A method for producing a porous laser-clad coating

Abstract

The present application relates to a kind of preparation methods of porous laser cladding coating, comprising the following steps: (1) polishing, cleaning treatment is carried out to metal base material;(2) configuring alloy powder added with C3N4 for laser cladding, the mixed alloy powder is evenly laid on the surface of metal base material by gravity powder feeding mode, and porous laser cladding coating is prepared by laser cladding operation;(3) polishing and polishing are carried out after the cooling of cladding coating to room temperature.The porous laser cladding coating prepared on the surface of metal base material can significantly improve the buffering and shock absorption performance of metal base material, and the porous laser cladding coating prepared has good noise reduction performance.

Description

Technical Field

[0001] This invention relates to the field of metal surface engineering technology, and in particular to a method for preparing a porous laser cladding coating. Background Technology

[0002] Porous metallic materials contain a large number of directional or random pores dispersed within them, with diameters ranging from approximately 2µm to 3mm. These pores can be foam-like, lotus-root-like, honeycomb-like, etc. Porous metallic materials are further divided into two main categories: independent pore types and continuous pore types. Independent pore materials are characterized by low specific gravity, high rigidity and specific strength, and good vibration and sound absorption properties. Continuous pore materials, in addition to the above characteristics, also possess good permeability and air permeability. Because porous metallic materials exhibit both structural and functional material properties, they are widely used in aerospace, transportation, construction engineering, mechanical engineering, electrochemical engineering, environmental protection engineering, and other fields.

[0003] The following methods are mainly used to manufacture porous metal materials: hot extrusion, such as mixing aluminum, magnesium and their alloy powders with certain carbonates, forming them under hot extrusion, and foaming at higher temperatures to produce porous materials; molten metal method, where a foaming agent is added to a low-melting-point metal in a molten state, and gas is uniformly distributed under strong stirring to generate bubbles in the metal; powder metallurgy method, where a foaming agent is added to powder, and the foaming agent volatilizes during sintering, leaving pores; electrochemical deposition method, where metal is deposited on the plastic using electroplating, and then the plastic is burned off, which also leaves pores.

[0004] Traditional metal surface modification technologies such as surfacing, plasma welding, and spray welding suffer from high dilution rates, resulting in coarse weld layer structures, uncontrollable porosity, and a high likelihood of multiple pores connecting to form large voids. This leads to a sharp decline in the mechanical properties of the weld layer, making it unable to meet usage requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a porous laser cladding coating, which can significantly improve the buffering and shock absorption properties of the surface of the metal substrate material and play a good noise reduction role, thus producing a functional composite material. Furthermore, the metal substrate and the porous laser cladding coating are metallurgically bonded, resulting in excellent mechanical properties.

[0006] The technical solution adopted in this invention is as follows:

[0007] The present invention provides a method for preparing a porous laser cladding coating, comprising the following steps:

[0008] (1) Grinding and cleaning the surface of the metal substrate;

[0009] (2) configuring laser cladding alloy powder, uniformly laying the laser cladding alloy powder on the surface of the metal base material by the way of gravity powder feeding, and then preparing the porous laser cladding coating through laser cladding operation;

[0010] (3) polishing after the porous laser cladding coating is cooled to room temperature.

[0011] Further, the step (2) specifically comprises: configuring laser cladding alloy powder; placing the configured laser cladding alloy powder into a drying box, setting the temperature to 200-250 DEG C, and setting the drying time to 3-5 hours; mixing the laser cladding powder after drying by using a three-dimensional powder mixer, and setting the mixing time to 3-5 hours; sealing and packaging the laser cladding alloy powder; placing the laser cladding alloy powder in a powder feeding cylinder of a laser cladding powder feeder, uniformly prepositioning on the surface of the metal base material by gravity powder feeding, and then performing laser cladding to obtain the porous laser cladding coating.

[0012] Further, the laser cladding alloy powder comprises the following components in percentage by weight: C: 0.15-0.35%, Cr: 8.6-13.5%, Mo: 0.28-0.35%, Ni: 12.5-16.5%, C3N4: 0.1-0.5%, and the balance of Fe.

[0013] Further, the purity of each component in the laser cladding alloy powder is greater than 99%, and the particle size of the powder is 135-325 mesh.

[0014] Further, the total thickness of the porous laser cladding coating is 2.0-2.5 mm.

[0015] Further, in the step (2), the process parameters of laser cladding are as follows: laser power: 3.2-4.0 KW; rectangular light spot: 2x14 mm; lap rate: 30-50%; scanning speed: 300-450 mm / min.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The laser cladding alloy powder adopted in the present application adds C3N4 in percentage by weight of 0.1-0.5%, obtains the porous laser cladding coating, significantly improves the buffering and shock absorption performance of the surface of the metal base material, and simultaneously obtains good noise reduction performance.

[0018] The porous laser cladding coating prepared in the present application is metallurgically combined with the metal base material, obtains the metal composite material with excellent bonding strength, and retains the high mechanical strength and other performances of the original metal base material.

[0019] By laser cladding, the heat effect on the substrate is reduced, the deformation of the substrate is avoided, and the performance of the micro surface and the key position is greatly improved.

[0020] The prepared porous laser cladding coating also has excellent wear resistance, and the addition of Cr, Mo and other elements in the iron-based alloy powder makes the alloy powder have high hardness characteristics; meanwhile, the addition of C3N4 realizes the preparation of independent holes dispersedly distributed in the laser cladding coating, so that the porous laser cladding coating has the characteristics of small specific gravity, good rigidity, good specific strength, good vibration absorption and sound absorption performance and the like.

[0021] By using the laser cladding advanced process, the obtained porous cladding alloy layer has excellent wear resistance, and the friction and wear experiment shows that the wear resistance of the cladding layer is improved by nearly 3 times.

[0022] The porous laser cladding coating is metallurgically combined with the substrate, and the dilution rate is 5-8%, so that the quality of the porous cladding coating is not diluted by the substrate.

[0023] The thickness of the porous laser cladding coating is 2.0-2.5mm, which ensures sufficient surface material layer thickness and strength, and realizes the functions of buffering, shock absorption and noise reduction.

[0024] The process flow of the porous laser cladding coating prepared by the present application is simple, the process quality is controllable, and the laser numerical control machining tool is used to realize the automation of the cladding preparation process, so that the uniformity of the product quality is ensured.

[0025] The C3N4 addition ratio range provided by the present application is the optimal result obtained through hundreds of experiments, when the C3N4 addition ratio range is less than the range provided by the present application, the prepared cavity content is too small, and the buffering, shock absorption performance of the laser cladding coating is basically not affected, and the noise reduction performance is almost unchanged; when the C3N4 addition ratio range is greater than the range provided by the present application, the prepared cavity content is significantly increased, but a large number of cracks and other defects appear in the laser cladding coating, and are mostly present at the joint with the substrate, which is easy to cause the cladding layer to fall off under external force, so that a porous laser cladding coating with no defects and high bonding strength with the substrate cannot be obtained. Through repeated experimental verification, it is determined that the C3N4 addition ratio provided by the present application is the best ratio. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the microstructure diagram of the porous laser cladding coating prepared in example 1;

[0027] Figure 2 is the microstructure diagram of the porous laser cladding coating prepared in example 2;

[0028] Figure 3 is the microstructure diagram of the porous laser cladding coating prepared in example 3;

[0029] Figure 4 is a microstructure diagram of the porous laser cladding coating prepared in Example 4. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Example 1

[0032] A method for preparing a porous laser cladding coating, comprising the following steps:

[0033] (1) polishing and cleaning the surface of the metal substrate;

[0034] (2) configuring laser cladding alloy powder, and uniformly placing the laser cladding alloy powder on the surface of the metal substrate by gravity powder feeding, and preparing a porous laser cladding coating by laser cladding operation;

[0035] The specific process is as follows: configuring laser cladding alloy powder, the laser cladding alloy powder comprises the following components by weight percentage: C: 0.15%, Cr: 8.6%, Mo: 0.28%, Ni: 12.5%, C3N4: 0.1%, the balance being Fe, and the purity of each component is greater than 99%, and the particle size of the powder is 135-325 mesh;

[0036] Placing the configured laser cladding alloy powder into a drying oven, setting the temperature to 200°C, and drying for 5 hours; mixing the dried laser cladding powder by using a three-dimensional powder mixer, and mixing for 3 hours; sealing and packaging the laser cladding powder; placing the laser cladding powder into a powder feeding cylinder of a laser cladding powder feeder, uniformly pre-placing on the surface of the metal substrate by gravity powder feeding, and then performing laser cladding to obtain a porous laser cladding coating;

[0037] In this embodiment, the process parameters of laser cladding are as follows: laser power is 3.2KW, rectangular spot is 2x14mm, overlap rate is 30%, and scanning speed is 300mm / min; the total thickness of the porous laser cladding coating is 2.0mm;

[0038] (3) polishing and polishing after the porous laser cladding coating is cooled to room temperature.

[0039] The microstructure of the porous laser cladding coating prepared in this example is shown in Figure 1 .

[0040] Example 2

[0041] A method for preparing a porous laser cladding coating includes the following steps:

[0042] (1) Grinding and cleaning the surface of the metal substrate;

[0043] (2) Prepare alloy powder for laser cladding, and uniformly spread the laser cladding alloy powder on the surface of the metal substrate by gravity powder feeding, and prepare a porous laser cladding coating by laser cladding operation;

[0044] The specific process is as follows: Prepare laser cladding alloy powder, which includes the following components by weight percentage: C: 0.25%, Cr: 12.5%, Mo: 0.30%, Ni: 12.5%, C3N4: 0.2%, with the balance being Fe, and the purity of each component is greater than 99%, and the particle size of the powder is 135-325 mesh;

[0045] Place the prepared laser cladding alloy powder into a drying oven, set the temperature to 250℃, and dry for 3 hours; mix the dried laser cladding powder using a three-dimensional powder mixer for 3 hours; seal the laser cladding powder in a sealed package; place the laser cladding powder in the powder feeding cylinder of a laser cladding powder feeder, and evenly pre-place it on the surface of the metal substrate by gravity feeding, and then perform laser cladding to obtain a porous laser cladding coating.

[0046] In this embodiment, the laser cladding process parameters are as follows: laser power: 3.6KW, rectangular spot size: 2×14mm, overlap rate: 35%, scanning speed: 350mm / min; the total thickness of the porous laser cladding coating is 2.2mm.

[0047] (3) After the porous laser cladding coating cools to room temperature, it is polished.

[0048] The microstructure of the porous laser cladding coating prepared in this embodiment is shown in the figure below. Figure 2 As shown.

[0049] Example 3

[0050] A method for preparing a porous laser cladding coating includes the following steps:

[0051] (1) Grinding and cleaning the surface of the metal substrate;

[0052] (2) Prepare alloy powder for laser cladding, and uniformly spread the laser cladding alloy powder on the surface of the metal substrate by gravity powder feeding, and prepare a porous laser cladding coating by laser cladding operation;

[0053] The specific process is as follows: Prepare laser cladding alloy powder, which includes the following components by weight percentage: C: 0.25%, Cr: 11.5%, Mo: 0.32%, Ni: 14.5%, C3N4: 0.3%, with the balance being Fe, and the purity of each component is greater than 99%, and the particle size of the powder is 135-325 mesh;

[0054] Place the prepared laser cladding alloy powder into a drying oven, set the temperature to 225℃, and dry for 4 hours; use a three-dimensional powder mixer to mix the dried laser cladding powder for 4 hours; seal the laser cladding powder in a sealed package; place the laser cladding powder in the powder feeding cylinder of the laser cladding powder feeder, and evenly pre-place it on the surface of the metal substrate by gravity feeding, and then perform laser cladding to obtain a porous laser cladding coating.

[0055] In this embodiment, the laser cladding process parameters are as follows: laser power: 3.8KW, rectangular spot size: 2×14mm, overlap rate: 40%, scanning speed: 400mm / min; the total thickness of the porous laser cladding coating is 2.4mm.

[0056] (3) After the porous laser cladding coating cools to room temperature, it is polished.

[0057] The microstructure of the porous laser cladding coating prepared in this embodiment is shown in the figure below. Figure 3 As shown.

[0058] Example 4

[0059] A method for preparing a porous laser cladding coating includes the following steps:

[0060] (1) Grinding and cleaning the surface of the metal substrate;

[0061] (2) Prepare alloy powder for laser cladding, and uniformly spread the laser cladding powder on the surface of the metal substrate by gravity powder feeding, and prepare a porous laser cladding coating by laser cladding operation;

[0062] The specific process is as follows: Prepare laser cladding alloy powder, which includes the following components by weight percentage: C: 0.35%, Cr: 13.5%, Mo: 0.35%, Ni: 16.5%, C3N4: 0.5%, with the balance being Fe, and the purity of each component is greater than 99%, and the particle size of the powder is 135-325 mesh;

[0063] Place the prepared laser cladding alloy powder into a drying oven, set the temperature to 250℃, and dry for 5 hours; use a three-dimensional powder mixer to mix the dried laser cladding powder for 5 hours; seal the laser cladding powder in a sealed package; place the laser cladding powder in the powder feeding cylinder of the laser cladding powder feeder, and evenly pre-place it on the surface of the metal substrate by gravity feeding, and then perform laser cladding to obtain a porous laser cladding coating.

[0064] In this embodiment, the laser cladding process parameters are as follows: laser power: 4.0KW, rectangular spot size: 2×14mm, overlap rate: 50%, scanning speed: 450mm / min; the total thickness of the porous laser cladding coating is 2.5mm.

[0065] (3) After the porous laser cladding coating cools to room temperature, it is polished.

[0066] The microstructure of the porous laser cladding coating prepared in this embodiment is shown in the figure below. Figure 4 As shown.

[0067] The above preparation method was tested using 45 steel as the substrate. The chemical composition of the 45 steel is as follows:

[0068] C Si Mn Cr Ni Cu 0.42-0.50％ 0.17-0.37％ 0.5-0.8％ ≤0.25％ ≤0.30％ ≤0.25％

[0069] The experimental results are as follows, using a continuous multi-pass lap cladding experiment:

[0070] Power (KW) Focal length (mm) Light spot (mm) Scan speed (mm) Overlap (%) 3.5 (Sample 1) 300 2×14 300 50 3.6 (Sample 2) 300 2×14 330 50 3.8 (Sample 3) 300 2×14 380 50 4.0 (Sample 4) 300 2×14 400 50

[0071] After the above experiments were completed, the porous laser cladding coating on the surface of all samples was spread evenly and flat, with a cladding layer thickness of 2.0 to 2.5 mm, and had good metallurgical bonding with the substrate. When the samples were subjected to penetrant testing with a flaw detector, no defects such as cracks were found on the porous cladding coating on the surface of all samples.

[0072] The microhardness of the cladding zone was measured using a microhardness tester (FM-700e digital microhardness tester). The microhardness of the cladding layer is shown in the table below:

[0073] Sample 1 Sample 2 Sample 3 Sample 4 528 HV 533 HV 530 HV 532 HV

[0074] The microhardness of the 45 steel substrate after quenching and tempering is shown in the table below:

[0075] Hardness 1 Hardness 2 Hardness 3 Hardness 4 270 HV 275 HV 277 HV 272 HV

[0076] The above experimental results show that the hardness of the 45 steel substrate is significantly improved compared to that of the tempered steel substrate.

[0077] The above experiments used a microhardness tester to observe the interface between the laser cladding layer and the substrate. It was found that the porous laser cladding coating and the 45 steel substrate had a good metallurgical bond, and there were no crack defects at the interface.

[0078] This invention utilizes laser cladding technology, taking advantage of the rapid heating and cooling characteristics of laser cladding to obtain an ultra-fine cladding layer structure with good buffering and shock absorption properties. Furthermore, this invention uses specially formulated alloy powder to laser clad the surface of ordinary metal substrates, thus creating a porous laser cladding coating on the previously conventional dense metal surface.

[0079] All matters not covered in this invention are common knowledge.

[0080] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method of producing a porous laser cladding coating, characterized by: The method comprises the following steps: (1) polishing and cleaning the surface of the metal substrate; (2) preparing laser cladding alloy powder, uniformly laying the laser cladding alloy powder on the surface of the metal substrate through gravity powder feeding, and then preparing a porous laser cladding coating through laser cladding operation; (3) polishing and polishing after the porous laser cladding coating cools to room temperature; The laser cladding alloy powder comprises the following components in percentage by weight: C: 0.15-0.35%, Cr: 8.6-13.5%, Mo: 0.28-0.35%, Ni: 12.5-16.5%, C3N4: 0.1-0.5%, and the balance is Fe; The purity of each component in the laser cladding alloy powder is greater than 99%, and the particle size of the powder is 135-325 mesh.

2. The method of claim 1, wherein: The step (2) specifically comprises: preparing laser cladding alloy powder; placing the prepared laser cladding alloy powder into a drying oven, setting the temperature to 200-250℃, and drying for 3-5 hours; mixing the dried laser cladding powder using a three-dimensional powder mixer for 3-5 hours; sealing and packaging the laser cladding alloy powder; placing the laser cladding alloy powder in a powder feeding cylinder of a laser cladding powder feeder, uniformly prepositioning it on the surface of the metal substrate through gravity powder feeding, and then performing laser cladding to obtain a porous laser cladding coating.

3. The method of claim 1, wherein: The total thickness of the porous laser cladding coating is 2.0-2.5mm.

4. The method of claim 2, wherein: In the step (2), the process parameters of laser cladding are as follows: laser power: 3.2-4.0KW; rectangular light spot: 2x14mm; overlap rate: 30-50%; scanning speed: 300-450mm / min.

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