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Journal of Thermal Spray Technology
Journal Prestige (SJR): 0.688  Citation Impact (citeScore): 2 Number of Followers: 5  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1544-1016 - ISSN (Online) 1059-9630 Published by Springer-Verlag  [2468 journals]
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- Investigation on Tribological Characteristics of Plasma Transferred Arc
Cladded Co-TiC-CaF2 Metal Matrix Composite Coating Produced on Magnesium
Alloy AZ91D Substrate-
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Abstract: The demand for lightweight materials with enhanced mechanical and wear-resistance properties has spurred significant research in the field of surface modification of magnesium alloys. In this work, Co-TiC-CaF2 metal matrix composite (MMC) coating has been produced on magnesium alloy AZ91D substrate by plasma transferred arc (PTA) coating process. The effect of scan speed, PTA current, and CaF2 content on microhardness, coefficient of friction (COF), and wear rate of Co-TiC-CaF2 coating have been studied. The x-ray diffraction, SEM, and energy-dispersive x-ray spectrometry (EDS) have been used to determine the phases, morphology of the coated surface, and chemical elements. The findings revealed that the coatings are compact and uniform with some microcracks and voids, with Co, TiC, and CaF2 particles evenly distributed and metallurgically bonded to the substrate. Under optimal parameters, Co-TiC-CaF2 composite coating exhibits maximum average microhardness value of 958 HV0.05, compared to 68 HV0.05 of Mg alloy AZ91D substrate. This exhibits that the clad layer offers 14 times greater hardness than the magnesium alloy AZ91D substrate. The wear rate of Co-TiC-CaF2 MMC composite coating was measured as 2.05 × 10-8 g/N-m, while wear rate of the substrate AZ91D Mg was 79.23 × 10-8 g/N-m. Therefore, the coating has 38 times more wear resistance than Mg alloy AZ91D substrate. Comparison to substrate, sample CTC-10 exhibits smooth worn surface and lower COF. This comprehensive study offers valuable information on developing advanced surface coatings for magnesium alloys. Hence, lightweight materials with improved tribological performance can be used in the industries which require lightweight of the engineering components.
PubDate: 2025-04-03
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- Toward Highly Dense Yb-Silicate Microstructures Deposited by Air Plasma
Spray for Environmental Barrier Coating Applications I: Influence of Local
Deposition Rate-
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Abstract: Environmental barrier coatings (EBCs) are used to shield high-temperature Si-based ceramic matrix composite gas turbine components from the harsh, water vapor-rich operating environment. The success of this application is directly correlated to the intrinsic gas tightness or hermeticity of the EBC volatilization barrier, which are typically rare-earth disilicates. For the air plasma-sprayed (APS) EBCs, the hermeticity is directly related to the processing parameters during deposition. In this work, the effect of surface speed and feeding rate on the microstructural evolution of plasma-sprayed Yb2Si2O7 coatings was studied. A qualitative assessment by means of microstructure analysis of hermeticity after crystallization heat treatment and the influence of the aforementioned processing parameters is discussed. It was found that utilizing lower feeding rates can minimize certain types of disadvantageous cracking in the as-deposited Yb2Si2O7 coatings. Moreover, at these low feeding rates (~1-5.4 g/min) regardless of the selected surface speed (250-1250 mm/s), highly dense Yb2Si2O7 microstructures could be obtained in the as-sprayed state. Contrastingly at higher feeding rates (~46.2 g/min), deleterious Yb2SiO5 band formation was observed at the top of each spray pass, which correlated to worsened cracking in the microstructures, particularly at low surface speed (250 mm/s). The monosilicate band formation was linked to the fine particle fraction of the feedstock (i.e., particles
PubDate: 2025-04-02
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- Oxidation Dominated High-Temperature Friction and Wear Behavior of
Composite Coating NiCr-Cr3C2-BaF2/CaF2-
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Abstract: NiCr-Cr3C2-BaF2/CaF2 is a commonly used self-lubricating composite coating prepared on the surface of the moving components operating at high temperatures. The role of oxidation in high-temperature friction and wear behavior was studied in NiCr-Cr3C2-BaF2/CaF2 composite coatings. The coefficient of friction and wear rate of as-sprayed composite coatings decreased with increasing temperature from 600 to 800 °C due to the formation of tribo-layer mainly containing BaCrO4 and CaCrO4. However, the wear resistance of coatings decreased significantly as the oxidation time increased at 800 °C. The supporting effect of the near surface on the upper tribo-layer was weakened due to the generation of voids near the surface of composite coating after prolonged oxidation. The present study helps further understand the failure mechanism of NiCr-Cr3C2-BaF2/CaF2 coating in long service and provides an insight into the interactions between oxidation and wear in the sliding interface for multi-phase composite coatings.
PubDate: 2025-04-01
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- Microstructure and Properties of Ni-TiCN Composite Coatings on Ti-6Al-4V
Substrate by Laser Cladding-
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Abstract: Some new Ni-based composite coatings with different amount of TiCN particles were prepared on the surface of Ti-6Al-4V (TC4) substrate by laser cladding. The microstructure and phases were obtained by scanning electron microscopy, energy-dispersive spectrometer and x-ray diffractometer. The microhardness and wear resistance were also tested by Vickers hardness tester and friction and wear tester. The results showed that all coatings had a good metallurgical bonding with TC4 substrate. Some new phases appeared in coating, such as Ti, Ti2Ni, TiCN, TiC, TiN, Cr2Ti and TiAl3. The microstructure was mainly composed of block crystals and dendrites. When the amount of TiCN was 15% and 20%, spherical crystals appeared in coating. The values of average microhardness were 885.1, 890.6, 923.2, 973.7 and 943.1 HV0.2, respectively. And the wear volumes were 0.39, 0.13, 0.12, 0.09 and 0.44 mm3, respectively. When the amount of TiCN was 15%, the coating had the maximum average microhardness due to the appearance of TiC, TiN and Ti2Ni phases. It also had the best wear resistance. It can be seen that the average microhardness and wear resistance were improved obviously due to the addition of TiCN particles.
PubDate: 2025-03-26
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- Effect of WC Particle Size on the Microstructure and Properties of
FeCoNiCrMn High-Entropy Alloy Composite Coatings by Laser Cladding-
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Abstract: The FeCoNiCrMn high-entropy alloy (HEA) has attracted considerable attention in materials science owing to its outstanding wear resistance and corrosion resistance, rendering it highly suitable for diverse industrial applications. This study examines the effect of tungsten carbide (WC) particle size on the microstructure and properties of FeCoNiCrMn HEA coatings fabricated by laser cladding on a 1.0503 steel substrate. The findings reveal that the coatings predominantly comprise a face-centered cubic (FCC) phase, while the addition of WC particles facilitates the formation of the M6C phase. Furthermore, the concentration of the M6C phase increases with decrease in WC particle size. The incorporation of WC particles refines the microstructure of the coatings, strengthens interfacial bonding, and diminishes the formation of macroscopic pores and cracks. These effects are more pronounced with finer WC particles. Specifically, smaller WC particles markedly enhance the microhardness of the coatings, reduce the friction coefficient and wear rate, thereby improving wear resistance. However, the introduction of WC particles results in a decline in the corrosion resistance of the coatings and a gradual increase in residual surface stress, with these effects becoming more pronounced as the particle size decreases. In summary, this study demonstrates that optimizing the WC offers valuable insights for their industrial applications.
PubDate: 2025-03-24
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- Fabrication and Characterization of Magnesium-Doped Hydroxyapatite
Coatings via Solution Precursor Plasma Spraying-
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Abstract: Ion doping of hydroxyapatite (HA) has been increasing in popularity as a chemical approach to endow it with new properties. In this work, the solution precursor plasma spraying (SPPS) technique was used to prepare the magnesium (Mg)-doped HA coating on the titanium substrate. SPPS is a relatively new one-step deposition technique that allows ion doping and coating deposition to occur synchronously, saving time and costs. The XRD and FT-IR analysis confirm that Mg ions were incorporated into the HA structure and the main phase of the coatings belongs to the HA phase. The results demonstrate the feasibility of using the SPPS technique to prepare the doped HA coating. The addition of Mg ions causes lattice distortion of HA, which leads to a reduction in the chemical and thermal stability of the HA coating. The dissolution behavior of the coatings was investigated by immersing them in phosphate-buffered saline solution for different durations. The Mg-doped HA coating shows relatively higher solubility than the undoped HA coating. With the increase of Mg doping amount, more Ca2+ and Mg2+ are released from the coating samples. The adhesion strength of the coating is measured by scratch tests. The 5% Mg doped-HA coating shows the strongest bonding to the substrate. An improvement of 19.6 N is achieved compared to the undoped HA coating. The biocompatibility and bioactivity of the coating samples were evaluated based on the behavior of osteoblasts (MC3T3-E1) in vitro. Cell staining and MTT assay show better cell attachment and proliferation ability on the Mg-doped HA coatings. The presence of Mg in the coating also stimulates the expression of alkaline phosphatase (ALP) and the formation of mineralized nodules in MC3T3-E1 cells. Therefore, the Mg-doped HA coatings prepared by SPPS can be used as a promising implant coating material for orthopedic applications.
PubDate: 2025-03-24
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- Laser Irradiation Behavior of Plasma-Sprayed Y2SiO5 and Y2Si2O7 Coatings
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Abstract: With the rapid development of laser technology, laser protection for material surfaces has been a major concern. In this paper, Y2SiO5 and Y2Si2O7 coatings were applied to the surface of high-temperature alloy substrates by air plasma spraying and irradiated using high-energy laser. The phase structure, microstructure, element distribution, reflectivity, and chemical state of the coatings were characterized. During laser irradiation, Y2SiO5 and Y2Si2O7 coatings underwent melting and vaporization, and some areas also experienced mechanical spalling. Annealing can reduce the concentration of oxygen vacancy defects within the lattice, increase the reflectivity of the coating, and further enhance the laser protection capability of the coating. The annealed Y2Si2O7 coating showed no damage under 1000 W/cm2 laser irradiation for 15 seconds, and provided excellent protection for the substrate. Compared to Y2SiO5 coating, Y2Si2O7 coating exhibits superior laser protective capability due to the higher reflectivity and better structural stability.
PubDate: 2025-03-21
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- Effect of Substrate Surface Roughness on Properties of WC-12Co Coatings
Sprayed by High Velocity Oxygen Fuel Spraying on AZ31B Magnesium Alloy-
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Abstract: Magnesium alloy is a lightweight structural material, but commercial AZ31B magnesium alloy has poor wear and corrosion resistance. WC-12Co has high hardness, wear resistance and corrosion resistance. In this paper, WC-12Co coating was prepared on AZ31B substrate by high velocity oxygen fuel (HVOF) spraying technology to improve its comprehensive service performance. Based on the surface of AZ31B magnesium alloy substrate with different roughness, the coating microcharacterization experiment was carried out. The effects of substrate surface roughness on the hardness, adhesion, wear resistance and corrosion resistance of the coating were revealed. The results show that the adhesion between the coating and the substrate and the corrosion resistance of the coating are significantly improved with the increasing surface roughness.
PubDate: 2025-03-21
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- Hybrid Thermal Spray: A Pathway to Realize Novel Coating Microstructures
and Properties-
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Abstract: Thermal spray technology, a versatile coating technique, significantly impacts diverse industries and is pivotal in modern manufacturing processes. Like other technologies, it must continuously evolve to address new challenges and market demands. In this context, “hybrid thermal spraying” utilizing distinct feedstocks (such as powders, wire, suspensions, and solution precursors) offers a novel pathway to conveniently combine dissimilar materials at very different length scales to realize coatings with unique properties and enhanced performance. This approach seamlessly integrates into all thermal spray techniques. Introducing two or more distinct feedstocks simultaneously or sequentially with independent control over each can deposit coatings with varied architectures and novel microstructures. The present-day industry constantly demands enhanced performance and longevity of established wear-resistant coatings, thermal barrier coatings (TBCs), etc., and novel functionalities for emerging fields such as batteries. Hybrid thermal spray can potentially address these needs by elegantly combining established material systems with additional constituents. This review discusses the different variants of hybrid thermal spraying, and their relevance to practical applications is explored based on a comprehensive assessment of available literature. This review is intended to serve as a bridge between traditional and innovative approaches for inspiring further research to harness the advantages of hybrid thermal spray processes gainfully. It also discusses the challenges and limitations associated with this approach.
PubDate: 2025-03-19
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- Microstructures and Properties of High Strength and Toughness Fe-Based
Coatings Fabricated by Plasma Arc Deposition-
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Abstract: Currently, surface coatings on agricultural machinery are crucial for extending service life. However, achieving coating strength and toughness remains a challenge. In this paper, two types of high-hardness iron-based coatings, referred as S1 and S2, were prepared by modulating the Mo/V ratio in the Fe-C-V-Mo-B system, and their microstructural evolution and property changes were investigated. The results show that the S1 coating primarily consist of martensitic matrix, spherical VC, blocky Mo2B, and a small amount of skeleton-like Mo2B. In contrast, the S2 coating consist of martensitic matrix, petal-like VC, and skeleton-like Mo2B. Compared with S1, the VC volume fraction in S2 increases by 6.5%, and the Mo2B volume fraction increases by 16.3%. The average microhardness of S1 and S2 coatings are 737 HV0.5 and 954 HV0.5, respectively, indicating that the S2 coating exhibits a 22.7% higher microhardness compared with S1. The average friction coefficients of S1 and S2 coatings are 0.434 and 0.398, respectively. Furthermore, the wear loss of S2 coating is approximately half that of S1. The fracture toughness of S1 and S2 coatings are 51.9 MPa·m1/2 and 51.7MPa·m1/2, respectively. Fracture analysis reveals that the skeleton-like eutectic structure in S2 can deflect cracks generated by impact, increase the length of propagation path, and improve the toughness of coating. It allows S2 coating to achieve high hardness and wear resistance, while maintaining toughness comparable to S1 coating. This study provides a theoretical basis for the design and development of iron-based coatings with high hardness, high abrasion resistance, and impact resistance for agricultural machinery.
PubDate: 2025-03-19
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- Parameter-Dependent Bonding Properties of Sinusoidal-Texture-Modified
Plasma-Sprayed Coatings-
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Abstract: Laser surface texturing is widely acknowledged as an effective technique for enhancing coating bonding strength. However, the influence of texture parameters, particularly those of a novel sinusoidal configuration, on coating adhesion has been insufficiently explored. This gap in research underscores the necessity for a comprehensive investigation into the effects of these parameters. In this work, sinusoidal textures with varying width–depth ratios, sinusoidal amplitude, and sinusoidal wave number were engineered using nanosecond laser technology. Thereafter, Ni-based MoS2 coatings were deposited on these sinusoidal-textured surfaces. The coating bonding strength was subsequently evaluated using adhesion test in accordance with ASTM 633 standard. Concurrently, the fracture morphology, the relative adhesion area, and the surface roughness were characterized to investigate the fracture mechanisms. The experimental findings revealed a positive correlation between the coating bonding strength and the reduction in texture width–depth ratio, as well as the augmentation of sinusoidal amplitude and wave number. Notably, a reduced width–depth ratio may result in incomplete filling and large holes at the coating-substrate interface, which is detrimental to the coating adhesion strength. Optimal adhesion is achieved with a texture width–depth ratio ranging from 0.52 to 2.09, an sinusoidal amplitude exceeding 0.1 mm, and an wave number surpassing 10 rad/mm. It can be inferred that the judicious design of texture parameters is imperative to attain the desired level of coating adhesion.
PubDate: 2025-03-19
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- Automation of a Repair Process by Robot-Guided Cold Spray
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Abstract: The growing importance of conserving natural resources is driving the demand for advanced repair techniques. In this context, cold spray is emerging as a highly promising technique for repairing metallic components. This process offers significant advantages, such as the deposition of heat- and oxidation-sensitive materials. However, to utilize cold spray as an efficient and reliable repair technique, it is essential to integrate automation and robotics. This work proposes a concept for the automation of a repair process by robot-guided cold spray. The comprehensive workflow begins with the sensor-based inspection of the damaged region, followed by the automated extraction of the damage volume to define the dimensions for the subsequent material removal. In the next step, pre-machining is virtually planned and simulated to prepare the component surface for material deposition by removing the damaged volume while considering the surface preconditions for cold spray. This is followed by the planning and simulation of the material deposition for effective and material-efficient filling of the machined cavity. This includes automated planning of the robot trajectories, starting with initial trajectory planning, followed by trajectory optimization using mathematical optimization and a material deposition model to account for the various requirements and to ensure an optimal repair process. Once the simulations of pre-machining and material deposition have been completed, the control codes are transferred to the real robot control in the laboratory. Finally, the concept enables sensor-based inspection of the material deposit, allowing the deposit height to be compared with the simulation result as quality proof. The full workflow of this concept has been successfully applied by simulation and laboratory experiments. The results prove the utility of this concept and demonstrate the successful automation of a repair process by robot-guided cold spray.
PubDate: 2025-03-17
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- Study on the Sealing Treatment and Dielectric Properties of Al2O3
Insulating Coatings-
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Abstract: The sealing treatment of plasma-sprayed Al2O3 insulating coatings and its effect on the microstructure and dielectric properties were systematically investigated. To compare the penetration depth of sealants, various sealing processes were employed, utilizing two types of sealants and under two different ambient pressures. The microstructure of coatings was analyzed using scanning electron microscopy, energy dispersive spectrometer, and isothermal adsorption/desorption tests. Breakdown strength, resistivity, dielectric constant ($${\varepsilon }_{r}$$), loss tangent ($$\text{tan}\delta$$), and complex impedance were measured for both unsealed and sealed coatings. The results indicated that the maximum penetration depth percentage (50.8%) was achieved with the diluted sealant under low ambient pressure (20 Pa). A penetration model, that includes the ambient pressures, pore diameters, and physical properties of the sealant, was proposed and validated. The sealing treatment nearly doubled the breakdown strengths of coatings under DC, 50 Hz, and 500 Hz voltages and increased resistivity by nearly 100 times in environments with varying relative humidity (RH) levels. Additionally, the sealing treatment decreased the $${\varepsilon }_{r}$$ and $$\text{tan}\delta$$ of coatings in a 20% RH environment and increased their impedance in both 20% RH and 80% RH environments. This study provides a theoretical basis for the design and application of sealing treatments.
PubDate: 2025-03-13
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- Microstructural, Mechanical, and Tribological Evaluation of HVAF-Sprayed
Inconel 718 Coatings-
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Abstract: This study evaluates the mechanical and wear properties of IN718 coating on IN625 substrates deposited using the HVAF-spraying technique. The deposited coating was characterized by SEM, EDS, EBSD, Raman, nanoindentation, and microhardness. The integrity and adhesion of the coating were assessed using scratch tests aided by acoustic emission spectroscopy. The tribological evaluation was performed using a dry sliding wear test with a ball-on-coated disc configuration using alumina as the counterface. The coating microstructure comprises mostly unmelted particles with a small fraction of melted, with a porosity level
PubDate: 2025-03-11
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- Oxidation and Hot Corrosion Behaviour of Dual Phase 8YSZ + La2Zr2O7
and 8YSZ + Gd2Zr2O7 TBC Systems-
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Abstract: The article presents research results on thermal barrier coatings based on dual-phase systems of the type 8YSZ + Ln2Zr2O7. Previous studies have shown that composite materials of this type are characterized by an increased tolerance to deformation and a significantly lower thermal conductivity coefficient value than single-phase coatings. Therefore, two-phase composite coatings are expected to demonstrate the ability to operate for a more extended time without compromising their integrity and without ceramic layer spallation. The scope of the presented analysis included assessing the phase constituent stability under oxidation conditions at 1100 °C for 2000 hours and hot corrosion in Na2SO4 at 950 °C for 300 hours. The XRD analyses showed that in the 8YSZ + La2Zr2O7 system, there is no significant interaction between components of the TBC under analyzed conditions. In the case of the system containing Gd2Zr2O7, an intensive tendency to mutual interactions was demonstrated, expressed by the formation of non-stoichiometric GdxZr1−xO2−x/2 with a fluorite-type lattice. The intensity of this process was much higher with the assistance of Na2SO4. The XRD test results were confirmed by SEM/EDS analyses, which showed the presence of areas significantly different in chemical composition and morphology in the case of the 8YSZ + Gd2Zr2O7 coatings and relatively small morphological changes in the case of the 8YSZ + La2Zr2O7 system. These analyses were verified during tests on model powder mixtures. The model tests covered the temperature range from 800 to 1400 °C (24 h at each temperature). The research conducted confirmed the previously obtained results. The research suggests that two-phase coatings 8YSZ + Ln2Zr2O7 may be a very effective solution for applications in gas turbines. Despite intense phase changes, they showed high durability (at least 2000 hours), practically without the effects of the ceramic layer’s disintegration. However, the desirable or undesirable nature of the observed phenomena (order-disorder transition, formation of chromites) requires further analysis.
PubDate: 2025-03-10
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- Special Issue Featuring Papers from the International Thermal Spray
Conference (ITSC) 2024-
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PubDate: 2025-03-10
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- Corrosion Behavior of Thermal Sprayed ZrO2·38Y2O3 and
ZrO2·18TiO2·10Y2O3 Ceramic Coatings with Different Metallic Bonding
Layers in Acid Solution-
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Abstract: To protect 304L stainless steel from acid corrosion, ZrO2·38Y2O3 and ZrO2·18TiO2·10Y2O3 ceramic coatings were prepared by atmospheric plasma spraying (APS). CoMoCrSi and CoNiCrAlY were applied as bonding layers between substrates and ceramic coatings using high-velocity oxy-fuel spraying and APS, respectively. By exploring the phase composition, microstructure, and element contents of coatings, combined with corrosion behavior and hardness, it was found that though CoMoCrSi coating had denser microstructure, CoNiCrAlY bonding layer exhibited higher corrosion resistance. Direct contact between the bonding layers and the corrosive medium should be avoided. Compared with HNO3 solution, H3PO4 solution had a stronger influence on the microstructure and hardness. Low corrosion degree of the two ceramic coatings was observed in hydrothermal acid solution. From the perspective of preventing media penetration, ZrO2·18TiO2·10Y2O3 coating was superior due to the denser microstructure, whereas the own reactivity of ZrO2·38Y2O3 was lower than that of ZrO2·18TiO2·10Y2O3 coatings in hydrothermal acid solution. After weighing advantages and disadvantages, plasma-sprayed coating with CoNiCrAlY bonding layer and ZrO2·38Y2O3 ceramic coating was considered as a promising material for anti-corrosion applications. Spraying parameter optimization and sealant may further improve its performance. This work can provide insights for further protecting 304L components in acid environments.
PubDate: 2025-03-06
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- Cold Spray Additive Manufacturing: A Review of Shape Control Challenges
and Solutions-
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Abstract: Cold spray (CS) is a promising solid-state deposition method that offers several advantages over traditional thermal spray techniques. With rapid deposition, minimal thermal degradation and distortion, and unique flexibility in material selection and part size, it is an attractive option for additive manufacturing. Despite the latest steep technological advancements, a significant hindrance to the wide application of CS in this field is shape accuracy. The Gaussian-like deposit profiles characteristic of CS limit its resolution, causing waviness along the deposit, tapering, and edge losses, making shape control a difficult task. Deposit shape modeling can play a major role in addressing this challenge and counterbalancing the restrictive resolution issues by predicting the deposit shape, as a function of kinetic process parameters. Macroscale deposition modeling can furthermore boost automated process planning for high geometrical control. This paper depicts the current scenario and ongoing attempts to characterize and predict CS deposit shape. It categorizes CS shape prediction models into Gaussian-fit, physics-based, and data-driven. Through the critical evaluation of such models, research gaps and potential areas of improvement are identified, particularly in simultaneously achieving high prediction accuracy and computational efficiency, rather than framing them as competing objectives. Alternative recently developed strategies for geometrical control are furthermore explored, including advanced trajectory planning techniques, tailored to CS.
PubDate: 2025-03-06
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- Microstructure, Mechanical, and Dry Sliding Wear Performance of Equimolar
CoCrNiTiMo and CoCrNiTiW High-Entropy Alloy Coatings-
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Abstract: In the present investigation, mechanical alloyed CoCrNiTiMo and CoCrNiTiW equimolar HEA powders were employed as feedstock in the development of dense coatings using high-velocity oxy-fuel technique. The dry sliding wear behavior of uncoated substrate and high-entropy alloy (HEA) coatings were extensively investigated at different temperatures and loads using a pin-on-disk tribometer. The microstructures and phases of the mechanical alloyed powders, deposited coatings, and worn surfaces were thoroughly studied. The mechanical alloyed CoCrNiTiMo and CoCrNiTiW HEAs demonstrated the evolution of two BCC solid solutions. However, the deposited coatings reported the formation of additional phases, including Co3Ti intermetallic and NiTiO3 spinel. The microstructural analysis of CoCrNiTiMo and CoCrNiTiW coatings unveiled a compact lamellar structure characterized by robust mechanical interlocking to the substrate. The CoCrNiTiMo and CoCrNiTiW HEA coatings displayed porosities of 1.12 ± 0.05% and 1.39 ± 0.03%, respectively. Additionally, the microhardness assessments revealed superior values for CoCrNiTiMo and CoCrNiTiW HEA coatings, measuring at 927 ± 45 HV0.3 and 951 ± 38 HV0.3, correspondingly. The wear rate of CoCrNiTiMo HEA coating dropped by 70.5%, from 17.34 ± 2.8 × 10−6 mm3/N-m to 5.1 ± 1.6 × 10−6 mm3/N-m with an increment in the wear testing temperature from ambient to 600 °C. Concurrently, the CoCrNiTiW coating experienced a 76.3% drop in the wear rates from 15.8 ± 3.7 × 10−6 mm3/N-m to 3.73 ± 2.1 × 10−6 mm3/N-m. The significant fall in the wear rates at higher temperatures was accredited to the development of oxide tribofilms. CoCrNiTiMo exhibited discernible oxide phases, including CoMoO4, TiO2, and NiO. In contrast, its counterpart, CoCrNiTiW, generated WO3, CoWO4, and TiO2 oxides at a temperature of 600 °C. The adhesive wear at RT transitioned to predominant oxidative wear with slight fatigue and abrasive wear at high temperatures.
PubDate: 2025-03-06
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- Study on the Residual Stress in Film-Cooled Turbine Blade-Thermal Barrier
Coating System with 3D Finite Element Model-
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Abstract: In this study, a three-dimensional finite element model was developed with an air-film cooled turbine blade as a substrate on which a thermal barrier coating (TBC) was sprayed, considering the interface morphology of the TBC system. By means of a simulation study method, the residual stresses at the interface of the TBC are calculated when the temperature of the TBC decreases linearly from 1000 to 25 °C, the influence of air-film cooling holes geometry parameters on residual stress in TBC system was studied. In the study, it was found that the shape and positional characteristics of the air-film cooling holes, such as the position of the cooling hole, radius, ratio between upper and lower radii of a cooling hole, and space angle, have certain effect on the residual stress. When the air-film cooling holes are located at the lowest part of the TBC interface, there is minimal residual stress, while at the junction of the bond coat and the thermally grown oxide, there is a more severe stress concentration, which should be paid special attention to. The radius of air-film cooling holes not only affects the value of the residual stress but also affects the range of its extreme value, and the small radius of cooling hole can reduce the residual stress to a large extent. The proper ratio between upper and lower radii and space angle can reduce the residual stress to a certain extent. This can provide a preliminary optimization design scheme for air-film cooling blade and hole drilling.
PubDate: 2025-03-06
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