A kind of porous metal-ceramic composite binder diamond grinding wheel of prefabricated double-layer hollow particle and preparation thereof

Abstract

The present application relates to abrasive tool technology field, especially to a kind of prefabricated double-layer hollow particle porous metal-ceramic composite binder diamond grinding wheel and its preparation.The double-layer hollow particle provided by the present application is sequentially center cavity, ceramic binder layer and brazing alloy layer from inside to outside.The present application is used in the preparation of porous metal-ceramic composite binder diamond grinding wheel working layer section by prefabricating double-layer hollow particle, and the adjustment of porosity and the arrangement of pore structure of porous diamond grinding wheel can be realized, while improving porosity, increasing chip space, maintaining the strength of the grinding wheel, meeting the high quality processing requirements of different hard and brittle materials.

Description

Technical Field

[0001] This invention relates to the field of abrasive and grinding wheel technology, and in particular to a double-layer hollow particle and its preparation method, a porous metal-ceramic composite bonded diamond grinding wheel working layer segment and its preparation method, and a diamond grinding wheel. Background Technology

[0002] Rapid technological advancements have led to the emergence and widespread application of numerous new materials in engineering, including a large number of hard and brittle materials that are difficult to machine. When using grinding wheels to thin these materials, surface cracks and damage often occur due to the high grinding force and the material's hardness and brittleness. The part that performs the grinding action during the grinding wheel thinning process is the working layer of the grinding wheel. The microstructure of the working layer affects the grinding quality. For example, pores in the working layer can play a role in chip containment, chip removal, and heat dissipation. Too low a porosity can reduce the grinding efficiency and quality of the grinding wheel, while too high a porosity reduces the strength of the grinding wheel.

[0003] Currently, commonly used porous metal-bonded diamond grinding wheels are made by mixing the binder, diamond abrasive grains, and pore-forming agent, then pressing the powder into shape and sintering it. This results in good interfacial bonding and toughness, but poor self-sharpening properties and insufficient chip space within the working layer. Furthermore, the pore structure formed by the pore-forming agents used (such as titanium hydride, nickel hydride, and sodium chloride) has problems such as uneven pore shape, size, and distribution, which reduces the strength of the grinding wheel and the grinding quality. This can easily lead to problems such as insufficient workpiece machining accuracy, frequent grinding wheel dressing, and poor grinding quality stability. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a double-layer hollow particle and its preparation method, a porous metal-ceramic composite bonded diamond grinding wheel working layer segment and its preparation method, and a diamond grinding wheel. This invention can improve the porosity of the grinding wheel while ensuring its strength, optimize the shape, size, and distribution of the pore structure, and enhance the self-sharpening property of the grinding wheel.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a double-layer hollow particle, which, from the inside out, consists of a central cavity, a ceramic binder layer, and a brazing alloy layer.

[0007] Preferably, the outer diameter of the double-layer hollow particles is 0.08–1.00 mm, the thickness of the ceramic binder layer is 0.01–0.2 mm, and the thickness of the brazing alloy layer is 0.03–0.6 mm.

[0008] Preferably, the solder in the solder alloy layer includes Cu-Sn-Ti alloy solder and / or Ni-Cr alloy solder.

[0009] Preferably, the ceramic binder in the ceramic binder layer is a SiO2-Al2O3-B2O3-R2O system ceramic binder.

[0010] Preferably, the SiO2-Al2O3-B2O3-R2O ceramic binder comprises: 30-65 wt.% silicon dioxide, 5-10 wt.% aluminum oxide, 10-30 wt.% boric acid, and 20-30 wt.% sodium carbonate.

[0011] This invention provides a method for preparing the double-layer hollow particles described above, comprising the following steps:

[0012] A ceramic binder powder and a first adhesive are coated on the surface of polystyrene spherical particles, and after drying, an inner coating layer is formed; brazing alloy powder and a second adhesive are coated on the outside of the inner coating layer, and after drying, an outer coating layer is formed, resulting in a double-layer hollow particle blank.

[0013] The double-layer hollow granular preform is subjected to a first sintering process to remove the binder and polystyrene spherical particles, followed by heating and a second sintering process to obtain the double-layer hollow granules.

[0014] This invention provides a method for preparing porous metal-ceramic composite bonded diamond grinding wheel working layer segments, comprising the following steps:

[0015] Diamond abrasive grains and double-layer hollow particles are mixed, and the resulting mixture is pressed into shape to obtain a diamond grinding wheel segment blank.

[0016] The diamond grinding wheel segment blank is sintered to obtain the porous metal-ceramic composite bonded diamond grinding wheel working layer segment;

[0017] The double-layer hollow particles are the double-layer hollow particles described in the above scheme or the double-layer hollow particles prepared by the preparation method described in the above scheme.

[0018] Preferably, the content of diamond abrasive particles in the mixture is 30-55 wt.%, and the content of double-layer hollow particles is 45-70 wt.%.

[0019] The present invention provides a porous metal-ceramic composite bonded diamond grinding wheel working layer segment prepared by the preparation method described above.

[0020] The present invention provides a porous metal-ceramic composite bonded diamond grinding wheel, comprising a matrix and a working layer bonded to the matrix, wherein the working layer is composed of the working layer segments of the porous metal-ceramic composite bonded diamond grinding wheel described above.

[0021] This invention provides a double-layer hollow particle, which, from the inside out, consists of a central cavity, a ceramic binder layer, and a brazing alloy layer.

[0022] This invention utilizes pre-fabricated double-layer hollow particles, which are then used to prepare the working layer segments of porous metal-ceramic composite bonded diamond grinding wheels. This allows for the adjustment of the porosity and arrangement of the pore structure in the porous diamond grinding wheel, increasing porosity and chip space while maintaining wheel strength, thus meeting the high-quality processing requirements of various hard and brittle materials. Specifically, porosity can be controlled by adjusting the amount of double-layer hollow particles; the pore structure arrangement can be achieved by pre-arranging the double-layer hollow particles, for example, by using a binder to pre-arrange the hollow particles in a close-packed hexagonal or simple cubic structure; furthermore, because the pore structure of the double-layer hollow particles is uniform, it can maintain the uniformity of pore size in the working layer of the grinding wheel, avoiding stress concentration and pore wall rupture caused by uneven pore structure, thereby maintaining the strength of the grinding wheel.

[0023] In addition, the introduction of ceramic binder into the double-layer hollow particles ensures that it is evenly distributed in the porous metal-ceramic composite binder diamond grinding wheel, thereby enhancing the self-sharpening property of the grinding wheel. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a double-layered hollow particle.

[0025] Figure 2 A schematic diagram of a porous metal-ceramic composite bonded diamond grinding wheel;

[0026] Figure 3 This is a schematic diagram of the preparation process of the double-layer hollow particles in the embodiment. Detailed Implementation

[0027] like Figure 1 As shown, the present invention provides a double-layer hollow particle, which consists of a central cavity, a ceramic binder layer, and a brazing alloy layer from the inside out.

[0028] In this invention, the outer diameter of the double-layer hollow particle is preferably 0.08 to 1.00 mm. In specific embodiments, the outer diameter of the double-layer hollow particle can be 0.08 mm, 0.15 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1.00 mm.

[0029] In this invention, the thickness of the ceramic binder layer is preferably 0.01 to 0.2 mm. In specific embodiments, the thickness of the ceramic binder layer can be 0.01 mm, 0.05 mm, 0.1 mm, 0.15 mm, or 0.2 mm.

[0030] In this invention, the ceramic binder in the ceramic binder layer is preferably a SiO2-Al2O3-B2O3-R2O system ceramic binder; the SiO2-Al2O3-B2O3-R2O system ceramic binder preferably comprises: 30-65 wt.% silicon dioxide, 5-10 wt.% aluminum oxide, 10-30 wt.% boric acid, and 20-30 wt.% sodium carbonate. In specific embodiments, the content of silicon dioxide in the SiO2-Al2O3-B2O3-R2O ceramic binder can be 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, or 65 wt.%, the content of alumina can be 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%, the content of boric acid can be 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, or 30 wt.%, and the content of sodium carbonate can be 20 wt.%, 22 wt.%, 24 wt.%, 26 wt.%, 28 wt.%, or 30 wt.%. In this invention, the ceramic binder layer serves to enhance the self-sharpening properties of the working layer.

[0031] In this invention, the thickness of the solder alloy layer is preferably 0.03 to 0.6 mm. In specific embodiments, the thickness of the solder alloy layer can be 0.03 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or 0.6 mm.

[0032] In this invention, the solder in the solder alloy layer preferably includes Cu-Sn-Ti alloy solder and / or Ni-Cr alloy solder. This invention does not have special requirements for the specific composition of the Cu-Sn-Ti alloy solder and Ni-Cr alloy solder; compositions well-known in the art can be used. In embodiments of this invention, the Cu-Sn-Ti alloy solder can specifically be Cu-20wt.%Sn-10wt.%Ti alloy solder or Cu-30wt.%Sn-10wt.%Ti. In this invention, the function of the solder alloy layer is to wet the diamond abrasive grains and form a good bond with them, enabling the diamond wheel segments to better hold the diamond abrasive grains. Simultaneously, it forms a good bond with the ceramic binder, creating a metal-ceramic composite binder, which enhances the self-sharpening property of the grinding wheel.

[0033] This invention provides a method for preparing the double-layer hollow particles described above, comprising the following steps:

[0034] A ceramic binder powder and a first adhesive are coated on the surface of polystyrene spherical particles, and after drying, an inner coating layer is formed; brazing alloy powder and a second adhesive are coated on the outside of the inner coating layer, and after drying, an outer coating layer is formed, resulting in a double-layer hollow particle blank.

[0035] The double-layer hollow granular preform is subjected to a first sintering process to remove the binder and polystyrene spherical particles, followed by heating and a second sintering process to obtain the double-layer hollow granules.

[0036] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.

[0037] The present invention involves coating the surface of polystyrene spherical particles with ceramic binder powder and a first adhesive, which are then dried to form an inner coating layer.

[0038] In this invention, the outer diameter of the polystyrene spherical particles is preferably 0.05 to 0.20 mm. In specific embodiments, the particle size of the polystyrene spherical particles can be 0.05 mm, 0.10 mm, 0.15 mm, or 0.20 mm.

[0039] The present invention does not have special requirements for the preparation process of the ceramic binder powder; any preparation method well known in the art can be used. In the present invention, the preparation of the ceramic binder powder preferably includes: weighing the ceramic binder raw materials according to the specified ratio, grinding them, mixing them evenly in a ball mill, pressing them into blocks using a hydraulic press, placing them in a crucible, melting them in a high-temperature melting furnace, quenching the melted ceramic binder in water to form a glass material, drying it, ball milling it for 2 hours, pulverizing it, and sieving it to obtain the ceramic binder powder.

[0040] In this invention, when the ceramic binder is a SiO2-Al2O3-B2O3-R2O system ceramic binder, the raw materials of the ceramic binder include: 30-65 wt.% silicon dioxide, 5-10 wt.% aluminum oxide, 10-30 wt.% boric acid and 20-30 wt.% sodium carbonate.

[0041] In this invention, the melting temperature is preferably 1200-1500℃. In specific embodiments, the melting temperature can be 1200℃, 1300℃, 1400℃ or 1500℃.

[0042] In this invention, the ceramic binder powder is preferably able to pass through a 200-mesh sieve.

[0043] In this invention, the first adhesive is preferably a polyvinyl alcohol aqueous solution with a mass concentration of 2-6%.

[0044] In this invention, the mass ratio of the polystyrene spherical particles to the first binder is preferably 1:2 to 3, and in specific embodiments, it can be 1:2, 1:2.5, or 1:3; the mass ratio of the polystyrene spherical particles to the ceramic binder powder is preferably 1:20 to 30, and in specific embodiments, it can be 1:20, 1:22, 1:24, 1:26, 1:28, or 1:30.

[0045] In this invention, the coating is preferably performed in an automatic coating machine. Preferably, polystyrene spherical particles are placed in the automatic coating machine, the machine speed is adjusted to 25–50 r / min, and a first binder and ceramic binder powder are added into the machine using a nozzle device. The ceramic binder powder is then uniformly coated onto the surface of the polystyrene spherical particles. After coating for 2–5 minutes, the particles are removed, forming a wet inner coating layer.

[0046] The present invention does not have special requirements for the drying conditions.

[0047] After forming the inner coating layer, the present invention coats the outer surface of the inner coating layer with brazing alloy powder and a second binder, and after drying, forms an outer coating layer, thus obtaining a double-layer hollow granular blank.

[0048] In this invention, the second adhesive is preferably a polyvinyl alcohol aqueous solution with a mass concentration of 2-6%.

[0049] In this invention, the mass ratio of the second binder to the brazing alloy powder is preferably 1:20 to 40; in specific embodiments, it can be 1:20, 1:25, 1:30, 1:35 or 1:40.

[0050] In this invention, the particles coated with the inner coating layer are preferably put back into an automatic coating machine, and a second binder and brazing alloy powder are added to make the brazing alloy powder uniformly coated on the outside of the inner coating layer. After coating for 2 to 5 minutes, the particles are taken out to form a wet outer coating layer.

[0051] After obtaining the double-layer hollow granular preform, the present invention sequentially performs a first sintering to remove the binder and polystyrene spherical particles, followed by heating and a second sintering to obtain the double-layer hollow particles.

[0052] In this invention, the preferred temperature for the first sintering is 300–350°C, and the preferred holding time is 10–20 min. In specific embodiments, the temperature for the first sintering can be 300°C, 320°C, 340°C, or 350°C, and the preferred holding time can be 10 min, 15 min, or 20 min. In this invention, the rate of heating to the temperature for the first sintering is preferably 1–3°C / min. This invention uses the first sintering to volatilize and remove the binder and polystyrene spherical particles, forming a central cavity, a ceramic binder layer, and a solder alloy layer.

[0053] In this invention, the rate of heating from the temperature of the first sintering to the temperature of the second sintering is preferably 10 to 20 °C / min; in specific embodiments, it can be 10 °C / min, 13 °C / min, 15 °C / min, 17 °C / min or 20 °C / min.

[0054] In this invention, the preferred sintering temperature is 0.9 to 1.1 times the melting point of the brazing alloy powder, and the preferred holding time is 30 to 120 minutes. In specific embodiments, the sintering temperature can be 0.9, 1, or 1.1 times the melting point of the brazing alloy powder, and the holding time can be 30 minutes, 60 minutes, 90 minutes, or 120 minutes. This invention uses the second sintering to create a bond between the particles of the spherical wall, forming a complete spherical wall. In this invention, the first and second sintering are preferably performed under vacuum conditions.

[0055] This invention provides a method for preparing porous metal-ceramic composite bonded diamond grinding wheel working layer segments, comprising the following steps: mixing diamond abrasive grains with the above-mentioned double-layer hollow particles, pressing the resulting mixture into a molding shape to obtain a diamond grinding wheel segment blank;

[0056] The diamond grinding wheel segment blank is sintered to obtain the porous metal-ceramic composite bonded diamond grinding wheel working layer segment.

[0057] In this invention, the particle size of the diamond abrasive is preferably 75-150 μm; in specific embodiments, the particle size of the diamond abrasive can be 75 μm, 100 μm, 120 μm, 130 μm or 150 μm.

[0058] In this invention, the mixing is preferably carried out in a mixer.

[0059] In this invention, the preferred content of diamond abrasive particles in the mixture is 30-55 wt.%, and the preferred content of double-layer hollow particles is 45-70 wt.%. In specific embodiments, the content of diamond abrasive particles in the mixture can be 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, or 55 wt.%, with the remainder being double-layer hollow particles. This invention can regulate the porosity of the working layer by controlling the content of double-layer hollow particles; the higher the content, the higher the porosity. By controlling the content of double-layer hollow particles within the above range, this invention can improve the porosity of the grinding wheel while ensuring its strength.

[0060] In this invention, the pressing and molding is preferably cold pressing, and the pressure of the cold pressing is preferably 10-30 MPa. In specific embodiments, the pressure of the cold pressing can be 10 MPa, 20 MPa, or 30 MPa. This invention preferably uses a hydraulic press for pressing and molding.

[0061] In this invention, the sintering temperature is preferably 0.9 to 1.1 times the melting point of the brazing alloy powder, and the holding time is preferably 10 to 60 minutes. In specific embodiments, the sintering temperature can be 0.9, 1, or 1.1 times the melting point of the brazing alloy powder, and the holding time can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, or 60 minutes. In this invention, the sintering is preferably performed under vacuum conditions. This invention promotes a strong bond between diamond abrasive grains and double-layer hollow particles through sintering.

[0062] This invention provides a porous metal-ceramic composite bonded diamond grinding wheel working layer segment prepared by the method described above. The porous metal-ceramic composite bonded diamond grinding wheel working layer segment has high porosity and high strength. Specifically, the porosity of the porous metal-ceramic composite bonded diamond grinding wheel working layer segment is preferably 40-60%, and the strength is preferably 50-70 MPa.

[0063] The present invention provides a porous metal-ceramic composite bonded diamond grinding wheel, comprising a matrix and a working layer bonded to the matrix, wherein the working layer is composed of the working layer segments of the porous metal-ceramic composite bonded diamond grinding wheel described above.

[0064] The present invention does not have any special requirements for the preparation method of the porous metal-ceramic composite bonded diamond grinding wheel; the segments and the matrix can be directly bonded together by curing with an organic adhesive.

[0065] Figure 2 This is a schematic diagram of the structure of a porous metal-ceramic composite bonded diamond grinding wheel, as shown below. Figure 2 As shown, double-layer hollow particles and diamond abrasive grains are evenly distributed in the working layer, wherein the cavity of the double-layer hollow particles provides chip space during grinding.

[0066] The porous metal-ceramic composite bonded diamond grinding wheel provided by this invention can adjust the porosity and arrange the pore structure of the porous diamond grinding wheel by using pre-made double-layer particles. While increasing the porosity and chip space, it maintains the strength of the grinding wheel and meets the high-quality processing requirements of different hard and brittle materials.

[0067] In addition, the introduction of ceramic binder into the double-layer hollow particles ensures that it is evenly distributed in the porous metal-ceramic composite binder diamond grinding wheel, thereby enhancing the self-sharpening property of the grinding wheel.

[0068] The following detailed descriptions, in conjunction with embodiments, illustrate the double-layer hollow particles and their preparation method, the porous metal-ceramic composite binder diamond grinding wheel working layer segment and its preparation method, and the diamond grinding wheel provided by this invention. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0069] Example 1

[0070] Step 1: Weigh the raw materials according to the following proportions: 45 wt.% silicon dioxide, 6 wt.% aluminum oxide, 23 wt.% boric acid, and 26 wt.% sodium carbonate. Grind them in a mortar and grind them in a ball mill until evenly mixed. Press the mixture into blocks using a hydraulic press, place them in a crucible, and melt them in a high-temperature melting furnace at 1400°C. After holding the temperature, quench the molten ceramic binder with water to form a glass material. Dry the glass material in a drying oven at 80°C, and then ball mill it for 2 hours. After pulverizing, pass it through a 200-mesh sieve to obtain ceramic binder powder.

[0071] Step 2, as follows Figure 3 As shown, 1g of polystyrene spherical particles with an outer diameter of 0.1mm were placed into an automatic coating machine. The machine speed was adjusted to 40r / min. Using a nozzle device, 2g of a 3% polyvinyl alcohol aqueous solution and 20g of ceramic binder powder were added sequentially into the coating machine. Under the action of the binder, the ceramic binder powder was evenly coated on the surface of the spherical particles. After coating for 3 minutes, the particles were removed and placed in a dryer for drying. After drying, the resulting green blank was placed back into the coating machine, and 2g of a 3% polyvinyl alcohol aqueous solution and 40g of a brazing alloy with a composition of Cu-20wt.%Sn-10wt.%Ti were added sequentially into the coating machine. Powder (melting point 840℃) is used to uniformly coat the outside of the ceramic binder layer with brazing alloy. After coating for 3 minutes, the coated material is removed and dried in a dryer to obtain a double-layer granular blank. The blank is placed in a vacuum sintering furnace and heated to 300℃ at a heating rate of 2℃ / min, and held for 10 minutes to volatilize the polystyrene spherical particles. Then, the temperature is rapidly increased to 920℃ at a rate of 10℃ / min and held for 30 minutes to form hollow particles. After cooling in the furnace, the blank is removed to obtain a double-layer hollow particle with an outer diameter of 0.16mm, a ceramic binder layer thickness of 0.02mm, and a brazing alloy layer thickness of 0.06mm.

[0072] Step 3: Weigh out diamond abrasive grains with a particle size of 75μm and double-layer hollow particles with an outer diameter of 0.16mm, according to the ratio of 35wt.% diamond abrasive grains and 65wt.% double-layer hollow particles. Mix them evenly in a mixer. Pour the mixed material into a mold, place it on a hydraulic press and apply a pressure of 18MPa to cold press and form diamond grinding wheel segment blanks.

[0073] Step 4: Place the segment blank into a vacuum sintering furnace and sinter the segment blank at 900℃ for 10 minutes to promote the formation of a strong bond between the diamond abrasive grains and the double-layer hollow particles, and obtain a porous metal-ceramic composite bonded diamond grinding wheel working layer segment.

[0074] Step 5: The working layer segments are bonded to the aluminum substrate using an organic adhesive to obtain a porous metal-ceramic composite diamond grinding wheel containing prefabricated double-layer hollow particles, in which the working layer and the substrate are tightly bonded.

[0075] Example 2

[0076] Step 1: Weigh the raw materials according to the following proportions: 40 wt.% silicon dioxide, 6 wt.% aluminum oxide, 30 wt.% boric acid, and 24 wt.% sodium carbonate. Grind them in a mortar and grind them in a ball mill until they are evenly mixed. Press the mixture into blocks using a hydraulic press, place them in a crucible, and melt them in a high-temperature melting furnace at 1450°C. After holding the temperature, quench the molten ceramic binder with water to form a glass material. Dry the glass material in a drying oven at 80°C, and then ball mill it for 2 hours. After pulverizing, pass it through a 200-mesh sieve to obtain ceramic binder powder.

[0077] Step 2: Place 1g of polystyrene spherical particles with an outer diameter of 0.2mm into an automatic coating machine. Adjust the machine speed to 50r / min. Using a nozzle device, sequentially add 2g of a 4% polyvinyl alcohol aqueous solution and 25g of ceramic binder powder into the coating machine. Under the action of the binder, the ceramic binder powder is evenly coated on the surface of the spherical particles. After coating for 3 minutes, remove the particles and place them in a dryer to dry. After drying, place the resulting green blank back into the coating machine and sequentially add 2g of a 3% polyvinyl alcohol aqueous solution and 50g of a brazing alloy with a composition of Cu-30wt.%Sn-10wt.%Ti. Powder (melting point 780℃) is used to uniformly coat the outside of the ceramic binder layer with brazing alloy. After coating for 3 minutes, the coated material is removed and dried in a dryer to obtain a double-layer granular blank. The blank is placed in a vacuum sintering furnace and heated to 300℃ at a heating rate of 2℃ / min, and held for 20 minutes to volatilize the polystyrene spherical particles. Then, the temperature is rapidly increased to 850℃ at a rate of 10℃ / min and held for 120 minutes to form hollow particles. After cooling in the furnace, the blank is removed to obtain a double-layer hollow particle with an outer diameter of 0.38mm, a ceramic binder layer thickness of 0.05mm, and a brazing alloy layer thickness of 0.15mm.

[0078] Step 3: Weigh out diamond abrasive grains with a particle size of 100μm and double-layer hollow particles with an outer diameter of 0.38mm, according to the following ratio: 50wt.% diamond abrasive grains and 50wt.% double-layer hollow particles. Mix them evenly in a mixer. Pour the mixed material into a mold, place it on a hydraulic press and apply a pressure of 20MPa to cold press and form diamond grinding wheel segment blanks.

[0079] Step 4: Place the segmented blank into a vacuum sintering furnace and sinter it at 830℃ for 20 minutes to promote the formation of a strong bond between the diamond abrasive grains and the double-layer hollow particles, thereby obtaining a porous metal-ceramic composite bonded diamond grinding wheel working layer segment.

[0080] Step 5: The working layer segments are bonded to the aluminum substrate using an organic adhesive to obtain a porous metal-ceramic composite diamond grinding wheel containing prefabricated double-layer hollow particles, in which the working layer and the substrate are tightly bonded.

[0081] Example 3

[0082] Step 1: Weigh the raw materials according to the following proportions: 55 wt.% silicon dioxide, 7 wt.% aluminum oxide, 10 wt.% boric acid, and 28 wt.% sodium carbonate. Grind them in a mortar and grind them in a ball mill until evenly mixed. Press the mixture into blocks using a hydraulic press, place them in a crucible, and melt them in a high-temperature melting furnace at 1400℃. After holding the temperature, quench the molten ceramic binder with water to form a glass material. Dry it in a drying oven at 80℃, and then ball mill it for 2 hours. After pulverizing, pass it through a 200-mesh sieve to obtain ceramic binder powder.

[0083] Step 2: Place 1g of polystyrene spherical particles with an outer diameter of 0.2mm into an automatic coating machine. Adjust the machine speed to 50r / min. Using a nozzle device, sequentially add 2g of a 4% polyvinyl alcohol aqueous solution and 20g of ceramic binder powder into the coating machine. Under the action of the binder, the ceramic binder powder is evenly coated on the surface of the spherical particles. After coating for 5 minutes, remove the particles and place them in a dryer to dry. After drying, place the resulting green blank back into the coating machine and sequentially add 2g of a 3% polyvinyl alcohol aqueous solution and 40g of Ni-Cr brazing alloy powder (melting point 1050℃). The brazing alloy is uniformly coated on the outside of the ceramic binder layer. After coating for 3 minutes, the coated material is removed and dried in a dryer to obtain a double-layer granular blank. The blank is placed in a vacuum sintering furnace and heated to 320°C at a heating rate of 2°C / min and held for 20 minutes to volatilize the polystyrene spherical particles. Then, the temperature is rapidly increased to 1150°C at a rate of 15°C / min and held for 90 minutes to form hollow particles. After cooling in the furnace, the blank is removed to obtain a double-layer hollow particle with an outer diameter of 0.38 mm, a ceramic binder layer thickness of 0.05 mm, and a brazing alloy layer thickness of 0.15 mm.

[0084] Step 3: Weigh out diamond abrasive grains with a diameter of 150μm and double-layer hollow particles with an outer diameter of 0.38mm, according to the following ratio: 40wt.% diamond abrasive grains and 60wt.% double-layer hollow particles. Mix them evenly in a mixer. Pour the mixed material into a mold, place it on a hydraulic press and apply a pressure of 20MPa to cold press and form diamond grinding wheel segment blanks.

[0085] Step 4: Place the segmented blank into a vacuum sintering furnace and sinter it at 1050℃ for 10 minutes to promote the formation of a strong bond between the diamond abrasive grains and the double-layer hollow particles, thereby obtaining a porous metal-ceramic composite bonded diamond grinding wheel working layer segment.

[0086] Step 5: The working layer segments are bonded to the aluminum substrate using an organic adhesive to obtain a porous metal-ceramic composite diamond grinding wheel containing prefabricated double-layer hollow particles, in which the working layer and the substrate are tightly bonded.

[0087] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A double-layer hollow particle, comprising, from the inside out, a central cavity, a ceramic binder layer, and a brazing alloy layer; the outer diameter of the double-layer hollow particle is 0.08~1.00 mm, the thickness of the ceramic binder layer is 0.01~0.2 mm, and the thickness of the brazing alloy layer is 0.03~0.6 mm; The ceramic binder in the ceramic binder layer is a SiO2-Al2O3-B2O3-R2O system ceramic binder; The SiO2-Al2O3-B2O3-R2O ceramic binder includes: 30-65 wt.% silicon dioxide, 5-10 wt.% aluminum oxide, 10-30 wt.% boric acid and 20-30 wt.% sodium carbonate.

2. The double-layer hollow particle according to claim 1, characterized in that, The solder in the solder alloy layer includes Cu-Sn-Ti alloy solder and / or Ni-Cr alloy solder.

3. A method for preparing the double-layer hollow particles according to any one of claims 1 to 2, comprising the following steps: A ceramic binder powder and a first adhesive are coated on the surface of polystyrene spherical particles, and after drying, an inner coating layer is formed. The inner coating layer is coated with brazing alloy powder and a second binder, and after drying, an outer coating layer is formed, resulting in a double-layer hollow granular blank. The double-layer hollow granular preform is subjected to a first sintering process to remove the binder and polystyrene spherical particles, followed by heating and a second sintering process to obtain the double-layer hollow granules.

4. A method for preparing porous metal-ceramic composite bonded diamond grinding wheel working layer segments, characterized in that, Includes the following steps: Diamond abrasive grains and double-layer hollow particles are mixed, and the resulting mixture is pressed into shape to obtain a diamond grinding wheel segment blank. The diamond grinding wheel segment blank is sintered to obtain the porous metal-ceramic composite bonded diamond grinding wheel working layer segment; The double-layer hollow particle is the double-layer hollow particle according to any one of claims 1 to 2 or the double-layer hollow particle prepared by the preparation method according to claim 3.

5. The preparation method according to claim 4, characterized in that, The mixture contains 30-55 wt.% diamond abrasive particles and 45-70 wt.% double-layer hollow particles.

6. The porous metal-ceramic composite bonded diamond grinding wheel working layer segment obtained by the preparation method of claim 4 or 5.

7. A porous metal-ceramic composite bonded diamond grinding wheel, characterized in that, It includes a substrate and a working layer bonded to the substrate, the working layer being composed of porous metal-ceramic composite bonded diamond grinding wheel working layer segments as described in claim 5.

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