A laser cladding in-situ generated fibrous reinforcing phase reinforced nickel-based composite coating and a preparation method thereof

Abstract

The application belongs to the technical field of surface engineering, and particularly relates to a kind of laser cladding in-situ generation fibrous reinforcing phase reinforced nickel-based composite coating and its preparation method, and the preparation method comprises the following steps: 1) pretreating the surface of the substrate; 2) coating a certain thickness of the pre-layer on the pretreated substrate surface, the pre-layer is formed by mixing composite metal powder with alcohol, and the pre-layer is fully dried to remove alcohol; 3) laser cladding is carried out on the pre-layer; 4) the workpiece is naturally cooled to room temperature after cladding, and the fibrous reinforcing phase reinforced nickel-based composite coating is obtained. The nickel-based alloy cladding layer prepared by the application adds metal powder WC and Si, and through the alloying reaction of the high temperature of the laser molten pool, Cr-C, Cr-B and Cr-Si multi-element reinforcing system is formed in-situ, compared with directly adding WC reinforcing phase, the in-situ synthesized reinforcing phase is uniformly distributed and has fine structure, which significantly improves the hardness and wear resistance of the coating.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of surface engineering, and particularly relates to a laser cladding in-situ fiber-shaped reinforced phase reinforced nickel-based composite coating and a preparation method thereof. BACKGROUND

[0002] Laser cladding technology is a commonly used processing technology in the surface modification of metal materials. Wide-band laser cladding technology improves the spot shape on the basis of traditional laser cladding. By using an optical conversion mirror, the laser output by a high-power laser is converted, so that the circular spot is converted into a rectangular spot with an average energy density distribution, the single-pass cladding width is increased, the dilution rate is reduced, and the overlap coefficient and overlap times are effectively reduced, which shows significant advantages in large workpiece repair. Metal-based ceramic composite cladding layer is a very promising surface modification technology and is widely used in various fields such as aerospace, automobile, machinery, electronics, etc. It can help equipment work better in harsh environments such as high temperature, corrosion and friction. The nickel-based ceramic composite cladding layer can significantly improve the wear resistance, corrosion resistance and high temperature resistance of the material, making it more reliable in harsh environments and improving the performance and life of the equipment. The commonly used nickel-based alloy coating includes two series of Ni-Si-B and Ni-Cr-Si-B. The microstructure of the nickel-based coating is complex. Chromium can form various chromium carbides and borides with carbon or boron, which become the first reinforcing phase of the coating, effectively improving the wear resistance of the metal surface. This nickel-based coating has high toughness, good wear and corrosion resistance, and high temperature resistance, and is easy to machine, which has broad application prospects in engineering.

[0003] In order to be suitable for different use scenarios, researchers have tried various methods to optimize the mechanical properties of nickel-based coatings, including optimizing process parameters, improving component design, and assisting other composite fields to strengthen material performance. Process parameter improvement belongs to small-scale adjustment, which is difficult to achieve qualitative change and is limited by mechanical configuration. And the auxiliary composite field is not suitable for large-scale batch generation due to the complicated operation process. Relatively speaking, improving the component design can greatly improve the performance of the nickel-based coating, and the process is simple and suitable for industrial production, which has always been concerned by researchers at home and abroad.

[0004] According to the search, the Chinese patent document with the publication number CN114107742A discloses a nickel-based coating, by adding rare earth element Y and by in-situ synthesis of ceramic particles, effectively refining the matrix structure of the nickel-based alloy in the coating, enhancing the bonding force of the coating and the substrate interface, and improving the strength and toughness of the coating. The Chinese patent document with the publication number CN110172662A discloses a preparation method of a composite coated ceramic powder nickel-based coating, by using Ni60 powder, Co coated WC powder and NiCr coated Cr3C2 ceramic particles as raw materials to prepare a coating with good wear resistance and fatigue resistance.

[0005] In the above literature research, it is found that the strengthening phase formed by in-situ synthesis of ceramic particles to strengthen the nickel-based coating is mainly in the form of particles distributed in the nickel matrix. When resisting wear load, the microstructure mechanical properties of the cladding layer show isotropy, and good strengthening effect can be achieved. However, in some special application occasions such as engine piston rings, brake pad calipers, etc., the sliding friction direction is linear. At this time, the ceramic hard phase with directionality has more excellent anti-wear performance in a certain specific friction direction. Therefore, by means of technical means, the form of the ceramic hard phase is changed into fibrous shape, which can greatly improve the surface wear resistance of such workpieces, and has strong application prospect. SUMMARY

[0006] The purpose of the present application is to overcome the above-mentioned problems existing in the prior art, and to provide a laser cladding in-situ generated fibrous strengthening phase reinforced nickel-based composite coating and a preparation method thereof. By optimizing the composition of the cladding powder and controlling the structure of the in-situ strengthening phase, the microstructure of the in-situ synthesized fibrous reinforcing phase with a certain directionality is obtained, and the wear resistance of the material surface is further improved.

[0007] In order to achieve the above technical purpose and achieve the above technical effect, the present application is realized by the following technical scheme:

[0008] The present application provides a preparation method of a laser cladding in-situ generated fibrous strengthening phase reinforced nickel-based composite coating, comprising the following steps:

[0009] 1) Pretreating the surface of the substrate;

[0010] 2) Coating a certain thickness of a pre-layer on the pretreated surface of the substrate, the pre-layer being composed of a composite metal powder mixed with alcohol, and the pre-layer being fully dried to remove the alcohol;

[0011] The composite metal powder is composed of 45.0-94.0wt.% nickel-based alloy powder, 1.0-10.0wt.% Si powder and 5.0-45.0wt.% WC powder;

[0012] The nickel-based alloy powder is composed of raw materials with the following mass proportions:

[0013] C 0.85-1.0wt.%

[0014] B 3.0-4.0wt.%

[0015] Cr 12.0-18.0wt.%

[0016] Fe 12.0-20.0wt.%

[0017] Si 2.0-6.0wt.%

[0018] Ni 50.0-65.0wt.%;

[0019] 3) laser cladding on the pre-prepared layer;

[0020] 4) naturally cooling the workpiece after cladding to room temperature to obtain the fiber-shaped reinforced phase reinforced nickel-based composite coating.

[0021] Further, in step 1), the substrate is selected as a Q550 steel plate with a thickness of 10-30 mm, which is cut into a test block with a size of 20 mm x 100 mm; the specific operation of the pretreatment is that the surface of the substrate is polished to remove rust and oil stains, cleaned with alcohol, and ready for use.

[0022] Further, in step 2), the purity of the Si powder in the metal powder is ≥99.5%, and the particle size is 300-500 mesh.

[0023] Further, in step 2), the purity of the WC powder in the metal powder is ≥99.7%, and the particle size is 250-400 mesh.

[0024] Further, in step 2), before mixing with alcohol, the components are weighed and mixed according to the mass ratio, and a ball mill is used for mixing for 30-60 minutes to ensure uniform mixing of the metal powder.

[0025] Further, in step 2), the thickness of the pre-prepared layer is controlled to be 0.5-1.5 mm.

[0026] Further, in step 3), a fiber-coupled semiconductor laser is used in the laser cladding process, and the main process parameters include: spot size 15.0 mm x 2.0 mm, laser power 2.0-6.0 kW, laser scanning speed 2.0-15.0 mm / s, focal length 150 mm, defocusing amount controlled within ±2.0 mm, purity of 99.9% argon gas protection is used in the laser cladding process, and the gas flow is 12-25 L / min.

[0027] The application also provides a laser cladding in-situ fiber-shaped reinforced phase reinforced nickel-based composite coating prepared by the preparation method.

[0028] The application has the following beneficial effects:

[0029] 1. The nickel-based alloy cladding layer prepared by the application adds metal powder WC and Si, and through the alloying reaction of the laser molten pool high temperature, Cr-C, Cr-B and Cr-Si multi-element reinforcement system is formed in-situ, compared with directly adding WC reinforcement phase, the in-situ synthesized reinforcement phase is uniformly distributed and has a small structure, and the hardness and wear resistance of the coating are significantly improved.

[0030] 2. The application introduces a certain content of Si element, so that the form of the in-situ precipitated reinforcement phase is changed from blocky to long strip and needle-shaped fiber-shaped form, and the wear resistance in a certain wear direction can be greatly improved.

[0031] 3. The nickel-based alloy coating designed by the application can control the form, distribution and density of the precipitated phase by controlling the mass fraction of Si element in the original component and the wideband laser cladding process, and then optimize the hardness and other mechanical performance indicators of the cladding layer, so that the excellent comprehensive performance is ensured, and the structure and performance of the cladding layer are simple and controllable.

[0032] Of course, any product implementing the application does not necessarily need to achieve all the advantages above. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 Surface morphology diagram of laser cladding nickel-based composite coating containing 1wt.% Si and 20wt.% WC;

[0035] Figure 2 Precipitated phase form diagram of laser cladding nickel-based coating with different Si contents;

[0036] Among them, (a) 0.5wt.% Si addition, (b) 2.0wt.% Si addition, (c) 4.0wt.% Si addition, (d) 6.0wt.% Si addition;

[0037] Figure 3 XRD phase composition diagram of laser cladding nickel-based coating;

[0038] Figure 4 Performance test diagram of laser cladding nickel-based coating. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Specific embodiments of the present invention are as follows:

[0041] Example 1

[0042] 1) Using nickel-based alloy powder as the base powder, its chemical composition (mass fraction) is 0.85 wt.% C, 3.60 wt.% B, 14.00 wt.% Cr, 16.00 wt.% Fe, 4.50 wt.% Si, and 61.05 wt.% Ni. The composite powder contains 79 wt.% nickel-based alloy powder, with an additional 20 wt.% WC powder (purity greater than 99.7%, particle size 300 mesh) and 1 wt.% Si powder (purity ≥ 99.5%, particle size 400 mesh).

[0043] 2) After weighing and mixing the powder components according to the designed mass ratio, use a ball mill to mix for more than 20 minutes to ensure that the metal powder is mixed evenly;

[0044] 3) The base material is Q550 steel, cut into 20mm×100mm×10mm pieces, and surface oxides, oil stains, etc. are removed by mechanical grinding.

[0045] 4) Mix the alloy powder obtained after stirring with alcohol, and evenly pre-form it on the surface of the treated Q550 steel substrate to form a pre-formed layer with a thickness of 1.0 mm. Dry it at 60℃ for 30 min before use.

[0046] 5) The process parameters for laser cladding are as follows: laser power 3.0kW, spot size 15mm×2mm, laser scanning speed 4.0mm / s, and defocusing amount 0mm. The protective gas is argon gas with a purity of 99.99% and a flow rate of 12L / min. After laser cladding, the cladding layer is allowed to cool naturally to room temperature.

[0047] 6) Metallographic samples of the cladding alloy were cut and etched with a mixed acid (20% HF-30% HCl-50% HNO3), and then tested for metallographic hardness and wear resistance. The precipitated phase morphology of the cladding layer was blocky, with some transforming into elongated strips. The alloy in this example achieved an average hardness of 840.6 HV and an average coefficient of friction of 0.67.

[0048] Example 2

[0049] 1) The base powder is a nickel-based alloy powder with the following chemical composition (mass fraction): 0.85wt.% C, 3.60wt.% B, 14.00wt.% Cr, 16.00wt.% Fe, 4.50wt.% Si, and 61.05wt.% Ni. The composite powder contains 68wt.% of the nickel-based alloy powder, 30wt.% of WC powder (purity > 99.7%, particle size 300 mesh), and 2wt.% of Si powder (purity ≥ 99.5%, particle size 400 mesh).

[0050] 2) After weighing and mixing the component powders according to the designed mass ratio, a ball mill is used for mixing for more than 40 minutes to ensure uniform mixing of the metal powders.

[0051] 3) The base material is Q550 steel, which is cut into 20mm x 100mm x 10mm, and mechanical polishing is used to remove surface oxides, oil stains, etc.

[0052] 4) The alloy powder obtained after stirring and mixing is mixed with alcohol and uniformly pre-prepared on the surface of the treated Q550 steel substrate to form a pre-prepared layer with a thickness of 1.0mm. After drying, it is ready for use.

[0053] 5) The process parameters for laser cladding are: laser power 4.0kW, spot size 15mm x 2mm, laser scanning speed 3.0mm / s, and defocusing amount 0mm. The protective gas is argon with a purity of 99.99%, and the flow rate is 15L / min. After laser cladding, the cladding layer is naturally cooled to room temperature.

[0054] 6) The cladding alloy is cut into metallographic samples, which are etched with mixed acid (20%HF-30%HCl-50%HNO3) to detect the hardness and wear resistance. The morphology of the precipitated phase in the cladding layer is completely transformed into long strips. The average hardness of the alloy in this example is 830.9HV, and the average friction coefficient is 0.85.

[0055] Example 3

[0056] 1) The base powder is a nickel-based alloy powder with the following chemical composition (mass fraction): 0.85wt.% C, 3.60wt.% B, 14.00wt.% Cr, 16.00wt.% Fe, 4.50wt.% Si, and 61.05wt.% Ni. The composite powder contains 68wt.% of the nickel-based alloy powder, 30wt.% of WC powder (purity > 99.7%, particle size 300 mesh), and 2wt.% of Si powder (purity ≥ 99.5%, particle size 400 mesh).

[0057] 2) Each component powder is weighed and mixed according to the designed mass ratio, and then mixed for more than 50 minutes by using a ball mill to ensure uniform mixing of the metal powders;

[0058] 3) The base material is selected as Q550 steel, which is cut into 20 mm x 100 mm x 10 mm, and the surface oxides, oil stains and the like are removed by mechanical polishing.

[0059] 4) The alloy powder obtained after stirring and mixing is mixed with alcohol, uniformly pre-prepared on the surface of the treated Q550 steel substrate, to form a pre-prepared layer with a thickness of 1.0 mm, and dried for later use.

[0060] 5) The process parameters for laser cladding are: laser power 5.0 kW, spot size 15 mm x 2 mm, laser scanning speed 5.0 mm / s, and defocusing amount 0 mm. The protective gas is argon with a purity of 99.99%, and the flow rate is 20 L / min. After laser cladding, the cladding layer is naturally cooled to room temperature.

[0061] 6) The cladding alloy is cut into a metallographic sample, which is etched by mixed acid (20% HF-30% HCl-50% HNO3) to detect the hardness and wear resistance. The morphology of the precipitated phase of the cladding layer changes to fine needle shape, and is uniformly distributed. The average hardness of the alloy in this example is 903.4 HV, and the average friction coefficient is 0.95.

[0062] Example 4

[0063] 1) The nickel-based alloy powder is used as the base powder, and the chemical composition (mass fraction) is 0.85wt.% C, 3.60wt.% B, 14.00wt.% Cr, 16.00wt.% Fe, 4.50wt.% Si and 61.05wt.% Ni. The composite powder contains 64wt.% nickel-based alloy powder, additionally 30wt.% WC powder (purity greater than 99.7%, particle size 300 mesh), and 6wt.% Si (purity ≥ 99.5%, particle size 400 mesh) powder.

[0064] 2) Each component powder is weighed and mixed according to the designed mass ratio, and then mixed for more than 50 minutes by using a ball mill to ensure uniform mixing of the metal powders;

[0065] 3) The base material is selected as Q550 steel, which is cut into 20 mm x 100 mm x 10 mm, and the surface oxides, oil stains and the like are removed by mechanical polishing.

[0066] 4) The alloy powder obtained after stirring and mixing is mixed with alcohol, uniformly pre-prepared on the surface of the treated Q550 steel substrate, to form a pre-prepared layer with a thickness of 1.0 mm, and dried for later use.

[0067] 5) The process parameters of laser cladding are as follows: laser power 6.0 kW, spot size 15 mm x 2 mm, laser scanning speed 6.0 mm / s, and defocusing amount 0 mm. The protective gas is argon with purity of 99.99%, and the flow rate is 20 L / min. After laser cladding, the cladding layer is naturally cooled to room temperature.

[0068] 6) The cladding alloy is cut into a metallographic sample, which is etched by mixed acid (20% HF-30% HCl-50% HNO3) to detect the metallographic hardness and wear resistance. The morphology of the precipitated phase of the cladding layer is stable needle-shaped and uniformly distributed. The average hardness of the alloy of this example reaches 1016.8 HV, and the average friction coefficient is 0.69.

[0069] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details and limit the present application to the specific embodiments. Obviously, many modifications and variations can be made according to the content of the present application. The present application is selected and specifically described to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing a laser cladded in-situ generated fiber- reinforced phase reinforced nickel-based composite coating, characterized in that, It comprises the following steps: 1) pretreating the surface of the substrate; 2) coating a certain thickness of a pre-layer on the pretreated surface of the substrate, the pre-layer being formed by mixing composite metal powder with alcohol, and fully drying the pre-layer to remove alcohol; The composite metal powder is composed of 45.0-94.0wt.% nickel-based alloy powder, 1.0-10.0wt.% Si powder and 5.0-45.0wt.% WC powder; the purity of Si powder in the metal powder is ≥99.5%, and the particle size is 300-500 mesh; the purity of WC powder in the metal powder is ≥99.7%, and the particle size is 250-400 mesh; The nickel-based alloy powder is composed of the following mass ratio of raw materials: C 0.85-1.0wt.% B 3.0-4.0wt.% Cr 12.0-18.0wt.% Fe 12.0-20.0wt.% Si 2.0-6.0wt.% Ni 50.0-65.0wt.%; 3) laser cladding the pre-layer; 4) naturally cooling the workpiece after cladding to room temperature to obtain a fibrous reinforced phase reinforced nickel-based composite coating.

2. The production method according to claim 1, characterized by, In step 1), the substrate is a Q550 steel plate with a thickness of 10-30 mm, cut into a 20 mm x 100 mm test block; the specific operation of pretreatment is to polish the surface of the substrate to remove rust and oil stains, clean with alcohol, and prepare for use.

3. The preparation method according to claim 1, characterized in that, In step 2), before mixing with alcohol, the components are weighed and mixed according to the mass ratio, and a ball mill is used for mixing for 30-60 minutes to ensure uniform mixing of the metal powder.

4. The method of claim 1, wherein, In step 2), the thickness of the pre-layer is controlled to be 0.5-1.5 mm.

5. The preparation method according to claim 1, characterized in that, In step 3), a fiber-coupled semiconductor laser is used for laser cladding, and the main process parameters include: spot size 15.0 mm x 2.0 mm, laser power 2.0-6.0 kW, laser scanning speed 2.0-15.0 mm / s, focal length 150 mm, defocusing amount controlled within ±2.0 mm, laser cladding process using 99.9% pure argon gas protection, gas flow 12-25 L / min.

6. A laser cladding in-situ generated fibrous reinforced phase reinforced nickel-based composite coating prepared by the preparation method of any one of claims 1-5.

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