The commonly used method for preparing EBCs is atmospheric plasma spraying (APS), but it has problems such as easy oxidation of the coating, low spraying power, and low substrate temperature, resulting in the coating having multiple pores, cracks, and insufficient density. The new plasma spraying physical vapor deposition (PS-PVD) technology can solve these problems. This article compares the microstructure, mechanical properties, and phase composition of EBCs prepared using APS and PS-PVD processes.

This paper presents the development of a modified tool steel (X30CrMnMoN13-3-1) specifically designed for defect-free processing via laser powder bed fusion (LPBF) without requiring complex machine modifications. The research addresses the dual challenge of carbon-containing tool steels in additive manufacturing: maintaining wear resistance while preventing cracking. Through optimization of the alloying system—particularly with carbon, nitrogen, chromium, molybdenum, and manganese—and the use of moderate preheating (150 °C), the authors achieved crack-free components with hardness levels up to 57 HRC after appropriate heat treatment.

This study examines the effects of N 2 and He process gases and heat treatment on the microstructure and mechanical properties of 3D-printed pure copper produced using a low-pressure cold spray system. Microstructural analysis is performed through optical microscopy, while tensile tests are used to evaluate mechanical properties. Samples processed with N 2 demonstrate improved plastic deformation, leading to reduced porosity compared to those processed with He.

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.

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.

This research aims to enhance the deformability of Inconel 718 by modifying the feedstock microstructures prior to deposition through solution treatment process at 950 °C and 1050 °C. It was observed that the gamma phase has transformed into a stable delta precipitate at 950 °C. Higher treatment temperature at 1050 °C shows a complete solution transition, proven by EBSD phase map, and electron channelling contrast imaging (ECCI).

In this work, we investigated the potential of a dense oxide layer in resisting ammonia corrosion. First, the degradation behavior of Hastelloy X substrate and HVOF sprayed CoNiCrAlY coating (as-sprayed condition) was studied in an ammonia gas flow environment. The coating was then heat-treated in air to pre-oxidize the surface, enabling the formation of a dense and stable oxide layer. Thereafter, the degradation characteristics of the pre-oxidized coating was investigated under the same environment. The mechanisms of degradation and corrosion resistance of the materials are elucidated.

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.

All solid-state sodium-ion batteries (ASS-SIBs) have great potential for application to large-scale energy storage devices due to their safety advantages by avoiding flammable organics and the abundance of sodium. In this study, plasma spraying was used to deposit Na 3 Zr 2 Si 2 PO 12 (NZSP) electrolyte for assembling high performance ASS-SIBs. NZSP electrolyte layers were deposited at different spray conditions using NZSP powders in different particle sizes. The factors influencing the microstructure and compositions of NZSP layers were examined by characterizing the compositions of splat and cross-sectional microstructures of the deposits. It was found that the preferential evaporation loss of Na and P elements occurs severely to result in a large composition deviation from initial powders and spray particle size is key factor which dominates their evaporation loss. The APS NZSP electrolytes present a dense microstructure with well bonded splats which is attributed to low melting point of NZSP. The apparent porosity of the as-sprayed NZSPs was lower than 3 %. The effect of annealing on the microstructure of APS NZSP was also investigated. The performance of typical APS NZSP was also evaluated by assembling an ASS-SIB battery with APS NaxCoO2 (NCO), Na 3 Zr 2 Si 2 PO 12 (NZSP) and Li 4 Ti 5 O 12 (LTO) as cathode, electrolyte and anode, respectively. Results showed that columnar-structured grains with a chemical inter-splat bonding were formed across the interfaces between electrodes and electrolyte. There is no evidence of inter-diffusion of zirconium, cobalt and silicon across the NCO/NZSP interface. With the preliminary battery, the solid electrolyte exhibited an ionic conductivity of 1.21 × 10 -4 S cm -1 at 200 o C. The SIB can operate at 2.5 V with a capacity of 10.5 mA h g -1 at current density of 37.4 μA cm -2 .

Bond coats are used to protect the superalloy from oxidation and to serve as a bond between the ceramic thermal barrier coating (TBC) layer and the superalloy. During high temperature exposures, a thermally grown oxide (TGO) layer forms between the bond coat and the topcoat due to oxygen diffusion, leading to coating failure in the components. This study aimed to investigate the microstructure evolution of three TBCs with different cold-sprayed bond coat alloys after undergoing isothermal heat treatments. The TBCs were heat treated at 1100 °C for durations of 12, 25, and 50 hours to observe the effects of temperature on the microstructure and phase distribution. The microstructure of heat-treated bond coat alloys was examined using scanning electron microscopy and x-ray diffraction. The findings are discussed in relation to the characteristics of the coating alloy and the application process.

Surface coatings play a pivotal role in enhancing mechanical and functional properties of various materials. High Entropy Alloy (HEA) annealed coatings have garnered significant interest due to their potential to improve wear resistance and overall durability. This research presents a comprehensive study focused on the characterization of HEA annealed coatings. It focuses on evaluating their roughness and wear performance. In this research, a systematic approach is adopted to assess the effects of annealing on coating surface properties. The investigation begins with the deposition of the Al 0.1-0.5 CoCrCuFeNi and MnCoCrCuFeNi coatings using a well-established cold spray (CS) technique, followed by a controlled annealing process. The coating surface roughness is analyzed using profilometry and microscopy techniques. This offers insights into the changes induced by annealing. The wear performance of the annealed coatings is evaluated through tribological tests.

Revealed as a process for surface functionalization and repair, cold spray is currently used as a reliable additive manufacturing process thanks to its ability to fabricate dense solid-state deposits with high deposition efficiency. However, cold-sprayed deposits generally present limited mechanical and structural properties due to manufacturing defects such as microporosities and weak interfacial particle bonding. As solutions, post-processing methods such as heat treatment or hot isostatic pressing are proposed to reduce manufacturing defects and optimize final deposit properties. This paper investigates the heat treatment effect on structural and mechanical features of cold sprayed 3D Aluminium part by comparing deposits properties evolution with the additive growth in the as sprayed and heat-treated states. Thus, a study is carried out to identify the right heat treatment conditions for optimizing deposits properties.

Cold spray is a solid-state metal powder deposition technique that has proven to be highly effective in depositing a wide range of metals, including aluminum and its alloys. However, higher strength, heat treatable Al alloys appear to exhibit variable deposition efficiencies and responses to heat treatments designed to increase ductility. This work is aimed at understanding the sources of these variabilities. In this study, 6061 (0.9% Mg, 0.6% Si, 0.3% Cu, 0.1% Cr, 0.1% Fe) alloy is compared to 7075 (6% Zn, 1.6% Cu, 2.4% Mg, 0.2% Cr, 0.3% Fe) alloy. These are common heat treatable alloys, but they exhibit quite different cold spray characteristics. Generally, 7075 is more problematic in terms of deposition efficiency and the mechanical properties after heat treatment. The alloys were processed under various cold spray conditions, including laser assisted cold spray designed to soften the 7075, and subjected to heat treatments intended to increase ductility. The microstructure and mechanical properties of the as sprayed and heat-treated coatings were characterized and compared. The results of this investigation will reveal possible mechanisms explaining the different cold spray behaviors and some suggestions will be proposed to overcome the problems associated with 7075.

The Cold spray (CS) is a promising solid-state additive manufacturing method. The interesting physics involved in the CS process including cold, high strain rate, adiabatic and severe plastic deformation results in a unique and complex structure of CS deposits at different length scales that directly determines the properties of the deposits. Therefore process- structure properties (performance) (PSP) linkages explorations are pivotal. Integrated computational materials engineering (ICME) methods in complement with experimental analyses are required to evaluate materials properties and behaviour in PSP links exploration. Finite element modelling is used to simulate the thermomechanical response of materials and evolution of field variables in CS, i.e stress, strain, strain rate, and temperature, at structural scales. Molecular dynamics modellings of nano-particle impact have provided useful insights into atomic-scale phenomena of individual particle impact while the modelling of microstructure evolution in micro and mesoscale has yet to be investigated. In this study, we developed and implemented a thermodynamic phase field simulation method to capture the structure evolution of CS composite Ni-Ti deposit upon post-spray heat treatment (PSHT) in microstructure scale. The external or internal stimuli such as heat and strain either generated in the system because of phase transformation or stored as internal energy upon CS process are accounted for. The interface mobility and microstructure development are calculated by minimization of Gibbs free energy of the system. The comparison of the simulated microstructure with experimental results confirms that the phase field modelling precisely predicts the microstructure evolution of the CS deposits upon PSHT.

In conventional powder processing, there has been considerable work on classifying feedstock powders based on particle size distribution, morphology, microstructure and composition, since these influence processability and final properties. Cold spray is a new application for powders and conventional characterization may be insufficient to assess powder cold sprayability. In particular, metallic powders have an oxide layer, which breaks during impact with the substrate or with another coating layer during cold spray; this fragmentation facilitates bonding. It has been suggested that the thickness of the oxide layer can influence the mechanism of fragmentation; thicker oxides are easier to remove, revealing clean metal surfaces that can metallurgically bond. Consequently, not all high-purity powders or powders that are stored in ambient conditions have the potential to give good coating properties after cold-spray. This work focuses on surface oxidation of the powders, characterizing the variation of oxide film aspects with size and composition of nominally pure copper powders using X-ray Photoelectron Spectroscopy (XPS). The results indicate the presence of Cu (I) and Cu (II) oxide species on the surface of as-received, naturally aged and heat-treated powders; their thickness is determined using the depth profiling feature.

The performance of two distinct coating materials under alumina particle impingement was tested in this study. CrMnFeCoNi and WC-Ni coatings were applied to 2205 duplex stainless steel substrates using cold spray method with nitrogen as the process gas. In between the substrate and the high entropy alloy coating, an interlayer coating of 316 stainless steel was used. The presence of WC particles in the WC-Ni composite coatings was confirmed by SEM cross sectional inspection. Following deposition, the coatings were heat treated in an air furnace. The influence of heat treatment holding time on the WC-Ni coatings was studied using chemical analysis by X-ray diffraction. Heat treatments peak temperatures for the WC/Ni- Ni and high entropy alloy coatings were 600°C and 550°C, respectively. Coatings microhardness and porosity volume fraction were measured for all the samples. The HEA coating outperformed the WC/Ni-Ni hardness but exhibited a higher level of porosity. The coatings were then subjected to erosion experiments using alumina particles with variable impact angles (30°, 60°, and 90°). To compare the different materials, an average erosion value was calculated for each target specimen. The WC/Ni-Ni as-sprayed coating was the most effective against a 60° impingement angle. The HEA coating, on the other hand, demonstrated greater resistance to impact angles of 30° and 90°. SEM was utilized to examine the eroded areas and determine the main mechanisms of erosion.

Successful cold spray of tool steels and other hard steels would unlock several opportunities, including the repair of molds as well as ships and heavy industry components. However, the high hardness of typical atomized steel powders strongly limits their cold sprayability. It has been recently demonstrated that heat treatment in a rotating furnace can significantly improve H13 cold sprayability via softening and agglomeration. In this work, this powder modification method is extended to a range of transformation hardenable steels: 4340, SS420, A588, 1040 and P20. The results show that powder heat treatment improves the powder deposition efficiency and the quality of the final cold sprayed coating, probably as the result of the decreased powder micro-hardness. The effects of the powder heat treatment atmosphere, a key parameter, will also be presented and discussed.

Ni/Co-based alloys have been widely employed as bond coats (BCs) in thermal barrier coatings (TBCs) to provide oxidation resistance through the formation of a dense thermally grown oxide (TGO) layer. TGO thickening is a major contributor to TBC failure. Conventional approaches to minimize its growth have included refinement/optimization of the BC composition, deposition techniques, and post-treatments. However, these approaches have only led to incremental improvements in TBC performance and do not directly address the effect of the thin interfacial oxide layer on the TBC lifetime. In a shift from conventional thinking, the development of an Al 4 C 3 -Ni alloy composite BC aims to overcome the challenges generated by current TGOs. Post-deposition heat treatment tailors the coating microstructure to form a continuous internal carbide network. At elevated temperatures, the Al 4 C 3 preferentially oxidizes to form an interlacing protective Al 2 O 3 “root” that provides better TGO anchoring and reduces TBC thermal mismatch with the substrate. In this paper, the coatings were manufactured through gas-shrouded plasma spraying using various parameters to optimize the degree of inflight carbide dissolution and minimize the extent of coating porosity and cracking. XRD and carbon analysis were performed on the coatings and the microstructure was observed using SEM. Differences between coatings are discussed in relation to the spraying parameters.

Conventionally, bulk WC and Cr 3 C 2 -based carbide compositions have been used independently of each other. However, recent investigations have begun to explore combining these carbides together within the same composite/hardmetal coating system. This research builds on earlier work characterising 42%wt% WC-42%wt% Cr 3 C 2 - 16%wt% Ni coatings sprayed under “low”, “medium” and “high” thermal input conditions, to assess their compositions and microstructures after heat treatment in air at 900°C for up to 30 days. Coatings were deposited by HVOF, Ar-He and Ar- H 2 shrouded plasmas respectively, onto Alloy 625 substrates with Ni20Cr bond-coats and top-coats. The coating compositions and lattice parameters were quantified by Rietveld peak fitting of XRD patterns. The microstructures were analysed from cross sectional backscatter electron micrographs. Rapid phase development occurred within the first five days, beyond which the compositions and microstructures remained stable. The microstructures retained extremely fine, sub-micron grain sizes, while the carbide phases exhibited high degrees of metastable alloying, even after 30 days at 900°C. The coating compositions are discussed, and a mechanism proposed to account for the rate of development and overall metastable microstructure.