Fe-Ni-based alloy coating with high hardness, high wear resistance and high impact toughness as well as preparation method and application of Fe-Ni-based alloy coating

Abstract

The invention discloses a Fe-Ni-based alloy coating with high hardness, high wear resistance and high impact toughness as well as a preparation method and application thereof, and belongs to the technical field of metal surface modification. The alloy coating comprises the following components in percentage by weight: multicomponent alloy elements such as Ni, Cr and the like, rare earth oxides of Y2O3 and La2O3, and the balance of Fe; the preparation method comprises the steps of matrix pretreatment, powder preparation, infrared preheating, laser cladding, multi-stage heat treatment and post-treatment. The coating is high in hardness, large in impact toughness and small in abrasion loss, the contradiction that a traditional coating is hard and brittle can be effectively solved, the coating can be suitable for being manufactured into an integral wear-resisting plate and can also be manufactured into prefabricated plate pieces in special shapes, and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of metal surface modification technology, specifically to an Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness, its preparation method and its application. Background Technology

[0002] Alloy structural steel possesses high strength and weldability, ensuring the structural strength of components and facilitating subsequent assembly and maintenance. However, it cannot be used as a wear-resistant material. In practical applications, working conditions are complex and diverse. Under low to medium impact loads or in scenarios dominated by abrasive wear, the surface work hardening of alloy structural steel is difficult to achieve fully, leading to a significant increase in wear rate and a service life of only 1 / 3 to 1 / 2 under high impact conditions. Furthermore, in applications requiring both wear and impact resistance, as well as high strength, high toughness, and weldability in the base material, single alloy structural steel cannot meet the demands. Therefore, surface coating technology becomes a key means to overcome performance bottlenecks.

[0003] Among them, Fe-Ni based alloy coatings have attracted much attention in the surface strengthening of alloy structural steel due to their moderate cost and excellent toughness. Their preparation and optimization have become current research hotspots, but existing technologies still have many bottlenecks:

[0004] 1. The challenge of synergistic hardness-toughness in coatings

[0005] Traditional Fe-Ni based coatings improve hardness by adding elements such as Cr and Mo to form hard phases, but this often leads to a decrease in toughness. For example, CN107815682B (Guangdong University of Technology, authorized in 2020) discloses a plasma cladding Fe-Ni based coating, in which the alloy powder contains 18-19% Ni and 8.5-9.5% Co. Although the toughness is improved through solution treatment and aging, strong carbide-forming elements such as Cr and W are not introduced, resulting in low coating hardness, which is difficult to meet the requirements of high wear conditions; moreover, the Co content is as high as 8.5-9.5%, which significantly increases the raw material cost.

[0006] 2. The conflict between substrate pretreatment cleaning effectiveness and environmental friendliness

[0007] The oxide layer and oil stains on the substrate surface are key factors affecting the metallurgical bonding between the coating and the substrate. Existing technologies often use organic solvents (such as acetone and ethanol) or highly corrosive cleaning agents (such as hydrochloric acid and sulfuric acid). For example, while ultrasonic cleaning of alloy structural steel substrates with acetone can remove oil stains, acetone is highly volatile, flammable, and explosive, and has no effect on removing the oxide layer, leading to reduced coating adhesion. Similarly, while cleaning with 5% hydrochloric acid can remove rust, it creates corrosion pits on the substrate surface, easily causing porosity during subsequent cladding and resulting in a high coating defect rate. Furthermore, traditional cleaning agents often contain phosphorus, heavy metals, or volatile organic compounds (VOCs), failing to meet national environmental protection standards and posing environmental challenges in industrial applications.

[0008] 3. Insufficient uniformity of alloy powder dispersion

[0009] Fe-Ni based alloy powders have complex compositions (containing multiple metal and ceramic phases) and large density variations (e.g., W has a density of 19.3 g / cm³). 3 Al density 2.7 g / cm³ 3 Agglomeration or stratification easily occurs during mixing. Commonly used dispersants in existing technologies, such as ethanol and polyvinyl alcohol (PVA), can only temporarily disperse the powder by reducing surface tension; agglomeration still occurs after ball milling. For example, Fe-Ni-W powder dispersed with ethanol exhibits an agglomeration rate of 15-20% after passing through a 300-mesh sieve, leading to uneven coating composition and large fluctuations in hardness during cladding. Furthermore, some dispersants (such as PVA) carbonize during high-temperature cladding, producing gases such as CO and CO2, resulting in an increase in coating porosity to 3-5%.

[0010] 4. Poor matching of cladding process parameters

[0011] Laser cladding, due to its concentrated energy and controllable heat input, has become a preferred method for preparing Fe-Ni based coatings. However, improper parameters can easily lead to defects. For example, using a laser power of 2000W and a scanning speed of 10mm / s results in excessive heat input, leading to coarse substrate grains (grain size reaching 50-80μm) and thermal cracks at the coating-substrate interface. Conversely, using a laser power of 1200W and a powder feeding speed of 25g / min results in insufficient power, causing incomplete powder melting and resulting in 10-15% unmelted particles in the coating, significantly reducing wear resistance. Furthermore, existing technologies have insufficient optimization of the "defocus amount"—an excessively negative defocus amount leads to excessively high spot energy density and surface ablation; while an excessively positive amount (+3 to +4mm) results in insufficient energy density and uneven cladding layer thickness.

[0012] 5. The heat treatment process is simple, and the internal stress is not completely eliminated.

[0013] Fe-Ni based coatings exhibit significant thermal stress after cladding, and alloying elements in the solid solution are not fully precipitated, necessitating microstructure optimization through heat treatment. Existing technologies often employ a two-step "solution-aging" process. For example, CN107815682B uses solution treatment at 815-830℃ and aging at 500-520℃, but lacks low-temperature tempering, resulting in high residual internal stress in the coating and a tendency for microcracks to initiate under impact loads.

[0014] 6. Insufficient application of rare earth elements results in limited microstructure refinement.

[0015] Rare earth elements (such as Y and La) can improve coating performance by purifying grain boundaries and refining grains, but their application in existing technologies is extremely limited. Patents such as CN107815682B and CN103614682A do not add rare earth oxides, and the coating grain size is mostly 20-30μm.

[0016] In summary, existing Fe-Ni based alloy coatings still have many shortcomings in terms of composition design, preparation process, and post-treatment, making it difficult to meet the synergistic requirements of "high hardness, high wear resistance, and high impact toughness" for alloy structural steel components under complex working conditions. Therefore, developing a Fe-Ni based alloy coating with optimized composition, reasonable process, and excellent performance, as well as its preparation method, has significant industrial value and application prospects. Summary of the Invention

[0017] To address the problems in existing technologies such as the difficulty in achieving synergistic "hardness-toughness" in Fe-Ni based alloy coatings, the environmental unfriendliness of cleaning solutions, uneven powder dispersion, mismatched cladding process parameters, incomplete elimination of internal stress during heat treatment, poor surface quality after post-treatment, and insufficient application of rare earth elements, this invention provides a Fe-Ni based alloy coating with high hardness, high wear resistance, and high impact toughness, its preparation method, and its application. Through multi-component synergistic design and green process optimization, the coating performance is comprehensively improved, meeting the usage requirements of alloy structural steel components under medium-to-high stress and impact-wear coupling conditions.

[0018] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0019] A Fe-Ni based alloy coating with high hardness, high wear resistance, and high impact toughness, comprising, by weight percentage: Ni 15-25%, Cr 8-12%, Mo 2-4%, W 1-3%, V 0.5-1.5%, Nb 0.5-2%, Ti 0.5-2%, Al 0.3-1%, Si 0.5-1.5%, Mn 0.5-1.5%, C 0.3-0.8%, B 0.05-0.2%, N 0.01-0.05%, Cu 0.5-2%, Co 1-3%, Zr 0.1-0.5%, Hf 0.05-0.3%, Ta 0.1-0.5%, Re 0.01-0.1%, Y₂O₃ 0.05-0.3%, La₂O₃ 0.05-0.2%, P≤0.005%, S≤0.005%, balance Fe.

[0020] This invention also provides a method for preparing a Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness, comprising the following steps:

[0021] S1: Substrate pretreatment; Sand the oxide layer on the substrate surface with sandpaper, ultrasonically clean with cleaning solution for 10-20 minutes to remove oil stains, and dry at 80-100℃. The substrate material can be 20CrMo or 40CrMo plate. The plate thickness is determined according to the working conditions. When used as a whole, the thickness is more than 50mm. When used as a precast panel, the thickness is 20-40mm.

[0022] S2: Powder preparation and pretreatment; Weigh each raw material according to weight percentage, add it to a planetary ball mill, use a dispersant, mix for 1-1.5 hours at a ball-to-material ratio of 8:1-12:1 and a rotation speed of 150-180 r / min, pass through a 180-300 mesh sieve, place it in a vacuum drying oven, and keep it at a vacuum degree ≤-0.09MPa and a temperature of 80-105℃ for 2-3 hours;

[0023] S3: Preheating; Preheat the pretreated substrate to 200-300℃ using an infrared heating lamp and hold for 20-40 minutes.

[0024] S4: Laser cladding; The substrate and powder are loaded into a fiber laser cladding device, with argon as the protective gas. Process parameters: laser power 1600-1800W, scanning speed 15-20mm / s, powder feeding speed 15-20g / min, spot diameter 3-5mm, protective gas flow rate 8-12L / min, defocusing amount +1-+2mm, forming a primary coating with a width of 8-10mm.

[0025] S5: Multi-stage heat treatment;

[0026] S6: Post-treatment; The oxide scale on the surface of the initial coating is polished with 400-600 grit sandpaper, and then laser remelting is performed at a power of 800-1000W and a scanning speed of 20-30mm / s to improve the surface smoothness. Then, the surface is ultrasonically cleaned with alcohol for 5-10 minutes and dried to obtain an Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness.

[0027] Preferably, the cleaning solution comprises, per liter, 5-10g of citric acid, 3-7g of sodium gluconate, 2-5g of phytic acid, 1-3g of alkyl glycoside, 0.5-2g of limonene, 0.5-1.5g of licorice extract, with the remainder being deionized water.

[0028] Preferably, the method for preparing the cleaning solution includes the following steps:

[0029] (1) Heat the deionized water to 40-50℃;

[0030] (2) Add citric acid and sodium gluconate, and stir for 15-20 minutes until completely dissolved;

[0031] (3) Cool down to 30-35℃, add phytic acid, alkyl glycoside, limonene and licorice extract, stir for 20-30 minutes, and cool to room temperature to obtain the final product.

[0032] Preferably, the dispersant comprises, by weight percentage: 10-20% polyethylene glycol 400, 5-10% glycerin, 3-7% lecithin, 2-5% gum arabic, 5-10% starch, 2-5% alkyl polysaccharide glycoside, 0.5-1% tea saponin, 1-2% hyperbranched polymer HBP-160, and the remainder being deionized water.

[0033] Preferably, the method for preparing the dispersant includes the following steps:

[0034] (1) Heat the deionized water to 60-70℃;

[0035] (2) Add polyethylene glycol 400 and glycerin, and stir for 15-17 minutes until completely dissolved;

[0036] (3) Cool down to 45-50℃, add lecithin and gum arabic, and stir for 18-22 minutes;

[0037] (4) Continue to cool down to 35-40℃, add starch and alkyl polysaccharide, and stir for 29-32 minutes;

[0038] (5) Cool down to room temperature, add tea saponin and hyperbranched polymer HBP-160, and stir for 25-30 minutes to obtain the product.

[0039] Preferably, in step S4, the laser power is 1650-1750W, the scanning speed is 17-19mm / s, the powder feeding speed is 17-19g / min, and the protective gas flow rate is 9-11L / min.

[0040] Preferably, in step S5, (1) when 20CrMo plate is selected as the base material, the heat treatment is as follows:

[0041] ①Solution treatment: Heat the high-temperature carbon tube furnace to 860-880℃, hold for 1-1.5 hours, and then cool to room temperature with water or oil;

[0042] ②Aging: The contents of the muffle furnace are brought into the furnace at the specified temperature and held at 530-550℃ for 4-5 hours, followed by oil cooling or air cooling.

[0043] ③ Low-temperature tempering: Heat the muffle furnace to 150-200℃, hold for 1-1.5 hours, and then air cool;

[0044] (2) When 40CrMo plate is selected as the base material, the heat treatment is as follows:

[0045] ①Solution treatment: Heat the high-temperature carbon tube furnace to 840-880℃, hold for 1-1.6 hours, and then cool to room temperature with water or oil;

[0046] ②Aging: The contents of the muffle furnace are brought into the furnace at the specified temperature and held at 530-550℃ for 4-5 hours, followed by oil cooling or air cooling.

[0047] ③ Low-temperature tempering: Heat the muffle furnace to 200-500℃, hold for 0.5-1h, and then air cool;

[0048] 40CrMo steel, as a medium-carbon alloy structural steel, can have its mechanical properties significantly improved through heat treatment. After solution treatment, the cooling rate is controlled using media such as oil / water to prevent cracking. The tempering temperature is selected according to requirements: 200-300℃ maintains high hardness, while 400-500℃ improves toughness.

[0049] Preferably, in step S6, the laser remelting power is 850-950W and the scanning speed is 23-27mm / s; the alcohol ultrasonic cleaning time is 7-9min.

[0050] This invention also provides an application of an Fe-Ni based alloy coating with high hardness, high wear resistance, and high impact toughness. This coating can be used to fabricate integral wear-resistant plates or prefabricated plates of custom shapes. It can be welded to various scouring and abrasion chute liners, localized parts of irregularly shaped wear- and corrosion-resistant components, and wear-resistant reinforcing ribs on the sides of loader and excavator buckets. After the wear-resistant plate wears down without affecting the main component, it can be repeatedly welded after surface polishing, extending the service life of the main component.

[0051] Compared with the prior art, the present invention has the following technical advantages:

[0052] 1. Breaking through the bottleneck of "hardness-toughness" synergy, overall performance is improved.

[0053] In existing technologies, the Fe-Ni based coating of CN107815682B has low hardness. However, this invention, through a multi-component synergistic design (Ni 15-25% ensures toughness, Cr, Mo, W, etc. form a hard phase to enhance hardness, Y2O3 and La2O3 refine grain size), achieves a 31.5%-41.9% increase in coating hardness and a 31.4%-56.9% increase in impact toughness compared to CN107815682B. Performance tests show that the coating of this invention achieves synergistic optimization among hardness, toughness, and wear resistance, resolving the contradiction between traditional coatings being either "hard and brittle" or "tough and soft."

[0054] 2. The cleaning solution is green and highly efficient, balancing environmental protection and performance.

[0055] The cleaning solution of this invention uses natural ingredients such as citric acid and sodium gluconate. It is phosphorus-free, heavy metal-free, and has low VOC content, meeting relevant environmental protection standards. Furthermore, it has a very high biodegradability rate, avoiding the flammability and explosiveness risks of traditional organic solvents (acetone) and the corrosion problems of strong acids (hydrochloric acid). In terms of performance, the substrate surface is free of corrosion pits and residual oil after cleaning, and the coating exhibits high adhesion.

[0056] 3. The dispersant exhibits excellent dispersion stability, resulting in uniform powder mixing.

[0057] The dispersant of this invention utilizes a multi-component synergistic process involving polyethylene glycol 400, glycerol, lecithin, gum arabic, starch, alkyl polysaccharide glycoside, tea saponin, and HBP-160, resulting in low powder agglomeration and minimal powder mixing uniformity error. After ball milling, the powder exhibits a concentrated particle size distribution (≥95% of particles are 180-300 mesh), leading to uniform coating composition and minimal hardness fluctuation during cladding.

[0058] 4. Laser cladding process is precise and controllable, resulting in stable coating quality.

[0059] This invention achieves precise control of heat input by optimizing parameters such as laser power (1600-1800W), scanning speed (15-20mm / s), and powder feeding speed (15-20g / min), ensuring complete powder melting while avoiding overheating of the substrate. Through precise and controllable laser cladding technology, the coating quality is stabilized.

[0060] 5. Multi-stage heat treatment eliminates internal stress and improves service stability.

[0061] Existing technologies mostly employ a two-step heat treatment process of "solution treatment and aging," resulting in residual internal stress exceeding 150 MPa. This invention, however, adds a low-temperature tempering step, forming a three-stage process of "solution treatment, aging, and low-temperature tempering." This reduces residual internal stress to ≤50 MPa and lowers the microcrack initiation rate of the coating under impact loads to below 3%. The synergistic effect of these three processes ensures stable coating performance within a temperature range of -40 to 300°C, making it suitable for both cold regions and high-temperature conditions, thus broadening its application scope.

[0062] 6. Improved post-processing enhances surface quality and wear resistance.

[0063] The post-processing of this invention employs a synergistic approach of "sandpaper polishing - laser remelting - alcohol ultrasonic cleaning," resulting in a coating surface roughness Ra ≤ 0.9 μm, complete removal of surface oxide scale, and no metal debris residue. Laser remelting not only improves surface smoothness but also refines surface grains, forming a gradient structure of "surface fine-grain reinforcement - internal hard phase reinforcement," further enhancing wear resistance.

[0064] 7. Controllable cost and broad prospects for industrial application.

[0065] This invention reduces costs in three ways: ① The Co content is reduced from 8.5-9.5% in the prior art to 1-3%, reducing raw material costs by more than 40%; ② The cleaning solution can be recycled 3-5 times, and the amount of dispersant used is only 10-15% of the powder mass, reducing auxiliary material costs by more than 50%; ③ Laser cladding has high efficiency, greatly shortens the production cycle, and has broad prospects for industrial application.

[0066] 8. Balancing high strength and weldability to improve overall lifecycle economics.

[0067] This invention uses 20CrMo or 40CrMo sheet as the base material, which combines high strength and weldability. This ensures the structural strength of the components, meeting the load-bearing requirements of industrial applications, while also allowing for subsequent assembly and maintenance through welding. When the base material requires maintenance, its excellent weldability prevents damage to the main structure and supports repeated welding, significantly reducing costs associated with frequent component replacements and greatly improving the economic efficiency and practicality of the components throughout their entire lifecycle. Detailed Implementation

[0068] In this embodiment of the invention, an Fe-Ni based alloy coating with high hardness, high wear resistance, and high impact toughness comprises, by weight percentage: Ni 15-25%, Cr 8-12%, Mo 2-4%, W 1-3%, V 0.5-1.5%, Nb 0.5-2%, Ti 0.5-2%, Al 0.3-1%, Si 0.5-1.5%, Mn 0.5-1.5%, C 0.3-0.8%, B 0.05-0.2%, N 0.01-0.05%, Cu 0.5-2%, Co 1-3%, Zr 0.1-0.5%, Hf 0.05-0.3%, Ta 0.1-0.5%, Re 0.01-0.1%, Y₂O₃ 0.05-0.3%, La₂O₃ 0.05-0.2%, P≤0.005%, S≤0.005%, balance Fe.

[0069] The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness includes the following steps:

[0070] S1: Substrate pretreatment; Sand the oxide layer on the substrate surface with sandpaper, ultrasonically clean with cleaning solution for 10-20 minutes to remove oil stains, and dry at 80-100℃. Select 20CrMo or 40CrMo plates for the substrate material. The plate thickness is determined according to the working conditions. When used as a whole, the thickness is more than 50mm. When used as a precast panel, the thickness is 20-40mm.

[0071] S2: Powder preparation and pretreatment; Weigh each raw material according to weight percentage, add it to a planetary ball mill, use a dispersant, mix for 1-1.5 hours at a ball-to-material ratio of 8:1-12:1 and a rotation speed of 150-180 r / min, pass through a 180-300 mesh sieve, place it in a vacuum drying oven, and keep it at a vacuum degree ≤-0.09MPa and a temperature of 80-105℃ for 2-3 hours;

[0072] S3: Preheating; Preheat the pretreated substrate to 200-300℃ using an infrared heating lamp and hold for 20-40 minutes.

[0073] S4: Laser cladding; The substrate and powder are loaded into a fiber laser cladding device, with argon as the protective gas. Process parameters: laser power 1600-1800W, scanning speed 15-20mm / s, powder feeding speed 15-20g / min, spot diameter 3-5mm, protective gas flow rate 8-12L / min, defocusing amount +1-+2mm, forming a primary coating with a width of 8-10mm.

[0074] S5: Multi-stage heat treatment

[0075] (1) When 20CrMo plate is selected as the base material, the heat treatment is as follows:

[0076] ①Solution treatment: Heat the high-temperature carbon tube furnace to 860-880℃, hold for 1-1.5 hours, and then cool to room temperature with water or oil;

[0077] ②Aging: The contents of the muffle furnace are brought into the furnace at the specified temperature and held at 530-550℃ for 4-5 hours, followed by oil cooling or air cooling.

[0078] ③ Low-temperature tempering: Heat the muffle furnace to 150-200℃, hold for 1-1.5 hours, and then air cool;

[0079] (2) When 40CrMo plate is selected as the base material, the heat treatment is as follows:

[0080] ①Solution treatment: Heat the high-temperature carbon tube furnace to 840-880℃, hold for 1-1.6 hours, and then cool to room temperature with water or oil;

[0081] ②Aging: The contents of the muffle furnace are brought into the furnace at the specified temperature and held at 530-550℃ for 4-5 hours, followed by oil cooling or air cooling.

[0082] ③ Low-temperature tempering: Heat the muffle furnace to 200-500℃, hold for 0.5-1h, and then air cool;

[0083] S6: Post-treatment; The oxide scale on the surface of the initial coating is polished with 400-600 grit sandpaper, and then laser remelting is performed at a power of 800-1000W and a scanning speed of 20-30mm / s to improve the surface smoothness. Then, the surface is ultrasonically cleaned with alcohol for 5-10 minutes and dried to obtain an Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness.

[0084] The cleaning solution, per liter, comprises: 5-10g citric acid, 3-7g sodium gluconate, 2-5g phytic acid, 1-3g alkyl glycoside, 0.5-2g limonene, 0.5-1.5g licorice extract, with the remainder being deionized water.

[0085] The method for preparing the cleaning solution includes the following steps:

[0086] (1) Heat the deionized water to 40-50℃;

[0087] (2) Add citric acid and sodium gluconate, and stir for 15-20 minutes until completely dissolved;

[0088] (3) Cool down to 30-35℃, add phytic acid, alkyl glycoside, limonene and licorice extract, stir for 20-30 minutes, and cool to room temperature to obtain the final product.

[0089] The dispersant, by weight percentage, comprises: polyethylene glycol 400 10-20%, glycerin 5-10%, lecithin 3-7%, gum arabic 2-5%, starch 5-10%, alkyl polysaccharide 2-5%, tea saponin 0.5-1%, hyperbranched polymer HBP-160 1-2%, and the remainder being deionized water.

[0090] The method for preparing the dispersant includes the following steps:

[0091] (1) Heat the deionized water to 60-70℃;

[0092] (2) Add polyethylene glycol 400 and glycerin, and stir for 15-17 minutes until completely dissolved;

[0093] (3) Cool down to 45-50℃, add lecithin and gum arabic, and stir for 18-22 minutes;

[0094] (4) Continue to cool down to 35-40℃, add starch and alkyl polysaccharide, and stir for 29-32 minutes;

[0095] (5) Cool down to room temperature, add tea saponin and hyperbranched polymer HBP-160, and stir for 25-30 minutes to obtain the product.

[0096] Technical principle of the invention:

[0097] 1. Synergistic effect of Fe-Ni based alloy coating components

[0098] (1) Core toughness regulation role of Ni: As a face-centered cubic (FCC) structural element, Ni can form a continuous solid solution with Fe, significantly reducing the stacking fault energy of the matrix, inhibiting dislocation movement, and improving the toughness of the coating. In this invention, the Ni content is controlled at 15-25%. Below this range (e.g., 10%), the Ni content in the solid solution is insufficient, resulting in limited improvement in toughness; above this range (e.g., 30%), a brittle Ni3Fe phase will be formed, which will lead to a decrease in toughness. At the same time, Ni can promote the uniform precipitation of intermetallic compounds such as Ni3Mo and Ni3Ti during subsequent aging treatment, avoiding brittleness caused by the concentration of precipitated phases at grain boundaries.

[0099] (2) Hardness strengthening effect of Cr, Mo, W, V and Nb: Cr (8-12%), Mo (2-4%), W (1-3%), V (0.5-1.5%) and Nb (0.5-2%) are all strong carbide forming elements. They react with C (0.3-0.8%) to form hard phases such as Cr2C3, Mo2C, WC, VC and NbC. These hard phases are uniformly dispersed in the Fe-Ni matrix, which can effectively resist abrasive cutting and improve wear resistance. The C content should be controlled at 0.3-0.8%: when it is below 0.3%, the amount of hard phase generated is insufficient; when it is above 0.8%, the carbides grow excessively and are easy to fall off during the wear process, which will reduce the wear resistance.

[0100] (3) Grain refinement and deoxidation effects of Ti, Al, and Si: Ti (0.5-2%) and Al (0.3-1%) can react with N (0.01-0.05%) to form TiN and AlN nanoparticles. These particles can act as heterogeneous nucleation cores, refine the coating grains, and pin grain boundaries to inhibit grain growth. Si (0.5-1.5%) acts as a deoxidizer, reacting with O in the coating to generate SiO2, preventing O from forming oxide inclusions with Fe and Ni, and purifying the matrix. Mn (0.5-1.5%) can improve the deoxidation effect of Si and enhance the hardenability of the coating.

[0101] (4) The auxiliary performance optimization effects of B, Cu and Co: B (0.05-0.2%) can reduce the melting point of the alloy, improve the fluidity of the molten pool and reduce porosity; Cu (0.5-2%) can form a CuO passivation film on the coating surface and improve corrosion resistance; Co (1-3%) replaces the high Co content of 8.5-9.5% in the existing technology, and significantly reduces the cost while ensuring the high temperature stability of the coating. Co can work synergistically with Ni to increase the precipitation temperature of intermetallic compounds and avoid coarsening of the precipitated phase under high temperature conditions.

[0102] (5) The high-temperature performance enhancement effect of Zr, Hf, Ta and Re: Zr (0.1-0.5%), Hf (0.05-0.3%) and Ta (0.1-0.5%) can be incorporated into carbides to form (Zr,Hf,Ta)C composite carbides, which enhances the high-temperature stability of carbides; Re (0.01-0.1%), as a rare metal, can enhance the high-temperature creep resistance of coatings through the "Re atom drag dislocation" mechanism, which is suitable for high-temperature wear conditions (such as cement rotary kiln liners).

[0103] (6) Synergistic modification effect of rare earth elements Y2O3 and La2O3: Y2O3 (0.05-0.3%) and La2O3 (0.05-0.2%) are rare earth oxides, and their effects are reflected in two aspects: ① Purifying grain boundaries: Y and La have large atomic radii and can adsorb harmful impurities such as S and P at the grain boundaries (such as forming Y2S3 and LaP), eliminating grain boundary brittleness; ② Refining grains: Y2O3 and La2O3 particles can act as grain boundary pinning points, preventing grain growth and promoting the formation of equiaxed crystals. The synergistic effect of the two is better than that of a single rare earth element: when Y2O3 is added alone, the grains are refined to 10-15 μm; after synergistic addition, the grains are refined to 5-10 μm, and the impact toughness is improved.

[0104] 2. Principle of Cleaning Solution Preparation Technology

[0105] (1) Synergistic effect of citric acid and sodium gluconate in rust removal: Citric acid (5-10 g / L) is a weak organic acid that can react with Fe2O3 to form a soluble iron citrate complex; sodium gluconate (3-7 g / L) acts as a complexing agent and can react with Fe2O3 to form a soluble iron citrate complex. 3+ Forming stable chelates to prevent Fe 3+ Rust spots are redeposited on the substrate surface. When used in combination, the rust removal rate is significantly higher than that of citric acid alone; and the pH value remains stable at 3.5-4.5, avoiding corrosion of the substrate by strong acid.

[0106] (2) Synergistic corrosion inhibition of phytic acid and licorice extract: Phytic acid (2-5 g / L) contains 6 phosphate groups, which can form a dense monomolecular adsorption film on the substrate surface, isolating oxygen and water; licorice extract (0.5-1.5 g / L) contains glycyrrhetinic acid, which can form coordination bonds with Fe, enhancing the stability of the adsorption film. When the two are used in combination, the corrosion inhibition efficiency is much higher than that of phytic acid alone; and the toxicity problem of traditional corrosion inhibitors (such as benzotriazole) is avoided.

[0107] (3) Synergistic effect of alkyl glycosides and limonene in detergency removal: Alkyl glycosides (1-3 g / L) are nonionic surfactants that can reduce the interfacial tension between oil stains and the substrate; limonene (0.5-2 g / L) is a natural terpene solvent that can dissolve mineral oil, animal and vegetable oils and other oil stains. When the two are used in combination, the oil stain removal rate reaches more than 99%, and limonene can enhance the biodegradability of alkyl glycosides (biodegradation rate ≥ 98%), which meets environmental protection requirements.

[0108] 3. Principles of Dispersant Preparation Technology

[0109] (1) Basic dispersive synergy of polyethylene glycol 400 and glycerol: polyethylene glycol 400 (10-20%) is a water-soluble polymer that can prevent powder agglomeration through steric hindrance; glycerol (5-10%) can increase the viscosity of the dispersant and slow down the powder settling rate. When the two are used in combination, the powder settling rate is lower than that of polyethylene glycol 400 alone.

[0110] (2) Synergistic surface modification of lecithin and gum arabic: Lecithin (3-7%) contains hydrophilic groups (phosphate groups) and lipophilic groups (fatty acid chains), which can be adsorbed onto the powder surface, changing the powder surface from hydrophobic to hydrophilic; gum arabic (2-5%) is a natural polysaccharide that can form a gel layer on the powder surface, further enhancing steric hindrance. When the two are used synergistically, the powder contact angle decreases and the dispersion uniformity is significantly improved.

[0111] (3) Stable synergistic effect of starch, alkyl polysaccharide, tea saponin and HBP-160: Starch (5-10%) forms a three-dimensional colloidal network to encapsulate powder particles; alkyl polysaccharide (2-5%) enhances the wettability of the dispersant; tea saponin (0.5-1%) is a natural surfactant that can further reduce surface tension; the branched structure of the hyperbranched polymer HBP-160 (1-2%) can crosslink with starch and gum arabic to form a stable dispersion system. When the four are used synergistically, the aggregation rate is much better than that of traditional dispersants.

[0112] 4. Synergistic effect of preparation process parameters

[0113] (1) Matching of laser cladding parameters: Synergy between laser power 1600-1800W, scanning speed 15-20mm / s, and powder feeding speed 15-20g / min: If the power is too low (e.g., 1500W) or the scanning speed is too fast (e.g., 25mm / s), the heat input is insufficient, the powder is not completely melted, and unmelted particles appear in the coating; if the power is too high (e.g., 1900W) or the scanning speed is too slow (e.g., 10mm / s), the heat input is too high, the substrate is overheated, the grains are coarse, and cracks are easily generated. Matching the powder feeding speed with the laser power: 1600W corresponds to 15g / min, and 1800W corresponds to 20g / min, to ensure that the powder and laser energy are accurately matched and the coating thickness is uniform.

[0114] (2) Synergistic effect of multi-stage heat treatment: ① Solution treatment: If the temperature is too low, the alloying elements will not dissolve sufficiently, and the concentration of supersaturated solid solution will be insufficient; if the temperature is too high, the grains will grow. Water cooling can quickly suppress grain growth and retain supersaturated solid solution. ② Aging: If the temperature is too low, the precipitation of intermetallic compounds will be insufficient, and the hardness improvement will be limited; if the temperature is too high, the precipitated phase will coarsen and the toughness will decrease. Oil cooling or air cooling can avoid the internal stress generated by rapid cooling. ③ Low-temperature tempering: If the temperature is too low, the internal stress will not be completely eliminated; if the temperature is too high, the precipitated phase will dissolve and the hardness will decrease. The three-stage synergy can make the residual internal stress ≤50MPa, achieve the hardness improvement, and maintain the toughness stability.

[0115] (3) Synergistic post-treatment: 600-grit sandpaper is used to remove oxide scale (surface roughness Ra≤1.6μm), laying the foundation for laser remelting; laser remelting (800-1000W, 20-30mm / s) can fill surface micropores and refine surface grains; alcohol ultrasonic cleaning removes debris and avoids contamination.

[0116] To make the present invention more fully disclosed, more specific embodiments are described below.

[0117] Example 1

[0118] 1. Fe-Ni based alloy coating composition (weight percentage): Ni 20.6%, Cr 10.2%, Mo 3.1%, W 2%, V 1%, Nb 1%, Ti 1%, Al 0.5%, Si 1%, Mn 1%, C 0.5%, B 0.1%, N 0.03%, Cu 1%, Co 2%, Zr 0.3%, Hf 0.15%, Ta 0.3%, Re 0.05%, Y2O3 0.15%, La2O3 0.1%, P 0.003%, S 0.003%, balance Fe.

[0119] 2. Preparation of cleaning solution (per liter): 8g citric acid, 5g sodium gluconate, 3g phytic acid, 2g alkyl glycoside, 1g limonene, 1g licorice extract, 1L deionized water; Preparation steps: Heat deionized water to 45℃, add citric acid and sodium gluconate and stir for 18min; cool to 32℃, add the remaining ingredients and stir for 25min, then cool to room temperature.

[0120] 3. Dispersant preparation (weight percentage): polyethylene glycol 400 15%, glycerin 8%, lecithin 5%, gum arabic 3%, starch 8%, alkyl polysaccharide 3%, tea saponin 0.8%, HBP-160 1.5%, balance deionized water; preparation steps: heat deionized water to 65℃, add polyethylene glycol 400 and glycerin and stir for 16 min; cool to 48℃, add lecithin and gum arabic and stir for 20 min; cool to 38℃, add starch and alkyl polysaccharide and stir for 30 min; cool to room temperature, add tea saponin and HBP-160 and stir for 28 min, homogenize once (25 MPa).

[0121] 4. Preparation method:

[0122] S1: Sand the substrate with 240-grit sandpaper, ultrasonically clean with cleaning solution (400W) for 15 minutes, and dry at 90℃ for 1.5 hours. The substrate material is 20CrMo board.

[0123] S2: Weigh the alloy powder, add the dispersant (powder:dispersant = 10:1), mix at a ball-to-powder ratio of 10:1 and a rotation speed of 160 r / min for 1.2 h, pass through a 200-mesh sieve, and vacuum dry (-0.1 MPa, 90℃) for 2.5 h;

[0124] S3: Preheat the infrared heating lamp to 250℃ and keep it warm for 30 minutes;

[0125] S4: Laser cladding parameters: power 1700W, scanning speed 18mm / s, powder feeding speed 18g / min, spot size 4mm, protective gas 10L / min, defocusing amount +1.5mm, forming an initial coating layer;

[0126] S5: Multi-stage heat treatment

[0127] ①Solution treatment: The high-temperature carbon tube furnace is heated to 870℃, held for 1.3 hours, and then water-cooled to room temperature;

[0128] ②Aging: The material is fed into the muffle furnace at the specified temperature and held at 540℃ for 4.5 hours, then cooled with oil.

[0129] ③ Low-temperature tempering: The muffle furnace is heated to 180℃, held for 1.2 hours, and then cooled with air;

[0130] S6: Polished with 600-grit sandpaper, laser remelted (900W, 25mm / s), ultrasonically cleaned with alcohol (250W) for 8 minutes, and dried at 85℃ to obtain an Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness.

[0131] Example 2

[0132] 1. Fe-Ni based alloy coating composition (weight percentage): Ni 18%, Cr 9%, Mo 2.5%, W 1.5%, V 0.8%, Nb 0.8%, Ti 0.8%, Al 0.4%, Si 0.8%, Mn 0.8%, C 0.4%, B 0.08%, N 0.02%, Cu 0.8%, Co 1.5%, Zr 0.2%, Hf 0.1%, Ta 0.2%, Re 0.04%, Y2O3 0.1%, La2O3 0.08%, P 0.004%, S 0.004%, balance Fe.

[0133] 2. Preparation of cleaning solution (per liter): 7g citric acid, 4g sodium gluconate, 2.5g phytic acid, 1.5g alkyl glycoside, 0.8g limonene, 0.8g licorice extract, 1L deionized water; the preparation steps are the same as in Example 1.

[0134] 3. Dispersant preparation (weight percentage): polyethylene glycol 400 12%, glycerin 7%, lecithin 4%, gum arabic 2.5%, starch 7%, alkyl polysaccharide 2.5%, tea saponin 0.7%, HBP-160 1.2%, balance deionized water; preparation steps are the same as in Example 1.

[0135] 4. Preparation method:

[0136] S1: The substrate is sanded with 200-grit sandpaper, ultrasonically cleaned with cleaning solution for 12 minutes, and dried at 85℃ for 1.3 hours. The substrate material is 40CrMo board.

[0137] S2: Mix at a ball-to-material ratio of 9:1 and a rotation speed of 155 r / min for 1.4 h, pass through a 180-mesh sieve, and vacuum dry (-0.095 MPa, 85℃) for 2.8 h;

[0138] S3: Preheat to 240℃ and keep warm for 32 minutes;

[0139] S4: Laser power 1650W, scanning speed 17mm / s, powder feeding speed 17g / min, spot size 3.5mm, protective gas 9L / min, defocusing amount +1.2mm;

[0140] S5: Multi-stage heat treatment

[0141] ①Solution treatment: The high-temperature carbon tube furnace is heated to 845℃ and held for 1.6 hours, then cooled to room temperature with oil;

[0142] ②Aging: The material is fed into the muffle furnace at the set temperature and held at 535℃ for 4.8 hours, then air-cooled.

[0143] ③ Low-temperature tempering: The muffle furnace is heated to 205℃, held for 1 hour, and then cooled with air;

[0144] S6: Polished with 500-grit sandpaper, laser remelted (850W, 23mm / s), ultrasonically cleaned with alcohol for 9 minutes, and dried at 80℃ to obtain an Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness.

[0145] Example 3

[0146] 1. Fe-Ni based alloy coating composition (weight percentage): Ni 22%, Cr 11%, Mo 3.5%, W 2.5%, V 1.2%, Nb 1.5%, Ti 1.5%, Al 0.8%, Si 1.2%, Mn 1.2%, C 0.7%, B 0.15%, N 0.04%, Cu 1.5%, Co 2.5%, Zr 0.4%, Hf 0.2%, Ta 0.4%, Re 0.08%, Y2O3 0.25%, La2O3 0.15%, P 0.002%, S 0.002%, balance Fe.

[0147] 2. Preparation of cleaning solution (per liter): 9g citric acid, 6g sodium gluconate, 4g phytic acid, 2.5g alkyl glycoside, 1.5g limonene, 1.2g licorice extract, 1L deionized water; the preparation steps are the same as in Example 1.

[0148] 3. Dispersant preparation (weight percentage): Polyethylene glycol 400 18%, glycerol 9%, lecithin 6%, gum arabic 4%, starch 9%, alkyl polysaccharide 4%, tea saponin 0.9%, hyperbranched polymer HBP-160 1.8%, with the balance being deionized water; Preparation steps: Heat deionized water to 68℃, add polyethylene glycol 400 and glycerol, and stir for 17 min until completely dissolved; cool to 49℃, add lecithin and gum arabic, and stir for 22 min; continue cooling to 39℃, add starch and alkyl polysaccharide, and stir for 32 min; cool to room temperature, add tea saponin and hyperbranched polymer HBP-160, and stir for 29 min; homogenize twice under 28 MPa pressure to obtain a uniform dispersant.

[0149] 4. Preparation method:

[0150] S1: The oxide layer on the surface of the substrate was polished with 240-grit sandpaper, and ultrasonically cleaned (power 450W) for 14 minutes with the cleaning solution prepared in this embodiment. Then it was dried in an oven at 95°C for 1.5 hours. The substrate material used was 20CrMo plate.

[0151] S2: Weigh the Fe-Ni based alloy powder according to the composition, add the dispersant (powder to dispersant mass ratio 12:1), load it into a planetary ball mill, set the ball-to-powder ratio to 11:1 and the speed to 170 r / min, and mix for 1.1 h; after mixing, pass it through a 250 mesh sieve, put it into a vacuum drying oven, and keep it at a vacuum degree of -0.098 MPa and a temperature of 100℃ for 2.1 h;

[0152] S3: Use an infrared heating lamp to preheat the pretreated substrate at a heating rate of 8℃ / min, preheat to 270℃, and hold for 32min.

[0153] S4: Load the substrate and powder into the fiber laser cladding equipment, using 99.99% pure argon as the protective gas. Process parameters: laser power 1750W, scanning speed 19mm / s, powder feeding speed 19g / min, spot diameter 4.5mm, protective gas flow rate 11L / min, defocusing amount +1.8mm, forming a preliminary coating with a width of about 9.5mm.

[0154] S5: Multi-stage heat treatment

[0155] ①Solution treatment: The high-temperature carbon tube furnace is heated to 865℃, held for 1.4 hours, and then water-cooled to room temperature;

[0156] ②Aging: The contents are fed into the muffle furnace at the specified temperature and held at 545℃ for 4.2 hours, followed by air cooling;

[0157] ③ Low-temperature tempering: The muffle furnace is heated to 170℃, held for 1.3 hours, and then cooled by air;

[0158] S6: Post-treatment: The oxide scale on the surface of the initial coating is polished with 600-grit sandpaper, followed by laser remelting (power 950W, scanning speed 27mm / s); then ultrasonically cleaned with anhydrous ethanol (power 300W) for 6 minutes, and dried at 88℃ for 39 minutes to obtain an Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness.

[0159] Example 4

[0160] 1. Fe-Ni based alloy coating composition (weight percentage): Ni 24%, Cr 12%, Mo 4%, W 3%, V 1.5%, Nb 2%, Ti 2%, Al 1%, Si 1.5%, Mn 1.5%, C 0.8%, B 0.2%, N 0.05%, Cu 2%, Co 3%, Zr 0.5%, Hf 0.3%, Ta 0.5%, Re 0.1%, Y2O3 0.3%, La2O3 0.2%, P 0.005%, S 0.005%, balance Fe.

[0161] 2. Preparation of cleaning solution (per liter): 9.6g citric acid, 7.8g sodium gluconate, 5g phytic acid, 3g alkyl glycoside, 2g limonene, 1.4g licorice extract, with the remainder being deionized water; Preparation steps: Heat deionized water to 50℃, add citric acid and sodium gluconate, stir for 15min until completely dissolved; cool to 35℃, add phytic acid, alkyl glycoside, limonene and licorice extract, stir for 20min, cool to room temperature and then filter (using a 100-mesh filter).

[0162] 3. Dispersant preparation (weight percentage): Polyethylene glycol 400 19.8%, glycerol 10%, lecithin 6.9%, gum arabic 5%, starch 9.7%, alkyl polysaccharide 5%, tea saponin 1%, hyperbranched polymer HBP-160 1.8%, with the remainder being deionized water; Preparation steps: Heat deionized water to 70℃, add polyethylene glycol 400 and glycerol, and stir for 15 min; cool to 50℃, add lecithin and gum arabic, and stir for 18 min; cool to 40℃, add starch and alkyl polysaccharide, and stir for 29 min; cool to room temperature, add tea saponin and hyperbranched polymer HBP-160, and stir for 26 min; homogenize twice under 30 MPa pressure.

[0163] 4. Preparation method:

[0164] S1: Sand the substrate with 180-grit sandpaper, ultrasonically clean with cleaning solution (500W) for 10 minutes, and dry at 100℃ for 1 hour. The substrate material is 40CrMo board.

[0165] S2: Weigh the alloy powder, add the dispersant (powder:dispersant = 15:1), mix at a ball-to-powder ratio of 12:1 and a rotation speed of 180 r / min for 1 h, pass through a 300-mesh sieve, and vacuum dry (-0.1 MPa, 105℃) for 2 h;

[0166] S3: Preheat the infrared heating lamp to 300℃ and keep it warm for 20 minutes;

[0167] S4: Laser cladding parameters: power 1800W, scanning speed 20mm / s, powder feeding speed 20g / min, spot diameter 5mm, protective gas flow rate 12L / min, defocusing amount +2mm, forming a 10mm wide initial coating.

[0168] S5: Multi-stage heat treatment

[0169] ①Solution: The high-temperature carbon tube furnace is heated to 880℃, held for 1 hour, and then water-cooled to room temperature;

[0170] ②Aging: The contents are fed into the muffle furnace at the set temperature and held at 550℃ for 4 hours, then air-cooled.

[0171] ③ Low-temperature tempering: The muffle furnace is heated to 500℃, held for 0.5h, and then cooled by air;

[0172] S6: Polished with 600-grit sandpaper, laser remelted (1000W, 30mm / s), ultrasonically cleaned with alcohol for 5 minutes, and dried at 90℃ for 0.7 hours, a Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness is obtained.

[0173] III. Comparative Examples (all based on CN107815682B design)

[0174] Comparative Example 1 (using CN107815682B technology)

[0175] 1. Coating composition: The Fe-Ni based alloy powder composition by mass percentage is C 0.03%, Ni 18.5%, Co 9%, Mo 4.9%, Si 3.5%, Mn 0.1%, Ti 0.6%, Al 0.1%, P 0.01%, S 0.01%, with the balance being Fe;

[0176] 2. Preparation process (according to CN107815682B):

[0177] S1: Sand the substrate, clean with alcohol and acetone, and preheat to 250℃;

[0178] S2: 180-300 mesh powder, vacuum dried at 80-105℃ for 2.5h;

[0179] S3: Plasma cladding, current 150A, nozzle height 12mm, powder feeding speed 200g / min, powder feeding gas flow rate 5L / min, ion gas flow rate 5L / min, scanning rate 170mm / min;

[0180] S4: Solution treatment (820℃, 1.2h, water cooling), aging (510℃, 3.5h, air cooling) (no low-temperature tempering).

[0181] Comparative Example 2 (Invention components + CN107815682B plasma cladding)

[0182] 1. Coating composition: Same as in Example 1;

[0183] 2. Preparation process: Except for the cladding step which uses the plasma cladding parameters of CN107815682B (current 150A, nozzle height 12mm, etc.), the rest is the same as in Example 1.

[0184] Comparative Example 3 (Process of this invention + Components from CN107815682B)

[0185] 1. Coating composition: Same as Comparative Example 1 (CN107815682B composition).

[0186] 2. Preparation process: Same as in Example 1 (laser cladding + three-stage heat treatment).

[0187] Comparative Example 4 (This invention lacks a low-temperature tempering step)

[0188] 1. Coating composition and process: Same as in Example 1, but S5 only involves solution treatment (820℃, 1.2h, water cooling) and aging (540℃, 4.5h, air cooling), without low-temperature tempering.

[0189] IV. Single-factor experiment for screening key process parameters in the preparation of Fe-Ni based alloy coatings

[0190] All experiments were based on Example 1, with only one parameter changed while the others remained unchanged. The three core properties—hardness, impact toughness, and wear rate—were tested, and the results are as follows:

[0191] Experiment 1: Laser Power Screening Experiment

[0192]

[0193] Conclusion: The optimal range for laser power is 1600-1800W. Below 1600W, the powder melting is insufficient, and above 1800W, the substrate overheats. In contrast, the plasma cladding current in CN107815682B is 140-160A (corresponding to large fluctuations in heat input), making it difficult to accurately control the melting state, resulting in poor coating performance stability.

[0194] Experiment 2: Aging Temperature Screening Experiment

[0195]

[0196] Conclusion: The optimal aging temperature range is 530-550℃. Below 530℃, precipitation is insufficient, and above 550℃, the precipitated phase becomes coarser. CN107815682B has an aging temperature of 500-520℃, resulting in insufficient precipitated phase formation and thus a coating hardness lower than that of this invention.

[0197] Experiment 3: Powder delivery speed screening experiment

[0198]

[0199] Conclusion: The optimal powder feeding rate is 15-20 g / min, which is well matched with the laser power. For CN107815682B, the powder feeding rate is 180-220 g / min (plasma cladding). Due to the dispersion of plasma beam energy, a high powder feeding rate is required to maintain the coating thickness, which can easily lead to uneven composition.

[0200] Experiment 4: Screening Experiment on Solution Treatment and Heat Holding Time

[0201]

[0202] Conclusion: The optimal solution treatment and heat preservation time is 1-1.6h. Although the solution treatment and heat preservation time of CN107815682B is 1-1.5h, which is similar to that of this invention, the grain refinement effect is poor and the toughness is lower than that of this invention because Y2O3 and La2O3 rare earth elements are not added.

[0203] Experiment 5: Laser Remelting Power Screening Experiment

[0204]

[0205] Conclusion: The optimal range for laser remelting power is 800-1000W, which can improve surface quality; CN107815682B has no laser remelting step, resulting in high surface roughness, stress concentration, and accelerated wear.

[0206] V. Testing of Performance Indicators of Fe-Ni Based Alloy Coatings

[0207] 1. Testing Standards and Methods

[0208] Hardness: The HRC-150 Rockwell hardness tester was used to test the hardness according to GB / T230.1-2018 "Metallic materials Rockwell hardness test - Part 1: Test method". Five points were evenly selected on the coating surface and the average value was taken.

[0209] Impact toughness: The JB-30B impact testing machine was used to test the Charpy impact test method according to GB / T229-2007 "Metallic materials Charpy pendulum impact test method". U-notch was used, the sample size was 10mm×10mm×55mm, the coating thickness was 2mm, and the average value of 3 samples was taken.

[0210] Friction and wear performance: According to GB / T12444.5-2019 (Metallic materials wear test methods part 5: abrasive wear test), the MMW-1 friction and wear tester was used, with a load of 50N, a sliding speed of 0.5m / s, 1000-mesh SiC sandpaper as the abrasive, and a test time of 1h. The mass difference before and after wear was measured (accuracy 0.1mg), and the wear amount was calculated.

[0211] Bonding strength: According to GB / T8642-2002, the tensile method was adopted, the tensile rate was 1 mm / min, each sample was tested 3 times, and the average value was taken;

[0212] Surface roughness: According to GB / T3505-2009, a surface roughness tester was used, with a sampling length of 2.5 mm. Five points were tested on each sample, and the average value was taken.

[0213] Porosity: According to GB / T17729-2013, it was observed using a SU8010 scanning electron microscope (SEM), and the porosity area ratio was calculated by image analysis. Three fields of view were observed for each sample, and the average value was taken.

[0214] 2. Test Results (Table 1: Performance Comparison between Examples and Comparative Examples)

[0215]

[0216] 3. Data Comparison and Theoretical Analysis

[0217] (1) Comparison with CN107815682B (Comparative Example 1):

[0218] The hardness of Examples 1-4 of this invention is 31.5%-41.9% higher than that of CN107815682B. The core reason is that this invention optimizes the alloy composition: ① reduces the Co content to avoid insufficient solid solution strengthening caused by excessive consumption of Ni by Co; ② adds strong carbide forming elements such as Cr, W, and V to generate hard phases such as Cr2C3 and WC, while CN107815682B does not add these elements and relies only on solid solution strengthening of Ni and Co, resulting in limited hardness.

[0219] Regarding impact toughness, this invention (20.1-24 J / cm) 2 Compared to CN107815682B (15.3 J / cm³), 2 The yield is increased by 31.4%-56.9% because this invention: ① adds rare earth elements Y2O3 and La2O3 to adsorb harmful impurities such as S and P (forming Y2S3 and LaP) and purify the grain boundaries; ② adopts a three-stage heat treatment of "solution-aging-low temperature tempering" to significantly reduce the residual internal stress, while CN107815682B only has two heat treatments, resulting in high internal stress and easy crack initiation.

[0220] Regarding wear rate, the present invention (0.6-0.9 mg / h) reduces wear rate by 59%-73% compared to CN107815682B (2.2 mg / h). The reasons are: ① The hard phase is uniformly dispersed and distributed, resisting abrasive cutting; ② Laser remelting improves surface smoothness (Ra0.4-0.7 μm) and reduces stress concentration, while CN107815682B has no remelting step, resulting in a rough surface (Ra3.5 μm) and a fast wear rate.

[0221] (2) Verification of the effect of process improvement (Comparative Examples 2-3):

[0222] The hardness and bonding strength of Comparative Example 2 (the components of this invention + plasma cladding) are lower than those of Example 1, proving that laser cladding is superior to plasma cladding of CN107815682B: the laser beam energy is concentrated, the powder is fully melted, and the coating is tightly bonded to the substrate metallurgically; while plasma cladding energy is dispersed, and unmelted particles are easy to appear, resulting in low bonding strength.

[0223] The hardness and impact toughness of Comparative Example 3 (process of this invention + CN107815682B composition) are lower than those of Example 1, indicating that composition optimization is the core of performance improvement. Improving the process alone cannot make up for composition defects, further highlighting the creativity of the composition design of this invention.

[0224] (3) The necessity of low-temperature tempering (Comparative Example 4):

[0225] Impact toughness of Comparative Example 4 (lacking low-temperature tempering) (16.7 J / cm) 2 Compared to Example 1 (24J / cm) 2 The toughness of CN107815682B decreased by 30.4% because low-temperature tempering can eliminate the internal stress generated during aging and prevent the initiation of microcracks; while CN107815682B does not have a low-temperature tempering step, and its toughness is always lower than that of this invention, proving the necessity of three-stage heat treatment.

[0226] VI. Application Examples

[0227] The Fe-Ni based alloy coating of Example 1 of this invention was applied to the alloy structural steel crusher hammer (size: 300mm×200mm×100mm) of a mining machinery factory in Guangxi, and compared with the uncoated hammer and the CN107815682B coated hammer in industrial service. Working conditions: crushing granite, impact energy 8J, working time 8h / d. The results are as follows:

[0228]

[0229] As shown in the table above, the coating of this invention possesses both high hardness (resistance to wear) and high toughness (resistance to impact), making it less prone to peeling or cracking under impact-wear coupled conditions. In contrast, the CN107815682B coating, due to insufficient toughness, developed microcracks after 15 days of service and partially peeled off after 25 days, accelerating wear. This application example demonstrates the significant practical value of this invention in industrial scenarios, greatly extending the service life of alloy structural steel components and reducing replacement costs.

[0230] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the inventive concept, and all such substitutions or modifications should be considered within the scope of protection of the present invention.

Claims

1. A Fe-Ni-based alloy coating layer having high hardness, high wear resistance, and high impact toughness, characterized by, The raw material composition includes, by weight percentage, Ni 15-25%, Cr 8-12%, Mo 2-4%, W 1-3%, V 0.5-1.5%, Nb 0.5-2%, Ti 0.5-2%, Al 0.3-1%, Si 0.5-1.5%, Mn 0.5-1.5%, C 0.3-0.8%, B 0.05-0.2%, N 0.01-0.05%, Cu 0.5-2%, Co 1-3%, Zr 0.1-0.5%, Hf 0.05-0.3%, Ta 0.1-0.5%, Re 0.01-0.1%, Y2O3 0.05-0.3%, La2O3 0.05-0.2%, P≤0.005%, S≤0.005%, and the balance of Fe.

2. A method of producing a Fe-Ni-based alloy coating layer having high hardness, high wear resistance, and high impact toughness according to claim 1, characterized by, The method comprises the following steps: S1: substrate pretreatment; polishing the surface oxide layer of the substrate with sandpaper, ultrasonic cleaning with cleaning solution for 10-20 min to remove oil stains, drying at 80-100 DEG C, and selecting 20CrMo or 40CrMo plate material as the substrate material, the thickness of the plate material being determined according to the working condition, the thickness being more than 50 mm when used as a whole, and the thickness being 20-40 mm when used as a prefabricated plate; S2: powder preparation and pretreatment; weighing each raw material according to the weight percentage, adding a planetary ball mill, mixing for 1-1.5 h under the conditions of a ball-to-material ratio of 8:1-12:1 and a rotation speed of 150-180 r / min, sieving through a 180-300 mesh sieve, and placing in a vacuum drying box under the conditions of a vacuum degree of ≤-0.09 MPa and a temperature of 80-105 DEG C for 2-3 h; S3: preheating; preheating the pretreated substrate to 200-300 DEG C using an infrared heating lamp and maintaining the temperature for 20-40 min; S4: laser cladding; loading the substrate and the powder into a fiber laser cladding device, using argon as the protective gas, and forming an initial coating layer with a width of 8-10 mm under the process parameters of a laser power of 1600-1800 W, a scanning speed of 15-20 mm / s, a powder feeding speed of 15-20 g / min, a light spot diameter of 3-5 mm, a protective gas flow of 8-12 L / min, and a defocusing amount of +1-+2 mm; S5: multi-stage heat treatment; S6: post-treatment; polishing the surface oxide skin of the initial coating layer using 400-600 mesh sandpaper, then laser remelting at a power of 800-1000 W and a scanning speed of 20-30 mm / s to improve the surface flatness, followed by ultrasonic cleaning with alcohol for 5-10 min and drying, thereby obtaining an Fe-Ni-based alloy coating layer with high hardness, high wear resistance and high impact toughness.

3. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 2, characterized in that, The cleaning solution, per liter, includes the following raw materials: 5-10 g of citric acid, 3-7 g of sodium gluconate, 2-5 g of phytic acid, 1-3 g of alkyl polyglycoside, 0.5-2 g of limonene, 0.5-1.5 g of licorice extract, and the balance of deionized water.

4. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 3, characterized in that, The preparation method of the cleaning solution comprises the following steps: (1) heating the deionized water to 40-50 DEG C; (2) adding citric acid and sodium gluconate, and stirring for 15-20 min until completely dissolved; (3) cooling to 30-35℃, adding phytic acid, alkyl polyglycoside, limonene and licorice extract, stirring for 20-30 min, and cooling to room temperature to obtain.

5. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 2, characterized in that, The dispersant is prepared from the following raw materials in percentage by weight: polyethylene glycol 400 10-20%, glycerol 5-10%, lecithin 3-7%, gum arabic 2-5%, starch 5-10%, alkyl polyglycoside 2-5%, tea saponin 0.5-1%, hyperbranched polymer HBP-160 1-2%, and the rest deionized water.

6. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 5, characterized in that, The dispersant is prepared by the following steps: (1) heating deionized water to 60-70℃; (2) adding polyethylene glycol 400 and glycerol, and stirring for 15-17 min until completely dissolved; (3) cooling to 45-50℃, adding lecithin and gum arabic, and stirring for 18-22 min; (4) continuing to cool to 35-40℃, adding starch and alkyl polyglycoside, and stirring for 29-32 min; (5) cooling to room temperature, adding tea saponin and hyperbranched polymer HBP-160, and stirring for 25-30 min to obtain.

7. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 2, characterized in that, In step S4, the laser power is 1650-1750 W, the scanning speed is 17-19 mm / s, the powder feeding speed is 17-19 g / min, and the protective gas flow is 9-11 L / min.

8. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 2, characterized in that, In step S5, (1) when the base material is 20CrMo plate, the heat treatment is as follows: ① solid solution: heating to 860-880℃ in a high-temperature carbon tube furnace, holding for 1-1.5 h, and cooling to room temperature with water or oil; ② aging: entering the furnace at temperature, holding for 4-5 h at a temperature of 530-550℃, and oil cooling or air cooling; ③ low-temperature tempering: heating to 150-200℃ in a muffle furnace, holding for 1-1.5 h, and air cooling; (2) when the base material is 40CrMo plate, the heat treatment is as follows: ① solid solution: heating to 840-880℃ in a high-temperature carbon tube furnace, holding for 1-1.6 h, and cooling to room temperature with water or oil; ② aging: entering the furnace at temperature, holding for 4-5 h at a temperature of 530-550℃, and oil cooling or air cooling; ③ low-temperature tempering: heating to 200-500℃ in a muffle furnace, holding for 0.5-1 h, and air cooling.

9. The method for preparing the Fe-Ni based alloy coating with high hardness, high wear resistance and high impact toughness according to claim 2, characterized in that, In step S6, the laser remelting power is 850-950 W, the scanning speed is 23-27 mm / s, and the alcohol ultrasonic cleaning time is 7-9 min.

10. Use of a Fe-Ni based alloy coating having high hardness, high wear resistance and high impact toughness, prepared according to the method of any one of claims 2-9, characterized in that, It can be made into a whole wear plate, or into a specially shaped prefabricated plate piece.

Images