Nanometer superhard material super-precision grinding tool and its preparation method

Abstract

The embodiment of the application discloses a nano superhard material super-precision grinding tool and a preparation method thereof; the method comprises the following steps: S1, the surface of the nano superhard material is subjected to strong oxidation treatment to remove surface impurities and generate hydrophilic groups; S2, a water-soluble sugar and a transition metal salt are dissolved in deionized water to form a mixed solution; S3, the nano superhard material is uniformly dispersed in the mixed solution, and a polymer composite nano superhard material is obtained through hydrothermal treatment; S4, the polymer composite nano superhard material is mixed and dispersed in deionized water with boric acid, and dried for standby; S5, the dried polymer composite nano superhard material is formed and placed in a graphite mold; S6, the polymer composite nano superhard material in the graphite mold is subjected to rapid sintering in a plasma discharge device, the polymer in the polymer composite nano superhard material is subjected to in-situ reaction with the surface of the nano superhard material under the catalysis of transition metal ions to generate boron carbide, and a nano superhard material super-precision grinding tool bonded with boron carbide is obtained.

Description

Technical Field

[0001] This application belongs to the field of superhard composite materials technology, specifically relating to ultra-precision abrasives made of nano-superhard materials and their preparation methods. Background Technology

[0002] Nanomaterial superhard abrasives are widely used in grinding cemented carbide tools and molds. Their high hardness and wear resistance can effectively remove excess material from the surface of cemented carbide, and can achieve high surface finish and dimensional accuracy.

[0003] Currently, the main method for preparing nano-superhard material abrasives involves mechanically mixing nano-superhard materials with binders and other additives, followed by sintering under high temperature and pressure. Binders can be categorized into ceramic binders, metal-based binders, resin binders, and their composite binders. However, due to the extremely small particle size of nano-superhard materials, agglomeration easily occurs when mixed with binders and other raw materials, leading to uneven mixing and affecting the consistency of abrasive performance. Furthermore, binders can cause problems such as insufficient holding force leading to short service life, and excessive holding force causing frequent dressing after the abrasive becomes dull.

[0004] Boron carbide, as a superhard material second only to diamond and cubic boron nitride, has the potential to become a novel nanomaterial binder for superhard materials. Typically, superhard material particles and boron carbide particles are directly mixed and then sintered under high temperature and pressure. However, this method, which uses boron carbide powder mixed with nanomaterials for sintering, results in uneven distribution of nanomaterials and boron carbide within the mold due to the agglomeration effect of the nanoparticles, ultimately leading to insufficient mold performance. Furthermore, the sintering of boron carbide powder with nanomaterials usually requires high temperature and pressure conditions, which may cause the nanomaterial grains to grow, and the preparation cost is too high. Summary of the Invention

[0005] In view of this, some embodiments disclose a method for preparing ultra-precision abrasives made of nano-superhard materials, including the following steps:

[0006] S1. The surface of the nano-superhard material is subjected to strong oxidation treatment to remove surface impurities and generate hydrophilic groups; the nano-superhard material is cubic boron nitride or diamond; the particle size of the nano-superhard material is 1-100 nm.

[0007] S2, water-soluble sugars and transition metal salts dissolve in deionized water to form a mixed solution;

[0008] S3. The nano-superhard material is uniformly dispersed in a mixed solution and subjected to hydrothermal treatment to coat the surface of the nano-superhard material with water-soluble sugar and transition metal ions, thereby obtaining a polymer composite nano-superhard material.

[0009] S4. The polymer composite nano-superhard material is mixed and dispersed with boric acid in deionized water, and then dried for later use; wherein, the mass ratio of the polymer composite nano-superhard material to boric acid is 1:0.5-2.

[0010] S5. The dried polymer composite nano-superhard material is molded and placed in a graphite mold; wherein the molding pressure is 10-50 MPa.

[0011] S6. The polymer composite nano-superhard material in the graphite mold is rapidly sintered with boric acid in a plasma discharge device. Under the catalysis of transition metal ions, the polymer in the polymer composite nano-superhard material reacts in situ with the boric acid on the surface of the nano-superhard material to generate boron carbide, thus obtaining a boron carbide-bonded nano-superhard material ultra-precision grinding tool.

[0012] Furthermore, in some embodiments of the preparation method of ultra-precision abrasives made of nano-superhard materials, in step S1, the nano-superhard materials are treated with a strong acid solution, wherein the strong acid solution is concentrated nitric acid, or a mixture of concentrated sulfuric acid and 30% hydrogen peroxide solution, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide solution is 7:3; the treatment time is 15-30 min; and the mass-volume ratio of nano-superhard materials to strong acid solution is 1-2 g: 5 ml.

[0013] Some embodiments disclose a method for preparing ultra-precision abrasives from nano-superhard materials, wherein the water-soluble sugars include glucose, sucrose, fructose, and lactose, and the transition metal salts include Fe, Co, Ni, Cr, Mo, W, V, or Mn salts; in the mixed solution, the concentration of the water-soluble sugars is 0.04–0.12 g / ml, and the concentration of the transition metal salts is 0.03–0.10 mol / L.

[0014] In some embodiments of the preparation method of ultra-precision abrasives made of nano-superhard materials, in step S3, the temperature of the hydrothermal treatment mixed solution is 150-220°C and the time is 18-36 hours.

[0015] The method for preparing ultra-precision abrasives using nano-superhard materials disclosed in some embodiments further includes step S3 of washing the polymer composite nano-superhard material and drying the washed polymer composite nano-superhard material at 120°C for more than 6 hours in a vacuum or air atmosphere to obtain dried polymer composite nano-superhard material.

[0016] In some embodiments of the preparation method of ultra-precision abrasives made of nano-superhard materials, step S4 involves drying the polymer composite nano-superhard material and the boric acid mixture by freeze-drying.

[0017] In some embodiments of the preparation method of ultra-precision abrasives made of nano-superhard materials, in step S6, sintering is carried out in a vacuum environment, the sintering temperature and pressure are 30-80 MPa, the temperature is 1200-1500℃, the holding time is 10-20 min.

[0018] On the other hand, some embodiments disclose ultra-precision abrasives made of nano-superhard materials, which are obtained by using a method for preparing ultra-precision abrasives made of nano-superhard materials.

[0019] The method for preparing ultra-precision abrasives from nano-superhard materials disclosed in this application involves thoroughly removing impurities from the surface of the nano-superhard material and subjecting it to hydrophilic treatment. A carbon source material and a catalyst are uniformly coated onto the surface of the superhard material. Under the action of the catalyst, the water-soluble sugar from the carbon source material reacts in situ with boric acid on the surface of the nano-superhard material to generate a boron carbide binder, which is uniformly distributed on the surface of the nano-superhard material. In the resulting ultra-precision abrasive from nano-superhard materials, the nano-superhard material and the binder are uniformly dispersed. The resulting ultra-precision abrasive from nano-superhard materials exhibits a uniform microstructure, high grinding precision, and long service life, showing promising application prospects in the field of ultra-precision abrasives. Attached Figure Description

[0020] Figure 1 A schematic diagram of the process for preparing ultra-precision abrasives from nano-superhard materials;

[0021] Figure 2 Example 1: Schematic diagram of the process flow for preparing ultra-precision abrasives from nano-superhard materials. Detailed Implementation

[0022] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0023] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0024] The terms “basic” and “approximately” used in this document are to describe small fluctuations. For example, they can mean less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in range format in this document are used for convenience and brevity only, and should therefore be flexibly interpreted to include not only the explicitly listed values ​​that define the range, but also all independent values ​​or subranges contained within that range. For example, a numerical range of “1–5%” should be interpreted to include not only the explicitly listed values ​​from 1% to 5%, but also the independent values ​​and subranges within the indicated range. Thus, this numerical range includes independent values ​​such as 2%, 3.5%, and 4%, and subranges such as 1%–3%, 2%–4%, and 3%–5%, etc. This principle also applies to ranges that list only one value. Furthermore, this interpretation applies regardless of the width of the range or the characteristics described.

[0025] In this document, including in the claims, conjunctions such as "comprising," "including," "with," "having," "containing," "involving," and "accommodating" are understood to be open-ended, meaning "including but not limited to." Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0026] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0027] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0028] In some implementations, such as Figure 1 As shown, the preparation method of ultra-precision abrasives made of nano-superhard materials includes the following steps:

[0029] S1. The surface of the nano-superhard material undergoes strong oxidation treatment to remove surface impurities and generate hydrophilic groups; the nano-superhard material is cubic boron nitride or diamond; typically, the nano-superhard material is a powder with a particle size of 1–100 nm; strong oxidation treatment of the nano-superhard material surface can remove surface impurities, improve material purity, and simultaneously form hydrophilic groups on the material surface, improving the dispersion performance of the nano-superhard material in aqueous solution, which is beneficial for better dispersion in aqueous solution in subsequent processes to form a uniform mixed solution; strong acid solution is usually used for strong oxidation treatment, and the treatment time is 15–30 min; the mass-volume ratio of nano-superhard material to strong acid solution is 1–2 g: 5 ml.

[0030] In some embodiments, the strong acid solution is concentrated nitric acid, or a mixture of concentrated sulfuric acid and 30% hydrogen peroxide solution, with a volume ratio of concentrated sulfuric acid to hydrogen peroxide solution of 7:3; wherein, concentrated nitric acid and concentrated sulfuric acid are commonly used analytical grade reagents in the art, and the concentration of hydrogen peroxide solution is a mass content concentration;

[0031] S2. Water-soluble sugars and transition metal salts dissolve in deionized water to form a mixed solution. Typically, the water-soluble sugars generate carbon during subsequent sintering processes, serving as a carbon source for in-situ reactions on the surface of the nanomaterials, forming boron carbide. The water-soluble sugars, as a carbon source, can dissolve completely and effectively in deionized water, forming a uniformly dispersed mixed solution, which is beneficial for uniformly coating the surface of the nanomaterials. Transition metal ions can dissolve in deionized water, forming a uniform mixed solution with the water-soluble sugars, which also promotes uniform coating of the transition metal ions and water-soluble sugars on the surface of the nanomaterials. During plasma sintering, the transition metals act as catalysts, promoting the reaction of carbon with boric acid to generate boron carbide, which acts as a binder material, uniformly dispersed on the surface of the nanomaterials. Simultaneously, it effectively reduces the sintering temperature, preventing the carbon material from graphitizing the nanodiamonds.

[0032] In some embodiments, the water-soluble sugar is glucose, sucrose, fructose, or lactose, etc., with a concentration of 0.04–0.12 g / ml in the mixed solution; the transition metal salt is Fe, Co, Ni, Cr, Mo, W, V, or Mn salt, etc., with a concentration of 0.03–0.10 mol / L in the mixed solution.

[0033] S3. The nano-superhard material is uniformly dispersed in a mixed solution and subjected to hydrothermal treatment to coat the surface of the nano-superhard material with water-soluble sugar and transition metal ions, thereby obtaining a polymer composite nano-superhard material.

[0034] Typically, during hydrothermal treatment, water-soluble sugar molecules can undergo condensation reactions and preferentially coat the surface of nano-superhard materials, while transition metal ions are also simultaneously coated in the condensation product coating layer.

[0035] In some embodiments, the temperature of the hydrothermal treatment solution is 150–220°C, and the time is 18–36 h;

[0036] In some embodiments, the mixed solution is subjected to hydrothermal treatment to obtain a product containing polymer composite nano-superhard material. The product is then washed, for example, with deionized water and anhydrous ethanol to remove residues and impurities until the washing liquid is colorless and transparent. The washed polymer composite nano-superhard material is then dried in a vacuum or air atmosphere at 120°C for more than 6 hours to obtain dried polymer composite nano-superhard material.

[0037] S4. The polymer composite nano-superhard material is mixed and dispersed with boric acid in deionized water, and then dried for later use; wherein, the mass ratio of polymer composite nano-superhard material to boric acid is 1:0.5-2; mixing polymer composite nano-superhard material with boric acid and dispersing it in deionized water can uniformly disperse boric acid and polymer composite superhard material, and after drying, boric acid molecules are uniformly distributed on the surface of polymer composite superhard material.

[0038] In some embodiments, the polymer composite nano-superhard material and the boric acid mixture are dried by freeze drying. Freeze drying can ensure that the polymer and boric acid molecules coated on the surface of the nano-superhard material are in uniform contact, which facilitates a uniform in-situ reaction in the subsequent sintering process.

[0039] S5. The dried polymer composite nano-superhard material is molded and placed in a graphite mold. Typically, the mixture obtained in step S4 is transferred to a mold steel mold and cold-pressed by a manual hydraulic press at a pressure of 10-50 MPa. The molded material is then placed in a graphite mold.

[0040] S6. Polymer composite nano-superhard material and boric acid in a graphite mold are rapidly sintered in a plasma discharge device. Under the catalysis of transition metal ions, the polymer in the polymer composite nano-superhard material reacts in situ with the surface of the nano-superhard material to generate boron carbide, resulting in a boron carbide-bonded nano-superhard material ultra-precision grinding tool. During the sintering process, the polymer undergoes carbonization to generate carbon. Under the catalysis of transition metal ions, the carbon reacts in situ with boric acid to generate boron carbide. The generated boron carbide is uniformly dispersed on the surface of the nano-superhard material as a binder. The uniformly dispersed binder boron carbide and the nano-superhard material form a nano-superhard material ultra-precision grinding tool.

[0041] In some embodiments, sintering is carried out in a vacuum environment with a sintering temperature and pressure of 30–80 MPa, a temperature of 1200–1500 °C, and a holding time of 10–20 min.

[0042] On the other hand, some embodiments disclose ultra-precision abrasives made of nano-superhard materials, which are obtained by using a method for preparing ultra-precision abrasives made of nano-superhard materials.

[0043] Example 1

[0044] The method for preparing ultra-precision abrasives using nanomaterials of superhard material disclosed in Example 1, such as... Figure 2 As shown, it includes:

[0045] Add 10–20 g of nano-superhard material to 50 mL of piranha solution and stir for 15–30 min; wash the nano-superhard material with a large amount of deionized water until the washing solution is neutral, and then dry it at 120 °C in air or vacuum for later use; perform strong oxidation treatment on the surface of the nano-superhard material to remove surface impurities and generate hydrophilic groups such as hydroxyl and carboxyl groups, making it easy to achieve uniform dispersion in aqueous solution.

[0046] Take 2-5g of water-soluble sugar and transition metal salt, and dissolve them together in 45mL of deionized water to form a mixed solution of sugar and transition metal salt; prepare a precursor that achieves co-coating of carbon and boron carbide catalyst. During the sintering process, the transition metal can catalyze the reaction between carbon and boric acid, thereby reducing the synthesis temperature of boron carbide. Too high a synthesis temperature of boron carbide will lead to the graphitization of nanodiamonds.

[0047] Meanwhile, 1-2g of nano-superhard material was dispersed into the mixed solution using ultrasonic dispersion. Ultrasonic dispersion can effectively disperse the nano-superhard material, and the high solution density due to the presence of sugar organic molecules and the hydrophilic functional groups on the surface of the nano-superhard material particles can ensure that the nanoparticles can be well dispersed and suspended in the solution.

[0048] The mixed solution was transferred to a hydrothermal reactor and hydrothermally treated at 150–220°C for 18–36 hours. During the hydrothermal process, sugar molecules can undergo condensation and preferentially coat the surface of the nano-superhard material, while transition metal ions are also simultaneously coated in the carbon coating layer.

[0049] The solid residue in the hydrothermal reactor was washed with deionized water and anhydrous ethanol until the washing liquid was colorless and transparent. The solid residue was then transferred to a drying oven and dried at 120°C for more than 6 hours under vacuum or air atmosphere. After washing and drying, the residue was collected for later use. During the washing process, the carbon-coated nano-superhard material was purified to remove residual small molecule organic matter and other impurities.

[0050] The obtained polymer carbon-coated nano-superhard material was dissolved and dispersed in deionized water with boric acid in a certain proportion, and then freeze-dried in a vacuum freeze dryer to obtain a dry mixed powder for later use. The uniform mixing of the precursor and the use of freeze-drying method can ensure that the coated carbon and catalyst can be in uniform contact with boric acid molecules, which is convenient for synthesis and sintering.

[0051] The mixed powder is cold-pressed into shape and assembled into a graphite mold;

[0052] The graphite mold is transferred to a discharge plasma device for rapid sintering at a pressure of 30–80 MPa and a temperature of 1200–1500 °C in a vacuum environment for 10–20 min. After demolding, an in-situ synthesized boron carbide-bonded nano-superhard material ultra-precision abrasive can be obtained.

[0053] The method for preparing ultra-precision abrasives from nano-superhard materials disclosed in this application involves thoroughly removing impurities from the surface of the nano-superhard material and subjecting it to hydrophilic treatment. A carbon source material and a catalyst are then uniformly coated onto the surface of the superhard material. Water-soluble sugars from the carbon source material react in situ with boric acid under the action of the catalyst to generate a boron carbide binder, which is uniformly distributed on the surface of the nano-superhard material. The resulting ultra-precision abrasive from nano-superhard materials exhibits uniform dispersion of the nano-superhard material and the binder, resulting in a uniform microstructure, high grinding precision, and long service life, demonstrating promising application prospects in the field of ultra-precision abrasives.

[0054] The technical solutions and technical details disclosed in the embodiments of this application are merely illustrative of the inventive concept of this application and do not constitute a limitation on the technical solutions of this application. Any conventional changes, substitutions or combinations made to the technical details disclosed in this application have the same inventive concept as this application and are within the protection scope of the claims of this application.

Claims

1. A method for preparing ultra-precision abrasives from nano-superhard materials, characterized in that, Including the following steps: S1. The surface of the nano-superhard material is subjected to strong oxidation treatment to remove surface impurities and generate hydrophilic groups; the nano-superhard material is cubic boron nitride or diamond; wherein the particle size of the nano-superhard material is 1-100 nm. S2, water-soluble sugars and transition metal salts dissolve in deionized water to form a mixed solution; S3. The nano-superhard material is uniformly dispersed in a mixed solution and subjected to hydrothermal treatment to coat the surface of the nano-superhard material with water-soluble sugar and transition metal ions, thereby obtaining a polymer composite nano-superhard material. S4. The polymer composite nano-superhard material is mixed and dispersed with boric acid in deionized water, and then dried for later use; wherein, the mass ratio of the polymer composite nano-superhard material to boric acid is 1:0.5-2. S5. The dried polymer composite nano-superhard material is molded and placed in a graphite mold; wherein the molding pressure is 10-50 MPa. S6. The polymer composite nano-superhard material in the graphite mold is rapidly sintered with boric acid in a plasma discharge device. Under the catalysis of transition metal ions, the polymer in the polymer composite nano-superhard material reacts in situ with the boric acid on the surface of the nano-superhard material to generate boron carbide, thus obtaining a boron carbide-bonded nano-superhard material ultra-precision grinding tool.

2. The method for preparing ultra-precision abrasives from nano-superhard materials according to claim 1, characterized in that, In step S1, the nano-superhard material is treated with a strong acid solution, wherein the strong acid solution is concentrated nitric acid, or a mixture of concentrated sulfuric acid and 30% hydrogen peroxide solution, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide solution is 7:3; the treatment time is 15-30 min; and the mass-volume ratio of nano-superhard material to strong acid solution is 1-2 g: 5 ml.

3. The method for preparing ultra-precision abrasives from nano-superhard materials according to claim 1, characterized in that, Water-soluble sugars include glucose, sucrose, fructose, and lactose; transition metal salts include Fe, Co, Ni, Cr, Mo, W, V, or Mn salts; in the mixed solution, the concentration of water-soluble sugars is 0.04–0.12 g / ml, and the concentration of transition metal salts is 0.03–0.10 mol / L.

4. The method for preparing ultra-precision abrasives from nano-superhard materials according to claim 1, characterized in that, In step S3, the temperature of the hydrothermal treatment solution is 150–220°C, and the time is 18–36 h.

5. The method for preparing ultra-precision abrasives from nano-superhard materials according to claim 1, characterized in that, Step S3 also includes washing the polymer composite nano-superhard material, and drying the washed polymer composite nano-superhard material at 120°C for more than 6 hours in a vacuum or air atmosphere to obtain dried polymer composite nano-superhard material.

6. The method for preparing ultra-precision abrasives from nano-superhard materials according to claim 1, characterized in that, In step S4, the polymer composite nano-superhard material and the boric acid mixture are dried by freeze drying.

7. The method for preparing ultra-precision abrasives from nano-superhard materials according to claim 1, characterized in that, In step S6, sintering is carried out in a vacuum environment with a sintering temperature and pressure of 30-80 MPa, a temperature of 1200-1500℃, and a holding time of 10-20 min.

8. A nano-superhard material ultra-precision abrasive, characterized in that, The ultra-precision abrasive tool made of nano-superhard material is obtained using the preparation method described in any one of claims 1 to 7.

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