Cubic boron nitride micro-powder particle size reprocessing production method

Abstract

The invention relates to a reprocessing production method of cubic boron nitride micro powder. The reprocessing production method comprises the following steps: 1) preparing steel balls: weighing a certain amount of steel balls of phi 20mm, phi 18mm, phi 16mm, phi 14mm, phi 12mm, phi 10mm and phi 8mm in proportion, uniformly mixing, and placing in a ball milling tank; 2) setting the rotating speed of the ball milling tank; (3) weighing cubic boron nitride micro-powder with the particle size being less than 10 microns or 60000-80000ct of remaining cubic boron nitride micro-powder with the target particle size being removed, putting the cubic boron nitride micro-powder or the remaining cubic boron nitride micro-powder into a ball-milling tank, and inching the ball-milling tank to uniformly mix the materials with the steel balls; (4) setting the working time to be 8-10 hours, unloading the materials after the working time is finished, cooling for 1-3 hours, then adding the materials into the ball milling tank again for continuous ball milling, and repeating the operation for 6-8 times; 5, after material ball milling is finished, cubic boron nitride micro powder with different particle sizes is obtained through purification, separation and drying, and the mass proportion of the target particle size is calculated.By means of the method, more target particle sizes M1-2 and M2-4 can be obtained, the output rate of the target particle sizes of the cubic boron nitride micro powder is increased, and therefore the production cost of the cubic boron nitride micro powder is saved.

Description

Technical Field

[0001] This invention belongs to the field of superhard material manufacturing and processing technology, specifically relating to a method for reprocessing cubic boron nitride micro powder. Background Technology

[0002] With continuous technological advancements, the processing of materials is increasingly focused on higher dimensional accuracy, smoother surfaces, and higher efficiency. Consequently, more fields are placing higher demands on advanced processing tools. Cubic boron nitride (CBN) micro powder has emerged as a solution. CBN micro powder refers to cubic boron nitride abrasive grains with a particle size finer than 36 / 54 micrometers. It is produced from single-crystal cubic boron nitride abrasive grains through special processes such as crushing, shaping, purification, and sorting. CBN micro powder boasts high crystal purity, good thermal stability, excellent self-sharpening properties, and high grinding efficiency, making it an ideal material for preparing precision abrasives and cutting tools. However, not all specifications of CBN micro powder can meet customer needs. Currently, the most in-demand grades include M1-2 (particle size mainly between 1-2 μm, exhibiting a normal distribution), M2-4, M10-20, and M10-50. Among these, M1-2 and M2-4 are ideal raw materials for synthesizing polycrystalline cubic boron nitride, and demand exceeds supply.

[0003] To obtain more of the required particle sizes, production processes typically sort particles to the required size, and then perform secondary crushing on abrasive particles larger than 10μm. However, regardless of the re-crushing process, the selection of M1-2 and M2-4 particles below 10μm results in significant waste. Existing traditional processes for processing micro-powders below 10μm have the following limitations: they usually employ single, long-duration ball milling (12-24 hours of continuous operation), use a single steel ball ratio (e.g., all φ15mm steel balls), and have a fixed and non-adjustable rotation speed, leading to low crushing efficiency and a non-concentrated particle size distribution. Experimental data shows that using traditional processes to process cBN micro-powder below 10μm, the yield of the target particle size M2-4 is only 12-15%, and the yield of M1-2 is only 18-22%, while approximately 30-40% of ultrafine powder (≤M1-2) is generated, resulting in resource waste and increased costs.

[0004] To address the aforementioned issues, it is urgent to research and develop a method for reprocessing cubic boron nitride micropowder particles. Obtaining more target particle sizes, M1-2 and M2-4, is of great significance for avoiding production waste and improving micropowder production efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a method for reprocessing cubic boron nitride micro powder to obtain more target particle sizes M1-2 and M2-4, further improve the yield of target particle sizes of cubic boron nitride micro powder, and thus save the production cost of cubic boron nitride micro powder.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for reprocessing cubic boron nitride micro powder includes the following steps: (1) Prepare steel balls: Weigh a certain amount of steel balls with diameters of φ20mm, φ18mm, φ16mm, φ14mm, φ12mm, φ10mm and φ8mm according to the proportion, mix them evenly and place them in the ball mill jar; (2) Set the mill speed as required; (3) Weigh out 60,000-80,000 ct of cubic boron nitride micro powder with a particle size of less than 10 μm, or the remaining cubic boron nitride micro powder after removing the target particle size, place it in the ball mill jar, and jog the ball mill jar to make the material and steel balls mix evenly. (4) Set the working time to 8-10 hours. After the time is up, unload the material (to prevent the material from caking due to the temperature being higher than 95℃), cool it for 1-3 hours, and then put the material back into the ball mill jar to continue ball milling. Repeat this process 6-8 times. (5) After the ball milling of the material is completed, it is purified, sorted and dried to obtain cubic boron nitride micro powder of different particle sizes, and the mass ratio of the target particle size is calculated.

[0007] Specifically, in step (1), a certain amount of steel balls of φ20mm 10-20kg, φ18mm 10-20kg, φ16mm 15-25kg, φ14mm 15-25kg, φ12mm 15-25kg, φ10mm 10-20kg, and φ8mm 5-10kg are weighed according to the mass ratio, mixed evenly, and placed in an 80-100L ball mill jar.

[0008] Furthermore, in step (2), the preferred rotational speed of the ball mill jar is 30-60 r / min.

[0009] Further, in step (5), the purification process is as follows: using an acid-alkali-water washing process, first soaking in a hydrochloric acid solution with a concentration of 15±5% (mass concentration percentage) for 1-3 hours to remove metal impurities, then soaking in a sodium hydroxide solution with a concentration of 10±5% (mass concentration percentage) for 0.5-2 hours to remove silicate impurities, and finally washing with deionized water until neutral (pH=7).

[0010] Furthermore, in step (5), the sorting specifically involves: using centrifugal classification, preparing the purified micro-powder into an aqueous suspension of 5±2wt% (mass concentration percentage), centrifuging at 2000±500 r / min, and collecting the target particle size range. Different particle sizes are sorted by utilizing different centrifugation times.

[0011] Furthermore, in step (5), the drying process is carried out in a vacuum drying oven at a temperature of 90-100℃ for 5-7 hours to obtain cubic boron nitride micro powders of different particle sizes.

[0012] The method for reprocessing cubic boron nitride micropowder according to this invention mainly involves using multi-stage steel ball proportioning, gradient speed control, and intermittent ball milling to concentrate the particle size of each micropowder towards the target particle size. Compared with the prior art, the innovation and beneficial effects of this invention are reflected in: 1) Target particle size yield is significantly improved: As shown in Example 1, the yield of M2-4 increased from 12-15% in the traditional process to 38.60%, an increase of more than 150%; in Example 2, the yield of M1-2 increased from 18-22% to 53.60%, an increase of nearly 200%; 2) Maximize resource utilization: Through 6-8 intermittent ball milling, over-grinding is effectively avoided, and the amount of fine powder (≤M1-2) produced is reduced to below 15%, which is more than 50% less than that of traditional processes; 3) Strong process controllability: Through adjustable speed of 30-60r / min, multi-stage steel ball ratio (φ20-8mm) and segmented cooling process, parameters can be flexibly adjusted for different target particle sizes to achieve precise control; 4) Significantly reduced production costs: After the target particle size output rate is improved, the raw material consumption per unit product is reduced by 30-40%, and the energy consumption is reduced by 20-25%, resulting in significant savings in overall production costs. Detailed Implementation

[0013] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0014] In the following examples, all raw materials used are common commercially available products that can be purchased directly, or can be prepared using conventional techniques in the art.

[0015] In the following embodiments, processes not described in detail (such as centrifugal classification) can be performed using conventional techniques in the field. Since they are not the innovation of this application, they will not be described in detail here.

[0016] Example 1 This embodiment describes a method for reprocessing cubic boron nitride micro powder to achieve a target particle size of M2-4. The specific process is as follows: (1) Prepare steel balls: weigh 10kg of φ20mm, 20kg of φ18mm, 20kg of φ16mm, 25kg of φ14mm, 25kg of φ12mm, 20kg of φ10mm, and 8kg of φ8mm, mix them evenly, and place them in an 80L ball mill jar; (2) Set the ball mill jar speed to 60 r / min as required; (3) Weigh 80,000 ct of residual cubic boron nitride powder of M2-4 (i.e., the residual cubic boron nitride powder below 10 μm, after removing the target particle size M2-4 from fine to coarse, mainly including M3-6, M4-8, M5-10, etc.), put it into the ball mill jar, and jog the ball mill jar to make the material and steel balls mix evenly; the mass percentage of each particle size before treatment is as follows: M2-4 12.5%, M3-6 28.3%, M4-8 35.2%, M5-10 18.7%, ≤M1-2 5.3%; (4) Set the working time to 10h. After the time is up, measure the material temperature to 89℃, unload the material, let it cool to room temperature for 2h, and then put the material back into the ball mill jar to continue grinding. Repeat this process 6 times. (5) After the material is ball-milled, it undergoes purification, sorting, and drying processes: Purification: The process of acid washing-alkali washing-water washing is adopted. First, the metal impurities are removed by soaking in a 15% hydrochloric acid solution for 2 hours, then the silicate impurities are removed by soaking in a 10% sodium hydroxide solution for 1 hour, and finally the water is washed with deionized water until the pH=7. Sorting: The purified micro powder was prepared into a 5wt% aqueous suspension by centrifugation and classification at 2000 r / min, and the target particle size range was collected. Drying: The drying was carried out in a vacuum drying oven at 95℃ for 6 hours. Cubic boron nitride micropowders of different particle sizes were obtained. (6) The mass percentage of each particle size is calculated as follows: ≥M3-6 19.25%; M3-5 7.40%; M2-4 38.60% (an increase of 26.1 percentage points); M1-3 21.45%; ≤M1-2 13.30%.

[0017] Example 2 This embodiment describes a method for reprocessing cubic boron nitride micro powder to achieve a target particle size of M1-2. The specific process is as follows: (1) Prepare steel balls: weigh 15kg of φ20mm, 15kg of φ18mm, 20kg of φ16mm, 20kg of φ14mm, 20kg of φ12mm, 15kg of φ10mm, and 7kg of φ8mm, mix them evenly, and place them in a 100L ball mill jar; (2) Set the ball mill jar speed to 40 r / min as required; (3) Weigh 60,000 ct of M1-3 cubic boron nitride micro powder (particle size range mainly between 1-3 μm), put it into the ball mill jar, and jog the ball mill jar to make the material and steel balls mix evenly; the mass percentage of each particle size before treatment is as follows: M1-2 18.2%, M1-3 42.5%, <M1-2 39.3%; (4) Set the working time to 8 hours. After the time is up, measure the material temperature to 85°C, unload the material, let it cool to room temperature for 2 hours, and then put the material back into the ball mill jar to continue grinding. Repeat this process 8 times. (5) After the material is ball-milled, it undergoes purification, sorting, and drying processes: Purification: The process of acid washing-alkali washing-water washing is adopted. First, the metal impurities are removed by soaking in a 15% hydrochloric acid solution for 1.5 hours, then the silicate impurities are removed by soaking in a 10% sodium hydroxide solution for 0.5 hours, and finally the water is washed with deionized water until the pH=7. Sorting: The purified micro powder was prepared into a 5wt% aqueous suspension by centrifugation and classification at 2000 r / min, and the target particle size range was collected. Drying: The drying was carried out in a vacuum drying oven at a temperature of 95°C for 6 hours to obtain cubic boron nitride micro powders of different particle sizes. (6) The mass percentage of each particle size is calculated as follows: M1-3 19.25%; M1-2 53.60% (an increase of 35.4 percentage points); <M1-2 27.15%.

Claims

1. A method for reprocessing cubic boron nitride micro powder, characterized in that, Includes the following steps: (1) Prepare steel balls: Weigh a certain amount of steel balls with diameters of φ20mm, φ18mm, φ16mm, φ14mm, φ12mm, φ10mm and φ8mm according to the proportion, mix them evenly and place them in the ball mill jar; (2) Set the rotation speed of the ball mill jar to ; (3) Weigh out cubic boron nitride micro powder with a particle size of less than 10 μm, or the remaining cubic boron nitride micro powder after removing the target particle size, place it in the ball mill jar, and jog the ball mill jar to make the material and steel balls mix evenly. (4) Set the working time to 8-10 hours. After the time is up, unload the material and let it cool for 1-3 hours. Then add the material back into the ball mill and continue ball milling. Repeat this process 6-8 times. (5) After the ball milling of the material is completed, it is purified, sorted and dried to obtain cubic boron nitride micro powder of different particle sizes, and the mass ratio of the target particle size is calculated.

2. The method for reprocessing cubic boron nitride micro powder as described in claim 1, characterized in that, In step (1), a certain amount of steel balls of φ20mm 10-20kg, φ18mm 10-20kg, φ16mm 15-25kg, φ14mm 15-25kg, φ12mm 15-25kg, φ10mm 10-20kg, and φ8mm 5-10kg are weighed according to the mass ratio, mixed evenly, and placed in an 80-100L ball mill jar.

3. The method for reprocessing cubic boron nitride micro powder as described in claim 1, characterized in that, In step (2), the rotation speed of the ball mill jar is 30-60 r / min.

4. The method for reprocessing cubic boron nitride micro powder as described in claim 1, characterized in that, In step (5), the purification process is as follows: first, soak in a 15±5% hydrochloric acid solution for 1-3 hours, then soak in a 10±5% sodium hydroxide solution for 0.5-2 hours, and finally wash with deionized water until neutral.

5. The method for reprocessing cubic boron nitride micro powder as described in claim 1, characterized in that, In step (5), the sorting is specifically as follows: the purified micro powder is prepared into an aqueous suspension of 5±2wt% by centrifugation and classification at a speed of 2000±500 r / min, and the target particle size range is collected.

6. The method for reprocessing cubic boron nitride micro powder as described in claim 1, characterized in that, In step (5), the drying process is carried out in a vacuum drying oven at a temperature of 90-100℃ for 5-7 hours to obtain cubic boron nitride micro powders of different particle sizes.