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.

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.

The main goal of the project was to investigate the influence of different gas properties, in combination with different spraying parameters, on the wire arc spraying process. For this purpose, investigations with several gas compositions (pure nitrogen as well as nitrogen combined with hydrogen or ethene – compared to compressed air) have been carried out for different spraying materials which are currently being used in today’s industries, such as copper, carbon (St0.8) and stainless steels (316L). The preheating of the process gas as well as the variation of the gas pressure up to 1,400 kPa (14 bar) were also subject to research. The resulting coating properties have been analyzed in terms of oxide content, porosity and hardness as well as deposition efficiency and adhesive tensile strength. Additionally, in order to enhance the process stability, a system to detect the cause of cold shuts has been developed.

This study investigates the effect of different gas compositions on the size, velocity, and temperature of particles in a wire arc gas jet. In the experiments, two wire materials (316L and G3Si1) were sprayed via compressed air, nitrogen, and a nitrogen-hydrogen mixture and high-speed shadow imaging was used to record in-flight particle characteristics. Deposition efficiency was also measured along with the hardness and oxide content of the coatings. The spraying process, equipment, and test methods employed in the study are described and the results are presented and discussed.

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.

The trend in thermal spraying is increasingly towards a globally uniform level of high-grade spray coatings. It is therefore extremely important that auxiliaries such as spray materials or industrial gases undergo precise examination in order to exactly define their influence. This is not only made possible by selecting the right system, but also by choosing the right gas and gas mixture. In order to broaden the range of thermal spray applications, we have endeavoured to investigate the issue of the right gas mix for arc spraying. In doing so, it was concluded that, by using wire as the spray material, this cost-effective process can often be used as an equally viable alternative to other methods. The optimization of costs, extended lifetime of systems and tailoring of coating properties to suit specific applications are just some of these influencing variables

GTS is now almost 20 years old and has nearly 200 members from all thermal spray sectors. In this time, a great deal has been accomplished and GTS members are already using those tools GTS has made available to them and which are important for them. Here, the original idea of enhancing the quality of our technology and maintaining it at a high level continues to be an essential building block. In addition, many areas have been accessed in which an association can make more effective progress than each company on its own. With respect to issues such as further education and training, safety, environment, REACH and the compilation of guidelines, to name but a few, this idea has been successfully applied. The work of many in our organization has yielded many fruits and continues to make a difference. However, the benefits for each of us only become visible if we all actively work together. What is central to all the advantages which GTS offers is the candid discussion among its members and the opportunity for each member to quickly find his place in the group and to put these benefits to good use. The fundamental idea which GTS represents has therefore not changed in all this time: a high quality standard, cooperation, education and training, public relations all combined within the association’s guidelines and many working papers which are available to its members.

The trend in thermal spraying is more and more towards a globally uniform level of high-grade spray coatings. It is therefore extremely important that auxiliaries such as spray materials or industrial gases undergo precise examination in order to exactly define their influence. A further point is of particular significance in today’s business world. With ever-increasing raw material prices, it is absolutely essential that spray processes are optimized to the maximum. This is not only made possible by selecting the right system, but also by choosing the right gas and gas mixture. The optimization of costs, extended lifetime of systems and tailoring of coating properties to suit specific applications are just some of these influencing variables. Gas producers test countless facilities and thermal spray systems in their own laboratories and are therefore always in a position to provide the right solution for existing and new applications.

Equipment engineering, materials, gases and know-how are integral to the smooth operation of any system. The user often focuses on the attributes of the individual systems, but it is only in conjunction with all their components that the merits of the process can be exploited to the full. Here, industrial gases serve as essential building blocks which positively affect the process in an endless variety of ways. The optimization of costs, extended lifetime of systems and tailoring of coating properties to suit specific applications are just some of these influencing variables. Gas producers test countless facilities and thermal spray systems in their own laboratories and are therefore always in a position to provide the right solution for existing and new applications.

The gas industry not only offers the most effective gas for all thermal spray processes, it also provides a variety of supply concepts and hardware with which maximum profitability can be achieved. The operator of the thermal spray equipment is responsible for ensuring that sufficient gas quantities are available at all times, comparable to the logistics involved in spray material management. Linde is now offering a fully automatic gas supply concept, including everything from consultancy and installation, through to the types of gases which can be used. The customer can therefore choose to manage his stocks himself as before, or to have the gas delivered and the bundles replaced by the supplier. With a minimum of time and effort, this electronic aid enables a reliable and fail-safe gas supply

Industrial gas product supply has a dramatic influence on the quality, consistency, and performance of thermal spray coatings and their application equipment. The various thermal spray processes test the limits of common gas supply modes in the areas of safety, pressure, purity, storage, and recovery. Selection criteria for the gas and supply mode, using the latest methods, are discussed for plasma, HVOF and cold spray techniques.

This paper investigates the microstructure and properties of TiC-based nanocrystalline coatings produced by HVOF and VPS processes. It assesses the extent to which nanocrystalline cermet powders can be tailored for specific applications using high-energy milling and the commercial viability of HVOF sprayed coatings made from such powders. Paper includes a German-language abstract.

This paper assesses the potential of thermal spraying in the context of rapid production tooling. The tooling described, which is intended for sheet metal forming, overcomes the limitations of rapid tooling techniques by leveraging the benefits of rapid prototyping and thermal spray technologies. Paper text in German.

This paper discusses the gases used in different thermal spraying processes and the factors that determine purity requirements, consumption rates, and working temperature and pressure. It explains how process gases are supplied to and distributed within manufacturing facilities and how gas-handling systems and related equipment are tested for operational suitability and safety. Paper includes a German-language abstract.

This paper provides an overview of the equipment used in cold gas spraying. It discusses the general design and operation of key components, including the nozzle, the control system, the gas heater, and powder feeder. It also describes a typical gas supply system, the recycling of helium, and the provisions for health and safety that are necessary in a spray booth. Paper includes a German-language abstract.

Being able to offer a consistently high level of spray coatings on a global scale has become more and more the trend in thermal spraying. For this reason it is extremely important that auxiliary materials such as industrial gases or spray materials of a high quality are provided world-wide. In connection with their respective applications, industrial gases must always be available at a specified purity level. In order to ensure such a purity, industrial gas producers invest a great deal of time and energy in analysis and supply concepts which guarantee this purity from the tank or cylinder through to the transfer point. This paper will provide an overview of state-of-the-art supply and purity concepts, as seen by the gas industry, and the influence of fluctuating gas quality. Examples will also be given for the differing gas qualities in individual countries.

Thermal spray processes using wires as feedstock are widely used to produce wear and corrosion protective coatings of nickel, cobalt or iron based alloys. In general, these coatings are processed by flame or arc spraying. In view of using massive wires as spraying material, the hardness and wear resistance of layers is limited by the possibility to produce the corresponding wires of such materials. In addition, the performance of wire sprayed coatings can be restrained by the amount of defects in the microstructure, like pores, oxides and cracks, which are particularly evident in the cases of flame and arc spraying. New High Velocity Combustion Wire (HVCW) systems open the opportunity to reduce the amount and size of the defects by an increased particle velocity. Also, improvements on wear resistance may be achieved by using cored wires. The paper gives an overview on recent developments in HVCW spraying using massive and cored wires.

This paper presents a low-cost in situ diagnostic method that monitors and controls thermal spray processes using a CCD camera and a PC. The method, called particle flux imaging (PFI), records light emitted by thermal spray particles and the hot propellent carrier-medium in which they are conveyed. Brightness distributions corresponding to temperature and density profiles are represented by sets of ellipses that are compared in real time to a reference image. An image analysis algorithm adjusts relevant spray parameters based on the comparisons, maintaining a constant and unchanged spraying process.