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US-12617023-B2 - Silicon nitride ceramic tool comprising diamond film and method of preparing the same

US12617023B2US 12617023 B2US12617023 B2US 12617023B2US-12617023-B2

Abstract

A cutting tool, including a silicon nitride (Si 3 N 4 ) ceramic substrate, and a diamond film coated on the surface of the Si 3 N 4 ceramic substrate. The diamond film has a thickness of 7-12 μm. The cutting tool includes a tool nose, a blade, and a handle. The blade has a rake angle γ of 5-15°, a clearance angle α of 10-14°, and a helix angle of 15-45°. The blade includes four cutting edges.

Inventors

  • Chengyong WANG
  • Yuhai ZHOU
  • Lijuan ZHENG

Assignees

  • GUANGDONG UNIVERSITY OF TECHNOLOGY

Dates

Publication Date
20260505
Application Date
20210329

Claims (4)

  1. 1 . A method of preparing a cutting tool, the method comprising: 1. Putting a silicon nitride (Si 3 N 4 ) ceramic substrate in a hexane suspension mixed with diamond powders, and ultrasonically vibrating the hexane suspension, to grow diamond seeds on the Si 3 N 4 ceramic substrate, wherein the Si 3 N 4 ceramic substrate further comprises TiN particles; and 2. Ultrasonically cleaning the Si 3 N 4 ceramic substrate in acetone for 3-8 min, and then in 92-98% anhydrous alcohol for 2-4 min; drying the Si 3 N 4 ceramic substrate and placing the Si 3 N 4 ceramic substrate in a hot-wire chemical vapor deposition (CVD) vessel to produce the cutting tool; wherein the cutting tool comprises a diamond film coated on a surface of the Si 3 N 4 ceramic substrate, and the diamond film having a thickness of 7-12 μm, an arithmetic average roughness (Ra) value of 8.1 nm, and a root mean square roughness (RMS) value of 8.6 nm.
  2. 2 . The method of claim 1 , wherein prior to 1), a rake face of the silicon nitride (Si 3 N 4 ) ceramic substrate is grinded in a diamond slurry on a cast iron grinding plate, and then the rake face is roughened in a nano size by CF4 plasma dry etching.
  3. 3 . The method of claim 1 , wherein in 2), the hot-wire chemical vapor deposition (CVD) vessel operates with the following parameters: a filament temperature of 2000-2400° C., a substrate temperature of 750-800° C., a total pressure of 3.0-5.0 kPa, a total flow of 300-350 sccm, a volume ratio of CH 4 /H 2 of 1-3%, and a deposition time of 6-10 h.
  4. 4 . The method of claim 1 , wherein a particle size of the diamond powders is 0.5-1 μm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of International Patent Application No. PCT/CN2018/108380 with an international filing date of Sep. 28, 2018, designating the United States, now pending, the contents of which, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P. C., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, MA 02142. BACKGROUND The disclosure relates to the field of cutting tools, and more particularly to a silicon nitride (Si3N4) ceramic tool comprising diamond film and a method of preparing the same. Cemented carbide (WC—Co) and silicon nitride ceramic are two main matrix materials for cutting tools. The existence of Co phase on the surface of cemented carbide is not conducive to the nucleation of the diamond film and will reduce the adhesion between the film and the substrate. The silicon nitride ceramic tools are easy to wear down. SUMMARY The disclosure provides a cutting tool, comprising a silicon nitride (Si3N4) ceramic substrate, and a diamond film coated on a surface of the Si3N4 ceramic substrate. The diamond film having a thickness of 7-12 μm. In a class of this embodiment, the cutting tool comprises a tool nose, a blade, and a handle; the blade has a rake angle γ of 5-15°, a clearance angle α of 10-14°, and a helix angle of 15-45°; and the blade comprises four cutting edges. In a class of this embodiment, the radius R of the tool nose is 0.18-0.22 mm. In a class of this embodiment, the blade has a length H1 of 4.7-5.3 mm. In a class of this embodiment, the cutting tool has a length H2 of 49.5-50.5 mm. The disclosure also provides a method of preparing the cutting tool, the method comprising: 1) putting silicon nitride (Si3N4) ceramic substrate in a hexane suspension mixed with diamond powders, and ultrasonically vibrating the hexane suspension, to grow diamond seeds on the Si3N4 ceramic substrate; and2) ultrasonically cleaning the Si3N4 ceramic substrate in acetone for 3-8 min, and then in 92-98% anhydrous alcohol for 2-4 min; drying the Si3N4 ceramic substrate and placing in a hot-wire chemical vapor deposition (CVD) vessel. In a class of this embodiment, prior to 1), a rake face of the silicon nitride (Si3N4) ceramic substrate is grinded in diamond slurry on a cast iron grinding plate, and then the rake face is roughened in a nano size by CF4 plasma dry etching. In a class of this embodiment, in 2), the hot-wire chemical vapor deposition (CVD) vessel operates with the following parameters: a filament temperature of 2000-2400° C., a substrate temperature of 750-800° C., a total pressure of 3.0-5.0 kPa, a total flow of 300-350 sccm, a volume ratio of CH4/H2 of 1-3%, and a deposition time of 6-10 h. In a class of this embodiment, the particle size of the diamond powders is 0.5-1 μm. In another aspect, the disclosure also provides a method of machining a graphite mold for hot bending of glass for a curved surface mobile phone, the method comprising machining the graphite mold using the cutting tool. The following advantages are associated with the cutting tool of the disclosure. The cutting tool comprises a silicon nitride (Si3N4) ceramic substrate; and a diamond film coated on a surface of the Si3N4 ceramic substrate, and the diamond film has a thickness of 7-12 μm. Owing to excellent chemical and physical properties, the diamond films of the disclosure obtained through chemical vapor deposition (CVD) have high hardness, excellent wear resistance and chemical stability. Integrating the advantages of the coating materials and the ceramic substrate, the cutting tool of the disclosure exhibits good cutting performance, high hardness and wear resistance, and low friction coefficient. The thermal expansion coefficient of the silicon nitride ceramic material is close to that of diamond (3.0 and 3.7, respectively), which can reduce the thermal expansion stress of the CVD diamond film and silicon nitride ceramic substrate, thus producing good adhesion therebetween. Because there is no cobalt in the ceramic substrate, there is no need to pretreat the substrate and remove cobalt (Co) through corrosion. The cutting tool of the disclosure is suitable for high speed machining of a graphite mold for hot bending of glass for curved surface mobile phones. The CVD diamond film coated on the surface of silicon nitride ceramic substrate improves the interface conditions of the tool, and the cutting tool features high hardness and wear resistance, high thermal conductivity and low wear resistance. The cutting tool can be used to process graphite, ceramics and so on, and the problems such as tool loss, electrode collapse and slow processing speed when processing graphite electrode are prevented. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a local view of cuttin