High bond strength metal spray coating material and method of making same

Abstract

The application discloses a high-bonding-strength metal spraying coating material and a preparation method thereof, and belongs to the technical field of metal surface coating. The coating is composed of a micron-sized metal skeleton phase, a nanometer metal glass amorphous phase and rare earth oxides, a metal-oxygen-rare earth transition phase is generated in situ at an interface through a low-temperature spraying process, a gradient connection structure is formed, and metallurgical-mechanical double bonding is realized. The application solves the problems of low bonding strength, easy peeling and large internal stress of a traditional coating, the bonding strength of the coating is 40-50 MPa, and the cold and hot cycle resistance of the coating is significantly improved. The process is simple, the cost is low, the practicality is high, and the application is suitable for the field of metal surface protection and strengthening with high requirements on bonding strength and reliability.

Description

Technical Field

[0001] This invention belongs to the field of metal surface protection and strengthening technology, specifically relating to a high-bonding-strength metal spray coating material and its preparation method. Background Technology

[0002] Metal surface coating technology is widely used in fields such as machinery manufacturing and aerospace. Its core requirement is to improve the wear resistance, corrosion resistance, and interfacial bonding strength of the substrate. Most existing metal surface coatings are prepared by using single metal or aero-glass materials through processes such as thermal spraying and cold spraying. Among them, aero-glass coatings have attracted much attention due to their excellent mechanical properties. However, single aero-glass coatings have defects such as high internal stress, insufficient toughness, and easy peeling.

[0003] To improve bonding performance, related technologies have attempted to use metal-glass composite spraying or add intermediate layers, but the problem of unstable bonding still exists. Intermediate layer design increases process complexity and cost, and fails to fundamentally solve the bonding instability problem caused by interfacial energy differences. Furthermore, existing composite coatings often lack targeted interfacial structure design, and the synergistic effect of the micron-scale metallic phase and the nano-reinforcing phase is not fully utilized, resulting in high coating porosity and poor resistance to thermal cycling.

[0004] Therefore, developing a high-strength composite coating material with simple processing, controllable cost, and the ability to achieve both metallurgical and mechanical bonding through interface structure optimization has become an urgent technical challenge in this field. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a high-bonding-strength metal spray coating material and its preparation method. The material achieves metallurgical-mechanical dual bonding by generating a metal-oxygen-rare earth interface transition phase in situ. The coating has high bonding strength, low porosity, and low internal stress. The preparation process is simple and widely applicable, and it can meet the high-performance surface protection and strengthening requirements of various substrates such as aluminum alloys and steel.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-bonding-strength metal spray coating material includes a substrate and a composite coating applied to the surface of the substrate. The coating material is prepared from the following raw materials in parts by weight: 40-70 parts of micron-sized metallic framework phase powder, 30-60 parts of nano-sized metallic glass amorphous phase powder, and 0.5-3 parts of rare earth oxide nano powder; The micron-sized metal framework phase is Al alloy powder, Zn alloy powder, or Cu alloy powder, with a particle size of 50-200 μm; the nano-sized metallic glass amorphous phase is iron-based amorphous alloy powder or cobalt-based amorphous alloy powder, with a particle size of 20-80 nm; the rare earth oxide is La2O3 or CeO2; and the bonding strength between the composite coating and the substrate is 40-50 MPa.

[0007] Optionally, the mass ratio of the micron-sized metal framework phase to the nano-sized metal glass amorphous phase is 7:3 to 3:7.

[0008] Optionally, the matrix is ​​one of aluminum alloy, steel, cast iron or magnesium alloy.

[0009] Optionally, the thickness of the composite coating is 100-500 μm.

[0010] Optionally, the preparation method of the high-bonding-strength metal spray coating material is specifically as follows: S1. Weigh 40-70 parts by weight of micron-sized metal framework phase powder, 30-60 parts by weight of nano-sized metal glass amorphous phase powder, and 0.5-3 parts by weight of rare earth oxide nano powder. Place them in a planetary ball mill and mix them. The ball milling speed is 200-300 rpm and the ball milling time is 1-3 hours to obtain a uniformly mixed powder. S2. The substrate is degreased sequentially with an alkaline degreasing agent at 40-60℃ for 10-20 minutes, and then sandblasted with white corundum sand at a pressure of 0.4-0.6MPa to make the surface roughness Ra of the substrate 1.5-3.0μm. S3. Use supersonic cryogenic spraying equipment with nitrogen or argon as the working gas and a gas pressure of 1.5-2.5MPa; control the spraying temperature to 60%-80% of the glass transition temperature Tg of the amorphous phase of nano-metallic glass, the spraying distance to 100-200mm, and the powder feeding rate to 5-15g / min. Spray the mixed powder onto the pretreated substrate surface to form a composite coating. S4. Place the sprayed substrate and composite coating in a tempering furnace and keep it at 150-250℃ for 1-2 hours, then cool it to room temperature with the furnace.

[0011] Optionally, the ball-to-material ratio of the planetary ball mill in S1 is 5:1-10:1, and the grinding media are agate balls or zirconia balls.

[0012] Optionally, the alkaline degreasing agent in S2 is a mixed aqueous solution of sodium hydroxide and sodium carbonate, wherein the mass concentration of sodium hydroxide is 5%-10% and the mass concentration of sodium carbonate is 3%-5%.

[0013] Optionally, the glass transition temperature Tg of the nano-metallic glass amorphous phase in S3 is 500-700℃, corresponding to a spraying temperature control of 300-560℃.

[0014] Optionally, the heating rate of the tempering furnace in S4 is 5-10℃ / min, the cooling rate is ≤15℃ / min, and the tempering atmosphere is air or an inert gas.

[0015] The beneficial effects of this invention are as follows: The metal spray coating prepared by this invention has excellent interfacial bonding effect, with a coating bonding strength of 40-50 MPa. Furthermore, through the in-situ generated metal-oxygen-rare earth composite interfacial transition phase, a metallurgical-mechanical dual bonding between the coating and the substrate is achieved, significantly improving the bonding stability and resistance to thermal cycling. The coating of this invention has a dense microstructure with a porosity of ≤2%, which can effectively reduce internal defects and residual stress. The micron-sized metal skeleton and the nano-sized metal glass form a synergistic reinforcing structure, which, combined with the interfacial regulation effect of rare earth oxides, greatly improves the density and structural stability of the coating, effectively blocking the intrusion of external corrosive media, and exhibiting excellent overall mechanical properties and protective effects. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Example 1: A high-bonding-strength metal spray coating material of Example 1 is prepared from the following raw materials in parts by weight: 60 parts of micron-sized metallic framework phase powder (Al alloy powder, 50-200μm), 40 parts of nano-sized metallic glass amorphous phase powder: iron-based amorphous alloy powder, and 1.5 parts of rare earth oxide nanopowder: La2O3 nanopowder. This embodiment describes a method for preparing a high-bonding-strength metal spray coating material, the specific preparation steps of which are as follows: S1. Accurately weigh each raw material and place them together in the zirconium oxide jar of the planetary ball mill. Add agate balls (5mm in diameter), control the ball-to-material ratio to 8:1, and introduce argon gas into the jar to replace the air (to protect the powder from oxidation). Set the speed to 250 rpm and continue ball milling for 2 hours. After stopping the machine, take out the uniformly mixed powder and seal it for later use. S2. Select a 100mm×50mm×5mm Q235 steel substrate. First, wipe the surface oil stains with anhydrous ethanol, then immerse it in a mixed aqueous solution of 5% NaOH and 3% Na2CO3 at a constant temperature of 50℃ for 15 minutes to remove oil. After removal, rinse with deionized water until neutral and blow dry. Then, use 120-mesh white corundum abrasive to sandblast the substrate surface at a pressure of 0.5MPa. The sandblasting distance is 100mm and the spraying angle is 90°. After treatment, the surface roughness of the substrate Ra=2.0μm. Clean it again with anhydrous ethanol and dry it. S3. A supersonic cryogenic spraying device is used, with argon gas of ≥99.99% purity as the working gas and a gas pressure of 2.0 MPa set. The glass transition temperature Tg of the iron-based amorphous alloy powder is pre-measured to be 600℃ using a differential scanning calorimeter, so the spraying temperature is controlled at 420℃ (70% of Tg). The spraying distance is adjusted to 150 mm and the powder feeding rate is 10 g / min. The mixed powder is fed into the spray gun at a uniform speed and sprayed onto the pretreated steel substrate surface in a single pass to form a composite coating. During the spraying process, La2O3 reacts with the oxides on the substrate and powder surface to generate a metal-oxygen-rare earth composite interface transition phase in situ. S4. Immediately place the sprayed substrate along with the composite coating into a tempering furnace, set the heating rate to 8℃ / min, heat to 200℃ and hold for 1.5h, then cool with the furnace to room temperature at a rate of ≤15℃ / min, and take it out to obtain the target coating.

[0018] Example 2: A high-bonding-strength metal spray coating material of Example 2, the coating material is prepared from the following raw materials in parts by weight: 60 parts of micron-sized metallic framework phase powder (Al alloy powder, 50-200μm), 40 parts of nano-sized metallic glass amorphous phase powder: cobalt-based amorphous alloy powder, and 1.5 parts of rare earth oxide nanopowder: La2O3 nanopowder. The preparation method of a high-bonding-strength metal spray coating material in this embodiment is the same as that in Embodiment 1, except that the nano-metal glass amorphous phase powder is replaced with cobalt-based amorphous alloy powder.

[0019] Example 3: A high-bonding-strength metal spray coating material of Example 3 is prepared from the following raw materials in parts by weight: 60 parts of micron-sized metallic framework phase powder (Al alloy powder, 50-200μm), 40 parts of nano-sized metallic glass amorphous phase powder: iron-based amorphous alloy powder, 1.5 parts of rare earth oxide nano powder: CeO2 nano powder. The preparation method of a high-bonding-strength metal spray coating material in this embodiment is the same as that in Example 1, except that rare earth oxide nanopowder is replaced with CeO2 nanopowder.

[0020] Comparative Example 1: The coating material of Comparative Example 1 was prepared from the following parts by weight of raw materials: 60 parts of micron-sized metallic framework phase powder (Al alloy powder, 50-200μm), 40 parts of nano-metallic glass amorphous phase powder: iron-based amorphous alloy powder. The preparation method of the coating material in this comparative example is the same as that in Example 1, except that rare earth oxide nanopowder is not added.

[0021] Comparative Example 2: The coating material of Comparative Example 2 was prepared from the following parts by weight of raw materials: 60 parts of micron-sized metallic framework phase powder (Al alloy powder, 50-200μm), 40 parts of nano-sized metallic glass amorphous phase powder: iron-based amorphous alloy powder, and 1.5 parts of rare earth oxide nanopowder: La2O3 nanopowder. The preparation method of the coating material in this comparative example is the same as that in Example 1, except that tempering treatment is not performed.

[0022] Performance testing 1. Coating bonding strength test The coating bond strength test was performed according to GB / T 8642-2012 "Test Method for Bond Strength of Thermal Spray Coatings". The specific steps were as follows: Select the coating samples prepared in the examples and comparative examples, cut them into standard specimens of 100mm×25mm×5mm according to the coating thickness, and use epoxy structural adhesive to bond the coated surface of the specimen to a carbon steel pull-out block of the same size. Cure at room temperature for 24 hours to ensure a firm bond. After curing, remove excess adhesive layer and unbonded areas from the edges of the specimen. Install the bonded specimen on the fixture of a universal testing machine and perform an axial pull-out test at a loading rate of 5mm / min until the coating peels off or breaks from the substrate. Record the maximum pull-out force during the test. Calculate the coating bond strength by the ratio of the maximum pull-out force to the coating bonding area. Each specimen was tested in parallel 3 times, and the average value was taken as the final test result.

[0023] Table 1. Test data on the bonding strength of coatings for different samples.

[0024] The coating bond strengths of Examples 1-3 were 44.9 MPa, 43.0 MPa, and 44.1 MPa, respectively, demonstrating stable performance. Comparative Examples 1 and 2 had bond strengths of only 31.9 MPa and 34.9 MPa, significantly lower than the Examples, confirming the synergistic effect of rare earth oxides and the tempering process, which effectively improves the adhesion between the coating and the substrate.

[0025] 2. Resistance to thermal cycling The thermal cycling resistance test was performed according to the conventional thermal cycling method. The specific steps were as follows: Select the coating samples prepared in the examples and comparative examples, place them in a constant temperature oven, set the oven temperature to 200℃, and keep the samples at this temperature for 10 minutes; after the holding time, immediately remove the samples from the oven and quickly place them in a room temperature environment to cool naturally for 10 minutes, thus completing one thermal cycle; repeat the above operation of "holding at 200℃ for 10 minutes + cooling at room temperature for 10 minutes" for a total of 50 thermal cycles; during and after the cycle, observe the surface condition of the coating periodically, and focus on recording whether defects such as cracking, blistering, peeling, and edge curling occur, so as to evaluate the thermal cycling resistance stability of the coating.

[0026] Table 2. Test data on the thermal cycling resistance of different samples

[0027] The coatings in Examples 1-3 showed no core defects such as cracking or peeling after 50 thermal cycles, demonstrating excellent temperature change stability and highlighting the effectiveness of low-temperature spraying and tempering processes in eliminating internal stress. Comparative Examples 1 and 2, however, exhibited insufficient stability, further verifying the crucial role of rare earth oxides in optimizing interfacial bonding and the tempering process in enhancing temperature change resistance.

[0028] 3. Corrosion resistance test The neutral salt spray test was conducted according to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". The specific steps were as follows: Select the coating samples prepared in the examples and comparative examples, wipe the surface with anhydrous ethanol to remove oil and impurities, and after drying, fix the samples on the sample rack of the salt spray test chamber, so that the coating surface is at an angle of 15°-30° with the vertical direction to ensure uniform salt spray deposition; prepare a 5% NaCl aqueous solution, adjust the pH value of the solution to 6.5-7.2, maintain the temperature in the test chamber at 35℃, spray continuously for 48 hours, and control the spray pressure at 0.07-0.17MPa; observe the surface condition of the sample regularly during the test, remove the sample after the test, rinse the surface with running deionized water to remove residual salt solution, and allow it to dry naturally. Observe and record whether the coating has corrosion defects such as rust, blistering, peeling, and cracking. Evaluate the corrosion resistance of the coating by the proportion of defect area and the degree of corrosion.

[0029] Table 3. Test data on corrosion resistance of different samples

[0030] After a 48-hour neutral salt spray test, the coatings in Examples 1-3 showed no serious corrosion defects and demonstrated good protective effects, thanks to the dense structure formed by the synergistic effect of the raw materials. Comparative Example 1 showed rust and blistering, while Comparative Example 2 had sporadic rust spots, indicating that rare earth oxides can enhance the density of the coating, and the tempering process improves the corrosion resistance and stability. Together, these two factors ensure the long-term protective performance of the coating.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-bonding-strength metal spray coating material, comprising a substrate and a composite coating applied to the surface of the substrate, characterized in that, The coating material is prepared from the following raw materials in parts by weight: 40-70 parts of micron-sized metallic framework phase powder, 30-60 parts of nano-sized metallic glass amorphous phase powder, and 0.5-3 parts of rare earth oxide nano powder; The micron-sized metal framework phase is Al alloy powder, Zn alloy powder, or Cu alloy powder, with a particle size of 50-200 μm; the nano-sized metallic glass amorphous phase is iron-based amorphous alloy powder or cobalt-based amorphous alloy powder, with a particle size of 20-80 nm; the rare earth oxide is La2O3 or CeO2; and the bonding strength between the composite coating and the substrate is 40-50 MPa.

2. The high-bonding-strength metal spray coating material according to claim 1, characterized in that, The mass ratio of the micron-sized metallic framework phase to the nano-sized metallic glass amorphous phase is 7:3-3:

7.

3. The high-bonding-strength metal spray coating material according to claim 1, characterized in that, The matrix is ​​one of aluminum alloy, steel, cast iron or magnesium alloy.

4. The high-bonding-strength metal spray coating material according to claim 1, characterized in that, The thickness of the composite coating is 100-500 μm.

5. A method for preparing a high-bonding-strength metal spray coating material, used to prepare the high-bonding-strength metal spray coating material according to any one of claims 1-4, characterized in that, The specific preparation method is as follows: S1. Weigh 40-70 parts by weight of micron-sized metal framework phase powder, 30-60 parts by weight of nano-sized metal glass amorphous phase powder, and 0.5-3 parts by weight of rare earth oxide nano powder. Place them in a planetary ball mill and mix them. The ball milling speed is 200-300 rpm and the ball milling time is 1-3 hours to obtain a uniformly mixed powder. S2. The substrate is degreased sequentially with an alkaline degreasing agent at 40-60℃ for 10-20 minutes, and then sandblasted with white corundum sand at a pressure of 0.4-0.6MPa to make the surface roughness Ra of the substrate 1.5-3.0μm. S3. Use supersonic cryogenic spraying equipment with nitrogen or argon as the working gas and a gas pressure of 1.5-2.5MPa; control the spraying temperature to 60%-80% of the glass transition temperature Tg of the amorphous phase of nano-metallic glass, the spraying distance to 100-200mm, and the powder feeding rate to 5-15g / min. Spray the mixed powder onto the pretreated substrate surface to form a composite coating. S4. Place the sprayed substrate and composite coating in a tempering furnace and keep it at 150-250℃ for 1-2 hours, then cool it to room temperature with the furnace.

6. The method for preparing a high-bonding-strength metal spray coating material according to claim 5, characterized in that, The ball-to-material ratio of the planetary ball mill in S1 is 5:1-10:1, and the grinding media are agate balls or zirconia balls.

7. The method for preparing a high-bonding-strength metal spray coating material according to claim 5, characterized in that, The alkaline degreasing agent in S2 is a mixed aqueous solution of sodium hydroxide and sodium carbonate, wherein the mass concentration of sodium hydroxide is 5%-10% and the mass concentration of sodium carbonate is 3%-5%.

8. The method for preparing a high-bonding-strength metal spray coating material according to claim 5, characterized in that, The glass transition temperature Tg of the nano-metallic glass amorphous phase in S3 is 500-700℃, corresponding to a spraying temperature control of 300-560℃.

9. The method for preparing a high-bonding-strength metal spray coating material according to claim 5, characterized in that, The heating rate of the tempering furnace in S4 is 5-10℃ / min, the cooling rate is ≤15℃ / min, and the tempering atmosphere is air or inert gas.

Images