Method for processing diamond material by abrasive flow

Abstract

The invention discloses a method for processing a diamond material by abrasive flow, which comprises the following steps of: bombarding the surface of a diamond to form a surface graphite layer by using an elastic abrasive material wrapped with 45-85 percent by weight of diamond abrasive particles under the bombardment pressure of 0.1-0.8 MPa at the bombardment speed of 100-5000ml / min; and bombarding the surface graphite layer by adopting an elastic abrasive material wrapped with silicon carbide abrasive particles or diamond abrasive particles to obtain the processed diamond material. According to the method, the complex diamond surface can be efficiently machined.

Description

Technical Field

[0001] This invention relates to a processing technology for diamond superhard materials, specifically a method for abrasive flow processing of diamond materials. Background Technology

[0002] Abrasive flow machining is an unconventional finishing method. It utilizes hard abrasive grains (such as silicon carbide and diamond) coated in a semi-solid viscoelastic abrasive medium to polish the surface of a workpiece within a closed cavity under reciprocating extrusion or jetting conditions. This medium has fluidity, can adapt to complex geometries, and removes material through the micro-cutting action of the abrasive grains.

[0003] Based on the differences in abrasive medium viscosity and the movement of the abrasive medium relative to the workpiece, particle flow machining technology can be subdivided into traditional extrusion abrasive flow machining, rotary abrasive flow machining, and soft abrasive flow machining. Traditional extrusion abrasive flow machining and rotary abrasive flow machining both use highly viscoelastic abrasive media with a polymer matrix, and the media flow is laminar. The difference lies in that traditional extrusion abrasive flow machining drives the media flow through extrusion, and the workpiece is usually kept stationary; while rotary abrasive flow machining involves the rotation of either the abrasive medium or the workpiece. Soft abrasive flow machining uses low-viscosity abrasive media such as hydraulic oil, aviation kerosene, or water as the matrix, and the media flow is generally turbulent, making it suitable for polishing micropores and long, narrow channels where higher abrasive medium flowability is required.

[0004] Patent application CN112917398A discloses a viscoelastic fluid soft abrasive for surface finishing of difficult-to-machine materials. It is suitable for surface finishing of difficult-to-machine materials such as nickel-based superalloys, titanium alloys, and stainless steel. The viscoelastic fluid soft abrasive uses 20-25% (by mass) methyl vinyl silicone rubber as a carrier medium, and adds 5-10% (by mass) alkyl silicone oil, 10-15% white oil, 2-5% dimethyl silicone oil, 2-7% paraffin wax, 1-3% sodium stearate, and 35-60% abrasive particles to the carrier medium. The abrasive of this invention exhibits good viscoelasticity, good flowability, good integration between the abrasive particles and the carrier medium, no adhesion between the abrasive particles and the workpiece, good high-temperature resistance, and good finishing quality. The abrasive finishing method disclosed in this patent application is mainly applied to the surface finishing of materials such as nickel-based superalloys, titanium alloys, and stainless steel, but the quality for machining ultra-high hardness diamond needs further improvement.

[0005] Diamond's extremely high hardness (microhardness exceeding HV10000) due to its atomically close-packed crystal structure leads to a strong coupling contradiction between precision and efficiency in traditional machining systems, making it long recognized by the international materials processing community as the most difficult material to machine. Currently, advanced machining technologies for diamond mainly encompass a variety of process paths, including electrical discharge machining (EDM), abrasive waterjet machining (AWJM), ultra-precision mechanical grinding (such as flying cut technology based on single-crystal diamond tools), and pulsed laser ablation (nanosecond / picosecond laser micromachining).

[0006] With the development of diamond preparation technology, some extreme-sized and irregularly shaped diamond parts have emerged, and the surface processing technology of complex diamond parts has become the key to solving the problem. Summary of the Invention

[0007] This invention provides a method for abrasive flow machining of diamond materials, which can efficiently process complex diamond surfaces.

[0008] This invention provides a method for abrasive flow machining of diamond materials, comprising: (1) A surface graphite layer is formed by bombarding the diamond surface with an elastic abrasive containing (45~85) wt% diamond abrasive grains, wherein the bombardment pressure is 0.1~0.8 MPa and the bombardment speed is 100ml-5000ml / min; (2) The surface graphite layer is removed by using an elastic abrasive that encapsulates silicon carbide or diamond abrasive grains to obtain the processed diamond material.

[0009] Preferably, in step (1), the elastic abrasive comprises, by mass percentage of each component, 5-45 wt% carrier medium, 10-20 wt% additives and 45-85 wt% diamond abrasive grains.

[0010] More preferably, the carrier medium is one or more combinations of styrene-based thermoplastic elastomers, rubber, thermoplastic polyurethane, and polyolefin elastomers, and the additive is silicon carbide, white fused alumina, or boron nitride.

[0011] This invention modifies the carrier medium by adding appropriate amounts of additives to adjust its rheological and physical properties, thereby enhancing the force of high-content diamond materials on the diamond surface and enabling more efficient graphitization formation on the diamond surface.

[0012] Preferably, in step (1), the particle size of the diamond abrasive is 0.1~5 μm. This invention further enhances the force of the elastic abrasive on the diamond surface by controlling the particle size of the diamond abrasive, while avoiding damage to the diamond subsurface.

[0013] Preferably, in step (1), the bombardment cycle is 5 to 15 times, and the time of each cycle is 1 to 3 minutes.

[0014] Preferably, in step (2), the content of silicon carbide abrasive or diamond abrasive in the elastic abrasive is 5-10 wt%.

[0015] Preferably, in step (2), the elastic abrasive comprises, by mass percentage of each component, 60-85 wt% carrier medium, 10-30 wt% additives and 5-20 wt% silicon carbide abrasive or diamond abrasive.

[0016] More preferably, the carrier medium is one or more combinations of styrene-based thermoplastic elastomers, rubber, thermoplastic polyurethane, and polyolefin elastomers, and the additive is silicon carbide, white fused alumina, or boron nitride.

[0017] Preferably, in step (2), the bombardment rate is 100ml-1000ml / min and the pressure is 0.1~0.5 MPa.

[0018] This invention first bombards the diamond surface with abrasive grains to graphitize it. Then, it removes the graphite layer using low pressure and low abrasive grain content, while minimizing damage to the subsurface diamond. This method can solve the machining of non-planar or irregularly shaped diamond parts. For planar parts, this invention can be combined with further grinding and polishing to achieve very low surface roughness. This advantage in machining planar parts is the ability to achieve rapid removal of low roughness in the early stages.

[0019] Preferably, the diamond material processed by abrasive flow machining is single-crystal diamond or polycrystalline diamond.

[0020] Compared with existing technologies, the beneficial effects are: This invention first selects an elastic abrasive with a high content of diamond abrasive grains to bombard and compress the diamond surface under high pressure and high speed. By using the "soft against hard" processing of the abrasive grains, the subsurface loss of the diamond material is effectively reduced. At the same time, the high hardness of the diamond abrasive grains under high pressure and high speed conditions efficiently forms a graphite layer on the diamond surface, and the graphite layer can be removed quickly. The processing speed of the above method is very fast, and the diamond can be processed within 3 to 15 minutes, achieving efficient and fast polishing. Attached Figure Description

[0021] Figure 1 This is a topographic image of the diamond sample on the curved surface during the graphite layer removal process in Example 1. Figure 2 This is a topographic image of the diamond sample on a planar surface during the graphite layer removal process in Example 1.

[0022] Figure 3 The image shows the AFM image of the diamond sample after polishing on a flat surface during the process of removing the graphite layer in Example 1. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 This embodiment uses a water-particle fluid polishing machine developed by Suzhou Smanker Flow Co., Ltd. to polish diamond materials. The specific process includes: (1) A surface graphite layer is formed by bombarding the diamond surface with an elastic abrasive containing diamond abrasive grains. The elastic abrasive comprises 40 wt% carrier medium, 15 wt% additive and 45 wt% diamond abrasive grains by mass percentage of each component. The carrier medium is thermoplastic polyurethane and the additive is silicon carbide. The bombardment pressure is 0.2 MPa, the bombardment speed is 2000 ml / min, the cycle is 10 times, the time of each cycle is 3 min, and the diamond particle size is 3 μm.

[0025] (2) The surface graphite layer is removed by using an elastic abrasive coated with silicon carbide abrasive grains to obtain the processed diamond material. The elastic abrasive comprises 65% carrier medium, 18 wt% additive and 17 wt% silicon carbide by mass percentage of each component. The bombardment speed is 500 ml / min, the pressure is 0.5 MPa, the cycle is 8 times and the time of each cycle is 2 min.

[0026] like Figure 1 As shown, the present invention removes the graphite layer from the diamond layer on the curved surface by means of step (2).

[0027] like Figure 2 As shown, the present invention removes the graphite layer from the diamond layer on a flat surface using the method in step (2). Because there is a graphite layer on the surface, it can be easily removed by grinding and polishing, such as... Figure 3 As shown, the surface roughness reaches 3.23 nm.

[0028] Example 2 Compared with Example 1, the difference is that a mirror sandblasting machine developed by Suzhou Smankeru Co., Ltd. is used to polish the diamond material.

[0029] Step 1: This involves bombarding the diamond surface with an elastic abrasive that encapsulates diamond abrasive grains to form a surface graphite layer. The elastic abrasive comprises, by mass percentage, 25 wt% carrier medium, 15 wt% additives, and 60 wt% diamond abrasive grains, wherein the bombardment pressure is 0.6 MPa and the bombardment speed is 4000 ml / min. Step two involves bombarding the graphite layer formed on the diamond surface with an elastic abrasive coated with silicon carbide abrasive grains to remove the graphite layer. The bombardment pressure is 0.4 MPa, and the bombardment speed is 1000 ml / min. The surface graphite layer is then removed using a mixed elastic abrasive composed of coated diamond and silicon carbide abrasive grains to obtain the processed diamond material. This method can efficiently process complex diamond surfaces.

Claims

1. A method for abrasive flow machining of diamond materials, characterized in that, include: (1) A surface graphite layer is formed by bombarding the diamond surface with an elastic abrasive containing (45~85) wt% diamond abrasive grains, wherein the bombardment pressure is 0.1~0.8 MPa and the bombardment speed is 100ml-5000ml / min; (2) The diamond material is obtained by bombarding the surface graphite layer with an elastic abrasive that encapsulates silicon carbide or diamond abrasive.

2. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, In step (1), the elastic abrasive comprises, by mass percentage of each component, 5-45 wt% carrier medium, 10-20 wt% additives and 45-85 wt% diamond abrasive grains.

3. The method for abrasive flow machining of diamond materials according to claim 2, characterized in that, The carrier medium is one or more of styrene-based thermoplastic elastomers, rubber, thermoplastic polyurethane, and polyolefin elastomers, and the additive is silicon carbide, white fused alumina, or boron nitride.

4. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, In step (1), the particle size of the diamond abrasive grains is 0.1~5 μm.

5. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, In step (1), the bombardment cycle is 5 to 15 times, and the time for each cycle is 1 to 3 minutes.

6. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, In step (2), the content of silicon carbide abrasive or diamond abrasive in the elastic abrasive is 5-10 wt%.

7. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, In step (2), the elastic abrasive comprises, by mass percentage of each component, 60-85 wt% carrier medium, 10-30 wt% additives and 5-20 wt% silicon carbide abrasive or diamond abrasive.

8. The method for abrasive flow machining of diamond materials according to claim 7, characterized in that, The carrier medium is one or more of styrene-based thermoplastic elastomers, rubber, thermoplastic polyurethane, and polyolefin elastomers, and the additive is silicon carbide, white fused alumina, or boron nitride.

9. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, In step (2), the bombardment rate is 100ml-1000ml / min and the pressure is 0.1~0.5 MPa.

10. The method for abrasive flow machining of diamond materials according to claim 1, characterized in that, The diamond material used in abrasive flow machining is either single-crystal diamond or polycrystalline diamond.

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