In this study, nine coating systems of Yb 2 Si 2 O 7 /Si-HfO 2 EBCs with varying spraying process parameters were deposited on silicon carbide (SiC) substrates using the air plasma spraying (APS) process and an orthogonal experimental method. The effects of variations in spraying distance, current, and hydrogen flow rate on spraying power and coating bond strength were investigated.

This research examines the combination of a corrosion-resistant CoNiCrAlY binder with Cr 3 C 2 carbide particles. The powder was applied using two contrasting thermal conditions: low-energy HVOF and high-energy shrouded plasma spraying. This approach created a wide range of carbide dissolution and peritectic decomposition outcomes. The study includes detailed characterization of the feedstock powder composition to explain the phase formation during sintering compared to the original powder components.

This study aims to investigate the influence of alumina in-flight particle characteristics on coating properties and deposition efficiency. To this end, velocity and surface temperature measurements were carried out on the in-flight particles. Resulting coatings were characterized in terms of porosity, hardness, and related to particle properties. The final goal was to obtain an optimized coating with low porosity, high hardness, manufactured with a high powder flow rate and deposition efficiency.

In this study, we deposited alumina (Al 2 O 3 ) coatings from powder consisting of dense particles using aerosol deposition. The powders were ball milled with zirconia (ZrO 2 ) milling media for 0 to 9 hours to optimize the deposition performance. We investigated the impact of high-energy ball milling on the shape, size, and crystal structure of the Al 2 O 3 powders, as well as their deposition behaviors.

Additive brazing is a highly advanced process for producing functional and highly durable coatings. By creating a material bond between components through diffusion without the use of flux, dense, wear-resistant, and crack-free layers are formed, which are particularly useful in areas such as wear protection and the reclamation of components. The ability to adjust the coating thickness and hardness makes the process extremely flexible, allowing it to meet the specific requirements of a wide range of applications. Particularly innovative is the ability to precisely and locally braze using laser energy, further enhancing the efficiency and precision of the process. This paper provides an overview of the process, properties of brazed coatings, and applications.

The aim of this study is to develop a solid shroud to minimize in-flight oxidation using the particle swarm optimization (PSO) algorithm. Additionally, the shroud is specially designed to use air as a cooling medium instead of water and is made from common stainless steel to help reduce equipment and process costs.

This research proposes an experimental methodology towards visually observing high strain rate polymer deformation characteristics at scales relevant to cold spray particle impacts. Macro-scale (~ 3 mm) polymer impact testing via a light gas gun has shown evidence of cold spray indicative features at certain (material, particle/substrate temperature, velocity, etc.) conditions.

This work aims to evaluate the viability of laser heat treatments as a method to recover cold-sprayed coating ductility, i.e., to achieve with laser heat treatment a gain in elongation equivalent to a furnace heat treatment. A 4kW YAG laser was employed to heat treat 4-5 mm thick coldsprayed copper coatings produced on coupons and on prototypes of large components. Surface temperatures were monitored during the heat treatment using an infrared camera. Hardness and tensile properties were measured on as-sprayed and heat-treated coatings. Microstructural examinations provided additional insights to explain the properties evolution during heat treatment.

In the present study, isothermal oxidation behavior of two multi-layered thermal barrier coatings (MLTBCs) has been investigated. Moreover, the property of the produced coatings were compared with a conventional bilayered TBC. For this purpose, nanostructured and micro YSZ were used as ceramic powder feedstocks and TBCs were deposited by air plasma spray (APS) procedure.

In this study, axisymmetric two-dimensional numerical analysis was performed to clarify the particle behavior in supersonic hybrid aerosol deposition (HAD). The predicted result showed that the small particles, which can deposit via HAD, impact the substrate on a wide region while the large particles, which can abrade the surface of film and substrate, impact around the center.

In this study, columnar yttria-stabilized zirconia (YSZ) topcoats were deposited by suspension plasma spraying (SPS). A laser treatment was used to create a remelted layer at the surface of the SPS coatings. The influence of key laser parameters, such as scanning speed and laser power, on the microstructure of the remelted top layer of the columns in the SPS coatings was investigated. It is hypothesized that such a process could significantly improve the durability and performance of SPS-deposited TBCs by minimizing calcium-magnesium-alumino-silicate (CMAS) penetration.

Cold spraying mixed metal-ceramic powders creates metallic matrix composites, but typically achieves low hard phase content in deposits. We investigated this challenge using various hard phases (SiC, diamond, WC, W) with Al and Cu metal matrices. Our results reveal that density difference—not hardness—between components primarily determines deposition efficiency. When using Al with similarly dense materials (diamond, SiC), deposit compositions remained comparable despite hardness variations. However, mixing Al with 50 vol.% of WC or W produced deposits containing 57.9 vol.% and 79.8 vol.% hard phases, respectively. Based on these findings, we established a ballistic theory-based criterion for effective hard particle deposition.

In this study, the effect of laser heat treatment on the deposition of oxide ceramic coatings has been examined preliminary. As the energy source, a fiber-laser irradiation experiment on the fine particle ceramic spray has been examined. This trial will give a new possibility to survey a new type of hybrid aerosol deposition, laser-assisted HAD.

Design, manufacturing, and utilization of efficient heating systems for pipelines and closed-pressure equipment are necessary for cold regions to compensate for heat loss and prevent damages that are caused by freezing of the enclosed liquid. Given large-scale financial losses that stem from failure and bursting of the pipes, the development of novel, efficient, and affordable heaters, which can lead to improved efficiency, cost savings, and environmental benefits across various industries and applications, is of crucial importance. Heating systems have already been produced via different high-temperature thermal spraying techniques to achieve higher efficiency compared to conventional heating cables. In this study, tin, as the heating element, was deposited by using the cold spray process onto alumina coating that was fabricated by flame spraying (FS) to provide electrical insulation. Techno-economic assessment of fabrication and utilization of the coating-based heaters was conducted. It was found that cold-sprayed heater coatings exhibit improved performance compared to other thermally sprayed heater coatings and conventional heater cables. Further, their fabrication and utilization were more economically feasible. The results suggest that the new generations of coating-based heating systems may be competitive with conventional heat tracers that are widely used in industry.

In this work, thermally sprayed sustainable coatings with spray additives recycled from dry alkaline batteries and solid-oxide fuel cells are developed to allow the growth of drought-resistant plants like moss, microclover and chamomile. It is assumed that these plants anchor to the coating with their rhizoids and hence can be grown without the presence of soil. Preliminary tests of a thermally sprayed Yttrium Stabilized Zirconia (YSZ) ceramic coating on sheet metal confirms the growth of chamomile plant.

This work focuses on the processing and deposit by suspension plasma spraying (SPS) of ZrO 2 -based ceramic materials for Thermal Barrier Coatings (TBC's) applications. The system of interest is ZrO 2 -16mol%Y 2 O 3 -16mol%Ta 2 O 5 (16YTZ). This ceramic has been reported to keep a non-transformable tetragonal phase (t'-phase), suitable to overcome the thermodynamic limits of the mostly used conventional 7-8wt.% yttria stabilized zirconia (YSZ). The research consists into evaluate the t'-phase stability and performance of the 16YTZ SPS coating. Synthesis of 16YTZ and, the evolution of the resulting microstructure in the dense ceramic and in the coating are a central part of the study. Sintering behavior in dense ceramics prepared from both precursor derived and milled powders is evaluated. Microstructural characterization by XRD, SEM and RAMAN spectroscopy of the as-deposited ceramic coating is presented and discussed.

In this study, the in-situ technique was used to observe crack formation and growth in multilayer suspension plasma spray (SPS) thermal barrier coatings (TBCs). Utilizing synchronized three-point bending (3PB) and scanning electron microscopy (SEM), coupled with digital image correlation (DIC), we provide real-time insights into strain field dynamics around cracking zones. Bending-driven failure was induced in both single and composite-layer SPS coatings to investigate the crack behavior in these columnar-structured multilayer TBCs. The real-time observations showed that columnar gaps can facilitate crack initiation and propagation from the coatings' free surface. The composite-layer SPS coating exhibits lower susceptibility to vertical cracking than the single-layer SPS coating, possibly due to the presence of a gadolinium zirconate (GZ) dense layer at the coating's free surface that enhances the bonding strength within the coating's columnar structure. The splat structure of the bond coat (BC) layer contributes to the crack path deflection, thereby potentially improving the SPS coating' fracture toughness by dissipating the energy required for crack propagation. Moreover, it was revealed that grit particles at the BC/substrate interface seem to promote crack branching near the interface, localized coating delamination, and serve as nucleation sites for crack development. Hence, optimizing the grit-blasting process of the substrate before BC layer deposition is crucial for minimizing the possibility of crack formation under operational conditions, contributing to enhanced durability and prolonged lifespan. This study underscores the critical role of in-situ observation in unravelling the complex failure mechanisms of multi-layered coatings, paving the way for the design of advanced coatings with enhanced structural complexity and improved performance for more extreme environments.

The ingestion of siliceous particulate debris into the gas turbine engines during operation caused the deposition of so-called CMAS (calcium-magnesium-alumino-silicate) on the hotter thermal barrier coating (TBC) surfaces. The penetration of these particles into the TBC at temperatures above 1200°C caused the loss of strain tolerance and premature failure of the TBCs. To mimic real-world conditions, a commercially available CMAS precursor dust powder was sprayed onto 8YSZ coatings using an atmospheric plasma spraying process. The substrate temperature was maintained at an average of 1100°C and 525°C during spraying. The effect of the spraying parameters on the deposition, microstructure, and composition of the CMAS coatings was investigated. In addition, to understand the CMAS build-up on the high-temperature surfaces, the CMAS splat formation behavior was also analyzed on the polished samples at temperatures ~1100°C. SEM/EDS analyzes were performed to identify and quantify the elements of the CMAS deposits. It was found that the surface temperature, deposition time, and different nozzles could play a significant role in having different phases of CMAS deposits.

The need for effective electrical insulation coupled with good thermal conductivity in power electronics has led to an exploration of suitable solutions for components like Insulated-Gate Bipolar Transistors (IGBTs). Considering its material properties, AlN emerges as a promising candidate for this application due to its high thermal conductivity, good electrical insulation and ample dielectric strength. However, aluminium nitride (AlN) has a low deposition efficiency when applied by atmospheric plasma spraying (APS). In contrast to AlN, alumina has a very good deposition efficiency during thermal spraying. Feedstock development was conducted to enhance the coating deposition for AlN. Therefore, a parameter study was carried out with AlN feedstock material to form a protective alumina shell around the AlN particles. Subsequently, the heat-treated powder was applied on an aluminium substrate by APS. X-ray diffraction (XRD) analysis displayed that, the heat-treated feedstock material contained AlN and α-Al 2 O 3 phases. It was observed from scanning electron microscopy (SEM) analysis that the AlN particles formed an oxide shell which led to an enhanced deposition efficiency with a high amount of AlN in the coating. The coatings were also investigated by XRD and SEM to prove the presence of AlN and alumina. For the first time, oxide shelled AlN was successfully applied by thermal spraying with sufficient coating deposition and enhanced AlN-content in the coating.

One of the promising thermal barrier coatings (TBC) options for use above 1250 °C has been La 2 Ce 2 O 7 (LC). This work explored the role of dual layered ceramic coatings in the top layer of the TBC system that has been prepared using atmospheric plasma spraying (APS). Above the NiCrAlY bond coat, 8 mol.% yttria stabilized zirconia (8YSZ) coating has been deposited with optimized APS parameters. Over the top layer (8YSZ), another layer that comprises composite with LC and 8 wt.% of 8YSZ (spray dried) has been deposited. Investigations into the hot-corrosion behavior of 8YSZ-LC based TBC subjected to Na 2 SO 4 +V 2 O 5 salt at 950 °C for 4 hours. A porous layer made mostly of LaVO 4 , CeO 2 , CeO 1.66 and YVO 4 was developed on the LC+8wt.% YSZ layer after being subjected to a hot corrosion test in Na 2 SO 4 +V 2 O 5 salt. Dissociation of LC and 8YSZ leads to the formation of new phases, such as CeO 1.66 , CeO 2 , LaVO 4 and YVO 4 as the corrosion by-products in the extreme environment. The findings indicated that delamination has occurred due to the phase transformation, cavities and cracks in the 8YSZ-LC based TBCs. The molten salt's hot corrosion mechanisms of the 8YSZ-LC based TBC are discussed in detail. Further, the potential use of 8YSZ-LC based dual coatings and scope for the future work have been derived from the current study.