In some applications like car armouring for personal safety, in bulk containers in pebbles working, in off-shore applications or in offroad-vehicles, impact of bodies with different sizes and high velocities has to be calculated in material design. A possibility to design under economical aspects is to use to low-cost material as substrate with a protective coating on its surface instead of using expensive bulk materials. One conceivable material system to be used as protective coating is WC-CoCr, which is usually applied by HVOF and shows high hardness combined with a good toughness of the matrix. These properties are very important for dissipation of the impact energy and for high fracture toughness. In the presented case study, WC-CoCr coatings with different carbide sizes were produced with the JP5000 system from TAFA. Projectiles with high velocities of more than 250 m/s were shot by an experimental shooting device on the coatings and for comparability on the uncoated substrate. Impact tests were done with balls and cylinders with varying impact angles between 10° and 90°. The powders and the coatings were characterized by means of microscopy and XRD. Furthermore, the hardness of the coatings was measured. After impact tests, the coatings were investigated with optical microscopy. In the case of ball impact, a significant dependency can be found between the impact behaviour and carbide size. Coatings with coarse carbides show the lowest impact depth. The dependency of the impact depth of coatings with one carbide size on their hardness level is relatively low. No dependencies of the carbide size or the hardness level can be found for impact with cylinders.

MoSi 2 -TiB 2 coatings were applied on Ti6Al4V substrates by means of low pressure plasma spraying with and without a surface pre-treatment with plasma-transferred-arc. The coatings were characterized by optical and scanning electron microscopy, X-ray diffraction analysis and hardness measurements. No difference in the microstructure between the coatings was detectable. The microstructure shows the typical lamellar structure of thermal spray coatings with a good embedding of the titanium borides in the matrix. At the interface between matrix and some borides a reaction zone is visible. In comparison to the feedstock powder, the phase composition of the coatings has change, because a great amount of the tetragonal MoSi 2 phase transformed into the hexagonal high temperature modification. The content of titanium diboride is lower in the coating. Coatings on substrates with a pre-treatment show a good adhesion to the substrate, while the adhesion of the coatings on the pre-treated substrates is poor.

During the last decades, the application of copper alloys has become very prominent in engineering. Judging from the properties of bulk materials or galvanic copper coatings, a thermal sprayed coating shows significant disadvantages. The reason for this effect is the build up of a thermal sprayed coating by individual droplets. The main aim of this work is to improve the properties of the twin wire arc sprayed copper alloys, thereby expanding the application of these kind of coatings to the areas where galvanic copper plating technique are mainly used. A copper-cobalt-beryllium alloy has been investigated and the possibility of its application in the twin wire arc process evaluated. The arc sprayed coatings were classified based on the properties of bulk material. The improvement of properties like hardness is based on an investigation of several spraying parameters of the arc spray process. To achieve a maximum value of thermal or electrical conductivity, minimum porosity of the coatings was the aim. Furthermore, a post heat treatment of the sprayed coatings, with the aim of reducing residual tensile stresses within the coating and to improve the wear resistance by means of hardening effects, was carried out. The investigations involved metallographic examination of the coatings using optical microscopy and scanning electron microscopy. Phase composition and residual stresses were detected by X-ray diffraction analysis. Microhardness was measured in the as sprayed as well as in the heat treated state.

This paper investigates the adhesion of thermally sprayed ceramic particles on metal substrates. Two aluminum oxide powders are applied to nickel-oxide coated steel substrates by detonation and vacuum plasma spraying. SEM and XRD fracture analysis is used to examine the ceramic-metal interface and the morphology of fracture surfaces. In all test samples, failure occurs in the alumina, not at the interlayer boundary, indicating a high level of adhesion between the ceramic and nickel oxide layers. Paper includes a German-language abstract.

This paper investigates the effect of laser treatment on alumina-TiO 2 coatings deposited by detonation spraying. It describes the changes observed in the microstructure and hardness of the remelted layers. The originally lamellar structure is transformed into a fine, pore-free columnar structure in which the grains are oriented perpendicular to the interface between the layer and substrate. The remelted zones contain alpha-aluminum oxide as the main phase and are characterized by high microhardness, although a few defects were observed on the periphery. Paper includes a German-language abstract.

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.

Conducted are investigations of powders for plasma spray of wear resistant coatings. Studied are shape, relief and particle size of NiCr-Fe+50(80)%Cr 3 C 2 , NiCr-Fe+50(80)%SiC powders using scanning electron microscopy. Investigations is supplemented by the results of X-ray structural studies. Investigations serve to develop coatings with the improved oil trap capability, increased hardness and wear resistance, sprayed by a plasma jet. The developed coatings will be used to restore and strengthen machines components

Molybdenum silicides have the potential as protective coatings for high-temperature applications because of their high melting point and their high-temperature oxidation resistance. Reinforcing MoSi2 with SiC shows an improvement of its low toughness at room temperature and low creep resistance at temperatures above the brittle-ductile transition temperature of approximately 700-1000 °C. A new kind of powder processing was used to produce MoSi2 and MoSi2-SiC as a feedstock for thermal spraying. Mixtures of the elemental powders, molybdenum and silicon, were prepared by milling and subsequent heat treatment to get highly dispersed, pre-reacted powders. As high-energy milling equipment, a planetary ball mill was used to prepare the powders. In the case of reinforcement, SiC was mixed to the pre-reacted MoSi2 at the end of the milling process, that means before heat treatment. On these as-milled powders, X-ray diffraction characterization (XRD), scanning electron microscopy (SEM), electron probe micro analysis (EPMA) and determination of the oxygen level were carried out. Vacuum plasma spraying has been used to deposit the powders onto a carbon steel substrate. Evaluated coating characteristics were the microstructure (SEM), phases (XRD), EPMA, oxygen content, microhardness and surface roughness. Tests at high temperatures will be considered in future work.

High Velocity Oxygen Fuel (HVOF) spraying established itself as an effective method in addition to the conventional thermal spray processes within a very short period. Self fluxing nickel alloys, cermets (e.g. WC-Co / Cr3C2-NiCr) as well as oxide ceramic coatings have proved themselves suitable for wear protection applications. Weight reduction, the care of resources and the increase of efficiency for structural components leads to the substitution of customary hard particles. Titanium carbide (TiC) characterizes itself on account of the material features such as the high hardness, the high melting point, the high strength and the low density for the substitution of conventional carbides. The Self Propagating High Temperature Synthesis (SHS) is a suitable process for the production of composite powders. The powders produced by SHS show a high carbide content, which is finely distributed with an almost stoichiometric composition of the TiC inside the powder particles. The carbides are protected against dissociation and oxidation during the thermal spray process by a complete velum of matrix alloy. The current investigations deal with the wear resistance of TiC-composite coatings produced by HVOF compared to conventional wear resistant coatings. The investigations contain the analysis of the microstructure by optical and scanning electron microscope (SEM) and the measurement of the microhardness of the deposited coatings. Special attention is drawn to the interface between the hard particles and the matrix alloy. The optimized coatings are tested with different wear tests, such as Taber-Abraser test, sliding and oscillating wear test and are compared with common wear resistant coatings in order to underline the high potential for different wear applications. Moreover an additional corrosion test (salt fog test) is carried out with regard to the corrosion resistance of the different matrix alloys.

The following contribution deals with carbide composite powders. These composite powders were made by the SHS-process. The present work is a result of a co-operation between the Institute for Powder Metallurgy Minsk (PMI) and the Department of Composites and Surface Technology at the Chemnitz University of Technology (TUC). The main aspect of this research activity is the improvement of the wear protection due to the deposition of the composite coatings. Paper text in German.

Thermal spraying of composite materials is an effective method for surface protection against wear and corrosive attacks. There are different possibilities to produce composite-materials for thermal spray applications. The self-propagating-high- temperature-synthesis (SHS) is a very promising method to obtain fine carbide particles homogeneously distributed in a metal matrix. In the present investigation TiC-based composite materials were applied to steel substrate samples by thermal spraying. The coating characteristics were determined by the use of different investigation methods. The results of the wear test show the great potential for industrial application. Further progress is expected from the optimisation of the thermal spray processes and the compounds composition. Paper includes a German-language abstract.

In order to improve the properties profile of thermally sprayed coats (in particular, the corrosion resistance), the coats are, amongst other items, posttreated with organic and/or inorganic posttreatment media. The coat combinations used are Al 2 O 3 /TiO 2 (87/12), APS-sprayed, and WC-Co (88/12), HVOF-sprayed. Commercially available sealants and two products from other areas of application were used for sealing purposes. The main contribution of the sealing agents to the anti-corrosion protection lies in the fact that they seal open, (inter)connected pores and/or cracks and thus prevent corrosive media from penetrating into the sprayed coat and from reaching the substrate. In this respect, the best results are achieved with sealing agents which form a dense film extending into the pores of the coat. The component underneath can be protected optimally by the combination of the sprayed coat and the sealing agents. Paper text in German.

Laser shock processing (LSP) is a surface treatment similar to shot peening, in which the compressive stresses in the material are created by laser-induced mechanical impacts. The tensions are of sufficient intensity to modify the microstructure and properties. In this paper, the laser pulses are generated with a power density of 5 to 8 GW/centimetres square with a neodymium laser. The glass laser is used to treat Al+SiC composite coatings, which were initially applied using the high-speed oxygen fuel spray technique. The laser-processed samples are prepared metallographically and examined for their microstructure with a scanning electron microscope. The latter is also used to investigate the surface morphology of laser-treated samples. Finally, the microhardness and the vibration wear resistance of the coatings are tested and compared with the data obtained for the samples in the sprayed state. Paper includes a German-language abstract.

This work evaluates the potential of using new competitive powders of Fe/TiC system for plasma spraying of wear resistant coatings. To improve coating properties, Cr and Ni were added to the iron matrix. The results of complex investigations of plasma coatings from such materials are presented.

The characterisation of the effectiveness of sealing was studied by metallographical investigations as well as comparing the investigations with respect to the corrosion- and wear behaviour of the used thermal sprayed coatings and last but not least by measuring of the insulation resistance of the coating system. The obtained results show that there are differences between the used sealants and it is possible through a mechanical treatment of sealed coatings to remove the sealants from the coatings. In the corrosion test the sealants show their efficiency. The sealants insulate the open porosity and prevent the corrosion attack owing to the interconnected pores.

For reasons of the decrease in weight in the industry light cage design materials like aluminum alloys are frequently used. Because the wear resistance of aluminum alloys and/or aluminum generally is not sufficient, an increased wear resistance can be reached by means of particle reinforced aluminum coatings. The installation of ceramic reinforcing components (for example oxide particles) in the ductile metal matrix brings an essential improvement of the wear resistance particularly with regard to abrasion and short time fatigue wear. The results presented in the paper refer to research works concerning thermally sprayed Al - coatings with Al 2 O 3 - and SiC - particles as reinforcement components by vacuum plasma spraying.