In order to utilize the blasting process for preparing surfaces of precision products, the factors affecting the work piece distortion and the degree of the distortion were investigated. The long and flat shaped specimens of the different materials and the thickness were blasted, and the phenomena induced by the blasting were investigated. In the result, almost the linear relationship between the surface roughness and the maximum deflection existed. In addition, the equivalent load was applied to the simple model of the distortion, and the correlative expression among the maximum deflection, the specimen's size, and the equivalent load was deduced. The results made it possible to select and design beforehand the products, and to optimize the blasting condition.

A cost effective manufacturing process for molds which are used to produce components of carbon fiber reinforced plastics (CFRP) is proposed. A wire arc spray process has been employed to reinforce a thin electroformed nickel shell by a several millimeter thick layer of thermally sprayed deposit, forming a vacuum tight mold system in a time saving and cost effective way. To achieve a low thermal expansion equivalent to CFRP, Fe 64 Ni 36 is used as spray material. Here, the main challenge is the successful control of distortion which occurs due to residual stresses. In this paper, the influence of process parameters on shell temperature and distortion distribution is discussed. Key parameters influencing the heat flow into the substrate leading to distortion like continuous cooling, atomizing gas and spray distance are addressed. Temperature measurements were performed using infrared pyrometry as well as by use of thermocouples. Distortion measurements were carried out by use of optical measurement devices recording 3D surface coordinates before and after the thermal spray process. Further, mechanical and thermophysical properties of the as-sprayed composite are part of the investigations to evaluate how the Fe 64 Ni 36 bulk material properties can be achieved. Differences between air atomized and inert gas atomized coatings are presented in detail.

It is generally believed that residual stresses in cold spray coatings are caused by particle impact and deformation and are hence predominantly compressive, as opposed to thermal spraying where thermal effects, particularly solidification, play the lead role. This study aims to provide a preliminary review of this notion through finite element analysis, distortion measurements on copper-coated steel, and the consideration of thermal history. The dimensions and elastic properties of the coating and substrate are key factors in the study along with heat input. Based on the review, a simple model is proposed to predict the final state of residual stress and distortion in flat surfaces coated by cold spraying.

Numerical simulations focused on the impacting behavior of cold-sprayed particles are usually conducted with the Lagrangian method. However, the calculated output is much dependent on the mesh size due to the mesh distortion and/or the element-averaged variables in simulations. While the Eulerian method is attractive to overcome the mesh distortion. In this study, an investigation on the impacting behavior of cold-sprayed particles using the Eulerian formulation available in ABAQUS/Explicit was conducted with typical copper material. The results show that a jet can not be formed at the impacting velocities of 200-300m/s, but a continuous and smooth jet composed of the particle and substrate materials can be formed as the impacting velocity is in the extent of about 300-400 m/s which could be a theoretical value of the critical velocity for a successful bonding. At this velocity extent, the maximum PEEQ almost keeps unchanged accompanying with a temperature fluctuation. In addition, the jet presents discontinuous and the splashing causes the loss of material as the impacting velocity exceeds this velocity extent. Therefore, this model could be also used to predict the critical velocity of other materials besides the copper.

This paper presents a study of the residual stress and microstructural properties of thick, spray-formed components, produced using the High Velocity Oxy-Fuel (HVOF) thermal spraying process. The forming material used is Tungsten carbide cobalt (WC-Co), a material which is more usually processed using expensive press and sinter technology. The aim of this study is to examine the effect of production parameters on the formation of thick components. In order to fabricate thick specimens, certain problems have to be overcome. More specifically these problems include the minimizing residual stresses, which cause shape distortion in the components and maining the integrity of the coating on a microstructural scale. The dependence of residual stress, and sprayed material characteristics on spraying distance, and powder feed rate conditions is presented. Results show that cylindrical WC-Co components up to a thickness of 9mm can successfully be produced, by careful control of these parameters. This represents a significant improvement on maximum thickness values previously reported for WC-Co [1,2].

Substrates protected by thermal spray coatings are usually found intact after use, making them viable candidates for recycling and reuse. The key is to remove the coating without damaging the component. This requires a process that minimizes the development of residual stresses and the associated distortion. The purpose of this work is to determine the optimal descaling technique for Ni-base sheets with a thermal barrier coating. Test specimens were produced following industry procedures. Thin sheets (<3 mm) of Ni-base superalloy were plasma sprayed with a NiCrAlY bond coat and a Y203-stabilized ZrO2 topcoat. The coating layers were then removed using different methods, including pickling, shot blasting, and water jet descaling, and the substrates were assessed based on X-ray diffraction and chord width measurements. The findings of the study show that water jetting removes all surface materials, particularly the bond coat, without damaging the underlying surface. It also produces the least amount of stress and deformation and is relatively easy to automate.

Aiming at clarifying the individual splat formation mechanism in thermal spray process, commercially available metallic powders were thermally sprayed onto AISI304 substrate surface. The splats changed from a distorted shape with splash to a disk-shaped splat in flattening after collision onto substrate surface, through substrate preheating and/or reducing the ambient pressure. Accordingly, both substrate temperature and ambient pressure have an equivalent effect on the shape transition. The observation on the bottom surface morphology of single splat indicated that the ring-shaped initial solidification might play an important role during splat formation process. As a simulation of the real thermal spray process, free falling experiment has been conducted. The thermal history of the free falling metal droplet onto AISI304 substrate indicated that the flattening pattern is decided so quicky just after collision onto solid surface, which is enough earlier to the finalization of the flattening.

High-entropy alloys (HEAs) represent a new class of advanced metallic alloys that have gained significant interest. They offer a unique combination of mechanical, thermal, and functional properties, making HEAs ideal for various industrial applications. One such alloy is the recently developed equiatomic body-centred cubic phase AlCoCrFeMo. In particular, thermally sprayed AlCoCrFeMo coatings have gained wide interest due to their exceptional mechanical properties compared to common industrial steel. In the current study, the effect of Mo concentrations on the strength of single crystal AlCoCrFeMo HEA was investigated using molecular dynamics simulation and the phase stability of the alloy was studied using polyhedral template matching. Our results indicate that the local lattice distortion of the alloy is not significantly related to Mo concentration. The yield strength of AlCoCrFeMo HEA obtained through tensile loading, was found to increase with Mo concentration, at a molar ratio of Mo higher than 0.5. Investigation of the deformation behavior of the HEA revealed that bands with high shear strains evolved during plastic deformation. The formation of shear bands after the yield point elucidated the softening exhibited by the material due to localized deformation. These findings provide guidance for tailoring the mechanical properties of AlCoCrFeMo HEA by adjusting Mo concentrations, offering new avenues for designing functional coating materials.

Laser cladding shows an increasing interest to apply high-quality tailored surface coatings, as well as 3D-deposits for repair and additive manufacturing of metallic parts. The industry is requesting powerful technologies that maintain the quality advantages of the laser technology, but also make the process more productive, as well as time and cost efficient. At Fraunhofer IWS a Laserline fiber-coupled diode laser of 20 kW power has been employed for over a decade to develop competitive coating solutions. The deposition rates achieved with this technology are comparable to those of common PTA technique, while at the same time bringing significant advantages in terms of reduced heat affected zone, distortion and savings in material resources.

The H-class turbine, introduced nearly a decade ago, has reached a significant milestone with its 100th global sale. With 108 units sold and 91 in operation across four continents, accumulating over 3.2 million fired hours, the SGT5-8000H has established itself as a market leader, setting industry benchmarks for performance. Since its launch, the SGT5-8000H's output has increased from 375 MW to 450 MW, and combined cycle efficiency has surpassed 62%. To maintain optimal performance, the platform combustion system (PCS) of the SGT5-8000H has undergone refurbishment in Berlin since 2017. Beginning with a PCS from Samsun, Turkey, the process involves a detailed inspection, repair, recoating, and final assembly. Advanced technologies, such as blue light scanning, enhance efficiency and enable lifecycle assessments. Innovative repair methods, including 3D printed patch repairs using laser powder bed fusion (LPBF), reduce costs. Laser-based cutting and welding automation further minimizes heat input and distortion, ensuring the PCS's reliability and longevity. These technological advancements contribute to the SGT5-8000H's stable and dependable operation.

Carbon fiber (CF) composites are widely used in the aerospace industry due to their light weight and favorable mechanical properties. Nevertheless, applying protective coatings (e.g. erosion resistance) through thermal spraying presents specific challenges with defects such as distortion, oxidation, and poor coating adhesion. This study presents a new technique that combines electroless plating processes and thermal spray for depo-siting metals onto polymer-reinforced composites. Samples of low melting polyaryletherletone (LMPAEK) thermoplastic polymer reinforced with carbon fibers aligned in the normal direction (ZRT film) are plated (with copper, silver, or nickel) to provide an adhesion layer for the thermal spray processes. Subsequently, pure tin and titanium (i.e. Ti-6Al-4V) is deposited on the samples using High Velocity Air-Fuel (HVAF) and atmospheric plasma spray (APS) processes. Cross-sections of the resulting coatings are compared, and the materials are characterized for surface roughness, cracks and pores.

For the last seven years, Oxford University and the Ford Motor Co. have been researching jointly the development of the large-scale spray forming of steel tooling capable for use in mass production, particularly for the pressing of sheet metal in automotive applications. These investigations have involved: comprehensive microstructure and property studies, modelling of shape evolution and heat flow, real-time feedback control of tool temperature to eliminate tool distortion, high speed imaging and particle image velocimetry of droplet deposition on 3D shapes, the testing of full-scale tools for different applications in the production environment, and detailed studies of the cost and time savings realised for different tooling applications. This paper will provide an overview of the scientific and technical progress to date, present latest results, and describe the current state-of-the-art. Many of the insights described have relevance and applicability across the family of thermal spray processes and applications.

Thermal spray usually involves high temperatures in short times. This phenomenon is enhanced with the use of an HPPS system (Plazjet from Tafa). To spray a Zirconia coating, high powers are necessary such as 200 kW providing for the substrate an important increase in the surface temperature. Furthermore, the good quality of a thermal spray coating results in the low surface roughness, a satisfactory microstructure cohesion, a minimal distortion of the part when spraying on large sheets with a thick thermal barrier coating. Cooling with compressed air is widely used but other solutions are studied concurrently; CO 2 , nitrogen, and air; these gas are tested in different conditions of pressure and flow. Some improvements in terms of temperature in the coating and roughness have been found.

In metal die casting as well as plastic injection molding, controlling the heat balance during the injection and solidification process can lead to fewer defects and a better component quality. An appropriate cooling channel design for the mold can help to control the solidification to a certain extent. But the heat control achievable by cooling channels is limited due to the high effective thermal mass, and therefore near-cavity energy input is of interest. In this paper, a simulation study is performed demonstrating the use of plasma sprayed ceramic coating as a heating coating at the cavity of the mold. The goal is to apply heat faster and locally focused during the solidification process in metal die casting as well as before the injection phase in plastic injection molding. The heat generation of these ceramic coatings is modelled using experimentally measured values and the effects of this approach on defects such as distortion and hot tearing is discussed.

High entropy alloys (HEAs) are classified as a new class of advanced metallic materials that have received significant attention in recent years due to their stable microstructures and promising properties. In this study, three mechanically alloyed equiatomic HEA coatings – AlCoCrFeMo, AlCoCrFeMoW, and AlCoCrFeMoV – were fabricated on stainless steel substrates using flame spray manufacturing technique. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Vicker’s microhardness were utilized to characterize the fabricated HEA coatings. Furthermore, Joule heating experiments using a modified version of a two-probe test was used to measure the electrical resistivity of the HEA coatings. To prevent short-circuiting of the metallic coatings, a thin layer of alumina was deposited as a dielectric material prior to the deposition of HEA coatings. The microstructure of the HEA coatings showed the presence of multiple oxide regions along with solid-solution phases. The porosity levels were approximately 2 to 3% for all the HEA coatings. The HEA coatings had a thickness of approximately 130 to 140 μm, whereas the alumina layer was 120 to 160 μm thick. The electrical resistivity values were higher for all the HEA coatings compared to flame-sprayed Ni-20Cr and NiCrAlY coatings and AlCoCrFeNi HEA thin film, which may be attributed to the characteristics of HEAs, such as severe lattice distortion and solute segregations. The combined interaction of high hardness and increased electrical resistivity suggests that the flame-sprayed HEA coatings can be used as multifunctional wear-resistant materials for energy generation applications.

An efficient temperature control on tool surfaces is essential in processes like injection moulding or die casting. A thermally sprayed heating coating could combine dynamic heating properties with a small assembly space as it is sprayed directly onto the cavity surface. With their intrinsically high electrical resistivity and low thermal expansion as compared with traditional alloys, High Entropy Alloys (HEA) show promising properties for the use as heating elements. Thus, the well-studied HEA Al 0.5 CoCrFeNi was used as a starting material for additional alloying with Zr and Si to force further lattice distortion in the solid solution. HEAs of differing compositions were melted and characterized. In the process, the potential of HEAs was assessed by characterizing their phase composition, thermal stability, and electrical resistivity. The characterized HEAs show a solid solution mainly consisting of fcc and bcc structure. Moreover, the composition Al 0.5 CoCrFeNiZr 0.2 Si 0.2 was determined as stable after heat treatment at 600 °C for 324 h. In addition, the electrical resistivity was raised by over 20 % relative to the starting material. As a result, a hitherto unknown HEA composition was detected to possess superior properties to traditional alloys for the application as heating coating.

Solid oxide fuel cell are being widely considered as the promising answer to the fossil energy decrease. To achieve high efficiency and longevity for SOFC stack it is essential to maintain stable hermetic sealing. In order to obtain an efficient airtightness between two SOFC layers, the authors had developed a solid seal composed with a ceramic matrix charged with glass particles. The seal is plasma-sprayed using low-cost manufacturing methods such as atmospheric plasma spraying. This technical deposit can be plasma-sprayed on a wide range of substrates: whatever its nature and shape. It is solid, distortable and adhesive to its support at ambient temperature. The sealing properties are acquired when the SOFC is put into service: the glassy phase migrates into the peculiar plasma-sprayed microstructure of the ceramic matrix towards the interface involving the airtightness. The performance of this seal are pretty good: the leak rate observed at 70 mbar is 0.0042 mbar.l/s whereas the preconisation of the US Department of Energy is 0.005 mbar.l/s.

This paper describes recent improvements in metal supported solid oxide fuel cells produced by plasma spraying. By optimizing the process, incorporating nano-micro structured electrodes, and introducing additional layers to prevent interlayer diffusion, the power density of these cells has doubled, voltage has increased to 1.1 V, degradation rates have been cut in half, and redox stability has improved. Although upscaling to larger substrates initially caused distortion in the metal supports, the problems were successfully overcome.

In this study, cold spay particle impact behavior of a typical copper material is examined using ABAQUS finite element analysis software. Various combinations of calculation settings are explored, such as element type, adaptive meshing, contact interaction, and material damage, with the main focus on element distortion and its effect on output. The influence of mesh size on modeling accuracy is also discussed as are fundamental aspects of modeling cold spray particle deformation.

In this study, (La 0.9 Ca 0.1 )(Cr 0.9 Mg 0.1 )O 3 ceramic powders prepared by solid-state synthesis were deposited on nickel-base superalloy substrates by atmospheric plasma spraying. Powder morphology and coating surfaces were examined by SEM, and composition and phase structure were evaluated by EDS and XRD. Coating porosity and bond strength were measured and emissivity and thermal shock tests were carried out. The results show that the powders maintained their perovskite structure during spraying and that no impurities were introduced in flight. The emissivity of the coatings was found to be 0.88 at 600 °C and 0.89 at 800 °C, which is attributed to lattice distortion stemming from differences between doping and original ions and the valence states of Mg 2+ and Cr 3+ . Coating crystal structure was stable over the thermal shock range from room temperature to 1100 °C and no spalling or fracture occurred after ten shock cycles.