Agglomerated diamond powder and preparation method thereof

Abstract

The invention relates to agglomerated diamond powder and a preparation method thereof, and the agglomerated diamond powder comprises the following components in percentage by weight: 40-60% of diamond micro-powder with the particle size of 1.5-5 microns and 40-60% of a ceramic bond, the ceramic bonding agent is prepared from the following components in percentage by weight: 35 to 42 percent of B2O3, 15 to 20 percent of Al2O3, 15 to 20 percent of SiO2, 6 to 8 percent of alkaline activating agent, 1 to 3 percent of rare earth oxide, 6 to 7 percent of Si, 1 to 3 percent of TiC, 2 to 3 percent of MnO and 3 to 4 percent of Cr2O3; 1%-2% of CeO2 and 0.5%-1% of V2O5. It can be known from the table 4 that a grinding wheel prepared from the agglomerated diamond powder prepared through the method has good grinding performance, the bending strength ranges from 55 MPa to 60 MPa, the Vickers hardness ranges from 67 HRB to 75 HRB, and the grinding ratio ranges from 736 to 789. The agglomerated diamond powder disclosed by the invention can be used for diamond grinding liquid, and is matched with grinding leather to process hard and brittle materials such as sapphire wafers, silicon carbide wafers and functional ceramics; and the cutting fluid is matched with cutting fluid to process hard and brittle materials such as glass ceramic cover plates, sapphire wafers and silicon carbide wafers.

Description

Technical Field

[0001] This invention relates to an agglomerated diamond powder and its preparation method, belonging to the field of diamond abrasives. Background Technology

[0002] Diamond abrasives are primarily used for grinding and polishing hard and brittle materials such as glass, ceramics, gemstones, and cemented carbide. Traditional diamond abrasives mainly use single-crystal diamond micropowder as the abrasive and ceramic, resin, or metal binders as the matrix. Ceramic-bonded diamond wheels have high rigidity, good self-sharpening properties, strong holding force for diamond abrasive grains, and adjustable porosity, making them suitable for machining hard and brittle materials. Diamond, due to its series of excellent properties, is the most widely used abrasive in the abrasive and grinding wheel industry. However, because diamond has a smooth surface and some defects, its mechanical properties often differ significantly from those of resins, ceramics, and other materials. The bonding force between diamond and the matrix is ​​difficult to control. If the bonding force is too weak, the abrasive grains easily detach from the matrix during machining, resulting in significant waste. If the bonding force is too strong, the diamond grains are not easily detached after wear during grinding, resulting in poor self-sharpening properties. Therefore, developing agglomerated diamond powder with spherical particles, consistent internal and external structure, good self-sharpening properties, and stable cutting force is of great significance. Summary of the Invention

[0003] This invention provides an agglomerated diamond powder and its preparation method, which solves the problems of poor self-sharpening property and poor cutting force stability of existing agglomerated diamond powder.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An agglomerated diamond powder, by weight percentage, comprises 40-60% diamond particles with a particle size of 1.5-5μm and 40-60% ceramic binder; the ceramic binder, by weight percentage, comprises B2O3: 35-42%, Al2O3: 15-20%, SiO2: 15-20%, alkaline activator: 6-8%, rare earth oxides: 1-3%, Si: 6-7%, TiC: 1-3%, MnO: 2-3%, Cr2O3: 3-4%; CeO2: 1-2%, V2O5: 0.5-1%.

[0005] Further, preferably, the alkaline activator is sodium carbonate or sodium hydroxide.

[0006] Further, preferably: the rare earth oxides are Y2O3 and Nd2O3, and the weight ratio of Y2O3 to Nd2O3 is 1:1-3:1.

[0007] Furthermore, preferably, the ceramic binder is prepared by the following method: (1) Mix B2O3, Al2O3 and SiO2 in proportion, add deionized water, water-to-material ratio 1:3, ball mill for 4 hours to form a uniform basic glass phase slurry; (2) Dry mix the remaining raw materials for 30 minutes to disperse them evenly, and obtain the additive mixture; (3) Composite powder: The base glass phase slurry is mixed with the additive mixture, spray dried and granulated to obtain particles with a particle size of 60-80μm; (4) Dehydrate the mixture at 350-450℃, and then melt it at 1100℃-1200℃ for 1-2 hours to obtain glass melt; (5) The glass melt is quenched with water, stirred and ground, and dried to obtain a ceramic binder with a particle size of 0.5-1μm.

[0008] The method for preparing agglomerated diamond powder of the present invention includes the following steps: (1) Mixing: Diamond micron, ceramic binder and silane coupling agent are mixed in proportion, water is added to form a suspension with a solid content of 50%, ball milling for 30 min, ball-to-material ratio 3:1; (2) Spray granulation: Spray granulation is carried out under the conditions of inlet temperature 180-190℃ and outlet temperature 100-110℃; (3) Sintering: Heat to 350-400℃ at 5℃ / min and hold for 1-1.5 hours; Heat to 600-650℃ at 10℃ / min and hold for 1-2 hours, then cool naturally; (4) Hydraulic classification; (5) Drying: 100-105℃, dry for 6-8 hours to obtain agglomerated diamond powder.

[0009] The beneficial effects of this invention are: The agglomerated diamond powder of the present invention has a round shape, a small cutting edge, and is not likely to cause deep scratches to the workpiece being processed; it has the isotropic characteristics of polycrystalline diamond, has no fixed dissociation surface, and has good wear resistance; the spherical particles have a consistent internal and external structure, good self-sharpening properties, and stable cutting force.

[0010] Grinding wheels prepared using the agglomerated diamond powder of this invention exhibit excellent grinding performance, with a bending strength of 55-60 MPa, a Vickers hardness of 67-75 HRB, and a grinding ratio of 736-789. The agglomerated diamond powder of this invention can be used in diamond grinding fluids (with grinding pads) to process hard and brittle materials such as sapphire wafers, silicon carbide wafers, and functional ceramics; and in diamond grinding pads (with cutting fluids) to process hard and brittle materials such as microcrystalline glass covers, sapphire wafers, and silicon carbide wafers.

[0011] The agglomerated diamond powder of the present invention can be used in precision polishing and ultra-precision polishing, and as a lubricant or additive to other materials, it can improve friction performance. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 Scanning electron microscope image of aggregated diamond powder with a diameter of 30 μm; Figure 2 Scanning electron microscope image of aggregated diamond powder with a diameter of 10 μm; Figure 3 The graphs show the grinding ratios for different embodiments. Detailed Implementation

[0014] 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are also described.

[0015] Examples 1-6 An agglomerated diamond powder, by weight percentage, comprises 50% diamond particles with a particle size of 1.5 mm and 50% ceramic binder; the ceramic binder, by weight percentage, comprises B2O3: 35-42%, Al2O3: 15-20%, SiO2: 15-20%, alkaline activator: 6-8%, rare earth oxides: 1-3%, Si: 6-7%, TiC: 1-3%, MnO: 2-3%, Cr2O3: 3-4%; CeO2: 1-2%, V2O5: 0.5-1%. The specific raw material composition and proportion of the ceramic binder are shown in Table 1.

[0016] The alkaline activator is sodium carbonate; the rare earth oxides are Y2O3 and Nd2O3, wherein the weight ratio of Y2O3 to Nd2O3 is 3:1; The preparation method of ceramic binder is as follows: Mix various raw materials in proportion, add deionized water at a water-to-material ratio of 1:3, ball mill for 4 hours to form a uniform slurry; dehydrate the mixture at 400℃, and then melt it at 1100℃ for 2 hours to obtain glass melt; quench the glass melt with water, grind it finely with stirring mill, and dry it to obtain ceramic binder with particle size of 0.5-1μm.

[0017] The preparation method of agglomerated diamond powder includes the following steps: (1) Mixing: Diamond micron and ceramic binder are mixed in proportion, water is added to form a suspension with a solid content of 50%, ball milling for 30 minutes, ball-to-material ratio 3:1; (2) Spray granulation: Spray granulation is carried out under the following conditions: inlet temperature 190℃, outlet temperature 110℃, feed rate 100 ml / min, and centrifugal speed 12000 rpm. (3) Sintering: Heat to 3400℃ at 5℃ / min and hold for 1 hour; Heat to 650℃ at 10℃ / min and hold for 1 hour, then cool naturally; (4) Hydraulic classification; (5) Drying: Dry at 105℃ for 6 hours to obtain agglomerated diamond powder with a particle size of 32μm.

[0018] Table 1. Raw material composition and proportions of ceramic binders in different embodiments

[0019] Scanning electron microscopy (SEM) images were taken of the agglomerated diamond powder prepared in Example 1, as detailed in the image. Figure 1 and 2 .

[0020] Depend on Figure 1 and 2 It is known that the agglomerated diamond powder prepared by the present invention has a round shape and a small cutting edge, and is not likely to cause deep scratches to the workpiece being processed.

[0021] The energy of the prepared ceramic-bonded diamond grinding wheel was measured according to the following method, and the specific results are shown in Table 2.

[0022] 1. Sample preparation for determination: (1) The ceramic-bonded diamond grinding wheel material is composed of the following components by mass percentage: agglomerated diamond powder prepared in Examples 1-6: 60%, ceramic binder prepared in Examples 1-6: 35%, and dextrin powder: 5%. The mixture is made uniform, and the raw materials are free of lumps and loose, to obtain a uniformly mixed diamond grinding wheel raw material. (2) Weigh the mixed diamond raw materials according to the formula, put them into the grinding wheel strip pressing mold, and press them on the electric tablet press. Adjust the pressure of the electric tablet press to 6.0 MPa and the holding time is 20 seconds. After the holding time is completed, take out the diamond grinding wheel strip. The size of the pressed diamond grinding wheel strip is 30×6×6 mm. (3) De-gumming: De-gumming the dry-pressed blank; (4) Sintering: After the glue removal is completed, the vacuum inside the furnace is evacuated to 0.004MPa~0.006MPa, and then 0.03MPa of argon gas is introduced. The temperature is raised to 260℃ at a heating rate of 3℃ / min and held for 60min. Then the temperature is raised to 660℃ at a heating rate of 2℃ / min and held for 60min. The sample is then cooled with the furnace to obtain the test sample.

[0023] 2. Bending strength and Vickers hardness of ceramic-bonded diamond grinding wheels:

[0024] The ceramic-bonded diamond grinding wheels prepared in Examples 1-3 were subjected to bending strength tests using the three-point bending method according to GB / T 6569-2006 standard, wherein the indenter loading rate was 0.5 mm / min and the lower span L was 16 mm.

[0025] The Vickers hardness of ceramic bonded diamond grinding wheels was tested using a Vickers hardness tester according to the GB / T4340.1-2009 standard. The load used was 0.2 kg, the holding time was 10 s, and the indentation shape was conical.

[0026] 3. Grinding ratio of grinding wheel: Grinding tests were conducted on 5-inch monocrystalline silicon using a rotary table grinding method. The workpiece rotation speed was 400 rpm, the feed rate was 0.2 μm / s, the grinding coolant was water, and the grinding time was 0.5 h. The grinding ratio was tested by measuring the height changes of the grinding wheel and the workpiece before and after grinding, calculating the volume change value, and calculating the grinding ratio G of the grinding wheel according to Formula 1.

[0027] G =(V W1 -V W2 ) / ( V S1 -V S2 )× 100% (1) In the formula: G is the grinding ratio of the grinding wheel, and Vw1 is the volume of the workpiece before grinding (mm). 3 Vw2 is the volume of the workpiece after grinding (mm). 3 Vs1 is the volume before grinding (mm). 3 Vs2 is the volume after grinding by the grinding wheel (mm). 3 ).

[0028] Table 2. Grinding performance test results of grinding wheels from different embodiments

[0029] As shown in Table 2, the grinding wheel prepared using the agglomerated diamond powder of the present invention exhibits good compressive strength, Vickers hardness, and grinding ratio. Compared with Examples 2 and 3, Example 1 uses Si powder and TiC powder as agglomerants. Compared with using Si powder and TiC powder alone, the ceramic binder of the present invention can effectively agglomerate diamond micropowder. Si powder encapsulates the microcrystals by forming an amorphous glass phase, retaining part of the cutting edge, while TiC powder enhances the bonding strength by generating TiO2 crystals. The synergy of the two can achieve the best agglomeration effect and performance balance, so that the bonding force between diamond and matrix is ​​in a good balance. The prepared agglomerated diamond powder not only has good self-sharpening properties but also stable grinding force.

[0030] Compared to Examples 4-6, this invention employs a composite additive containing MnO, Cr2O3, CeO, and V2O5. Through their interaction, the bonding strength and self-sharpening properties of the product can be effectively improved. The addition of Cr2O3 enhances chemical bonding by forming a CrC transition layer, while V2O5 enhances mechanical bonding by forming a VC transition layer and promoting liquid phase formation. Together, these enhance the binder's holding power over diamond. The grain boundary refining effect of CeO2 synergistically complements the glass phase formation effect of Si, improving the compactness and uniformity of the binder and reducing porosity, thereby enhancing overall bonding strength. The oxygen vacancy characteristics of CeO2 synergistically complement the thermal stability of Al2O3, significantly reducing the binder's coefficient of thermal expansion, making it more compatible with the coefficient of thermal expansion of diamond. This reduces interfacial failure caused by thermal stress and improves the service life of the abrasive.

[0031] MnO promotes micro-edge breakage by reducing wettability, while CeO2 introduces controllable microcracks through oxygen vacancies. Their synergistic effect allows the abrasive grains to continuously expose new cutting edges during use, extending the dressing interval and improving the self-sharpening property of the abrasive. The high hardness of Cr2O3 and the interfacial activity of V2O5 work synergistically to enhance bonding strength while maintaining appropriate brittleness, allowing abrasive grains to detach and expose new cutting edges during use, further improving the self-sharpening property of the abrasive. The microcrack introduction effect of MnO, combined with the strength-enhancing effect of Al2O3, can introduce appropriate microcracks while maintaining sufficient binder strength, promoting self-sharpening.

[0032] Example 7 The method is basically the same as in Example 1, except that the ceramic binder is prepared as follows: (1) Mix B2O3, Al2O3 and SiO2 in proportion, add deionized water, water-to-material ratio 1:3, ball mill for 4 hours to form a uniform basic glass phase slurry; (2) Dry mix the remaining raw materials for 30 minutes to disperse them evenly, and obtain the additive mixture; (3) Composite powder: The base glass phase slurry is mixed with the additive mixture, spray dried and granulated to obtain particles with a particle size of 60-80μm; (4) Dehydrate the mixture at 400°C and then melt it at 1100°C for 2 hours to obtain molten glass; (5) The glass melt is quenched with water, stirred and ground, and dried to obtain a ceramic binder with a particle size of 0.5-1μm.

[0033] The grinding performance of the samples prepared in Examples 1 and 7 was determined, as detailed in Table 3. The grinding ratio of the samples was measured every 0.5 hours, and the specific results are shown in Table 3. Figure 3 .

[0034] Table 3. Grinding performance test results of grinding wheels from different embodiments

[0035] From Table 3 and Figure 3 It is understood that the preparation method of the present invention significantly improves the compositional uniformity, microstructure density and thermodynamic stability of the ceramic binder through stepwise mixing, spray drying granulation and gradient sintering, thereby effectively improving the grinding performance of the prepared grinding wheel: matching the thermal expansion coefficient of diamond, reducing binder cracking caused by grinding heat; improving diamond holding force, reducing abrasive grain shedding.

[0036] Examples 8-9 It is basically the same as Example 1, except that the raw material composition ratio of the ceramic binder is different, as shown in Table 4.

[0037] Table 4. Grinding performance test results of grinding wheels from different embodiments

[0038] As shown in Table 4, grinding wheels prepared using the agglomerated diamond powder of this invention exhibit excellent grinding performance, with a bending strength of 55-60 MPa, a Vickers hardness of 67-75 HRB, and a grinding ratio of 736-789. The agglomerated diamond powder of this invention can be used in diamond grinding fluids to process hard and brittle materials such as sapphire wafers, silicon carbide wafers, and functional ceramics; and in diamond grinding pads to process hard and brittle materials such as microcrystalline glass covers, sapphire wafers, and silicon carbide wafers.

[0039] The particle size of agglomerated diamond powder can be prepared by using diamond micron powders of different particle sizes. For example, 1.5 μm diamond micron powder can be used to prepare agglomerated diamond powders with particle sizes of 22 μm, 32 μm, and 46 μm; 3.0 μm diamond micron powder can be used to prepare agglomerated diamond powder with a particle size of 35 μm; and 4.0 μm diamond micron powder can be used to prepare agglomerated diamond powder with a particle size of 45 μm. The appropriate specifications and particle size can be selected according to specific requirements.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A mass of agglomerated diamond powder, characterized in that: The composition, by weight percentage, comprises 40-60% diamond micron powder with a particle size of 1.5~5μm and 40-60% ceramic binder; the ceramic binder, by weight percentage, comprises B2O3: 35-42%, Al2O3: 15-20%, SiO2: 15-20%, alkaline activator: 6-8%, rare earth oxides: 1-3%, Si: 6-7%, TiC: 1-3%, MnO: 2-3%, Cr2O3: 3-4%; CeO2: 1-2%, V2O5: 0.5-1%.

2. A compacted diamond powder according to claim 1, characterised in that: The alkaline activator is sodium carbonate or sodium hydroxide.

3. A compacted diamond powder according to claim 1, characterised in that: The rare earth oxides are Y2O3 and Nd2O3, and the weight ratio of Y2O3 to Nd2O3 is 1:1 to 3:

1.

4. A compacted diamond powder according to any one of claims 1 to 3, characterised in that: The ceramic binder is prepared as follows: (1) Mix B2O3, Al2O3 and SiO2 in proportion, add deionized water, water-to-material ratio 1:3, ball mill for 4 hours to form a uniform basic glass phase slurry; (2) Dry mix the remaining raw materials for 30 minutes to disperse them evenly, and obtain the additive mixture; (3) Composite powder: The base glass phase slurry is mixed with the additive mixture, spray dried and granulated to obtain particles with a particle size of 60-80μm; (4) Dehydrate the mixture at 350-450℃, and then melt it at 1100℃-1200℃ for 1-2 hours to obtain glass melt; (5) The glass melt is quenched with water, stirred and ground, and dried to obtain a ceramic binder with a particle size of 0.5-1μm.

5. A method of producing agglomerated diamond powder according to any one of claims 1 to 4, characterised in that, Includes the following steps: (1) Mixing: Diamond micron, ceramic binder and silane coupling agent are mixed in proportion, water is added to form a suspension with a solid content of 50%, ball milling for 30 min, ball-to-material ratio 3:1; (2) Spray granulation: Spray granulation is carried out under the conditions of inlet temperature 180-190℃ and outlet temperature 100-110℃; (3) Sintering: Heat to 350-400℃ at 5℃ / min, hold for 1-1.5 hours, heat to 600-650℃ at 10℃ / min, hold for 1-2 hours, and then cool naturally; (4) Hydraulic classification; (5) Drying: 100-105℃, dry for 6-8 hours to obtain agglomerated diamond powder.

Images