Journal of Thermal Spray Technology最新文献

The cold gas spray (CS) technique has emerged as a promising coating deposition method in the last decades for many materials, including Ti and most recently metal matrix composites, such as graphene-reinforced Ti. In this study, CS Ti coatings reinforced with two types of carbon nanofibers (GFs), HCNFs and MWCNTs, were evaluated regarding their electrochemical, electrical, and thermal properties before and after heat treatments (HT) at 700 and 1000 °C. The results indicated that incorporating GFs did not alter the CS Ti coatings deposition efficiency, porosity, or hardness in as-sprayed condition. HT reduced the CS Ti and Ti-GFs coatings resistivity by 21 and 23%, respectively, as well as improved their thermal conductivity by 25 and 32%, respectively. CS Ti-GFs coatings demonstrated an impressive reduction in corrosion rate of up to 80% compared to unreinforced Ti. These findings highlight the potential of CS Ti-GFs composite coatings applied through CS for industrial applications requiring high corrosion resistance. However, improvements by incorporating GFs in Ti powder in thermal and electrical properties were limited, indicating the need to optimize matrix–reinforcement interaction and CS process parameters to maximize their performance in these areas.

Cold spray (CS) is a recent addition to the thermal spray family with extensive research conducted on the effects of different process parameters during CS deposition various metallic powders. While mechanical and fatigue strengths of cold-sprayed deposits have been evaluated through static and dynamic testing, identifying the sequence of failure mechanisms—whether cracks within the coating occur before delamination at the coating–substrate interface—remains visually challenging but crucial for pinpointing weak points within the deposit. To address this, acoustic emission (AE) testing was employed in this study to reliably determine the failure sequence through in situ monitoring. Using a four-point bending setup, a 2.5-mm-thick Al6061 coating on an Al6061-T6 substrate was analyzed in real time with AE data and video correlation. The findings revealed that cracks associated with higher AE frequencies (≥ 100 kHz) appeared first, accompanied subsequently by delamination, which was correlated with lower-frequency AE events (< 100 kHz). This AE methodology shows promise for integration with other static tests, such as open-hole tension as well as fatigue testing to determine similar failure sequences. By providing a clear understanding of failure mechanisms, this approach advances the structural evaluation of cold-sprayed deposits and their potential applications.

FeAl intermetallic compounds have several advantages over other Fe-based alloys. Surface engineering was used to prepare intermetallic FeAl coatings to exploit the properties of these components. However, this method requires complex processing, and controlling the phase composition of the coating makes it difficult to prepare Fe-Al coatings using conventional surface engineering. In this study, a novel constrained wire electrical explosion spraying device was used to prepare FeAl coatings. A FeAl intermetallic coating was successfully synthesized by electrical explosion spraying of twisted 316L/Al wires. The charging voltage affected the phase compositions, microstructures, and deposition efficiencies of the coatings. Considering the phase composition, deposition efficiency, and microstructure of the coating, a charging voltage of 8.8 kV was determined to be suitable based on the overheating factor of the twisted wires, which influenced the amount of liquefied and gasified metal. Intermetallic FeAl compounds were formed as the clusters of liquefied and gasified 316L and Al were cooled. In addition to the overheating factor, the wire expansion velocity was influenced by the charging voltage. The combined effects of the overheating factor and expansion velocity determine the temperature and velocity of the explosive products, ultimately affecting the degree of product flattening and coating microstructure.

To optimize the heat treatment temperature for enhancing the microstructure and performance of Sm₂O₃/FeCoNiCrMn high-entropy alloy (HEA) composite coatings fabricated by laser cladding, the microstructural evolution and mechanical properties of coatings heat-treated at 500 °C, 700 °C, and 900 °C were investigated. XRD, SEM, and EDS analyses revealed that the phase composition remained primarily face-centered cubic (FCC), with secondary phases Co_5.24Sm_0.97 and Fe₇Sm, regardless of temperature. Increasing the treatment temperature from 500 to 900 °C elevated surface residual stress from 412.35 to 461.89 MPa and intensified internal elemental segregation. At 500 °C, the coatings exhibited optimal performance, achieving the highest average hardness (317 HV_0.4), lowest wear rate (0.11 mm³/N·m), smallest wear depth (134.27 μm), and minimal elemental segregation, surpassing untreated samples in hardness, wear resistance, and corrosion resistance. These findings highlight the critical influence of heat treatment temperature on HEA composite coatings, with 500 °C identified as the optimal temperature for enhancing mechanical and corrosion properties. This study provides valuable insights for applying laser cladding and heat treatment technologies in aerospace, medical, and automotive industries.

This study investigates the phase and elemental distribution in a suspension plasma-sprayed (SPS) Li₄Ti₅O₁₂ (LTO) thin-film anode for solid-state lithium batteries, deposited on an SS-304 substrate. Advanced synchrotron-based µXRD and µXRF techniques were employed for micro-scale characterization, revealing distinct phase regions influenced by thermal exposure during the SPS process. The dominant Li₄Ti₅O₁₂ phase was retained across most of the film, with localized transformations to secondary phases Li₂Ti₃O₇, Li₂TiO_3, and TiO₂ near the substrate interface, primarily due to prolonged high-temperature exposure and subsequent lithium loss. These findings underscore the importance of controlling SPS parameters to minimize lithium loss and optimize phase stability and interfacial integrity in solid-state battery components.

Nickel-based self-fusing alloy (Ni-Cr-Si-B) coatings are vital for their exceptional wear and corrosion resistance in industries like coal, metallurgy and mining. However, challenges like high remelting temperatures and limited wear resistance hinder their widespread application. In this study, a data-driven approach: correlation analysis combined with thermodynamic high-throughput calculations and Pareto-boundary optimization searches were used to design T1 coatings (the novel designed alloy) with easy processing, suitability for the remelting process, superior high-temperature stability, high wear resistance and better corrosion resistance. Microstructure and performance comparisons were made with the C1 alloy coating (commercial reference alloy) prepared by the same process. The results show that compared with C1, the newly designed T1 coating had lower porosity and surface roughness; in the wear test at 400 °C, the wear rate was reduced by about 11.5%; in the electrochemical corrosion experiment with 0.1 mol/L Na₂SO₄ solution, the corrosion rate of T1 was decreased by about 38.8%. Based on the design logic of composition-process-microstructure-property, a novel nickel-based self-fusing alloy coating was successfully designed to be suitable for the existing process, easy to process and with better comprehensive performance, which also provides new clues for the efficient design of coatings and alloys.

A novel laser pinning reinforcement process was employed to enhance the thermal shock resistance of NiCoCrAlY coatings. The process parameters of the Gaussian laser pinning strengthening were tested and optimized to obtain the optimal process parameters. The influences of the central single-point, triangular, quadrilateral, hexagonal, and annular pinning on the microstructure and thermal shock performance of the coatings were studied. In the laser pinning zone, the uniformity and compatibility of the microstructure were significantly improved and the bonding mechanism between the coating and the substrate shifted from mechanical bonding to metallurgical bonding. The thermal shock cycling experiments demonstrated that after 9 cycles, the coating with the annular layout peeled off and failed. After 45 thermal shock cycles, the coating with the hexagonal layout peeled off and failed. However, after 296 thermal shock cycles, the coatings not pinned by the laser failed and the coatings with the central single-point, triangular, and quadrilateral pinning layouts had relatively intact surfaces, and the crack propagation was not obvious. Among them, the coating with the triangular pinning layout had the fewest cracks. Longitudinal cracks and edge cracks were generated within the limited area. As the thermal shock cycling continued, the edge cracks extended toward the center and connected with the longitudinal cracks, ultimately leading to the preferential peeling and failure of the coating. In contrast, the number of tiny cracks within the local range of the pinning points of the triangular layout was the least, and it was difficult for the cracks to connect, so the anti-thermal shock performance was the strongest.

Because of harsh working conditions, the tooth surface of the active wheel gear ring experiences severe corrosion and wear under high-impact loads. Current tooth surface reinforcement techniques do not substantially increase impact and corrosion resistance. Hence, this study designed a ‘sandwich’ composite coating with an interfacial layer, a toughening layer and a wear-resistant layer on the ZG42CrMoA material. The coating comprises γ-Ni, M₂₃C₆, MoNi, MoNi₄, Ni₃B, WC and W₂C. The interface layer removes pores and inclusions in the substrate, thereby creating a strong metallurgical bond and fortified coating-substrate adhesion. The toughened layer, enriched with Mo at grain boundaries, impedes Cr diffusion. Moreover, tungsten carbide (WC) nanoparticles refine the grain structure, strengthen grain boundaries, limit dislocation slip and improve impact resistance. The toughened layer absorbs energy via plastic deformation, further augmenting impact resistance. As a result, the composite coating exhibits better impact toughness than high-frequency quenched specimens. Impact tests and finite element analysis demonstrate that the composite coating’s maximum compressive stress is 253.11 MPa, compared to 288.63 MPa for the high-frequency quenched layer. Due to its high hardness and brittleness, the high-frequency quenched layer endures restricted plastic deformation under the impact, developing stress concentration zones that lead to cracks and fracture and lowered impact resistance. Alternatively, the γ-Ni solid solution in the composite coating provides good toughness, allowing more plastic deformation, decreased stress, alleviated stress concentration and significantly improved impact resistance.

Depositing dense or bulk-like superhigh-temperature boride ceramic coatings by thermal spraying is a challenging but attractive method for applications in the electronics industry due to the excellent electrical and thermal conductivity of the resulting coatings. Herein, a dense TiB₂ coating deposited by plasma spraying was investigated by modifying the characteristics of the plasma jet in a controlled environment chamber. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to analyze the phase and microstructure of the sprayed coating. The coating was then used as the negative electrode for a lithium-ion battery. The results showed that a dense TiB₂ coating with fully bonded lamellae was obtained with an Ar/He plasma jet under a very low pressure, resulting in a porosity of 3.05%. A coarse coating with many unmelted particles was deposited with an Ar/H₂ plasma jet under a low pressure. The dense coating with a low electrical resistivity (1.17 × 10⁻³ Ω cm) presented charge/discharge performance, but its specific capacity of 17.22 mAh g⁻¹ requires improvement.

Four FeCrCoMn high-entropy alloy coatings with different preset body sizes are prepared on the surface of 45 steel substrates by laser cladding technology, and the effect of preset body size on the corrosion performance of the coatings is analyzed. The results show that the phase composition of samples with various preset body sizes are all FCC and HCP solid solution structures. However, the microstructure and morphology of the coating are transformed from equiaxial crystals to columnar dendritic crystals with the increase in the preset body size and the size of more than 10-mm grains coarsen obviously, which results in the gradual decrease in hardness and aggravation of the abrasion. The corrosion mechanism of the coating is mainly pitting, and the wear mechanism is mainly abrasive wear, adhesive wear and corrosive oxidative wear. With the increase in the preset body size, the corrosion and abrasion resistance of the coating increases first and then decreases. When the preset body size is 15 mm, the coating has high corrosion protection efficiency due to the dense structure of the coating and few solidification defects, which makes the coating show excellent corrosion and abrasion resistance.