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CN-121974695-A - Hexagonal boron nitride-nanometer polycrystalline diamond composite material and preparation method thereof

CN121974695ACN 121974695 ACN121974695 ACN 121974695ACN-121974695-A

Abstract

The invention discloses a hexagonal boron nitride-nanometer polycrystalline diamond composite material and a preparation method thereof, wherein the composite material is prepared by taking carbon nano shallot (OLC) and hexagonal boron nitride (h-BN) as raw materials through high-temperature and high-pressure sintering, wherein the mass ratio of the hexagonal boron nitride to the carbon nano shallot is 10:90-75:25, and the main phase composition of the composite material is cubic boron nitride and cubic diamond and can contain a small amount of wurtzite boron nitride. According to the invention, a diamond-hBN synergistic-enhanced microstructure is constructed at high temperature and high pressure, so that the sintering condition of OLC is reduced, the problem of high OLC sintering condition is solved, the synchronous improvement of hardness and toughness is realized through heterogeneous interface design, and a new way is provided for preparing the hexagonal boron nitride-nanoscale polycrystalline diamond composite material.

Inventors

  • ZOU QIN
  • LI YANGUO
  • LUO YONGAN
  • DAI LIFENG

Assignees

  • 燕山大学

Dates

Publication Date
20260505
Application Date
20260209

Claims (9)

  1. 1. The hexagonal boron nitride-nanometer polycrystalline diamond composite material is characterized in that the composite material is prepared by taking carbon nanometer shallot and hexagonal boron nitride as raw materials through high-temperature and high-pressure sintering, wherein the mass ratio of the hexagonal boron nitride to the carbon nanometer shallot is 10:90-75:25, and the main phase composition of the composite material is cubic boron nitride and cubic diamond and can contain a small amount of wurtzite boron nitride.
  2. 2. The hexagonal boron nitride-nano polycrystalline diamond composite material according to claim 1, wherein the average grain size of the carbon nano-onions is 5 nm.
  3. 3. The hexagonal boron nitride-nano polycrystalline diamond composite material of claim 1, wherein the hexagonal boron nitride has a grain size of 0.5-100 μm.
  4. 4. The method of preparing a hexagonal boron nitride-nano polycrystalline diamond composite material according to claim 1, comprising the steps of: S1, annealing nano diamond prepared by a detonation method serving as a raw material under the conditions that the temperature is 900-1600 ℃ and the vacuum degree is 1.0X10 -1 Pa and the temperature is not kept, so as to prepare carbon nano shallot (OLC); S2, uniformly mixing the hexagonal boron nitride powder and the carbon nano onion prepared in the step S1 according to the mass ratio of 10:90-75:25, and filling the mixture into a hard alloy die for prepressing forming, wherein the pressure is 400-600 MPa, and the pressure maintaining time is 30-60S; And S3, loading the pre-pressed and molded sample into an assembly module for high-temperature high-pressure sintering, wherein the sintering pressure is 5-40 GPa, the sintering temperature is 1200-3000 ℃, the heat preservation time is 0-60 min, then cooling, unloading and pressing to obtain a blank, and further finishing the blank to obtain the hexagonal boron nitride-nanometer polycrystalline diamond composite material.
  5. 5. The method of preparing a hexagonal boron nitride-nano polycrystalline diamond composite material according to claim 4, wherein carbon nano green Onion (OLC) containing diamond crystal cores is prepared in the step S1 at an annealing temperature of 900-1350 ℃, and carbon nano green Onion (OLC) containing no diamond cores is prepared in the step S1 at an annealing temperature of 1400-1600 ℃.
  6. 6. The method of claim 4, wherein the average grain size of the carbon nano-Onions (OLCs) obtained in step S1 is 5 nm.
  7. 7. The method for preparing the hexagonal boron nitride-nano polycrystalline diamond composite material of claim 4, the method is characterized in that the sintering temperature rise speed in the step S3 is 10 ℃ per minute.
  8. 8. The method of preparing a hexagonal boron nitride-nano polycrystalline diamond composite material according to claim 4, wherein the pressurizing time of the sintering pressure in step S3 is controlled within 10-30 h.
  9. 9. A method of preparing a hexagonal boron nitride-nano polycrystalline diamond composite material according to any one of claims 4 to 8, wherein the workblank trimming operation in step S3 comprises surface grinding and deburring.

Description

Hexagonal boron nitride-nanometer polycrystalline diamond composite material and preparation method thereof Technical Field The invention relates to the technical field of composite materials, in particular to a hexagonal boron nitride-nanometer polycrystalline diamond composite material and a preparation method thereof. Background Polycrystalline diamond (PCD) has high hardness and wear resistance, overcomes the defects of anisotropy and {111} crystal face dissociation and destruction of single crystal diamond, and is widely applied to various fields such as aerospace, electronics, construction, precious stone processing, petroleum drilling, geological exploration and the like. Lian Min, etc., to prepare extremely hard high-toughness nano polycrystalline diamond composite material, taking graphene as raw material, synthesizing a cubic phase diamond and cubic carbon two-phase composite structure at 22 GPa/1800-2000 ℃, wherein the mole percentage of the cubic diamond is 70-90% and the cubic carbon is 10-30%, so that the Vickers hardness of the material reaches 120-150 GPa, the fracture toughness is 12-15 MPa.m 1/2, and the toughness is improved by 1-2 times than that of single crystal diamond [ Lian Min, etc. ]. Zheng Linpeng and the like adopt a Chemical Vapor Deposition (CVD) method to prepare a high-purity polycrystalline diamond block as a precursor, the high-purity polycrystalline diamond block is converted into nano graphite through high-temperature medium-pressure graphitization (1-4 GPa/1800-2200 ℃) and then is subjected to secondary treatment at 15-25 GPa/2000-2400 ℃ to obtain colorless transparent nano polycrystalline diamond, so that powder pollution is avoided, vickers hardness reaches 115 GPa, and the method is suitable for extreme environments such as an optical window [ Zheng Linpeng and the like ]. Tian Yongjun and the like invent an ultra-high hardness nano twin crystal diamond block material and a preparation method thereof, wherein nano twin crystal diamond is synthesized by adopting OLC with high density defects at 18-25 GPa/1850-2000 ℃, the nano twin crystal diamond has a unique twin crystal structure, the Vickers hardness is 155-350 GPa, the Knoop hardness is 140-240 GPa, the twin crystal width is 1-15 nm, and the hardness is far higher than the hardness of diamond monocrystal and super-hard polycrystalline diamond [ Tian Yongjun; huang Quan. The ultra-high hardness nano twin crystal diamond block material and the preparation method thereof are disclosed in CN104209762A, yan Shanda, 2014, 12 and 17 days. Ma Shuailing and the like invent a polycrystalline diamond material with a bimodal structure, adopts carbon nano shallot (50 nm) and micron graphite (40-60 mu m) as raw materials, forms nano-and micron bimodal grain distribution by mechanical grinding and high-temperature high-pressure sintering (15 GPa/1800 ℃), has the Vickers hardness of 153-169 GPa and the toughness of 14-15 MPa m 0.5, and realizes the balance of high hardness and high toughness [ Ma Shuai collar and the like. The PCD synthesis by taking carbon nano-Onions (OLCs) as precursors requires extremely high pressure and temperature conditions (P is more than or equal to 18 GPa, T is more than or equal to 2300 ℃), has high equipment requirements and high cost, and the maximum size of the synthesized PCD is less than 3mm, so that the PCD is difficult to apply. Disclosure of Invention The technical problems to be solved are as follows: At present, extremely high pressure and temperature conditions (more than or equal to 18 GPa and 1800 ℃) are required for synthesizing PCD by taking OLC as a precursor, the requirement on equipment is high, the cost is high, and the application is difficult, so that a PCD preparation method for reducing sintering conditions is needed. Aiming at the technical problems, the invention takes the mixture of OLC and hexagonal boron nitride (hBN) prepared by an annealing method as a raw material, adopts high-temperature and high-pressure (5-40 GPa/1200-3000 ℃ per heat preservation time of 0-60 min) sintering to prepare the hexagonal boron nitride-nanometer polycrystalline diamond composite material, reduces sintering conditions by using the similarity and the correspondence of h-BN and diamond structures, and improves conductivity by using the cooperative doping of B atoms and N atoms, thereby obtaining the hexagonal boron nitride-nanometer polycrystalline diamond composite material with high hardness and good conductivity. Technical proposal The hexagonal boron nitride-nanometer polycrystalline diamond composite material is prepared by taking carbon nano shallot (OLC) and hexagonal boron nitride (h-BN) as raw materials and sintering the raw materials at high temperature and high pressure, wherein the mass ratio of the hexagonal boron nitride to the carbon nano shallot is 10:90-75:25, and the main phase composition is cubic boron nitride (cBN) and cubic diamond, and can contain a small amount of wurtzi