A low-resistance beaded system, its preparation method and application

Abstract

This invention relates to the field of cemented carbide brazed beads, specifically to a low-resistance bead, its preparation method, and its application. The low-resistance bead comprises: a substrate, a brazing filler layer, and cemented carbide particles; wherein the substrate is streamlined and has a central circular through-hole; the cemented carbide particles are welded to the outer surface of the substrate through the brazing filler layer, which is a metallurgical reaction layer between the brazing filler and the substrate; a portion of the cemented carbide particles is embedded in the brazing filler layer. The low-resistance bead exhibits low resistance in water flow and high cutting efficiency; the bonding between the cemented carbide particles and the substrate is highly reliable, and even if individual particles detach, it does not affect the overall cutting effect.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide brazing beads, and more specifically, to a low-resistance bead, its preparation method, and its application. Background Technology

[0002] Carbide beads are made by creating carbide blocks on the surface of a steel substrate, which serve as a wear-resistant and cutting working layer. Carbide beads, steel wire rope, and fixing sleeves together form a carbide wire saw, which is mainly used for cutting underwater reinforced concrete, steel cables, and shipwrecks.

[0003] Most existing wire saw beads are diamond beads, made by sintering a mixture of diamond particles and metal powder. These diamond beads are then strung onto a steel wire rope and fixed using an injection molding process. Before use, they need to be sharpened, i.e., the rubber material adhering to the working surface of the diamond beads needs to be removed. Due to the high price and complex manufacturing process of diamond beads, invention patent CN200910180207.0 discloses a carbide beaded wire saw blade. In this wire saw, the carbide beads are formed by welding the end faces of two or more cylindrical carbide grinding blocks together. The solder layer contains boron carbide or diamond powder, resulting in better wear resistance and higher cutting efficiency for the grinding blocks. However, the cemented carbide beads prepared by this method have the following problems: (1) The beads are cylindrical in shape. When used for underwater cutting projects, the water-facing surface of the beads is subject to greater water resistance, which seriously affects the cutting efficiency; (2) The beads are composed of cylindrical cemented carbide grinding blocks that are welded together. Without a steel substrate as a buffer, the weldability between the cemented carbide grinding blocks is very poor, the brazing rate of the solder layer is low, and it is a weak area. The grinding blocks are easy to peel off and fall off from the solder layer during the working process, which leads to a decrease in the cutting rate of the beads or even scrapping and failure to work.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a low-resistance bead, which has advantages such as low underwater resistance, high cutting efficiency, good wear resistance, and high reliability.

[0006] The second objective of this invention is to provide a method for preparing the low-resistance beads, which has the advantages of simple process and good quality beads.

[0007] The third objective of this invention is to provide a wire saw that has low resistance and high cutting efficiency when operating underwater.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] One aspect of the present invention relates to a low-resistance bead comprising: a substrate, a solder layer, and cemented carbide particles;

[0010] The substrate is streamlined and has a circular through hole in the center; multiple cemented carbide particles are welded to the outer surface of the substrate through a brazing filler layer, which is a metallurgical reaction layer between the brazing filler and the substrate.

[0011] A portion of the cemented carbide particles is embedded in the brazing filler layer.

[0012] The aforementioned beads exhibit low resistance when running in water flow, good wear resistance, and high cutting efficiency; the cemented carbide particles have high bonding reliability with the matrix, and even if individual particles fall off, it does not affect the overall cutting effect.

[0013] Another aspect of the present invention relates to a method for preparing the aforementioned low-resistance beads, comprising the following steps:

[0014] (a) Welding cemented carbide particles onto the outer surface of the substrate to obtain a beaded steel billet;

[0015] (b) After applying flux paste to the surface of the beaded steel billet, heat preservation is performed;

[0016] (c) After the heat-insulating steel billet is coated with the flux paste, it is immersed in the brazing filler metal solution for immersion brazing.

[0017] The method for preparing the low-resistance beads involves first spot welding hard alloy particles onto the surface of the substrate, then immersion brazing, and then embedding a layer of wear-resistant nanoparticles through cold spraying to form a brazing filler layer of a certain thickness containing wear-resistant powder. This allows the hard particles to be coated to a certain depth and have a sharp edge, making the beads both reliable and sharp.

[0018] Another aspect of the invention relates to a wire saw comprising the aforementioned low-resistance beads or beads prepared by the method for preparing the aforementioned low-resistance beads.

[0019] This wire saw experiences low resistance, high cutting efficiency, and high stability when cutting underwater.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The low-resistance beads provided by the present invention have a streamlined body design, which makes the beads run with less resistance in water flow, thereby improving the cutting efficiency; hard alloy particles are set on the surface of the base as a wear-resistant and cutting working layer, and the bonding performance between the hard alloy particles and the base is high, so even if individual particles fall off, it will not affect the overall cutting effect.

[0022] (2) The method for preparing low-resistance beads provided by the present invention involves spot welding hard alloy particles on the surface of the substrate, then forming a brazing filler layer of a certain thickness through impregnation brazing, and then forming a wear-resistant layer through thermal adhesion, so that the hard particles are covered to a certain depth and have a sharp edge, which is reliable, sharp and wear-resistant.

[0023] (3) The wire saw provided by the present invention has low resistance, high cutting efficiency and high stability when cutting underwater. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the beads provided by the present invention;

[0026] Figure 2 This is a topographic image of a Q235 steel plate after it has been cut.

[0027] Figure 3 This is a topographical diagram of the seam between the beads.

[0028] Figure label:

[0029] 1-Substrate, 2-Solver layer, 3-Hard alloy particles, 4-Wear-resistant nanoparticle layer. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0031] One aspect of the present invention relates to a low-resistance beaded system, such as... Figure 1 As shown, it includes: a substrate 1, a solder layer 2, and cemented carbide particles 3;

[0032] The substrate 1 is streamlined and has a circular through hole in the center; multiple cemented carbide particles 3 are welded to the outer surface of the substrate 1 through the brazing filler layer 2, which is a metallurgical reaction layer between the brazing filler and the substrate 1.

[0033] A portion of the cemented carbide particles 3 are embedded in the brazing filler layer 2.

[0034] This invention designs the base 1 of the beads as a streamlined shape, i.e., a falling water droplet, with the overall shape of the beads resembling a streamlined body. As a water droplet falls, it encounters air resistance, naturally deforming under this resistance to minimize the drag and form a typical streamlined shape. Streamlined bodies are typically rounded at the front and pointed at the back, with a smooth surface exhibiting laminar flow with little or no turbulence, ensuring minimal resistance. Compared to traditional welded carbide modular beads, this invention brazes several smaller, outward-pointing hard particles onto the outer surface of the base 1, serving as a wear-resistant, cutting working layer. The brazing performance between the hard particles and the base 1 is reliable; even if individual particles chip or fall off during operation, it does not affect the overall cutting effect of the beads and prevents the entire bead from being scrapped.

[0035] Preferably, the surface of the solder layer is provided with a wear-resistant nanoparticle layer 4.

[0036] Preferably, the wear-resistant nanoparticles are made of at least one of diamond, cubic boron nitride, silicon nitride, or aluminum oxide.

[0037] Preferably, the thickness of the wear-resistant nanoparticle layer 4 is 30–50 μm (e.g., 30 μm, 35 μm, 40 μm, 45 μm or 50 μm).

[0038] Preferably, the wear-resistant nanoparticles have a particle size of 20–30 μm (e.g., 20 μm, 22 μm, 24 μm, 26 μm, 28 μm or 30 μm).

[0039] Preferably, the height of the cemented carbide particles 3 is 4.8 to 6 mm (e.g., 4.8 mm, 5 mm, 5.2 mm, 5.4 mm, 5.6 mm, 5.8 mm or 6 mm).

[0040] Preferably, the thickness of the solder layer 2 is 2 / 3 to 3 / 4 of the height of the cemented carbide particles 3.

[0041] Preferably, the spacing between two adjacent cemented carbide particles 3 is 1 / 2 to 1 times the height of the cemented carbide particle.

[0042] Preferably, the cemented carbide particles 3 are cone-shaped with the tips pointing outwards.

[0043] Preferably, the material of the solder layer 2 includes at least one of BCu58ZnMn, BCu58ZnMnNi, or BCu58ZnMnCo.

[0044] Preferably, the material of the cemented carbide particles 3 includes at least one of YG6, YG8, YG15 or YG20.

[0045] Preferably, the base 1 has a circular through hole at its center.

[0046] One aspect of the present invention also relates to a method for preparing the aforementioned low-resistance beads, comprising the following steps:

[0047] (a) Welding cemented carbide particles 3 onto the outer surface of the substrate 1 to obtain a beaded steel billet;

[0048] (b) After applying flux paste to the surface of the beaded steel billet, heat preservation is performed;

[0049] (c) After heat preservation, the surface of the beaded steel billet is coated with the flux paste and then immersed in the brazing filler metal solution for impregnation brazing. The method for preparing the low-resistance beads involves first spot welding hard alloy particles 3 onto the surface of the substrate 1, then forming a brazing filler metal layer 2 of a certain thickness through impregnation brazing, and finally forming a thin layer of wear-resistant nanoparticles on the surface of the brazing filler metal layer through cold spraying; this allows the hard particles to coat the surface to a certain depth and extend to the edge, resulting in a product that is both reliable and sharp.

[0050] After the impregnation brazing in step (c), a brazing filler metal layer will form on the substrate surface, welding the cemented carbide particles to the substrate surface. The flux paste in this step is to prevent oxidation of the steel substrate during the heat preservation process.

[0051] Preferably, the method for preparing the low-resistance beads further includes:

[0052] Step (d): After the impregnation brazing is completed, wear-resistant nanoparticles are coated onto the surface of the beaded steel billet to form a wear-resistant nanoparticle layer 4.

[0053] Preferably, the immersion brazing time is 3 to 8 minutes (e.g., 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, or 8 minutes). By controlling the immersion brazing time, the thickness of the brazing filler metal layer on the surface of the steel substrate after immersion brazing can be adjusted. A longer time results in a thicker brazing filler metal layer, while a shorter time results in a thinner brazing filler metal layer.

[0054] Preferably, the temperature of the solder is 900–930°C (e.g., 900°C, 905°C, 910°C, 915°C, 920°C, 925°C, or 935°C). At this temperature, the solder alloy melts to form a molten metal solution, which is higher than the liquidus temperature of the solder.

[0055] Preferably, the insulation temperature is 650-700℃ (e.g., 650℃, 655℃, 660℃, 665℃, 670℃, 675℃, 680℃, 685℃, 690℃, 695℃ or 700℃).

[0056] Preferably, the heat preservation time is 20 to 30 minutes (e.g., 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes or 30 minutes).

[0057] Preferably, the flux paste comprises borax, boric acid, potassium fluoride, and alcohol. The flux paste prevents oxidation of the beaded steel billet and promotes a metallurgical reaction between the molten solder and the steel substrate, forming a reaction layer.

[0058] Preferably, the mass ratio of the borax, the boric acid, the potassium fluoride, and the alcohol is 45-55:30-40:10-20:15-25.

[0059] The mold for preparing substrate 1 has an inner hole, the shape of which is consistent with the streamline shape of substrate 1.

[0060] In one aspect, the invention also relates to a wire saw comprising the aforementioned low-resistance beads or beads prepared by the method for preparing the aforementioned low-resistance beads.

[0061] The wire saw described above experiences low resistance, high cutting efficiency, and high stability when cutting underwater.

[0062] The embodiments of the present invention will now be described in detail with reference to specific examples and comparative examples.

[0063] Example 1

[0064] The method for preparing low-resistance beads provided in this embodiment includes the following steps:

[0065] Step 1: Melt and cast the raw material of base 1 into a molding die to form the required streamlined body;

[0066] Step 2: Mount the base 1 on a milling machine and machine the base 1 with a circular through hole;

[0067] Step 3: A layer of cone-shaped cemented carbide particles 3 is uniformly cold-welded onto the surface of the substrate 1 from Step 2. The cemented carbide particles 3 are made of YG6, the height of the cemented carbide particles 3 is 4.8mm, and the distance between two adjacent cemented carbide particles 3 is 3mm, so that their tips face outwards, to obtain a beaded steel billet.

[0068] Step 4: Place BCu58ZnMn in a graphite crucible and melt it into a solder liquid, maintaining the temperature at 900℃ to make the solder liquid semi-solid.

[0069] Step 5: After uniformly coating the surface of the beaded steel billet from Step 3 with flux paste, place it in a box-type resistance furnace and hold it at 650℃ for 20 minutes.

[0070] Step 6: After taking out the beaded steel billet from Step 5, coat the surface evenly with a layer of flux paste, immerse it in the brazing filler metal solution from Step 4, keep it for 3 minutes, and then take it out.

[0071] Step 7: Using a cold spray gun, apply diamond micro powder to the surface of the preheated steel billet with impregnation, and cool to obtain cemented carbide brazed beads. The thickness of the brazing filler layer 2 containing diamond micro powder formed on the surface of the substrate 1 is 3mm.

[0072] Example 2

[0073] The method for preparing low-resistance beads provided in this embodiment includes the following steps:

[0074] Step 1: Melt and cast the raw material of base 1 into a molding die to form the required streamlined body;

[0075] Step 2: Mount the base 1 on a milling machine and machine the base 1 with a circular through hole;

[0076] Step 3: A layer of cone-shaped cemented carbide particles 3 is uniformly cold-welded onto the surface of the substrate 1 from Step 2. The cemented carbide particles 3 are made of YG8, with a height of 5mm and a spacing of 4mm between two adjacent cemented carbide particles 3, so that their tips face outwards, to obtain a beaded steel billet.

[0077] Step 4: Place BCu58ZnMnNi in a graphite crucible and melt it into a solder liquid, maintaining the temperature at 930℃ to make the solder liquid semi-solid.

[0078] Step 5: After uniformly coating the surface of the beaded steel billet from Step 3 with flux paste, place it in a box-type resistance furnace and hold it at 680℃ for 25 minutes.

[0079] Step 6: After taking out the beaded steel billet from Step 5, coat the surface evenly with a layer of flux paste, immerse it in the brazing filler metal solution from Step 4, keep it for 5 minutes, and then take it out.

[0080] Step 7: Using a cold spray gun, cubic boron nitride micro powder is cold sprayed onto the surface of the preheated steel billet containing impregnation. After cooling, hard alloy brazed beads are obtained. The thickness of the brazing filler layer 2 containing cubic boron nitride micro powder formed on the surface of the substrate 1 is 3.5 mm.

[0081] Example 3

[0082] The method for preparing low-resistance beads provided in this embodiment includes the following steps:

[0083] Step 1: Melt and cast the raw material of base 1 into a molding die to form the required streamlined body;

[0084] Step 2: Mount the base 1 on a milling machine and machine the base 1 with a circular through hole;

[0085] Step 3: A layer of cone-shaped cemented carbide particles 3 is uniformly cold-welded onto the surface of the substrate 1 from Step 2. The cemented carbide particles 3 are made of YG15, with a height of 6mm and a spacing of 6mm between two adjacent cemented carbide particles 3, so that their tips face outwards, to obtain a beaded steel billet.

[0086] Step 4: Place BCu58ZnMnCo in a graphite crucible and melt it into a solder liquid, maintaining the temperature at 920℃ to make the solder liquid semi-solid.

[0087] Step 5: After uniformly coating the surface of the beaded steel billet from Step 3 with flux paste, place it in a box-type resistance furnace and hold it at 700℃ for 30 minutes.

[0088] Step 6: After taking out the beaded steel billet from Step 5, coat the surface evenly with a layer of flux paste, immerse it in the brazing filler metal solution from Step 4, keep it for 6 minutes, and then take it out.

[0089] Step 7: Using a cold spray gun, silicon nitride micro powder is cold sprayed onto the surface of the preheated steel billet with impregnation. After cooling, hard alloy brazed beads are obtained. The thickness of the brazing filler layer 2 containing diamond micro powder formed on the surface of the substrate 1 is 3.8 mm.

[0090] Example 4

[0091] The method for preparing low-resistance beads provided in this embodiment includes the following steps:

[0092] Step 1: Melt and cast the raw material of base 1 into a molding die to form the required streamlined body;

[0093] Step 2: Mount the base 1 on a milling machine and machine the base 1 with a circular through hole;

[0094] Step 3: A layer of cone-shaped cemented carbide particles 3 is uniformly cold-welded onto the surface of the substrate 1 from Step 2. The cemented carbide particles 3 are made of YG20, with a height of 6mm and a spacing of 6mm between two adjacent cemented carbide particles 3, so that their tips face outwards, to obtain a beaded steel billet.

[0095] Step 4: Place BCu58ZnMn in a graphite crucible and melt it into a solder liquid, maintaining the temperature at 900℃ to make the solder liquid semi-solid.

[0096] Step 5: After uniformly coating the surface of the beaded steel billet from Step 3 with flux paste, place it in a box-type resistance furnace and hold it at 650℃ for 20 minutes.

[0097] Step 6: After removing the beaded steel billet from Step 5, coat the surface evenly with a layer of flux paste, immerse it in the brazing filler metal solution from Step 4, keep it for 7 minutes, and then remove it.

[0098] Step 7: Using a cold spray gun, aluminum oxide micro powder is cold sprayed onto the surface of the preheated steel billet with impregnation. After cooling, hard alloy brazed beads are obtained. The thickness of the brazing filler layer 2 containing diamond micro powder formed on the surface of the substrate 1 is 4 mm.

[0099] Example 5

[0100] The method for preparing low-resistance beads provided in this embodiment includes the following steps:

[0101] Step 1: Melt and cast the raw material of base 1 into a molding die to form the required streamlined body;

[0102] Step 2: Mount the base 1 on a milling machine and machine the base 1 with a circular through hole;

[0103] Step 3: A layer of cone-shaped cemented carbide particles 3 is uniformly cold-welded onto the surface of the substrate 1 from Step 2. The cemented carbide particles 3 are made of YG6, the height of the cemented carbide particles 3 is 4.8mm, and the distance between two adjacent cemented carbide particles 3 is 5mm, so that their tips face outwards, to obtain a beaded steel billet.

[0104] Step 4: Place BCu58ZnMnNi in a graphite crucible and melt it into a solder liquid, maintaining the temperature at 930℃ to make the solder liquid semi-solid.

[0105] Step 5: After uniformly coating the surface of the beaded steel billet from Step 3 with flux paste, place it in a box-type resistance furnace and hold it at 680℃ for 25 minutes.

[0106] Step 6: After taking out the beaded steel billet from Step 5, coat the surface evenly with a layer of flux paste, immerse it in the brazing filler metal solution from Step 4, keep it for 8 minutes, and then take it out.

[0107] Step 7: Using a cold spray gun, diamond micro powder is cold sprayed onto the surface of the preheated steel billet with impregnation. After cooling, hard alloy brazed beads are obtained. The thickness of the brazing filler layer 2 containing diamond micro powder formed on the surface of the substrate 1 is 3.5 mm.

[0108] Example 6

[0109] The method for preparing low-resistance beads provided in this embodiment includes the following steps:

[0110] Step 1: Melt and cast the raw material of base 1 into a molding die to form the required streamlined body;

[0111] Step 2: Mount the base 1 on a milling machine and machine the base 1 with a circular through hole;

[0112] Step 3: A layer of cone-shaped cemented carbide particles 3 is uniformly cold-welded onto the surface of the substrate 1 from Step 2. The cemented carbide particles 3 are made of YG8, with a height of 5.5 mm and a spacing of 5 mm between two adjacent cemented carbide particles 3, so that their tips face outwards, to obtain a beaded steel billet.

[0113] Step 4: Place BCu58ZnMnCo in a graphite crucible and melt it into a solder liquid, maintaining the temperature at 920℃ to make the solder liquid semi-solid.

[0114] Step 5: After uniformly coating the surface of the beaded steel billet from Step 3 with flux paste, place it in a box-type resistance furnace and hold it at 700℃ for 30 minutes.

[0115] Step 6: After taking out the beaded steel billet from Step 5, coat the surface evenly with a layer of flux paste, immerse it in the brazing filler metal solution from Step 4, keep it for 8 minutes, and then take it out.

[0116] Step 7: Using a cold spray gun, aluminum oxide nanopowder is cold sprayed onto the surface of the preheated steel billet with impregnation. After cooling, hard alloy brazed beads are obtained. The thickness of the brazing filler layer 2 containing diamond micropowder formed on the surface of the substrate 1 is 4mm.

[0117] Comparative Example 1

[0118] There are existing cylindrical beads. The existing cylindrical beads are made of cemented carbide grinding blocks, with an outer diameter of 110mm, an inner diameter of 55mm, and a length of 50mm. Two beads are welded together by a brazing filler layer and threaded with steel wire rope, as in patent CN200910180207.0.

[0119] Experimental Example 1

[0120] To examine the underwater cutting efficiency of the carbide beads in this embodiment of the invention compared to existing beads, a self-made testing device was used to test the cutting efficiency of the beads. The beads were clamped on the crossbeam of the reciprocating mechanism, and a Q235 steel plate (80mm×30mm) to be cut was fixed below. A force was applied to fix the beads, causing them to reciprocate and the steel plate to hold them in place. At the same time, a load was slowly applied and stabilized at 9.8KN. The test lasted for 3 minutes, and the cutting efficiency, i.e., the cutting amount (the weight of the steel plate before cutting minus the weight of the steel plate after cutting), was calculated. The test was performed 5 times, and the average value was taken. Throughout the process, the beads and the steel plate were placed in a water tank.

[0121] Tests revealed that the beads in the embodiment experienced less water resistance and moved faster under a fixed force, while the existing cylindrical beads experienced greater water resistance and moved slower. The cutting amount is shown in Table 1 below.

[0122] Table 1. Cutting quantity test results

[0123]

[0124] The shape of the Q235 steel plate after cutting is as follows: Figure 2 As shown, the left side is a steel plate cut from existing beads in a comparative example, and the right side is a steel plate cut from beads in the embodiment. Verification showed that the cutting amount of the beads in Embodiment 5, which has lower cutting efficiency in this invention, is 38 grams, which is 11.4 grams more than the cutting amount of 26.6 grams for existing cylindrical beads, representing an increase of approximately 42.8%.

[0125] Experimental Example 2

[0126] To examine the welding reliability of the beads of the present invention and existing beads, the beads were cut open and their weld bonding rate was compared, that is, the percentage of the actual bonding area to the nominal bonding area.

[0127] The morphological diagram of the beaded seam is as follows: Figure 3 As shown, the left side shows the morphology of the existing beaded seam in Comparative Example 1, and the right side shows the morphology of the beaded seam in Example 5. Verification showed that the brazing rate of the seam in Example 5 was 94.5%, while the brazing rate of the existing beaded seam was 75.4%. A higher brazing rate indicates better reliability and less likelihood of tooth loss.

[0128] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing low-resistance beads, characterized in that, Includes the following steps: (a) Spot welding or cold welding of cemented carbide particles onto the outer surface of the substrate to obtain a beaded steel billet; (b) After applying flux paste to the surface of the beaded steel billet, heat preservation is performed; (c) After heat preservation, the surface of the beaded steel billet is coated with the flux paste and then immersed in the brazing filler metal solution for impregnation brazing; (d) After the impregnation brazing is completed, wear-resistant nanoparticles are coated on the surface of the beaded steel billet to form a wear-resistant nanoparticle layer; The low-resistance beads comprise: a matrix, a solder layer, and cemented carbide particles; The substrate is streamlined and has a circular through hole in the center; multiple cemented carbide particles are welded to the outer surface of the substrate through the brazing filler layer, which is a metallurgical reaction layer between the brazing filler and the substrate; A portion of the cemented carbide particles is embedded in the brazing filler layer; The surface of the solder layer is provided with a wear-resistant nanoparticle layer.

2. The method for preparing low-resistance beads according to claim 1, characterized in that, The wear-resistant nanoparticles are made of at least one of the following materials: diamond, cubic boron nitride, silicon nitride, or aluminum oxide.

3. The method for preparing low-resistance beads according to claim 1, characterized in that, The thickness of the wear-resistant nanoparticle layer is 30~50μm.

4. The method for preparing low-resistance beads according to claim 1, characterized in that, The wear-resistant nanoparticles have a particle size of 20~30μm.

5. The method for preparing low-resistance beads according to claim 1, characterized in that, The height of the cemented carbide particles is 4.8~6mm.

6. The method for preparing low-resistance beads according to claim 1, characterized in that, The thickness of the solder layer is 2 / 3 to 3 / 4 of the height of the cemented carbide particles.

7. The method for preparing low-resistance beads according to claim 1, characterized in that, The spacing between two adjacent cemented carbide particles is 1 / 2 to 1 times the height of the cemented carbide particle.

8. The method for preparing low-resistance beads according to claim 1, characterized in that, The cemented carbide particles are cone-shaped with their tips pointing outwards.

9. The method for preparing low-resistance beads according to claim 1, characterized in that, The material of the solder layer includes at least one of BCu58ZnMn, BCu58ZnMnNi, or BCu58ZnMnCo.

10. The method for preparing low-resistance beads according to claim 1, characterized in that, The material of the cemented carbide particles includes at least one of YG6, YG8, YG15 or YG20.

11. The method for preparing low-resistance beads according to claim 1, characterized in that, The immersion brazing time is 3 to 8 minutes.

12. The method for preparing low-resistance beads according to claim 1, characterized in that, The temperature of the brazing filler fluid is 900~930℃.

13. The method for preparing low-resistance beads according to claim 1, characterized in that, The insulation temperature is 650~700℃.

14. The method for preparing low-resistance beads according to claim 1, characterized in that, The heat preservation time is 20-30 minutes.

15. The method for preparing low-resistance beads according to claim 1, characterized in that, The flux paste includes: borax, boric acid, potassium fluoride and alcohol.

16. The method for preparing low-resistance beads according to claim 15, characterized in that, The mass ratio of the borax, the boric acid, the potassium fluoride, and the alcohol is 45~55:30~40:10~20:15~25.

17. A wire saw, characterized in that, The beads include those prepared by the method for preparing low-resistance beads according to any one of claims 1 to 16.

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