Gradient Coatings Research Articles

Preparation of FeCoCrNiAl-X% Cr3C2 Gradient Coating by Laser Powder Bed Fusion: Research on Microstructure and Tribological Properties, Molecular Dynamics Simulation of Nanoindentation Behavior

Preparation of FeCoCrNiAl-X% Cr3C2 Gradient Coating by Laser Powder Bed Fusion: Research on Microstructure and Tribological Properties, Molecular Dynamics Simulation of Nanoindentation Behavior

Electric Field Regulation of DC-GIS Spacer by Surface Conductivity Gradient Coatings Under Variable Temperature Gradients

Electric Field Regulation of DC-GIS Spacer by Surface Conductivity Gradient Coatings Under Variable Temperature Gradients

Effect of the structure of PyC on the mechanical properties and oxidation resistance of SiC/PyC gradient coatings

Effect of the structure of PyC on the mechanical properties and oxidation resistance of SiC/PyC gradient coatings

ASSESSMENT OF NI-CR-AL HIGH-TEMPERATURE DETONATION COATINGS UNDER OPERATIONAL CONDITIONS

This study evaluates the high-temperature durability and oxidation resistance of homogeneous and gradient Ni-Cr-Al detonation coatings applied to 12Kh1MF steel substrates. Samples were exposed to operational conditions in a power plant for two weeks, simulating high-temperature industrial environments. The research utilizes X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze phase stability, surface morphology, and structural integrity of the coatings before and after thermal exposure. Findings reveal that gradient coatings outperform homogeneous ones, demonstrating superior oxidation resistance and reduced susceptibility to thermal stress-induced microcracks. The multi-layered oxide structure and compositional gradient of the gradient coatings contribute to their enhanced thermal stability and long-term durability. In contrast, homogeneous coatings exhibited surface roughness and microcracks, which may compromise their longevity under extreme conditions. These insights emphasize the advantages of gradient Ni-Cr-Al coatings for high-temperature applications, highlighting their potential for improved performance and reliability in demanding industrial settings. The study bridges knowledge gaps regarding the long-term behavior of these coatings, aiding their optimization for critical applications. Keywords: High-temperature coating, power plant, Ni-Cr-Al coating, detonation technology, steel 12Kh1MF.

INVESTIGATION OF TRIBOLOGICAL PROPERTIES OF DETONATION Ni-Cr-Al COATINGS

This study explores the tribological properties of Ni-Cr-Al coatings applied through detonation spraying technology, with a focus on the comparison between gradient coatings and homogeneous coatings. Ni-Cr-Al coatings, widely used in aerospace, automotive, and energy industries like power plants, are valued for their exceptional hardness, wear resistance, and high-temperature stability. Gradient coatings, produced by tailoring the detonation spraying parameters, exhibit a microstructure combining a hard, wear-resistant surface with a softer, ductile subsurface, enhancing their load-bearing capacity and tribological performance. Experimental results reveal that gradient coatings achieve lower and more stable friction coefficients (0.3-0.4) compared to homogeneous coatings (0,4-0,5), attributed to their optimized stress distribution and reduced adhesive interactions. These findings underscore the superior wear resistance and durability of gradient Ni-Cr-Al coatings, making them highly suitable for applications involving prolonged operation under sliding conditions. This research contributes to the development of advanced coating systems optimized for demanding operational environments.

DURABILITY AND CORROSION BEHAVIOR OF Ni-Cr-Al DETONATION COATINGS UNDER Na2SO4/NaCl EXPOSURE

This study investigates the durability and corrosion resistance of Ni-Cr-Al detonation-sprayed coatings when exposed to high-temperature environments containing molten Na₂SO₄ and NaCl. Such conditions are highly corrosive and frequently encountered in aerospace, energy, and chemical industries. Gradient and homogeneous Ni-Cr-Al coatings were compared to understand their behavior under aggressive exposure. The reveal of results those gradient coatings exhibit superior corrosion resistance due to their ability to retain protective oxides, such as Cr₂O₃, and mitigate stress-induced damage through compositional grading. In contrast, homogeneous coatings displayed significant degradation, including widespread corrosion, delamination, and the formation of sodium-based phases like NaNiO₂. XRD analysis confirmed the presence of oxidation and sulfidation products, with gradient coatings showing enhanced stability against phase transitions. These findings highlight the potential of gradient Ni-Cr-Al coatings to improve component performance in extreme conditions and provide valuable insights for optimizing coating compositions and processes to enhance operational reliability in harsh environments.

Study on the preparation and wear properties of laser cladded Incoel718/WC gradient composite coatings

Study on the preparation and wear properties of laser cladded Incoel718/WC gradient composite coatings

Optimized strategy for induction cladding of diamond/Ni-based wear-resistant coatings

Optimized strategy for induction cladding of diamond/Ni-based wear-resistant coatings

Effect of Si on Wear and Corrosion Resistance of Al0.5MnFeNiCu0.5Six/Al-Ni Gradient Coating by Laser Cladding

Effect of Si on Wear and Corrosion Resistance of Al0.5MnFeNiCu0.5Six/Al-Ni Gradient Coating by Laser Cladding

Structural characteristics and evolution in the crack propagation process of NiCrAlY/YSZ gradient coatings through thermal shock at 900 °C

In this study, four different thicknesses of NiCrAlY/8YSZ gradient coatings were fabricated using atmospheric plasma spraying (APS) technology. The failure behavior and lifetime of coatings were subsequently compared and analyzed through thermal shock experiments. The results revealed a pronounced correlation between the initiation and propagation of internal cracks within the gradient coatings and the thickness of the gradient region at a thermal shock temperature of 900°C. Both horizontal and vertical cracks were observed to propagate and interconnect, with horizontal crack propagation being the primary cause of coating failure. Notably, samples featuring a gradient region thickness of 150μm exhibited superior thermal shock resistance, suggesting promising prospects for enhanced coating durability.

Investigation of Structural Phase, Mechanical, and Tribological Characteristics of Layer Gradient Heat-Protective Coatings Obtained by the Detonation Spraying Method.

This paper presents the results of a study of layer gradient thermal protection coatings based on NiCrAlY and YSZ obtained by detonation spraying. Modern gas turbines and high-temperature units operate under extreme temperatures and aggressive environments, which requires effective protection of components from wear, corrosion, and thermal shocks. In this study, the use of layer gradient coatings consisting of alternating layers of NiCrAlY and YSZ was investigated with the aim of solving the problem of thermal stress accumulation due to a smooth change in the composition of the layers. Microstructural and phase analysis showed that alternating layers of NiCrAlY and YSZ formed a dense layer gradient structure with clear interphase boundaries and low porosity. Detonation spraying led to a complete transformation of the monoclinic ZrO2 phase into a tetragonal one, which significantly increased the mechanical strength of the coating and its resistance to thermal shocks. Sample 1D1 demonstrated excellent tribological and corrosion properties in a 3.5% NaCl solution, which can be explained by its higher density and reduced number of pores. Mechanical tests revealed stable values of hardness and wear resistance of the coating, especially for the 1D1 coating. Studies have shown that coatings are resistant to thermal shocks, but thicker layers show a tendency to peel off after thermal cycling. The obtained results indicate high prospects for the use of layer gradient coatings based on NiCrAlY and YSZ for the protection of gas turbine components and other high-temperature installations operating under extreme loads and aggressive environments.

Enhanced high temperature mechanical and oxidation behavior of direct energy deposited TiC/Inconel 718 gradient coatings

Enhanced high temperature mechanical and oxidation behavior of direct energy deposited TiC/Inconel 718 gradient coatings

Polyelectrolyte Complex Coated Cotton Fabrics with Hydrophobicity, Antibacterial Activity, and Flame Retardancy

AbstractCotton fabrics with the main constituent of cellulose, which is hydrophilic, bacterial infected, and flammable, are in urgent need of functionalization as a kind of widely applied material. To address these issues, in this work, modified polyelectrolyte complex (MPEC) coatings with polyethylenimine (PEI), polyphosphate (APP), and perfluorodecyltrichlorosilane modified PEI (PFTS‐PEI) are prepared to construct multi‐functionally gradient MPEC coatings on cotton fabrics. Stability and synergistic effects on hydrophobicity, antibacterial activity, and flame retardancy in this system have been studied. Notably, PFTS‐PEI with fluorine and silicone elements are confirmed to provide hydrophobicity and durability for MPEC coatings, which not only has no negative effect on other functions but also makes some improvement in antibacterial activity. This MPEC‐treated cotton fabric finally has an antibacterial rate against S. aureus and E. coli of 99.9% and 96.9%, limiting oxygen index of 28.5% and water contact angle of 118°, which can be almost maintained after 20 times washing. The modified PEC will provide an efficient strategy to achieve durable multi‐functions on cellulose‐based fabrics.

Design, fabrication, and hydrogen blocking performance of alumina/zirconia functional gradient coatings

Design, fabrication, and hydrogen blocking performance of alumina/zirconia functional gradient coatings

High-throughput preparation and quick characterization of oxidation behaviors of complex Al–Cr compositional gradient coatings on a novel Co–Al–W–based superalloy prepared using multi-arc ion plating technology

High-throughput preparation and quick characterization of oxidation behaviors of complex Al–Cr compositional gradient coatings on a novel Co–Al–W–based superalloy prepared using multi-arc ion plating technology

Effect of Thermal Exposure Temperature and Time on Friction and Wear Properties of TiAlSiN Gradient Coatings

Effect of Thermal Exposure Temperature and Time on Friction and Wear Properties of TiAlSiN Gradient Coatings

Effect of arc deposition process on mechanical properties and microstructure of TiAlSiN gradient coatings

Effect of arc deposition process on mechanical properties and microstructure of TiAlSiN gradient coatings

Development of Method for Applying Multilayer Gradient Thermal Protective Coatings Using Detonation Spraying

In this work, multilayer gradient coatings obtained by detonation spraying were studied. To obtain a multilayer gradient coating by detonation spraying, two modes with different numbers of shots of NiCrAlY and YSZ were developed. The presented results demonstrate the effectiveness of creating a gradient structure in coatings, ensuring a smooth transition from metal to ceramic materials. Morphological analysis of the coatings confirmed a layered gradient structure, consisting of a lower metallic (NiCrAlY) layer and an upper ceramic (YSZ) layer. The variation in the contents of elements along the thickness of the coatings indicates the formation of a gradient structure. X-ray analysis shows that all peaks in the X-ray diffraction patterns correspond to a single ZrO2 phase, indicating the formation of a non-transformable tetragonal primary (t′) phase characteristic of the thermal protective coatings. This phase is known for its stability and resistance to phase transformation under changing operating temperature conditions. As the thickness of the coatings increased, an improvement in their mechanical characteristics was found, such as a decrease in the coefficient of friction, an increase in hardness, and an increase in surface roughness. These properties make such coatings more resistant to mechanical wear, especially under sliding conditions, which confirms their prospects for use in a variety of engineering applications, including aerospace and power generation.

Construction of a Composite Sn‐DLC Artificial Protective Layer with Hierarchical Interfacial Coupling Based on Gradient Coating Technology Toward Robust Anodes for Zn Metal Batteries

AbstractDeveloping a robust zinc (Zn) anode, free from Zn dendrites and unwanted side reactions, relies on designing a durable and efficient interfacial protection layer. In this study, gradient coating technology is employed to construct a hierarchically structured composite of Sn with diamond‐like carbon (DLC/Sn‐DLC) as an artificial protective layer. The DLC framework endows DLC/Sn‐DLC layer with high stability and adaptability, achieving long‐term stability of the anode–electrolyte interface. The gradual‐composite Sn, with its Sn─O─C interface chemical bonds, facilitates rapid charge transfer and offers ample zincophilic sites at the base, promoting uniform Zn2+ reduction reaction and deposition. Additionally, the DLC/Sn‐DLC composite exhibits a “lotus effect” and favorable hydrophobic properties, preventing water‐reduced side reactions. Leveraging this structural design and the synergistic cooperation of DLC and Sn, the DLC/Sn‐DLC@Zn electrode demonstrates remarkable Zn plating/stripping reversibility, eliminating Zn dendrites and side reactions. Notably, under a high current density of 10 mA cm−2, the DLC/Sn‐DLC@Zn anode‐based symmetrical cell exhibits stable operation for over 1550 h, with a low nucleation overpotential of 101 mV. The DLC/Sn‐DLC@Zn||Mn3O4‐CNTs full battery delivers a high capacity of 109.8 mAh cm−2 after 5800 cycles at 2 A g−1, and the pouch cell shows potential for energy storage applications.

In-situ preparation and ablative resistance of multicomponent refractory carbide ceramic gradient coatings

In-situ preparation and ablative resistance of multicomponent refractory carbide ceramic gradient coatings