WO2017136969A1

WO2017136969A1 - Boron nitride composite coating, graded structure ultrafine hard alloy cutting tool with the composite coating, and method for manufacturing same

Info

Publication number: WO2017136969A1
Application number: PCT/CN2016/075342
Authority: WO
Inventors: 伍尚华; 陈健; 邓欣; 刘伟; 何福坡; 陈少华; 刘汝德
Original assignee: 广东工业大学
Priority date: 2016-02-11
Filing date: 2016-03-02
Publication date: 2017-08-17
Also published as: CN105603387B; CN105603387A

Abstract

A boron nitride composite coating comprising of a TiBCN layer, a Ni₃Si₂ layer, and a CBN layer, and a graded structure ultrafine hard alloy cutting tool with the coating. The cutting tool comprises a cutting tool base body and the boron nitride composite coating. The cutting tool base body is provided with a normal organization layer, a cobalt-rich transition layer, and a cobalt-poor cube-rich phase layer. The composite coating is deposited by an arc ion plating device. The boron nitride composite coating has good adhesion to the cutting tool base body, good layer-to-layer adhesion within the composite coating, and good resistance against high temperatures, corrosion, and abrasion. The graded structure ultrafine hard alloy cutting tool with the coating has excellent abrasion resistance and heat resistance.

Description

Boron nitride composite coating, gradient ultrafine cemented carbide tool having the composite coating and preparation method thereof

Technical field

The invention relates to the technical field of cemented carbide cutters, in particular to a boron nitride composite coating, a gradient ultrafine cemented carbide cutter having the composite coating and a preparation method thereof.

Background technique

The emergence of coated carbide tools is an important milestone in the history of tool development. It is formed by coating a thin layer of refractory metal or non-metal compound with good wear resistance by a vapor deposition method on a cemented carbide substrate having good strength and toughness.

As a chemical barrier and thermal barrier, the coating reduces the diffusion and chemical reaction between the tool and the workpiece, thus reducing crater wear. The coating has high hardness and heat resistance and reduces the coefficient of friction between the tool and the workpiece. Therefore, the coated tool can significantly improve the service life than the uncoated tool. Generally, the life of the coated tool can be compared with that of the uncoated tool. 2-5 times higher.

In order to improve the wear resistance of cemented carbide tools, different coatings are prepared by vapor deposition to coat hard coatings with higher wear resistance on the surface, such as TiC, TiN, TiCN and A1 ₂ 0 _3, etc., the hardness of these coatings is usually 15GPa to 40Gpa.

Cubic boron nitride (CBN) is the second ultra-hard material next to diamond. It has excellent physical and chemical properties, and is second only to diamond in hardness and thermal conductivity, while thermal stability is remarkable. Better than diamond, it will be oxidized when heated to 1200 °C in the atmosphere, and the oxidation temperature of diamond in the atmosphere is 600 °C. CBN has extremely stable chemical properties for ferrous metals and can be widely used in the cutting of steel products. It is suitable for the cutting of difficult-to-machine materials such as hardened steel, bearing steel, high-speed steel, tool steel, chilled cast iron, high-temperature alloy, and thermal spray materials. It is one of the best tools to achieve “cutting and grinding”. It is one of the most promising tool materials in the 21st century. However, due to the inability to solve key problems such as film stress and film-based bonding, the application of CBN film in cemented carbide tools is limited.

Therefore, in view of the deficiencies of the prior art, a boron nitride composite coating suitable for surface performance enhancement of a cemented carbide tool, a gradient ultrafine cemented carbide tool having the composite coating, and a preparation method thereof are provided to overcome the existing Technical deficiencies are necessary.

Summary of the invention

One of the objects of the present invention is to provide a boron nitride composite coating and a preparation method thereof, which avoids the deficiencies of the prior art, and the boron nitride composite coating has good bonding property with the tool substrate, and the coating of the composite coating is good. The adhesion between the layers is good, and the high temperature resistance, corrosion resistance, and wear resistance are good.

Another object of the present invention is to provide a gradient ultra-fine cemented carbide tool having a boron nitride composite coating having good wear resistance and temperature resistance.

The above object of the present invention is achieved by the following technical means.

Provided is a boron nitride composite coating comprising a TiBCN layer for deposition onto a surface of a tool substrate as a transition layer, a Ni ₃ Si ₂ layer deposited as a bonding layer on the transition layer, and deposited on the bonding layer as a wear layer CBN layer.

The transition layer has a thickness of 0.1-15 microns; the bonding layer has a thickness of 1.6-3 microns; The wear layer has a thickness of 0.1 to 3 microns.

Further, the transition layer has a thickness of 2-8 micrometers; the bonding layer has a thickness of 1.6-2 micrometers; and the wear layer has a thickness of 1.0-2.0 micrometers.

The content of boron in the TiBCN layer is 10 at% to 15 at%; the grain size of the TiBCN layer is a granular to columnar configuration of less than 2 μm, and the micro Vickers hardness of the TiBCN layer is 30 GPa or more.

Preferably, the grains of the TiBCN layer are in a columnar configuration of less than 500 nm.

Providing the preparation method of the above boron nitride composite coating layer, comprising the following steps,

(1) depositing a TiBCN layer as a transition layer by CVD;

(2) depositing a Ni ₃ Si ₂ layer as a bonding layer on the transition layer by a CVD method;

(3) A CBN layer as a wear layer is deposited on the bonding layer by a CVD method.

Further, the step (1) specifically adopts an MT-CVD method to prepare a TiBCN layer, the preparation temperature is 800-950 ° C, and BCl _{3 is} used as a boron source, and BCl ₃ accounts for 0.5%-10% of the total gas flow. Acetonitrile is used as a carbon source and a nitrogen source;

The step (2) specifically adopts a high-purity Ni ₃ Si ₂ alloy target, and uses high-purity nitrogen as a sputtering gas at a substrate temperature of 500 ° C, a pressure of 0.2 Pa, a sputtering power of 300 W, and a sputtering time of 2.5 to 4 hours. Preparing the bonding layer under sputtering conditions;

The deposited Ni ₃ Si ₂ layer substrate is placed in a direct plasma plasma chemical vapor deposition apparatus, firstly introduced into three gases BF3, N2 and Ar, and etched 25-35 under a positive bias of 30-40V. Minutes, the substrate is cleaned, after etching, H _{2 is introduced} , and then the CBN layer is deposited;

The process parameters of the step (3) for preparing the CBN layer are: BF3, N2, Ar and H2 flow rates are respectively 20 sccm, 2 slm, 4 slm, 5 sccm, total reaction gas pressure is 4 Kpa, substrate negative bias voltage is 65 V, lining The bottom temperature was 860 ° C and the deposition time was 60 min.

Providing a gradient ultra-fine cemented carbide tool having a boron nitride composite coating, comprising a tool base and a boron nitride composite coating disposed on the tool base;

The tool substrate comprises a normal tissue layer, a cobalt-rich transition layer and a cobalt-depleted cubic phase layer, and the normal tissue layer, the cobalt-rich transition layer and the cobalt-depleted cubic phase layer are arranged in order from the inside to the outside;

The boron nitride composite coating layer comprises a TiBCN layer deposited on the surface of the cobalt-depleted cubic phase layer as a transition layer, a Ni ₃ Si ₂ layer deposited as a bonding layer on the transition layer, and deposited on the bonding layer as resistance The CBN layer of the layer.

The content of cobalt in the tool base is 5-15 wt.%;

The normal tissue layer is an ultrafine cemented carbide, and the WC grain size is 1-1000 nm;

The thickness of the normal tissue layer is greater than 2 mm, the thickness of the cobalt-rich transition layer is 20-100 microns; and the thickness of the cobalt-depleted cubic phase layer is 20-50 microns;

The thickness of the transition layer is 0.1-15 microns; the thickness of the bonding layer is 1.6-3 microns; the thickness of the wear layer is 0.1-3 microns;

The content of boron in the TiBCN layer is 10 at% to 15 at%; the grain size of the TiBCN layer is a granular to columnar configuration of less than 2 μm, and the micro-Vickers hardness of the TiBCN layer is 30 GPa or more.

The content of cobalt in the tool base is 8-12 wt.%; the WC grain size of the normal tissue layer is 1 nm-400 nm; and the boron nitride composite coating is prepared by the method of claim 6 or 7.

The boron nitride composite coating of the present invention has good adhesion to the tool base, and has good adhesion between the coating layers of the composite coating, and has high temperature resistance, corrosion resistance and wear resistance. The gradient ultra-fine cemented carbide tool with the boron nitride composite coating has good wear resistance and temperature resistance.

DRAWINGS

The invention is further described with reference to the drawings, but the contents of the drawings do not constitute any limitation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the interlayer structure of a boron nitride composite coating of the present invention.

2 is a schematic view showing the interlayer structure of a gradient ultrafine cemented carbide tool having a boron nitride composite coating according to the present invention.

3 is a schematic view of a gradient ultrafine cemented carbide tool having a boron nitride composite coating of the present invention.

detailed description

The invention is further described in conjunction with the following examples.

Example 1.

A boron nitride composite coating, as shown in FIG. 1, includes a TiBCN layer for deposition onto a surface of a tool substrate as a transition layer, a Ni ₃ Si ₂ layer deposited as a bonding layer on the transition layer, and a deposition layer A CBN layer as an abrasion resistant layer.

The thickness of the transition layer is 0.1-15 microns, the thickness of the bonding layer is 1.6-3 microns, and the thickness of the wear layer is 0.1-3 microns.

Preferably, the transition layer has a thickness of from 2 to 8 microns, the bond layer has a thickness of from 1.6 to 2 microns, and the wear layer has a thickness of from 1.0 to 2.0 microns.

The TiBCN layer can prevent the penetration of tungsten, cobalt and other elements into the coating when depositing on the surface of the cemented carbide tool substrate, thereby improving the crystal growth direction, microstructure and bonding force of the coating. Improves the bond between the coating and the substrate and the adhesion between adjacent coatings. The content of boron in the TiBCN layer is 10 at% to 15 at%, the grain size of the TiBCN layer is a granular to columnar configuration of less than 2 μm, preferably the grain size of the TiBCN layer is a columnar configuration of less than 500 nm, and the microstructure of the TiBCN layer is Vickers hardness. More than 30Gpa.

The Ni ₃ Si ₂ layer is arranged to effectively deposit the wear layer because Ni has a close lattice constant with C-BN and has a face-centered cubic structure, which is easy for C-BN nucleation growth and is beneficial for improving C- The internal stress of BN deposition is set by the Ni ₃ Si ₂ layer as a bonding layer to make it bond well with the wear layer.

The CBN layer as the wear-resistant layer has a high hardness, and has good wear resistance and good temperature resistance.

The preparation method of the boron nitride composite coating includes the following steps,

(1) depositing a TiBCN layer as a transition layer by CVD; depositing on a specific tool substrate surface or depositing on a substrate as needed;

Further, in the step (1), the TiBCN layer is prepared by the MT-CVD method, and the preparation temperature is 800-950 ° C, and BCl _{3 is} used as the boron source, and BCl ₃ accounts for 0.5%-10% of the total gas stream, and acetonitrile. Used as a carbon source and a nitrogen source.

Step (2) specifically uses a high-purity Ni ₃ Si ₂ alloy target, using high-purity nitrogen as a sputtering gas, at a substrate temperature of 500 ° C, a pressure of 0.2 Pa, a sputtering power of 300 W, and a sputtering time of 2.5-4 hours. The bonding layer is prepared under shot conditions.

The deposited Ni ₃ Si ₂ layer substrate is placed in a direct plasma plasma chemical vapor deposition apparatus, firstly introduced into three gases BF3, N2 and Ar, and etched 25-35 under a positive bias of 30-40V. In minutes, the substrate is cleaned, and after etching, H _{2 is introduced} , and then the CBN layer is deposited.

Step (3) The process parameters for preparing the CBN layer are: BF3, N2, Ar, and H2 flow rates are 20 sccm, 2 slm, 4 slm, 5 sccm, total reaction gas pressure is 4 Kpa, substrate negative bias voltage is 65 V, substrate temperature The temperature was 860 ° C and the deposition time was 60 min.

The boron nitride composite coating of the present invention can be well bonded to the tool base, and the adhesion of the coating of the composite coating is good, and the high temperature resistance, corrosion resistance and wear resistance are good. The gradient ultra-fine cemented carbide tool with the boron nitride composite coating has good wear resistance and temperature resistance.

Example 2.

A gradient ultra-fine cemented carbide tool having a boron nitride composite coating is composed of a tool base and a boron nitride composite coating disposed on the tool base, as shown in FIGS. 2 and 3.

The tool substrate comprises a normal tissue layer, a cobalt-rich transition layer and a cobalt-depleted cubic phase layer, and the normal tissue layer, the cobalt-rich transition layer and the cobalt-depleted cubic phase layer are arranged in order from the inside to the outside. The content of cobalt in the tool base is 5-15 wt.%, preferably the content of cobalt is 8-12 wt.%. The normal tissue layer is an ultrafine cemented carbide having a WC grain size of 1-1000 nm, preferably a WC grain size of 1-500 nm.

The cobalt-depleted cubic phase layer is rich in cubic phase nitrides or carbonitrides, and the cubic phase nitrides and carbonitrides in the cemented carbide have a higher hardness than the densely packed hexagonal phase WC. Therefore, the cobalt-poor rich cube The surface layer of the phase has a higher hardness. The binder phase rich in the cobalt-rich transition layer, when the crack formed in the coating diffuses into the region, can absorb the energy of the crack diffusion due to its good toughness, and therefore can effectively prevent the crack from diffusing into the alloy. Moreover, it can better absorb the impact energy of the cutting tool, and thus has high impact toughness characteristics, thereby contributing to the improvement of the service life of the tool material. The core is a rigid tissue region, that is, a normal tissue layer, and the WC crystal grain distribution is uniform and fine, and the average WC grain size is ≤500 nm, which has excellent mechanical properties of the ultrafine cemented carbide.

The boron nitride composite coating layer comprises a TiBCN layer deposited on the surface of the cobalt-depleted cubic phase layer as a transition layer, a Ni ₃ Si ₂ layer deposited as a bonding layer on the transition layer, and deposited on the bonding layer as a wear layer CBN layer.

The thickness of the transition layer is 0.1-15 microns, the thickness of the bonding layer is 1.6-3 microns, and the thickness of the wear layer is 0.1-3 microns. Preferably, the transition layer has a thickness of from 2 to 8 microns, the bond layer has a thickness of from 1.6 to 2 microns, and the wear layer has a thickness of from 1.0 to 2.0 microns.

The gradient ultra-fine cemented carbide tool with boron nitride composite coating adopts nano-multilayer composite coating on the surface of the cobalt-rich and rich cubic phase gradient ultra-fine cemented carbide tool base, which can effectively control the matrix gradient And the structure and composition of the coating, the boron nitride composite coating has a good bonding force with the tool base, and the formed tool has good wear resistance and temperature resistance.

Example 3.

A gradient ultra-fine cemented carbide tool having a boron nitride composite coating, the preparation process comprises the preparation of a tool base and depositing a boron nitride composite coating on the surface of the tool base.

The specific preparation process of the tool base is as follows:

S1, using refractory metal carbides, bonding metals and TiCN and other powders such as TiC, TaC, or other strong nitride forming elements of carbides, carbonitrides as raw materials, by ball milling mixing, drying sieving, press forming and Sintering four steps to prepare a cemented carbide substrate precursor;

S2, performing fine grinding processing on the cemented carbide substrate precursor;

S3. Grad-sintering the cemented carbide substrate precursor after the finish grinding process to prepare a surface of the cobalt-depleted and cubic-rich phase-structured cemented carbide tool base.

After chemically cleaning the tool substrate, a boron nitride composite coating is deposited on the surface, including:

(1) The TiBCN layer is deposited by CVD to the surface of the tool substrate. Specifically, the TiBCN layer can be prepared by MT-CVD method, the preparation temperature is 800-950 ° C, and BCl _{3 is} used as the boron source, BCl ₃ accounts for 0.5-10% of the total gas stream, and acetonitrile is used as the carbon source and the nitrogen source. .

(2) A Ni ₃ Si ₂ layer as a bonding layer was deposited on the transition layer by a CVD method. Specifically, a high-purity Ni ₃ Si ₂ alloy target is used, and high purity nitrogen gas is used as a sputtering gas, and is prepared under sputtering conditions of a substrate temperature of 500 ° C, a pressure of 0.2 Pa, a sputtering power of 300 W, and a sputtering time of 2.5 to 4 hours. The bonding layer.

(3) A CBN layer as a wear layer is deposited on the bonding layer by a CVD method. The process parameters for preparing the CBN layer are: BF3, N2, Ar, and H2 flow rates are 20 sccm, 2 slm, 4 slm, respectively. 5 sccm, the total reaction gas pressure was 4 Kpa, the substrate negative bias was 65 V, the substrate temperature was 860 ° C, and the deposition time was 60 min.

Example 4.

The tool base is sintered from the following mass percent components: 5-15% TiC, 2-5% TaC, 10-15% alloy binder phase, and the balance is WC. The alloy binder phase consists of the following mass percentages of powder: 0.5-5.5% Cr, 0.5-5.5% Mo, 0.5-5.5% B, 0.5-5.5% Al, 0.5-5.5% V, 0.5- 5.5% Y, 0.5-5.5% Si, the balance is Co, and the sum of the masses of Cr, Mo, B, Al, V, Y and Si in the alloy binder phase is 7-20 of the quality of the alloy binder phase. %.

The preparation method of the tool base comprises the following steps:

S1. Preparation of alloy binder phase: Eight kinds of powders of Cr, Mo, B, Al, V, Y, Si and Co are weighed according to the mass percentage, and eight kinds of powders are uniformly mixed to obtain an alloy binder phase. Preferably, eight powders are placed in a ball mill, ball milled with a cemented carbide ball for 72 hours, and ball milled for 10 minutes after each ball mill for 1 hour to obtain an alloy binder phase.

S2. Preparation of billet: Weigh the alloy binder phase, TiC, TaC, WC according to the mass percentage, and the four components constitute the raw material powder; the paraffin wax is weighed according to the total mass of the raw material powder: 1.5-2.5%. The paraffin wax and the raw material powder are uniformly mixed to obtain a billet.

S3. Pressing the blank: The blank is press-formed to obtain a green body.

The blank can be first press-molded by a molding machine to obtain a green body; and the green body is further pressed by a cold isostatic press to obtain a green body.

S4, sintering: the blank is placed in a sintering furnace, heated to 1200-1250 ° C at a rate of 5-8 ° C / min, maintained for 18-22 min, and maintained at a vacuum below 10 ^-3 Pa; then into the sintering furnace Fill with nitrogen and raise the temperature to 1420-1450 ° C at 1-3 ° C / min, keep the pressure for 55-65 min and maintain the pressure above 0.2 MPa; then cool down to 1000-1200 ° C at 2-6 ° C / min, The temperature is maintained for 110-130 min, and the pressure of 0.2 MPa or more is maintained; then the green body is cooled with the furnace and maintained at a pressure of 0.2 MPa or more to obtain a surface hardened gradient cemented carbide.

Before the step S4, a pre-sintering step is performed in which the green body is placed in a sintering furnace and sintered at 1400 ° C for 10 min under an inert gas atmosphere; the green body is refined with the furnace to refine the shape of the green body.

The cemented carbide substrate prepared by the method has excellent mechanical properties and improves the red hardness of the cemented carbide. The grain in the cemented carbide matrix is fine, the surface layer of the cemented carbide is rich in cubic phase and lean in the binder phase, and there is also an excessive layer of alloyed binder phase under the surface layer, so that the cemented carbide has excellent hardness and resistance. Grindability and toughness.

After the alloy substrate is prepared, it is chemically cleaned, and then a boron nitride composite coating is deposited on the surface.

(3) A CBN layer as a wear layer is deposited on the bonding layer by a CVD method. The process parameters for preparing the CBN layer are: BF3, N2, Ar and H2 flow rates are 20sccm, 2slm, 4slm, 5sccm, the total reaction gas pressure is 4Kpa, the substrate negative bias voltage is 65V, and the substrate temperature is 860 °C. The deposition time was 60 min.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, those skilled in the art The technical solutions of the present invention are modified or equivalently substituted without departing from the spirit and scope of the technical solutions of the present invention.

Claims

A boron nitride composite coating comprising: a TiBCN layer for deposition onto a surface of a tool substrate as a transition layer, a Ni 3 Si 2 layer deposited as a bonding layer on the transition layer, and deposited on the bonding layer The CBN layer of the wear layer.
The boron nitride composite coating according to claim 1, wherein the transition layer has a thickness of 0.1 to 15 μm; the bonding layer has a thickness of 1.6 to 3 μm; and the thickness of the wear layer is 0.1-3 microns.
The boron nitride composite coating according to claim 2, wherein the transition layer has a thickness of 2 to 8 μm; the bonding layer has a thickness of 1.6 to 2 μm; and the thickness of the wear layer is 1.0-2.0 microns.
The boron nitride composite coating according to any one of claims 1 to 3, wherein the TiBCN layer has a boron content of 10 at% to 15 at%; and the TiBCN layer has a crystal grain of less than 2 μm. The granular to columnar configuration, the TiBCN layer has a micro Vickers hardness of 30 GPa or more.
The boron nitride composite coating according to claim 4, wherein the crystal grains of the TiBCN layer are in a columnar configuration of less than 500 nm.
A method for preparing a boron nitride composite coating according to any one of claims 1 to 5, comprising the steps of

(1) depositing a TiBCN layer as a transition layer by CVD;

(2) depositing a Ni 3 Si 2 layer as a bonding layer on the transition layer by a CVD method;

(3) A CBN layer as a wear layer is deposited on the bonding layer by a CVD method.
The method for preparing a boron nitride composite coating according to claim 6, wherein:

The step (1) is specifically to prepare a TiBCN layer by using an MT-CVD method, the preparation temperature is 800-950 ° C, and BCl 3 is used as a boron source, and BCl 3 accounts for 0.5%-10% of the total gas flow, and acetonitrile is used. As a carbon source and a nitrogen source;

The step (2) specifically adopts a high-purity Ni 3 Si 2 alloy target, and uses high-purity nitrogen as a sputtering gas at a substrate temperature of 500 ° C, a pressure of 0.2 Pa, a sputtering power of 300 W, and a sputtering time of 2.5 to 4 hours. Preparing the bonding layer under sputtering conditions;

The deposited Ni 3 Si 2 layer substrate is placed in a direct plasma plasma chemical vapor deposition apparatus, firstly introduced into three gases BF3, N2 and Ar, and etched 25-35 under a positive bias of 30-40V. Minutes, the substrate is cleaned, after etching, H 2 is introduced , and then the CBN layer is deposited;

The process parameters of the step (3) for preparing the CBN layer are: BF3, N2, Ar and H2 flow rates are respectively 20 sccm, 2 slm, 4 slm, 5 sccm, total reaction gas pressure is 4 Kpa, substrate negative bias voltage is 65 V, lining The bottom temperature was 860 ° C and the deposition time was 60 min.
A gradient ultra-fine cemented carbide tool with a boron nitride composite coating, characterized in that:

The utility model is composed of a tool base body and a boron nitride composite coating layer disposed on the tool base;

The tool substrate comprises a normal tissue layer, a cobalt-rich transition layer and a cobalt-depleted cubic phase layer, and the normal tissue layer, the cobalt-rich transition layer and the cobalt-depleted cubic phase layer are arranged in order from the inside to the outside;

The boron nitride composite coating layer comprises a TiBCN layer deposited on the surface of the cobalt-depleted cubic phase layer as a transition layer, a Ni 3 Si 2 layer deposited as a bonding layer on the transition layer, and deposited on the bonding layer as a resistance layer. The CBN layer of the layer.
The gradient ultrafine cemented carbide tool having a boron nitride composite coating according to claim 8, wherein:

The content of cobalt in the tool base is 5-15 wt.%;

The normal tissue layer is an ultrafine cemented carbide, and the WC grain size is 1-1000 nm;

The thickness of the normal tissue layer is greater than 2 mm, the thickness of the cobalt-rich transition layer is 20-100 microns; and the thickness of the cobalt-depleted cubic phase layer is 20-50 microns;

The thickness of the transition layer is 0.1-15 microns; the thickness of the bonding layer is 1.6-3 microns; the thickness of the wear layer is 0.1-3 microns;

The content of boron in the TiBCN layer is 10 at% to 15 at%; the grain size of the TiBCN layer is a granular to columnar configuration of less than 2 μm, and the micro-Vickers hardness of the TiBCN layer is 30 GPa or more.
The gradient ultrafine cemented carbide tool having a boron nitride composite coating according to claim 9, wherein the content of cobalt in the tool base is 8-12 wt.%; and the WC of the normal tissue layer The grain size is from 1 nm to 400 nm; and the boron nitride-based composite coating layer is prepared by the method of claim 6 or 7.