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.

This study aims to comprehensively examine and analyze the basic mechanical properties, oxidation resistance, high-temperature hardness, fretting wear, and simulated operating conditions of CuAl/PHB coatings. The objective is to investigate the optimal combination of resistance to fretting wear and abradability for these coatings.

This study analyzes the influence of reactive elements like H 2 regarding hydrogen embrittlement to determine whether the porous structure of the plasma sprayed coating itself, or the thermal treatment with H 2 is influencing the cohesion and microstructure. To exclude substrate-related influencing factors during testing, tensile rods of thermally sprayed coatings were manufactured.

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.

In this study, we focus on developing effective repair procedures by optimizing key processing parameters such as gas pressure, gas temperature, and traverse speed. To achieve this, a combination of machine learning and experimental testing was employed on cold-sprayed Ni-based superalloy (IN 625). The prepared samples were assessed for microhardness, adhesion strength, and porosity, and these experimental results were subsequently used to train a machine learning model. This model predicts material properties under varying process conditions, ensuring precision in parameter selection.

For this study, a fixed high-end primary parameter set with respect to gas pressure and temperature was selected for depositing Al6061 powder feedstock on Al6061-T6 substrate sheets. The influences of different parameter variations on spray deposit build-up and performance were investigated by evaluations of deposit efficiency, deposit microstructures, porosities, deposit hardness, and electrical conductivity.

In this research work, MoNbZrTiV and AlNbTaTiV refractory high-entropy alloy (RHEA) material combinations were investigated as potential candidates for feedstock materials for cold spray additive manufacturing. The two RHEA materials as precursors for developing micron-sized particles were alloyed mechanically through high-energy ball milling following a rigorous material design-of-experiments curriculum on account of elemental melting point differences. Detailed particle characterization techniques were employed to gain insights into the RHEA particle properties.

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 this paper, we evaluate the potential of ultrasonic atomization as a new feedstock manufacturing technique for cold spray by comparing the cold spray performance of an experimental stainless steel 316L powder obtained from ultrasonic atomization with a commercial stainless steel 316L powder produced through gas atomization.

This paper aims to relate the most important mechanical and fracture properties of Inconel 718 built by the 3DMD technology to the two process parameters directly influencing the thermal gradient, the scanning velocity, and the laser power. To gain a phenomenological understanding of the underlying mechanisms, a complex EBSD study of the obtained materials was performed.

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.

This study focuses on the deposition and post-processing behavior of commercially pure copper produced using cold spray additive manufacturing (CSAM) with compressed air. By evaluating the microstructural evolution and mechanical performance of as-deposited and heat-treated copper samples, this work aims to provide insights into optimizing CSAM processes for industrial applications.

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.

Extreme High -Speed Laser Cladding (EHLA) is a new process category of laser cladding. In this study, EH-LA layer was characterized by comparing with conventional laser cladding (LC) layer. Basic SUS316L layers, as well as WC-reinforced SUS316L layers, were formed on SUS304 substrates using both LC and EHLA processes. The macroscopic morphology, microstructure, microhardness, wear resistance, and residual stress of the four types of layers were evaluated. As a result, EHLA layers exhibited slightly higher micro-hardness and less wear loss than that of LC layers, despite the presence of more micropores. This can be due to their finer dendritic structures. Furthermore, residual stress of EHLA layer was lower than that of LC layer due to those micropores. Additionally, EHLA can add up to 45 wt.% WC into SUS316L layer without crack formation, resulting in higher wear resistance than that of LC where crack formation occurred at 25 wt.% WC. This enhanced crack resistance in EHLA is believed to be due to the less heat input during deposition.

Gas-fuel HVOF for thermal spraying of WC-CoCr powder is widely known and well described in literature. Focus are the various influencing factors like fuel-to-oxygen ratio, standoff-distance and powder feed rate on the coating characteristics like hardness and porosity. However, the total gas flow is usually not being described in this context despite its wide influence on particle characteristics and therefore on coating properties. In this study, the characteristic influence of the total gas flow on roughness, hardness and porosity is described as well as its effect on the particle characteristics. The study performed was based on technical standard values for thermally spraying WC-Co-Cr via gas-fuel HVOF (DJ2700 hybrid) and additional trials for increased and decreased total gas flow. It was possible to determine that with higher gas flow the deposition rate increases while the roughness and porosity decrease. However, these results cannot be viewed in isolation as other factors, such as the fuel-to-oxygen ratio, are affecting the particle and coating characteristics at the same time. Therefore, the total gas flow is also considered in combination with other factors.

Light alloys are being investigated as an alternative to ferrous-based engineering components. The manufacturing of such components requires a surface modification step necessary to eliminate the top surface's poor wear and corrosion response for improved functionality. Thermally sprayed cermet coatings offer improved surface resistance to wear and/or corrosion. This work presents a customized composition of WC-CoCr feedstock cut in fine and coarse powder size distribution (PSD) to fabricate different coatings on aluminium alloy and steel substrates using two high velocity spray techniques. The WC-CoCr coatings sprayed using the high velocity air-fuel (HVAF) technique at varied parameters consist of six different coatings (four thick, ~ 200 μm and two thin ones, 60-80 μm) to investigate the relationship between processing conditions, microstructure, and performance. Using scanning electron microscopy (SEM) and electro-dispersive X-ray spectroscopy (EDX) offered a comprehensive characterization of the respective coatings. Micro indentation, dry sliding wear, dry sand abrasion, and cavitation erosion tests conducted on the samples show the performance of the coatings based on the processing techniques and spray conditions. However, despite the similarities in the microstructural makeup of the coatings and the measured micro indentation hardness of the coatings (1000-1300 HV0.1), their respective specific wear rate (SWR) varied based on spray processing techniques and the substrate on which the coatings were deposited. Three of the HVAF coatings showed ~ 60 % more wear on the aluminium alloy substrate compared to the same coating deposited on a steel substrate. However, irrespective of the substrate used the HVAF coatings showed better wear resistance than the HVOF coating. The dry sand abrasion wear results of the two thick HVAF coatings show them superior to the HVOF coating in the three-body wear experiment conducted. The cavitation erosion resistance of the coatings varied based on the processing conditions and the driving mechanisms but the best two were the AF-2 and AF-6 samples.

Recently, laser deposition technologies have made significant advancements in their ability to manufacture high temperature metals and ceramics. One of these technologies, known as Direct Energy Deposition (DED), has the potential to deposit a wide range of materials from polymers to refractory materials, ceramics and functionally graded materials. This study evaluates major microstructural characteristics of WC-Co additively manufactured by DED technology. This material is commonly used for deposition of protective coatings due to its high hardness and excellent wear resistance. To this end, hardness and wear resistance of the DED processed samples were also investigated in this study. WC-Co coatings are generally deposited using various thermal spray technologies. However, it is speculated that DED deposited WC-Co could provide superior properties such as higher hardness and wear resistance. A DED manufactured WC-Co sample was examined by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD). Those studies could provide information about important microstructural features, chemical compositions and phase distribution. All the tests were also repeated on High-Velocity Oxygen Fuel (HVOF) deposited WC-Co with the same composition. Both DED and HVOF produced WC-Co coatings experience decomposition of the carbides into compound phases; however, the DED deposited sample displays unique dendritic and eutectic structures that improve the hardness and wear properties compared to the homogenous HVOF coating. In addition, DED produced samples show higher hardness and relatively better wear resistance compared to the HVOF deposited ones. The obtained results could establish a relationship between microstructural characteristics with hardness and wear properties of both samples.

Nowadays, Cr 3 C 2 -based cermet coatings by HVOF process are widely recognized for their corrosion and erosion resistance, particularly at high temperatures. These coatings also offer the advantage of being lightweight and exhibiting superior wear, corrosion and cavitation resistance in room-temperature applications. Their lightweight nature and high temperature capability make them an attractive alternative to WC-based alloy coatings and hard Cr plating coatings. The objective of this study is to develop optimal Cr 3 C 2 -NiCr coatings by comparing different feedstock materials, including feedstock with nanocrystalline and/or submicron sized Cr 3 C 2 phases. The focus of the investigation is on understanding the impact of feedstock features such as particle size, morphology, and carbide sizes, as well as sliding abrasive wear conditions (specifically SiC grit size and working load), on the coating properties and sliding wear performance. The results of the study indicate that the sliding wear resistance of the Cr 3 C 2 -NiCr coatings is highly influenced by the features of the Cr 3 C 2 carbides. The presence of nano, submicron and few microns sized carbides in the coatings improves their density and hardness, leading to a significant reduction in wear rates under test conditions. Furthermore, the size of the abrasive SiC grit on the counter surface plays a significant role in determining the sliding wear behavior of these coatings. Based on the analysis of the test data, the mechanisms behind the performance of the Cr3C2-NiCr coatings have been investigated and used to interpret their sliding wear behaviors. A high microhardness in the coating is considered a reliable indicator of high quality, full density, and satisfactory wear resistance. This study has identified and recommended optimized materials for improved coating properties based on the key findings. These findings contribute to the understanding of the relationship between feedstock features, sliding abrasive wear conditions, and the wear rates of HVOF-sprayed Cr 3 C 2 -NiCr coatings.

Thermally sprayed wear resistant coatings have proven their effectiveness in many applications. Their benefit is unquestionable in the case of mutual sliding contact or abrasive stress caused by hard particles. However, for the case of dynamic impact loading, either single or cyclic, the lifetime of different types of coatings is rarely described, probably due to the complex influence of many parameters. The paper deals with the evaluation of resistance to dynamic impact loading of two types of HVOF-sprayed Cr3C2-rich binary hardmetal coatings (Cr3C2-42%WC-16%Ni and Cr3C2-37%WC-18%NiCoCr) with respect to the variation of their deposition parameters and compares them to a well established Cr3C2-25%NiCr coating. For each coating, a Wohler-like curve was constructed based on a failure criterion of sudden increase in impact crater volume. Besides, coatings deposition rate, residual stress, microstructure and hardness were evaluated. Differences in the coatings dynamic impact wear resistance was found, related to their residual stress. The failure mechanism and crack propagation mode are analyzed using SEM of impact surface and cross-sections. Deformation and related stress changes in coated systems during dynamic impact loading are described using FEA analyzes.

In order to overcome the problem of insufficient abradability of existing metal based coatings that cannot meet the requirements of harsh working conditions, this article designs two types of metal based abradable sealing coating materials based on the particle structure of "peeling medium", and studies the basic performance and simulated working condition service performance of the coatings. The research shows that, after undergoing a 1000 hour heat exposure test at high temperature, the two coatings still maintain good hardness, bonding strength, and abradability, indicating that under long-term high-temperature service environment, the two coatings can fracture at the location where the abradable components are exposed, thereby maintaining the abradability and good thermal stability that meet the requirements of use.