The surfaces of machine components can be effectively protected against wear by highly resistant hardmetal-like coatings, such as WC-Co and Cr 3 C 2 -NiCr, deposited by different thermal spray processes. These composite materials are characterized by the presence of hard carbide particles embedded in a ductile metal binder matrix which have also found many applications as sintered parts (cutting tools, wear resistant parts, mining drills and others) obtained by a powder metallurgy route. Conclusions on the potentials of the different systems for coating applications can be made on the base of experiences and fundamental research from sintered hardmetals. In this paper a comparison of the properties of sintered parts and thermally sprayed coatings of the WC-Co, Cr 3 C 2 -NiCr and (Ti,Mo)C-NiCo systems is given. The structure and properties of the coatings depend strongly on the technology of spray powder preparation, the combination of spray process temperature and particle velocity, and other spray process parameters. It is shown that the TiC-Ni based system can be significantly improved by alloying. This makes the system suitable for coating applications where simultaneous high wear and corrosion resistance in combination with high temperature stability are required. This system can partially substitute the commercially introduced systems but has also the potential to explore new applications.

WC-Co-Cr represents an important composition for hardmetal-like coatings which is appHed when simuhaneous wear and corrosion resistance is required. In this paper five commercially available spray powders obtained by various production techniques (sintered and crushed as well as agglomerated and plasma-densified) of the composition WC-10%Co- 4%Cr have been thoroughly characterized and were sprayed by DCS, HVOF (CDS process) and APS. The microstructures of the coatings were characterized and their wear behaviour was investigated by means of an abrasion wear test. For the best of these powders the wear resistance was nearly equal for the DGS and HVOF coatings. Other powders show significant differences with respect to their processabilities in these spray processes. APS coatings from all powders, obtained with an Ar/H2 plasma showed inferior microstructures and significant lower wear resistance. The spray powder compositions, grain sizes and structures were found to determine the processability of the powders and the microstructure and properties of the coatings. COMPOSITE MATERIALS of the type hard phase - metallic binder with WC and CoCr as constituents are widely used for the preparation of hardmetal-like coatings. The chromium addition to the metallic binder is thought to improve its corrosion resistance in comparison with pure WC-Co. This has led to many applications of WC-CoCr coatings where simultaneous wear and corrosion resistance is required. Despite of its significant practical importance only a limited number of publications is devoted to detailed questions of structure and properties of WC-CoCr coatings (1-3). In some comparative studies such coatings have been investigated together with WC-Co and Cr3C2-NiCr coatings (4-8). However, systematic investigations of spray powder compositions and morphologies as well as investigations of the influence of different thermal spray processes on coating structures and properties which have repeatedly been provided for WC-Co (for example (9, 10)) are missing for WC-CoCr. In this paper a short survey of literature on the phase relationships in the WC-CoCr system and the effect of chromium additions on the properties of sintered parts and thermally sprayed coatings compared to WC-Co is given. In the experimental part a systematic study of the influence of the preparation process on composition and morphology of commercially available WC-10%Co-4%Cr spray powders was provided. These powders have been sprayed by DGS, HVOF and APS and the microstructure and basic properties of the coatings have been studied.

Preface for the International Thermal Spray Conference 2022.

This article illustrates the application of various cold spraying technologies for aircraft equipment of different countries. Presentation slides only; no full-text paper available.

Listings of the organizing committees and organizational sponsors for the International Thermal Spray Conference 2022.

This article discusses the influence of refrigerants on the cooling of thermal spray equipment. The discussion covers the cooling requirement for thermal spray equipment, basic cooling systems, improvement and adaptation of refrigerants, challenges for manufacturers and users of cooling technology, and ways to address the challenges.

Laser cladding or metal deposition (LMD/DED) is widely used for wear-resistant coatings, repair and additive manufacturing applications due to the excellent properties of the deposited material. However, processes on complex 3D surfaces are often a challenge because they require time-consuming programming. This is particularly the case when no CAD data is available for the parts on which metal coatings or structures have to be applied. As a solution, we describe a digital process chain that begins with a 3D scanning process within the laser cladding machine (either robotic or CNC type). Using special software, high-quality 3D models of the scanned parts are created. For coating applications, these models are visualized on a PC. The operator can define cladding areas with just a few clicks of the mouse. Based on predefined parameters, powerful software calculates all the required tool paths. An additional simulation step can be used to verify collision-free operation. Finally, robot or CNC programs are automatically generated that can be executed immediately. Similar software is used to create 3D parts directly from CAD files. Finally, by combining both approaches, 3D geometries can be printed directly onto existing 3D freeform parts using laser metal deposition/LMD, even if their shape is arbitrary and not well documented by CAD data.

Lead, lead-bismuth, or lead-lithium are candidate materials for liquid metal-based cooling media in the new generation of nuclear fission reactors and fusion systems. There are many benefits of using this concept; however, a new problem arises too: preventing degradation of structural materials that are supposed to come into a direct contact. Therefore, new steel grades are being designed, and technological workarounds are searched for. One of the pathways could be a deposition of thick, long-term stability protective coatings onto the steel surfaces. In our opening study, we have employed CS and RF-ICP technologies to deposit Mo and Fe coatings onto ferritic-type 9% Cr Eurofer steel and its ODS variant, and tested them in the PbLi environment at 600 °C for up to 1000 hours. The results suggest that the Fe coatings showed a promising resistance to the corrosive medium and are worth studying deeper.

Cutting tools in agricultural machines have to withstand high wear demands. Longer maintenance cycle intervals of these tools can be achieved using coatings reinforced with hard particles, applied onto tool substrates. This work was done to establish the qualified test procedure to characterize carbide containing spray & fuse coatings for agricultural demands under abrasion and impact. Simulating these field conditions in lab-scale, tests were performed with a standard ASTM G65 dry-sand rubber-wheel tester (3-body abrasion) and a special impeller-tumbler apparatus (combined impact and abrasion wear). The interaction of hardphase content and matrix composition was investigated to assess their response varying impact energy effects. The test procedure described is suited to optimize coatings by combining quantitative mass loss measurement with results of surface profilometry. It is shown, that crucial material criteria of carbide coatings, such as edge stability and wear progress, can be characterized in a way which is able to tailor coatings for targeted wear regimes in agriculture.

In the cold spray additive manufacturing (CSAM) process, layer-by-layer stacking is a good method to achieve coating AM. Different from AM processes such as selective laser cladding, which can quickly realize trajectory planning based on commercial software, the spraying trajectory of the CSAM process cannot be created easily due to the “one-stroke” character. The spray path cannot be intersected and the coating deposition cannot be interrupted during the spraying process. What’s more, the spray gun or the workpiece held by the robot usually needs to be deflected by a certain angle to compensate the coating edges. An accurate and efficient spraying trajectory for a given workpiece is the most basic and important part in CSAM process. This article proposes a novel parametric layered slicing algorithm for STL files and an optimized rapidly exploring random tree (RRT) algorithm, so as to generate spraying trajectory accurately and quickly, especially for a part with multiple features. The simulation results revealed that the algorithms can efficiently generate the corresponding spraying trajectory for CSAM.

Erosion and cavitation are the life-determining wear mechanisms of water power machines. Provided that suitable surface protection measures are taken, the availability of the machines can be increased and their maintenance costs can be significantly reduced. This paper provides the evaluation of various criteria for the selection of suitable coating systems. It describes results determined experimentally and achieved in operational use in hydropower plants. The paper also provides an estimate of the achievable extension of the maintenance according to the protective measures. Paper includes a German-language abstract.

Viruses and microbial pathogens can survive for hours on fabrics. This paper reports that copper-doping of natural and synthetic fabrics inactivates, within minutes, a human COVID surrogate pathogen. The fabric is embedded with copper particles by twin-wire arc thermal spray. The long-lasting fabric surface simultaneously provides good breathability, it is scalable and cost-effective. Virucidal activity is not affected by repeated washing of the fabric. Importantly, copper-embedded material will provide effective protection against all classes of pathogens, regardless of their mutation rates and infection strategies. It also can provide protection against all classes of pathogens, regardless of their mutation rates in industrial and residential filters.

A study on induction plasma shape forming with yttria stabilized zirconia (YSZ) was conducted as part of an effort to develop a new method for producing nuclear fuel. YSZ was selected because its melting point is similar to that of UO2. Nuclear fuel pellets were made using a large (70 mm) induction plasma flame that sprays more than 100 pellets simultaneously and a small (10 mm) supersonic plasma flame that produces one pellet at a time. Process optimization for the large induction plasma flame was done based on chamber pressure, plasma plate power, powder spraying distance, sheath gas composition, probe position, and particle size. The best results were 97.11% theoretical density (TD) for 5-mm thick pellets. For the single pellet approach, densities as high as 99% TD have been obtained in 12-mm thick free-standing pellets.

Carbides are interesting materials for many wear resistant and high temperature applications, however, the production of coatings with these materials represents a significant challenge as they tend to oxidise or decompose into gaseous phases when they are exposed to extreme thermal spray conditions. An innovative method merging suspension and solution precursors was developed to allow the production of carbide composite coatings. Suspensions of carbides and borides were modified with the addition of oxide precursors to obtain composite coatings by high-velocity oxy-fuel (HVOF) thermal spray. The transformation of these oxides precursors and their subsequent melting during spraying contribute to protect the carbides from oxidising conditions, avoid their degradation during the spray process and support the development of dense coatings, as it was demonstrated by dispersive X-ray spectroscopy and X-ray diffraction analysis. The relationships between processing and microstructure were studied in terms of porosity phase distribution and mechanical properties, proving that this novel approach could be applied to obtain coatings of materials that are prone to decompose during thermal spraying.

During the thermal cycling process in MCrAlY-YSZ thermal barrier coating system, stresses are produced at bondcoat (BC)-topcoat (TC) interface due to the mismatch of the thermal expansion coefficients of the two coating layers. The stresses at the interface are not a single value and can be affected by the coatings’ microstructure. In this paper, finite element (FE) modeling method was used to study the behavior of the stress distribution at the coatings’ interface. The influence of the pore structure in the ceramic TC and the micro bulge structure at the metal BC surface was investigated. The results showed that both structures can change the stress distribution. The pores played a “stone-in-river” role, which trapped higher stress around them and simultaneously reduced the size of the macro stress zones in TC. The micro bulges at the TC/BC interface also trapped high stresses which could cause more interaction between TC cracks and BC roughness.

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.

In a novel approach for guiding elements of sawing machines wear resistant coatings were applied on open-porous AlSi 7 Mg substrates by means of high velocity suspension flame spraying (HVSFS). The challenge is to establish a wear resistant coating but simultaneously maintain the open-porous structure that is necessary to serve as a permeable structure for liquid cooling or lubricant media under operation. In a first approach, a water-based suspension containing a mixed Al 2 O 3 -TiO 2 powder for HVSFS was used to deposit dense and well adherent mixed-oxide coatings. As the substrates exhibit an open-porous structure and a well-defined pore size distribution, transpiration cooling through the pores is possible and even necessary in order to ensure a low thermal impact on the fragile pore structure, preserving the open-porosity of the substrate. The coatings are characterized and compared by the means of light microscopy and hardness indentation.

Whenever large amounts of liquids or gases have to be transported over long distances, steel pipelines are used. They supply industry with raw materials, guarantee drinking water supplies to large cities, and convey energy sources around the globe. Despite the most stringent safety regulations, pipelines regularly suffer damage and leaks. Severe environmental pollution occurs when oil or gas pipelines, in particular, are damaged. In the case of both onshore and offshore pipelines, decontaminating the affected areas involves a great deal of time, effort, and cost. Moreover, in most cases the contamination cannot be eliminated completely. There are various reasons for damaged pipelines. Corrosion poses one of the greatest challenges here, and this can be influenced by the pipeline owners. There is a need for safe and reliable corrosion protection, and this is set to grow over the coming years. Based on current market data, between 13 and 18 million tons of line pipe were delivered in the years 2015 to 2020. This corresponds to a pipeline length of approx. 86,000 km per year. The objective of this paper is to illustrate why the corrosion protection currently used fails to work in some cases. It also aims to show how thermal coating can improve corrosion protection and what requirements its technical implementation must fulfil. To this end, line pipe is presented in the next chapter. Common standards and manufacturing processes are introduced. The third chapter outlines current corrosion protection measures. Moreover, weak points are analyzed by looking at damage that has already occurred. The requirements for thermal coating are determined based on this.

Machines and other equipment that are used in industry are generally long-term investments. Once invested, the machines usually run for several decades until a technical reinvestment is necessary. Nowadays, the 4th industrial revolution is taking place and digitalization is omnipresent. Big Data, Internet of Things (IoT) and Artificial Intelligence (AI) are just some of the technological innovations that are shaping the future right now. These innovations do not work with the manually driven equipment that has been invested some years ago because they are all based on data – and these (partly) manually operated equipment don´t produce data or they don´t collect it properly. In order to produce and collect data, the manually working machines have to be replaced – or retrofitted! voestalpine Stahl GmbH and its technical service and maintenance department (TSM, furthermore short voestalpine) decided to retrofit the existing equipment based on technological, economical as well as sustainability reasons. The approach, advantages and limitations are displayed here.

Coatings of Metal-Matrix-Composite (MMC) with enhanced wear resistance were created by thermal spraying. The used powders composed of iron and nickel aluminides reinforced with alumina, Cr- and Ti-carbides were produced before by self-propagating high temperature synthesis (SHS). The fused and crushed composite powders were sprayed by atmosphere plasma spraying (APS) and gas detonation spraying (D-Gun). Spray powder and coating properties like morphology, structure, microhardness, porosity, bond strength, wear and corrosion resistance are examined using optical and scanning electron microscopy, XRD analysis, pin-on-disc (wear resistance). The produced MMC coatings are compared to commercially used wear resistant coatings, e.g. high velocity oxyfuel flame sprayed Cr 3 C 2 -NiCr. The properties of a special coating type depend on the used spraying method. Plasma sprayed MMCs show a slightly higher porosity than D-Gun sprayed coatings. The chemical composition of used powders has a big influence on the coating properties. Fe- and Ni-aluminide matrix coatings reinforced additionally with carbides, especially Cr 3 C 2 , show a better wear resistance compared to coatings containing just oxides as hard material.