coating sector, coat thicknesses are measured either destructively or non-destructively. Many European and internationally applicable testing possibilities are available for this purpose, e.g. [1-13]. One common feature in all the procedures is the retraceability of the length or length differences measured using various methods to national or international units. In the range of the thin coats (< 10 µm), various coat standards exist today according to which, for example, device manufacturers or users can adjust their measuring devices. However, there are no such certifiable standards for the thick-coat range. The objective of this project was to manufacture standard coat thicknesses of approx. 50 - 1,000 µm using vacuum plasma spraying consisting of non-conductive, non-magnetic coats with the highest possible precision with regard to coat ho¬mogeneity and final-contour fabrication and then to certify them. This article describes the requirements concerning the material selection, spraying process and subsequent machining. Paper text in German.

In the present project, the widest possible variety of coats applied by means of high-speed flame spraying are investigated with regard to their applicability to components of hydroelectric power stations. The investigations concentrate on protective coats for the wear surfaces of turbine wheels and various guide vanes. The structural shapes and specific features of different turbine wheels, forms of wear phenomena and their causes as well as experience with different materials and coatings are described. The resulting planning and stipulation of suitable testing conditions for the targeted investigations with high-speed flame- sprayed coats are also described. Paper text in German.

The new Triplex-burner was used to develop 7 wt% Y 2 O 3 stabilised ZrO 2 thermal barrier coatings and to optimise the process parameters with respect to reproducibility. The investigations were focused on spray efficiency and coating porosity. Porosity levels and porosity distribution were measured with mercury intrusion, which turned out to be a very reliable characterisation technique. High reproducibility could be achieved in particular for low argon fluxes: the deviation of the porosity levels was below about 4%. Paper text in German.

This paper reviews the results of thermal spraying on the magnesium alloy AZ 91. By plasma, arc and HVOF spraying various metal based alloys were used as coating materials. The layers were investigated with regard to microstructure, bonding and corrosion resistance. Paper text in German.

A spectroscopic measurement system has been developed and used for thermal spray applications. The system provides on¬line information of the process and allows the determination of process fluctuations over various time scales. Paper text in German.

During the formation of coating systems we find strong temperature gradients within the coating-substrate system resulting in thermally induced stresses in the coating after the spraying process. The purpose of this investigation is to develop numerical tools which provide insight into the relationship between coating parameters and the thermomechanical response of the produced composite. Transient finite element modelling is applied to calculate temperature and stress histories in thermally sprayed coatings due to the deposition process. Two different models with different levels of complexity have been developed to investigate the spraying process on a macroscopic and on a microscopic scale. Experimental investigations of the temperature history during spraying in the substrate have been carried out to determine boundary conditions for the mathematical model and to enable a verification of the obtained results.

This paper describes the development of detonation-sprayed aluminum-matrix composite coatings reinforced with boron carbide. The goal is to achieve a homogeneous coating structure with low porosity, low oxide content, and high concentration of embedded carbides. Tensile tests of various types were conducted and different stages of deformation were analyzed using micro computed tomography, a 3D imaging technique that reveals the formation of cracks in real time.

Plasma spraying, commonly used for wear and heat resistant barriers, can be used to produce free-standing bulk ceramic parts as well. In this work the microstructure and phase development of a bulk plasma-sprayed alumina material with about 14 % porosity and splat like grains is investigated in the as-sprayed and various annealed material conditions, using electron microscopic and x-ray diffraction techniques. The fracture characteristics are investigated using standard CT specimens in in-situ SEM experiments. The mechanical response of the material is clearly a result of two features: the pronounced alignment of microstructure itself, and the occurrence of a splat-internal microcrack sub-structure in the as-sprayed condition. This microcrack substructure is a consequence of a splat internal columnar subgrain structure which occurs as a result of the rapid cooling conditions on deposition. The morphology of this subgrain structure and its phase composition is seen to change extensively on annealing. It is found that the mechanical behaviour of the as sprayed material is dominated by this internal subgrain structure, but the behaviour of sufficiently annealed material is dominated by the morphology and mechanical stability of the splat like grains themselves. The biggest change on annealing is not an overall sintering effect, but rather the recrystallisation of the splat internal substructure

The combination of excellent mechanical, thermal and chemical properties of silicon carbide (SiC) and titanium carbide (TiC) has made these materials very attractive both for structural ceramics applications and for thermal sprayed coatings. To suppress oxidation and to avoid the formation of silicides during spraying of SiC-based composites, feedstock spray powders have been developed containing 32 wt.-% of an alumina-yttrium ceramic binder matrix. The spray powders are prepared by spray-drying and sintering (a&s). Also, TiC-based composite spray powders showing the same matrix material and content have been developed and produced. Thermal spray processing of the described powders by atmospheric plasma spraying (APS) using an F6 APS torch and high velocity oxygen fuel spraying (HVOF) with the Top Gun G acetylene torch is carried out. Both the produced coatings and feedstock powder are characterized by optical microscopy, X-ray diffractometry (XRD) and scanning electron microscopy (SEM) including energy dispersive X-ray analyses (EDXS).

The central components for solid oxide fuel cells (SOFC) are the electrodes-electrolyte multilayer arrangement (PEN) and the separating bipolar plates. The PEN (Positive electrode- Electrolyte-Negative electrode) assembly consists of a dense gastight yttria-stabilized zirconia (YSZ) electrolyte and porous electrodes for which usually Ni-YSZ cermet anode and Sr-doped LaMnO 3 cathode layers are used. The various PEN units are connected in a cell stack by bipolar plates which are either metallic or ceramic ones. Furthermore, a protective layer on the metallic bipolar plates consisting of a chromium alloy is required to prevent chromium evaporation leading to a rapid and strong degradation of the SOFC performance. At the DLR Stuttgart both the DC and the RF vacuum plasma spraying technique have been further developed and adapted to meet the requirements for the manufacture of the different SOFC components. The DCVPS process using specially developed Laval-like nozzles is especially appropriate to the production of thin and dense coatings as required for the electrolyte and the protective layers. However, applying special spray parameters and nozzles it is also possible to deposit porous electrode layers. The production of the entire PEN arrangement in one consecutive DC-VPS process is the objective of the actual development. On the other hand, the RF plasma spray technique is suitable for the near net-shape production of bulk components such as the metallic bipolar plate. The development of the deposition processes for the production of SOFC components using DC and RF plasma spray methods and the results obtained concerning PEN fabrication, deposition of protective layers and the near net-shape production of metallic bipolar plates are presented in the paper.

Fine (median size 6 μm and 0.3 μm) cobalt spinel (Co 3 O 4 ) powders were processed suspended in a suitable liquid phase. Suspensions exceeding 50 wt.% solid phase content were successfully injected into an inductively coupled plasma. Spheroidized powders with large particle size (up to 80 μm) were prepared, and cobalt oxide coatings were produced by this novel RF-SPS method. The microstructural features of the coatings can be controlled by parameter optimization similarly to plasma spraying of dry powders. Numerous variations of the physical and chemical conditions of the process were performed in an attempt to overcome the main disadvantage of the process, i.e. the decomposition of the spinel phase to CoO. So far, the spinel phase could be reestablished only by a post-treatment of the deposited coatings with atomic oxygen in the RF plasma.