Ni2Al3 nano-composite coating containing CeO2 dispersed nano-particles and preparation method of Ni2Al3 nano-composite coating
By introducing CeO2 nanoparticles into the Ni2Al3 coating, the formation of α-Al2O3 is promoted, which solves the problems of oxide film peeling and interface voids in nickel aluminum oxide coatings at high temperatures, improves the coating's oxidation resistance and structural stability, and extends its service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-03-31
AI Technical Summary
Existing nickel-aluminate coatings suffer from oxide film peeling, interfacial voids, and slow crystal transformation rates in high-temperature corrosive environments, leading to coating performance degradation and affecting service life.
Introducing CeO2 nanoparticles into the Ni2Al3 coating promotes the formation of α-Al2O3, enhances the adhesion and interfacial bonding of the oxide film, controls aluminum diffusion, and inhibits the formation of Kirkendall voids.
It significantly improves the antioxidant properties of the coating, enhances the adhesion and interfacial bonding of the oxide film, improves the structural integrity of the coating, and extends its service life under high temperature environments.
Smart Images
Figure CN121760033A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of coating preparation technology, specifically relating to a Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles and its preparation method. Background Technology
[0002] In high-temperature, corrosive environments (such as the service environment of gas turbine components), the oxidation resistance of materials is a key factor determining their service life. Nickel-aluminate coatings, due to their excellent high-temperature oxidation resistance, have become one of the core protective coatings for such environments. Among them, NiAl phase and Ni2Al3 phase coatings are particularly widely used. Their core protective mechanism originates from the thermally grown alumina (TGO, i.e., Al2O3) layer formed on the surface. This oxide layer can act as a dense physical barrier, effectively blocking the contact between the substrate and the external oxidizing medium, thereby achieving long-term protection.
[0003] Alumina exists in various polymorphs, including γ-, θ-, and α-, among which α-Al₂O₃ is the most thermodynamically stable phase. It possesses a hexagonal close-packed (hcp) crystal structure and exhibits the lowest growth rate during high-temperature oxidation, making it a key phase for ensuring the long-term protective performance of nickel-aluminum oxide coatings. Therefore, the rapid formation and stable existence of the α-Al₂O₃ phase directly determine the oxidation resistance and durability of the coating.
[0004] However, existing nickel-aluminate (NiA) coatings still face significant performance degradation during actual high-temperature service, with their durability severely weakened. This is mainly manifested in two aspects: Firstly, the unequal diffusion rates of aluminum and nickel within the coating during oxidation lead to vacancy accumulation and aggregation at the TGO / coating interface, forming interfacial voids. Simultaneously, sulfur tends to segregate at the alumina / coating interface, significantly weakening the interfacial bonding force. The combined effect of these two factors causes oxide film peeling. Secondly, the crystal transformation rate (γ-→θ-→α-) of Al2O3 is crucial to coating performance: if the transformation from θ-Al2O3 to α-Al2O3 is slow, defects such as cracks, volume shrinkage, and microcracks / tears will appear in the oxide film after high-temperature oxidation, further exacerbating coating degradation.
[0005] To address the aforementioned issues, existing technologies have discovered that a small number of reactive elements (REs, such as Ce, Y, Hf, and La) or their oxides (CeO2, Y2O3, HfO2, and La2O3) can significantly improve the adhesion and anti-scraping properties of oxide films through the "reactive element effect" (REE). The core mechanisms include: suppressing sulfur segregation at the interface to enhance interfacial bonding, reducing void formation at the TGO / coating interface, and promoting the formation of a fine-grained oxide layer to alleviate stress and deformation, thereby inhibiting oxide film cracking and peeling. Furthermore, different reactive elements and their oxides exhibit significantly different effects on the phase transformation kinetics of Al2O3. For example, CeO2 can promote the transformation from θ-Al2O3 to α-Al2O3, while Y2O3 tends to delay or inhibit this transformation.
[0006] Based on the current state of the technology, in order to further optimize the high-temperature oxidation resistance of Ni2Al3 coating, this application aims to introduce CeO2 nanoparticles into Ni2Al3 coating through specific technical means. Although CeO2 itself does not have a hexagonal close-packed structure, it can serve as an active nucleation site for the α-Al2O3 phase, accelerating the phase transformation process from θ-Al2O3 to α-Al2O3. This fundamentally improves the degradation problems such as oxide film cracking and interface voids, and enhances the high-temperature protection performance of the coating. This technical concept constitutes the core research and development basis of this application. Summary of the Invention
[0007] This invention proposes a novel method for preparing Ni2Al3 nanocomposite coatings with or without CeO2 dispersed nanoparticles. This method aims to improve oxidation resistance by accelerating the formation of the stable α-Al2O3 phase, thus making it suitable for high-temperature environments. Furthermore, the introduction of CeO2 nanoparticles effectively controls aluminum diffusion, inhibits the formation of Kirkendall voids, and enhances the interfacial bonding between the alumina layer and the aluminide coating, thereby improving the structural integrity of the coating and making it highly suitable for high-temperature industrial applications.
[0008] To achieve the above technical objectives, the present invention adopts the following technical solution: A method for preparing a Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles includes the following steps: (1) The nickel plate was cut into samples.
[0009] (2) The sample was mechanically polished step by step with SiC sandpaper and then ultrasonically cleaned in deionized water, ethanol and acetone in sequence.
[0010] (3) Ni-CeO2 nanocomposite layer was prepared on nickel substrate by electrodeposition.
[0011] (4) The surface morphology and elemental composition of the obtained Ni-CeO2 nanocomposite layer were characterized by scanning electron microscopy and energy dispersive spectroscopy. The CeO2 content was quantitatively analyzed by INCA software.
[0012] (5) The particle size of the CeO2 nanoparticles used was confirmed by transmission electron microscopy.
[0013] (6) Ni-CeO2 nanocomposite film was treated by low-temperature embedding aluminizing process to obtain Ni2Al3–CeO2 composite coating.
[0014] Preferably, the nickel plate in step (1) has a purity >99.99%.
[0015] Preferably, the sample in step (1) is 15mm×10mm×2mm.
[0016] Preferably, the electrolyte composition in step (3) is 150 g / L NiSO4·6H2O, 12 g / L NaCl, 120 g / L C6H5Na3O7·2H2O and 35 g / L H3BO3.
[0017] Preferably, the CeO2 nanoparticles in step (5) have a particle size of 3.5–16.5 nm.
[0018] Preferably, the purity of the CeO2 nanoparticles is >99.9%.
[0019] Preferably, the aluminizing process in step (6) is carried out at 620°C for 5 hours in an argon atmosphere.
[0020] Preferably, the powder mixture used consists of micron-sized aluminum powder, 55 wt% Al2O3 and 5 wt% NH4Cl (activator).
[0021] Preferably, after aluminizing, the sample is washed in boiling water to remove loose particles on the surface, and then used for oxidation test.
[0022] Compared with the prior art, the present invention has the following technical advantages: 1. Enhanced antioxidant properties.
[0023] The present invention introduces CeO2 nanoparticles into the Ni2Al3 coating, which can promote the rapid transformation of metastable alumina (θ-Al2O3) to stable state (α-Al2O3), forming a dense and well-adhered protective oxide layer, thereby significantly improving the high-temperature oxidation resistance.
[0024] 2. Improved oxide film adhesion and anti-peeling properties.
[0025] The dispersed distribution of nanoparticles in this invention significantly enhances the adhesion of the oxide film / coating interface, thereby effectively inhibiting oxide film peeling. Simultaneously, this improvement mitigates the harmful effects of impurities during the oxidation process, ensuring the stability and durability of the protective layer.
[0026] 3. Refined microstructure and stress relief capabilities.
[0027] The presence of CeO2 promotes the formation of a fine-grained structure in the oxide film, giving it better strain adaptability under thermal stress and effectively preventing cracks or peeling during thermal cycling.
[0028] 4. Extend service life in harsh environments.
[0029] Due to the combined improvement in antioxidant properties, structural stability, and interfacial bonding, Ni2Al3 coatings exhibit higher durability and reliability in high-temperature industrial environments such as gas turbines and thermal reactors.
[0030] 5. The Ni–CeO2 nanocomposite material and diffused aluminide CeO2–Ni2Al3 coating proposed in this invention were successfully developed through a simple nickel electroplating process followed by a diffusion aluminization treatment at 620°C for 5 hours. These coatings exhibit excellent resistance to high-temperature oxidation and hot corrosion in harsh environments (such as marine, saline, and acidic conditions), marking a significant advancement in high-temperature protection technology.
[0031] 6. The coating method of this invention is applicable not only to pure nickel, but also to nickel-based superalloys, stainless steel, and other alloys such as Ni-Cr. It provides an economical, efficient, scalable, and effective solution for improving the durability of materials in high-temperature industrial applications. Attached Figure Description
[0032] Figure 1 : Figure 1 (a) is a TEM image of the purchased CeO2 nanoparticles. Figure 1 (b) is a SEM image of the surface morphology of a nickel film containing a CeO2 dispersed phase. Figure 1 (c) shows the SEM / EDS analysis results after electrodeposition.
[0033] Figure 2 : Figure 2 (a) SEM results of Ni2Al3 coating containing CeO2 dispersion phase; Figure 2 (b) and Figure 2 (c) The δ-Ni2Al3 phase / coating formed after aluminizing, as confirmed by XRD and SEM / EDS analysis.
[0034] Figure 3Surface morphology of Al2O3 thermally grown on Ni2Al3 coating containing CeO2 dispersion after different oxidation times at 900℃.
[0035] Figure 4 The surface morphology of Al2O3 thermally grown on a Ni2Al3 coating containing CeO2 nanoparticles, and the Ni, Al, O and Ce mapping of alumina formed on alumina containing CeO2 after oxidation at 900°C for 20 hours. Detailed Implementation
[0036] 1. Experimental Section 1.1. Materials Nickel samples measuring 15 mm × 10 mm × 2 mm were cut from a high-purity nickel plate with a purity greater than 99.99%. The samples were mechanically polished using SiC sandpaper, starting with grit 240 and gradually increasing to grit 800. They were then sequentially cleaned with deionized water, ethanol, and acetone to prepare the electrodeposition surface. The plating solution used consisted of the following chemicals: 150 g / L NiSO4·6H2O, 12 g / L NaCl, 120 g / L C6H5Na3O7·2H2O, and 35 g / L H3BO3. All chemicals were purchased from Sigma-Aldrich China.
[0037] 1.2. Preparation of Nanocomposite Materials and Ni2Al3 Coating High-purity nickel plates (>99.99%) were cut into 15mm × 10mm × 2mm samples. The samples were mechanically polished stepwise with SiC sandpaper (240#–800#) and then ultrasonically cleaned sequentially in deionized water, ethanol, and acetone. A Ni2Al3 coating containing a CeO2 dispersed phase was prepared using a two-step method. In the first step, a Ni-CeO2 nanocomposite layer was prepared by electrodeposition on a nickel substrate using an electrolyte composition of 150 g / L NiSO4·6H2O, 12 g / L NaCl, 120 g / L C6H5Na3O7·2H2O, and 35 g / L H3BO3. The surface morphology and elemental composition of the resulting coating were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), and the CeO2 content was quantitatively analyzed using INCA software. The CeO2 nanoparticles used (particle size 3.5–16.5 nm, purity >99.9%) were purchased from Shanghai McLean Pharmaceutical Co., Ltd., China, and their particle size was confirmed by transmission electron microscopy (TEM). In the second step, the Ni-CeO2 nanocomposite film was treated with a low-temperature embedding aluminizing process to obtain a Ni2Al3–CeO2 composite coating. The aluminizing process was carried out at 620°C for 5 hours in an argon atmosphere. The powder mixture used consisted of micron-sized aluminum powder, 55 wt% Al2O3, and 5 wt% NH4Cl (activator). After aluminizing, the samples were washed in boiling water to remove loose particles from the surface, and then used for oxidation experiments.
[0038] 1.3 Material Characterization The surface and cross-sectional morphology of the electrodeposited, aluminized, and oxidized samples were observed using a field emission scanning electron microscope (FE-SEM, Inspect F50, Holliboro) equipped with an energy-dispersive X-ray spectroscopy (EDS) system. The elemental composition of the coating before and after oxidation was determined by EDS analysis. The size of the CeO2 nanoparticles used was confirmed by transmission electron microscopy (TEM, JEM-2100F, JEOL, Japan). The phase composition of the Ni2Al3 coating was characterized by X-ray diffraction (XRD) using CuKα radiation at an operating voltage of 40 kV.
[0039] 2. Physical characterization 2.1 Transmission Electron Microscopy (TEM) The particle size of the purchased CeO2 nanoparticles was verified using transmission electron microscopy (TEM). Further analysis using NanoMeasurer software determined the average particle size to be approximately 7.5 nm. Figure 1 As shown.
[0040] 2.2 Scanning Electron Microscopy (SEM / EDS) Figure 1 (b) Figure 1(c) The surface microstructure of the electrodeposited nickel film containing CeO2 nanoparticles and the corresponding scanning electron microscopy (SEM) / energy dispersive spectroscopy (EDS) results are shown respectively. Figure 1 (b) shows the morphology of the Ni-CeO2 nanocomposite material, which has a dense and uniform surface with no visible cavities, cracks or pores. Figure 1 The EDS results in (c) confirm that the CeO2 nanoparticles have been successfully incorporated into the coating. After aluminum infiltration at 620°C for 5 hours, the surface morphology of the Ni2Al3 coating dispersed with cerium oxide (CeO2) is as follows: Figure 2 As shown in (a). To clearly observe the surface morphology of the δ-Ni2Al3 coating, the sample was polished and then etched using 10% (v / v) nitric acid (HNO3) + ethanol (C2H5OH). The etched surface shows that the aluminide coating consists of numerous grains, each with a size less than 1 micrometer, such as... Figure 2 As shown in (a). Furthermore, scanning electron microscopy (SEM) / energy dispersive spectroscopy (EDS) confirmed the formation of a δ-Ni₂Al₃ coating after low-temperature aluminizing at 620°C, as shown in [the image / image / image]. Figure 2 As shown in (b).
[0041] When the oxidation time increased from 5 hours to 20 hours, the surface morphology transformed into larger crystals and lamellar structures, such as Figure 3 As shown in (a) and 3(b), a low-lying area with white edges appeared, in which limited whisker-like and foliate growth was observed. Figure 3 (A) is marked with a light green circle. The magnified view shows the boundary details and confirms that these recessed areas correspond to the θ→α-Al₂O₃ transformation during oxidation. As indicated by the arrows, cracks form along the edges in these areas. The growth behavior of alumina changes significantly after the addition of CeO₂ nanoparticles to the Ni₂Al₃ coating, as shown... Figure 3 As shown in (c), with increasing CeO2 content, θ-Al2O3 whiskers become less prominent, and interfacial cavities decrease. After oxidation, CeO2 nanoparticles remain visible on the surface, as shown... Figure 3 (c) is indicated by the arrow.
[0042] 2.3. X-ray diffraction analysis Figure 2 (c) shows the X-ray diffraction (XRD) pattern, confirming the formation of the δ-Ni2Al3 phase after aluminizing at 620°C for 5 hours. The coating with dispersed CeO2 exhibits sharp diffraction peaks, indicating high crystallinity of the aluminide layer. No distinct peaks corresponding to CeO2 were detected, possibly due to its low concentration and possibly being below the XRD detection depth.
[0043] 2.4. Energy-dispersive spectroscopy (EDS) imaging Figure 4 (a) shows the cross-sectional morphology of the oxide layer formed on an aluminate coating dispersed with cerium oxide after oxidation at 900 °C for 20 hours. The oxide layer is dense, thin, and well-adhesive, with no visible pores or cavities at the oxide layer / coating interface. Corresponding energy dispersive spectroscopy (EDS) mapping results further confirm the uniform distribution and continuous formation of the oxidized alumina layer, such as... Figure 4 As shown.
Claims
1. A method for preparing a Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles, characterized in that, Includes the following steps: (1) The nickel plate was cut into samples; (2) The sample was mechanically polished step by step with SiC sandpaper and then ultrasonically cleaned in deionized water, ethanol and acetone in sequence. (3) Ni-CeO2 nanocomposite layer was prepared by electrodeposition on nickel substrate; (4) The surface morphology and elemental composition of the obtained Ni-CeO2 nanocomposite layer were characterized by scanning electron microscopy and energy dispersive spectroscopy, and the CeO2 content was quantitatively analyzed by INCA software. (5) The particle size of the CeO2 nanoparticles used was confirmed by transmission electron microscopy; (6) Ni-CeO2 nanocomposite film was treated by low-temperature embedding aluminizing process to obtain Ni2Al3–CeO2 composite coating.
2. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 1, characterized in that, The nickel plate mentioned in step (1) has a purity of >99.99%.
3. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 1, characterized in that, The sample mentioned in step (1) is 15mm×10mm×2mm.
4. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 1, characterized in that, In step (3), the electrolyte composition is 150 g / L NiSO4·6H2O, 12 g / L NaCl, 120 g / L C6H5Na3O7·2H2O and 35 g / L H3BO3.
5. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 1, characterized in that, The CeO2 nanoparticles in step (5) have a particle size of 3.5–16.5 nm.
6. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 5, characterized in that, The purity of the CeO2 nanoparticles is >99.9%.
7. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 1, characterized in that, In step (6), the aluminizing process is carried out at 620°C for 5 hours in an argon atmosphere.
8. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 7, characterized in that, The powder mixture used consists of micron-sized aluminum powder, 55 wt% Al2O3 and 5 wt% NH4Cl (activator).
9. The method for preparing the Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles according to claim 7, characterized in that, After aluminizing, the sample is washed in boiling water to remove loose particles from the surface, and then used for oxidation experiments.
10. A Ni2Al3 nanocomposite coating containing CeO2 dispersed nanoparticles prepared by the preparation method according to any one of claims 1-9.