Production method of diamond surface coated metal powder

Abstract

The present invention relates to the technical field of diamond tool preparation, and particularly to a production method of metal powder-coated diamond surface. The production method of the metal powder-coated diamond surface in this application is to dissolve a binder accounting for 1-5% of the organic solvent and a dispersant accounting for 1-5% of the organic solvent in the organic solvent according to the weight ratio of the organic solvent, to obtain a slurry solvent; then add at least two kinds of metal powders into the slurry solvent and stir evenly to obtain a mixed slurry required for coating; then put diamond particles into a coating container, and make the diamond particles in an air suspension state in the coating container; finally, spray atomized slurry on the surface of the diamond particles for coating to obtain diamond particles with at least two layers of metal powder coated on the surface, achieving the effect of double coating layers on the diamond surface with a single coating process, and various coating effects can be achieved by adjusting the types of inner and outer layer powders, greatly expanding the freedom of diamond tool production and processing.

Description

Technical Field

[0001] The present invention relates to the technical field of diamond tool preparation, and particularly to a production method for coating metal powder on the surface of diamond. Background Art

[0002] Synthetic diamond, as a super-hard and wear-resistant material, is widely used in the cutting and grinding processing fields of materials such as metals, stones, and reinforced concrete. Among them, using powder metallurgy technology to process metal powder and diamond into a mold is currently the mainstream production method for metal-based diamond tools. The main problem with diamond tools produced using powder metallurgy technology is that the mechanical friction force of the metal matrix on the diamond has a poor holding effect. Currently, the industry mainly uses metal elements with good wettability to diamond and strong carbide-forming elements to adjust the formula or directly coat them on the surface of diamond to improve the holding force. The former greatly increases the production cost, and the latter often faces the dilemma that the improvement of the holding force by a single powder coating is limited by the wettability element or the diamond structure is damaged by the strong carbide-forming element.

[0003] By searching for relevant technical patents, the main patents relatively close to the present invention are as follows:

[0004] 1. The "Diamond Bit Material and Its Preparation Method" disclosed in Patent No. CN104929526A involves a diamond particle with a double cladding layer, but the method adopted is to coat two layers of metal powder on the surface of diamond successively by a secondary rolling adhesion method.

[0005] 2. The "Process for Coating Cobalt Powder on Diamond Particles" disclosed in Patent No. CN102728832A involves a method for coating cobalt powder on the surface of diamond, but the method adopted is a drum granulation method to simultaneously sprinkle the binder and cobalt powder onto the rotating and rolling diamond particles to form a bonding and coating effect.

[0006] 3. The "Preparation Method of Cobalt Powder-Coated Diamond Balls, Cobalt Powder-Coated Diamond and Its Application" disclosed in Patent No. CN111872375A involves a method for coating cobalt powder on diamond balls, but the spray granulation method adopted is specifically limited to a single powder layer coating of cobalt.

[0007] 4. The "Preparation Method of an Inlaid Diamond Tool with High Holding Force" disclosed in Patent No. CN111318710A involves a method for coating a mixed powder on the surface of diamond by drum or spray granulation, but the mixed powder coated is still a single-layer structure.

[0008] It can be seen that the coating processes currently adopted in the industry are: single coating of a single powder or mixed powder in a single layer, multiple coatings of multiple powders, and there is no related technical solution to achieve the effect of double-layer powder coating in a single process. Summary of the Invention

[0009] The object of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a production method for coating metal powder on the surface of diamond.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows: A production method for coating metal powder on the surface of diamond, including the following steps:

[0011] S1. Weigh a binder accounting for 1-5% of the organic solvent and a dispersant accounting for 1-5% of the organic solvent according to the weight ratio of the organic solvent, and dissolve them in the organic solvent to obtain a slurry solvent.

[0012] S2. Add at least two kinds of metal powders to the slurry solvent in step S1 and stir evenly to obtain a mixed slurry required for coating.

[0013] S3. Put diamond particles into a coating container, and make the diamond particles in a suspended state in the coating container.

[0014] S4. Spray atomized slurry on the surface of the diamond particles for coating to obtain diamond particles with at least two layers of metal powder coated on the surface.

[0015] Further, the metal powders in step S2 include outer layer metal powder and inner layer metal powder, and the volume ratio of the outer layer metal powder to the inner layer metal powder is (1~5):1.

[0016] Further, the particle size of the outer layer metal powder is larger than that of the inner layer metal powder.

[0017] Further, the particle size of the inner layer metal powder is 1~15μm; the particle size of the outer layer metal powder is 15~75μm.

[0018] Further, the inner layer metal powder is one or more of Fe powder, Ni powder, Co powder, W powder, WC powder; the outer layer metal powder is one or more of Ti powder, Cr powder, V powder, Mo powder.

[0019] Further, the organic solvent includes alcohol-based organic solvents, and the alcohol-based organic solvents include isopropyl alcohol solution.

[0020] Further, the diamond being in a suspended state in step S3 includes blowing air upward from the bottom of the coating container by a blower.

[0021] Further, the distance between the spraying port of the atomized slurry and the suspended diamond particles in step S4 is 9-11cm.

[0022] Further, the coating time for spraying atomized slurry on the diamond surface in step S4 is 5~20min.

[0023] Further, it also includes pouring out the diamond particles after coating from the coating container, sieving off the floating powder on the surface of the diamond particles, and obtaining diamond particles with metal powder coated on the surface; finally, putting the diamond particles with metal powder coated on the surface into an oven for drying, and storing them sealed after drying is completed.

[0024] Advantages of the present invention: As can be seen from the above description of the present invention, compared with the prior art, a production method for coating metal powder on the surface of diamond in the present invention uses two metal powders with different particle sizes and physicochemical property differences, making them adhere to the surface of the diamond successively, so as to achieve the effect of obtaining diamond particles with double coating layers through a single coating process, and solve the deficiencies of the prior art.

[0025] The present invention can achieve various coating effects through different powder combinations, thus greatly expanding the freedom of production and processing of diamond tools. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of diamond particles without coated metal powder;

[0027] Figure 2 It is a schematic structural diagram of diamond particles coated with a single layer of fine-grained nickel powder;

[0028] Figure 3 It is a schematic structural diagram of diamond particles coated with a single layer of coarse-grained chromium powder;

[0029] Figure 4 It is a schematic structural diagram of diamond particles coated with nickel powder on the inner layer and chromium powder on the outer layer;

[0030] Figure 5 It is a schematic structural diagram of the sintering fracture morphology of diamond coated with a single layer of chromium powder;

[0031] Figure 6 It is a schematic structural diagram of the sintering fracture morphology of diamond coated with nickel powder on the inner layer and chromium powder on the outer layer. Detailed Embodiments

[0032] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0033] A preferred embodiment of the present invention, a production method for coating metal powder on the surface of diamond, includes the following methods:

[0034] S1. Weigh a binder accounting for 1 - 5% of the organic solvent and a dispersant accounting for 1 - 5% of the organic solvent respectively according to the weight ratio of the organic solvent, and dissolve them in the organic solvent to prepare a slurry solvent;

[0035] Among them, the organic solvent includes alcohol-based organic solvents, and the alcohol-based organic solvents include isopropyl alcohol solution, so that the binder, dispersant, and metal powder have good solubility, facilitating subsequent spray treatment;

[0036] S2. Add at least two kinds of metal powders to the slurry solvent in step S1 and stir evenly to obtain the mixed slurry required for coating;

[0037] Since fine-grained powder particles have better dispersion and greater surface energy in the solution, they are more likely to adhere to the diamond surface with atomized micro-droplets and form an inner-layer powder structure earlier; coarse-grained powder particles have poor dispersion and small surface energy in the solution, and have poor adhesion to the diamond after atomization and are easily blown away by the airflow. Therefore, it is necessary to increase the content so that it can form an outer-layer powder structure. Adjusting the powder ratio and coating time can change the coating layer thickness of the outer-layer powder. At the same time, in order to improve the holding force and avoid the etching damage of the diamond by strong carbide elements, the inner-layer powder can be selected from elements that cause little damage to the diamond and do not react strongly, and the outer-layer powder can be selected from elements that can react with the diamond to form a strong metallurgical bond. As a preferred embodiment of the present invention, the metal powder includes an outer-layer metal powder and an inner-layer metal powder, and the volume ratio of the outer-layer metal powder to the inner-layer metal powder is (1~5):1;

[0038] The outer-layer metal powder is coarse powder, and the inner-layer metal powder is fine powder; the particle size of the fine powder is 1~15μm; the particle size of the coarse powder is 15~75μm; further, the inner-layer metal powder is common matrix powders such as Fe, Ni, Co, W, WC, etc. that have good wettability to the diamond and do not react strongly; further, the outer-layer metal powder is common matrix powders such as Ti, Cr, V, Mo, etc. that are easy to react with the diamond to form carbides;

[0039] S3. Put the diamond particles into the coating container and make the diamond particles in a suspended state in the coating container;

[0040] That is, use a blower to make the diamond particles in a suspended state. The specific operation is to turn on the blower so that the air outlet of the blower blows upward against the bottom of the coating container, so that the diamond is in an air-flow suspended state; thus, it is convenient to spray-treat the diamond surface;

[0041] S4. Sprinkle the atomized slurry on the surface of the diamond particles for coating to obtain diamond particles with at least two layers of metal powder coated on the surface;

[0042] Among them, the distance between the spraying port of the atomized slurry and the suspended diamond particles is 9-11cm; and the coating time for spraying the atomized slurry on the diamond surface is 5~20min; thus, it is convenient to double-layer coat the metal powder on the diamond surface;

[0043] S5. Pour out the diamond particles after coating from the coating container, and sieve out the floating powder on the surface of the diamond particles to obtain diamond particles with a metal powder coating on the surface. Finally, put the diamond particles with a metal powder coating on the surface into an oven for drying, and store them sealed after drying is completed.

[0044] The following is illustrated with specific examples. Specific Example 1

[0046] S1. Measure 500 mL of isopropanol, weigh 12.5 g of binder BR118 and 5 g of dispersant PEG1500 and completely dissolve them in isopropanol. Then weigh 400 g of Co, Ti mixed powder and add it to the isopropanol solution and stir evenly. Among them, the volume ratio of Co to Ti is 1:3. The Co powder is the inner layer fine powder with a particle size of 3 μm, and the Ti powder is the outer layer coarse powder with a particle size of 80 μm.

[0047] S2. Weigh 200 g of 35 / 40 mesh diamond particles and add them to the coating container, and turn on the blower to make the diamonds in an air suspension state.

[0048] S3. Use an atomizing nozzle to spray the atomized slurry on the diamonds 10 cm above the diamonds, and the spraying time is 15 minutes.

[0049] S4. Turn off the atomizing nozzle and the blower, pour out the diamond particles after coating from the coating container, and sieve out the floating powder on the surface of the diamond particles to obtain diamond particles with a metal powder coating on the surface. Finally, put the diamond particles with a metal powder coating on the surface into an oven for drying, and store them sealed after drying is completed.

[0050] In this example, due to the large particle size of the outer layer Ti powder, the coating efficiency is extremely low. The coarse Ti powder has extremely poor dispersibility in the slurry and is prone to precipitation. It is also easy to block the nozzle during atomization. During the coating process, it is difficult to coat on the diamonds due to poor adhesion, and a large amount of powder is blown away, causing great waste and increasing the production cost at the same time. Specific Example 2

[0052] S1. Measure 500 mL of isopropanol, weigh 12.5 g of binder BR118 and 5 g of dispersant PEG1500 and completely dissolve them in isopropanol. Then weigh 400 g of Ni, Cr mixed powder and add it to the isopropanol solution and stir evenly. Among them, the volume ratio of Ni to Cr is 1:4. The Ni powder is the inner layer fine powder with a particle size of 5 μm, and the Cr powder is the outer layer coarse powder with a particle size of 35 μm.

[0053] S2. Weigh 200 g of 40 / 45 mesh diamond particles and add them to the coating container, and turn on the blower to make the diamonds in an air suspension state.

[0054] S3. Use an atomizing nozzle to spray the atomized slurry on the diamond at a position 10 cm above the diamond, and the spraying time is 10 min;

[0055] S4. Turn off the atomizing nozzle and the blower, pour out the diamond particles after coating from the coating container, and sieve out the floating powder on the surface of the diamond particles to obtain diamond particles with a metal powder coating on the surface; finally, put the diamond particles with a metal powder coating on the surface into an oven for drying, and store them sealed after drying, as Figure 4 shown.

[0056] Comparison Figure 4 and Figures 1-3 It can be seen that the diamond particles coated with nickel powder on the inner layer and chromium powder on the outer layer have a relatively obvious layered structure on the surface. The inner layer is dense fine-grained Ni powder, and the outer layer is relatively sparse Cr powder. On the basis of this embodiment, extending the coating time or increasing the Cr volume ratio can obtain a denser Cr powder layer, but the improvement effect of the outer layer powder coating gradually decreases with too long coating time. Specific Embodiment 3

[0058] S1. Measure 500 mL of isopropyl alcohol, weigh 12.5 g of binder BR118 and 5 g of dispersant PEG1500 and completely dissolve them in isopropyl alcohol, then weigh 400 g of W, V mixed powder and add it to the isopropyl alcohol solution and stir evenly, where the volume ratio of W to V is 1:5, W powder is the inner fine powder with a particle size of 5 μm, and V powder is the outer coarse powder with a particle size of 10 μm;

[0059] S2. Weigh 150 g of 45 / 50 mesh diamond particles and add them to the coating container, and turn on the blower to make the diamond in a suspended state by air flow;

[0060] S3. Use an atomizing nozzle to spray the atomized slurry on the diamond at a position 10 cm above the diamond, and the spraying time is 20 min;

[0061] S4. Turn off the atomizing nozzle and the blower, pour out the diamond particles after coating from the coating container, and sieve out the floating powder on the surface of the diamond particles to obtain diamond particles with a metal powder coating on the surface; finally, put the diamond particles with a metal powder coating on the surface into an oven for drying, and store them sealed after drying.

[0062] In this embodiment, due to the small difference in particle size between the inner and outer layer powders, the dispersibility of the two powders in the slurry is similar, and both are easily adhered to the diamond after spraying, resulting in only a layer of mixed powder on the surface of the coated diamond particles and no obvious layered effect.

[0063] Sintering Effect Experiment

[0064] Sinter the diamonds coated with a single layer of chromium powder and the diamonds coated with nickel powder on the inner layer and chromium powder on the outer layer, and their sintering effects are as Figure 5 and6 as shown

[0065] From Figure 5 It can be seen that after coating the carbide-forming element chromium powder commonly used in the matrix on the diamond surface and then undergoing high-temperature sintering, the diamond surface reacts with Cr, and a metallurgical layer of diamond - chromium carbide - chromium - matrix is formed at the boundary between the diamond and the matrix. Although a strong metallurgical bond is generated, the crystal structure of the diamond surface layer is damaged, resulting in a decrease in strength and a large amount of fragmentation and cracking;

[0066] while Figure 6 after sintering the diamond coated with nickel powder on the inner layer and chromium powder on the outer layer in [reference], partial metallurgical bonding also occurs between the diamond surface layer and the matrix. However, due to the isolation and protection effect of the inner-layer nickel powder, the situation of diamond fragmentation and cracking is greatly improved.

[0067] The present invention utilizes the different dispersion effects and physicochemical property differences of two kinds of powders with different contents and particle sizes in the slurry to achieve the effect of coating two layers of powder on the diamond surface at one time. Specifically, when the slurry is atomized and sprayed on the diamond particles in an air suspension state, the fine-grained powder with less content and good dispersibility is more likely to adhere to the diamond with the tiny droplets to form the inner layer first, and the coarse-grained powder with more content and poor dispersibility is less likely to adhere to the diamond and then forms the outer layer. The present invention realizes the effect of a double coating layer on the diamond surface with a single coating process, and can achieve various coating effects by adjusting the types of the inner and outer layer powders, thereby greatly expanding the freedom of production and processing of diamond tools.

[0068] On the premise of no conflict, those skilled in the art can freely combine and superimpose the above-mentioned additional technical features.

[0069] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A method for producing diamond surface coated metal powder, characterized in that: The following methods are included: S1. According to the weight ratio of the organic solvent, a binder accounting for 1-5% of the organic solvent and a dispersant accounting for 1-5% of the organic solvent are weighed and dissolved in the organic solvent to prepare a slurry solvent; S2, adding at least two metal powders to the slurry solvent of step S1 and stirring evenly to obtain a mixed slurry required for coating; The metal powder comprises an outer layer of metal powder and an inner layer of metal powder, the volume ratio of the outer layer of metal powder to the inner layer of metal powder is (1-5):1; the particle size of the outer layer of metal powder is larger than the particle size of the inner layer of metal powder; The particle size of the inner layer metal powder is 1-15 μm; the particle size of the outer layer metal powder is 15-75 μm; The inner layer metal powder is one or more of Fe powder, Ni powder, Co powder, W powder, and WC powder; the outer layer metal powder is one or more of Ti powder, Cr powder, V powder, and Mo powder; S3, placing diamond particles into a coating container, and making the diamond particles in a suspended state in the coating container; S4. Spraying the mist slurry onto the surface of the diamond particles for coating, thereby obtaining diamond particles with at least two layers of metal powder coated on the surface.

2. The method for producing diamond surface coated metal powder according to claim 1, characterized in that: The organic solvent includes an alcohol organic solvent, and the alcohol organic solvent includes an isopropanol solution.

3. The method for producing diamond surface coated metal powder according to claim 1, characterized in that: The step S3 wherein the diamond is in a suspended state includes using a blower to blow air upwards from the bottom of the coating container.

4. The method for producing diamond surface coated metal powder according to claim 1, characterized in that: In step S4, the distance between the spray port of the mist slurry and the suspended diamond particles is 9-11 cm.

5. The method for producing diamond surface coated metal powder according to claim 1, characterized in that: The coating time of spraying the atomized slurry onto the diamond surface in step S4 is 5 to 20 minutes.

6. The method for producing diamond surface coated metal powder according to claim 1, characterized in that: The method also includes pouring the coated diamond particles out of the coating container and sieving out the floating powder on the surface of the diamond particles to obtain diamond particles with metal powder coated on the surface; finally, putting the diamond particles with metal powder coated on the surface into an oven for drying, and sealing and storing them after drying.

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