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CN-121976169-A - Gradient diamond film and preparation method and application thereof

CN121976169ACN 121976169 ACN121976169 ACN 121976169ACN-121976169-A

Abstract

The invention belongs to the technical field of hard alloy cutter coatings, and particularly relates to a gradient diamond film and a preparation method and application thereof. The method comprises the steps of carrying out ultrasonic seeding on a hard alloy substrate by adopting a diamond suspension, and then adopting sectional chemical vapor deposition to prepare the gradient diamond film, wherein the gradient diamond film comprises a nanocrystalline diamond film layer and a boron-doped microcrystalline diamond film layer which are sequentially laminated, and the sectional chemical vapor deposition comprises a first-stage deposition and a second-stage deposition. The preparation method solves the core problem of uneven gradient structure and concentrated interface stress in the prior art through dynamic coupling of air pressure, temperature and air flow and design of the gradient diamond film, and provides technical support for engineering application of high-end tool coatings.

Inventors

  • LI KAI
  • CHEN CHAO
  • Mo Luozhi
  • WANG PEIXUN
  • JIANG SHIWEI
  • Mo Peicheng
  • ZHANG JUN
  • CHEN JIARONG
  • PAN XIAOYI

Assignees

  • 中国有色桂林矿产地质研究院有限公司

Dates

Publication Date
20260505
Application Date
20260226

Claims (10)

  1. 1. The preparation method of the gradient diamond film is characterized by comprising the following steps of: Carrying out ultrasonic seeding on a hard alloy substrate by adopting a diamond suspension, and then adopting sectional chemical vapor deposition to prepare the gradient diamond film, wherein the gradient diamond film comprises a nanocrystalline diamond film layer and a boron-doped microcrystalline diamond film layer which are sequentially laminated, and the sectional chemical vapor deposition comprises sequentially carrying out first-stage deposition and second-stage deposition; The first-stage deposition condition comprises that the air pressure is 1.1-1.3 kPa, the temperature is 920-950 ℃, the flow rate of H 2 is 400-600 sccm, the flow rate of CH 4 is 30-35 sccm, and the first-stage deposition is carried out on the surface of the hard alloy substrate to form a nanocrystalline diamond film layer; The conditions of the second-stage deposition comprise that the air pressure of the second-stage deposition process is increased at a constant speed from the air pressure of the first-stage deposition process, the pressure at the end of the second-stage deposition process is 2.5-3.5 kPa, the temperature of the second-stage deposition process is reduced at a constant speed from the temperature of the first-stage deposition process, the temperature at the end of the second-stage deposition process is 800-850 ℃, the flow rate of CH 4 is 15-25 sccm, H 2 is used as a carrier gas for conveying a boron source, the flow rate of H 2 is 50-150 sccm, the source of the boron source is trimethyl borate solution, and the second-stage deposition process forms a boron-doped microcrystalline diamond film layer on the surface of the microcrystalline diamond film.
  2. 2. The method of claim 1, wherein the mass concentration of diamond particles in the diamond suspension is 5-10 mg/100mL.
  3. 3. The method of claim 1 or 2, further comprising etching the cemented carbide substrate prior to performing the ultrasonic seeding, the etching being performed sequentially with a village reagent and a ‌ karl fischer reagent, respectively.
  4. 4. The method according to claim 1, wherein the second stage deposition time is 3 to 3.5 hours.
  5. 5. The method according to claim 1 or 4, wherein the rate of pressure rise in the second-stage deposition is 0.34 to 0.8kpa/h, and the rate of temperature drop in the second-stage deposition is 20 to 50 ℃.
  6. 6. The preparation method of the trimethyl borate aqueous solution is characterized in that the trimethyl borate aqueous solution is an acetone aqueous solution of trimethyl borate, and the volume ratio of the trimethyl borate to the acetone in the trimethyl borate aqueous solution is 4-5:150.
  7. 7. The preparation method of claim 1, wherein the first-stage deposition time is 5-5.5 h, and the thickness of the nanocrystalline diamond film layer is 1-2 μm.
  8. 8. The method according to claim 1 or 4, wherein the thickness of the boron doped microcrystalline diamond film layer is 3 to 5 μm.
  9. 9. The gradient diamond film prepared by the preparation method of any one of claims 1 to 8.
  10. 10. Use of the gradient diamond film of claim 9 in a tool coating, a semiconductor heat sink substrate, or an electrochemical electrode.

Description

Gradient diamond film and preparation method and application thereof Technical Field The invention belongs to the technical field of hard alloy cutter coatings, and particularly relates to a gradient diamond film and a preparation method and application thereof. Background Chemical Vapor Deposition (CVD) diamond films have extremely high hardness, excellent wear resistance, excellent thermal conductivity (> 2000W/mK) and chemical stability, and therefore, have an irreplaceable application value in the fields of high-end tool coatings, semiconductor heat dissipation substrates, electrochemical electrodes and the like. When the alloy is used as a hard alloy cutter coating, the performance bottleneck is that the high hardness and the fracture toughness are simultaneously considered, namely, the traditional single-structure diamond film, such as microcrystalline diamond (MCD) or nanocrystalline diamond (NCD), is difficult to reconcile, the MCD film has high hardness, coarse columnar crystal structure causes concentrated grain boundary stress and low fracture toughness, brittle peeling easily occurs during cutting, the NCD film improves the fracture toughness through the nanocrystalline structure, but the sp 2 carbon content of a grain boundary non-diamond phase is increased, the hardness is lower, and the bonding strength with a substrate is reduced due to the inhibition effect of interfacial Co elements. In order to break through the performance bottleneck, the prior art attempts to realize performance optimization through gradient structure regulation and control. For example, the gradient diamond film is prepared by adopting air pressure regulation and control, and toughness is improved through transition from micron level to nano level of grain size, but the method has the obvious defects that firstly, the transition of the grain size is uneven, the residual compressive stress at the interface is still higher, microcrack expansion is easy to induce, and secondly, the traditional double-layer structure has high-concentration sp 2 phase due to a sharp interface, and the stress is concentrated. In conclusion, the gradient structure diamond film prepared by the prior art still has the problems of uneven gradient structure and concentrated interface stress. Disclosure of Invention The invention aims to provide a gradient diamond film, a preparation method and application thereof, and the method provided by the invention solves the core problem of uneven gradient structure-concentrated interface stress in the prior art, and the residual stress of the interface of the prepared gradient diamond film is obviously reduced and uniformly distributed, thereby providing technical support for engineering application of high-end tool coatings. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a preparation method of a gradient diamond film, which comprises the following steps: Carrying out ultrasonic seeding on a hard alloy substrate by adopting a diamond suspension, and then adopting sectional chemical vapor deposition to prepare the gradient diamond film, wherein the gradient diamond film comprises a nanocrystalline diamond film layer and a boron-doped microcrystalline diamond film layer which are sequentially laminated, and the sectional chemical vapor deposition comprises sequentially carrying out first-stage deposition and second-stage deposition; The first-stage deposition condition comprises that the air pressure is 1.1-1.3 kPa, the temperature is 920-950 ℃, the flow rate of H 2 is 400-600 sccm, the flow rate of CH 4 is 30-35 sccm, and the first-stage deposition is carried out on the surface of the hard alloy substrate to form a nanocrystalline diamond film layer; The conditions of the second-stage deposition comprise that the air pressure of the second-stage deposition process is increased at a constant speed from the air pressure of the first-stage deposition process, the pressure at the end of the second-stage deposition process is 2.5-3.5 kPa, the temperature of the second-stage deposition process is reduced at a constant speed from the temperature of the first-stage deposition process, the temperature at the end of the second-stage deposition process is 800-850 ℃, the flow rate of CH 4 is 15-25 sccm, H 2 is used as a carrier gas for conveying a boron source, the flow rate of H 2 is 50-150 sccm, the source of the boron source is trimethyl borate solution, and the second-stage deposition process forms a boron-doped microcrystalline diamond film layer on the surface of the microcrystalline diamond film. Preferably, the mass concentration of the diamond particles in the diamond suspension is 5-10 mg/100mL. Preferably, before the ultrasonic seeding, the method further comprises the step of etching the hard alloy substrate, wherein the etching is sequentially performed by adopting a village reagent and ‌ Karl Fischer reagent. Preferably, the