CN119433494A

CN119433494A - Coated cutting tool and preparation method thereof

Info

Publication number: CN119433494A
Application number: CN202310973792.XA
Authority: CN
Inventors: 刘王平; 李秀萍; 陈响明; 周卓锐
Original assignee: Zhuzhou Cemented Carbide Cutting Tools Co Ltd
Current assignee: Zhuzhou Cemented Carbide Cutting Tools Co Ltd
Priority date: 2023-08-03
Filing date: 2023-08-03
Publication date: 2025-02-14

Abstract

The invention discloses a coated cutting tool and a preparation method thereof, wherein the coated cutting tool comprises a tool substrate and a multilayer coating covered on the surface of the tool substrate, the multilayer coating at least comprises a layer MTCVD TICN coating with a columnar crystal structure, the MTCVD TICN coating has a preferred texture orientation of a (220) crystal face, a texture coefficient Tc (220) is more than or equal to 3, a diffraction angle 2 theta of the (220) crystal face is 60.75-61.05 degrees, and the grain size of the MTCVD TICN coating is 0.1-0.4 mu m. The preparation method comprises the steps of preparing a cutter matrix and a multilayer coating. The coated cutting tool has the advantages of high hardness, high wear resistance, high impact resistance, high spalling resistance and the like, and the product quality stability is high.

Description

Coated cutting tool and preparation method thereof

Technical Field

The invention belongs to the field of preparation of coated cutting tools, relates to a coated cutting tool and a preparation method thereof, and in particular relates to a CVD coated cutting tool for metal cutting and a preparation method thereof.

Background

Chip forming (chip forming) machining of materials such as steel, cast iron, and superalloy generally employs cutting tools made of cemented carbide, cermet, cubic boron carbide, high speed steel, etc., while wear resistant coatings such as TiN, tiCN, tiAlN, al ₂O₃ are used to improve the wear resistance and tool life of the tools. CVD is widely used in tool preparation because it allows for large-scale deposition of TiN, tiCN, al ₂O₃ and other coating materials, and can accomplish surface coating of complex geometries.

The multi-layer composite coating which is prepared by adopting a medium-temperature chemical vapor deposition (MT CVD) technology and is formed by combining a MTCVD TICN coating with a columnar crystal structure and an alpha-Al ₂O₃ coating is a typical coating applied in the field of cutters. Aiming at the trends of diversity of cutting materials and cutting modes, high efficiency and intellectualization of cutting, the composition and microstructure of each coating in the multilayer composite coating are regulated and optimized, so that the performance of the cutter can be further improved, and the higher requirements of cutting are met.

Larsson(Microstructure and properties of Ti(C,N)coatings produced by moderate temperature chemical vapour deposition.Thin Sold Film 402(2002)203-210) A MTCVDTICN coating with a relatively large Tc (422) and a grain size of about 0.5 μm and an atomic ratio C/(C+N) of the sum of carbon and carbon nitrogen of about 0.6 is prepared on the surface of a cemented carbide by the MTCVD technique. Compared with TiCN coated cutting tools prepared by High Temperature Chemical Vapor Deposition (HTCVD) technology, MTCVD TICN coated cutting tools have better cutting edge strength due to no brittle eta phase, but have insufficient abrasion resistance.

CN101138900B discloses a (422) oriented columnar structure TiCN coating, by adding chain hydrocarbon with 2 to 20 carbon atoms in the reaction atmosphere, the C content in the TiCN coating is improved, the atomic ratio C/(c+n) of the sum of carbon and carbon nitrogen ranges from 0.7 to 0.9, and the average grain size is 0.05 to 0.5 μm. The hardness of the coating is improved, the wear resistance is improved, but the strength is insufficient and the stability is low.

CN104053815A discloses a (422) oriented TiCN coating, wherein the range of C/(C+N) is 0.5-0.65, and the average grain size is 0.05-0.4 mu m. Tc (422) +TC (311) >5.5. Compared with the conventional MTCVD TICN, the coating has a smooth surface and achieves a smooth effect. The thickness is controlled to be 5-15 mu m, so that the performance of ductile cast iron turning and high-speed turning is improved, but the abrasion resistance is insufficient.

CN105308210B discloses a fine-grain TiCN coating, wherein the C/(C+N) range is 0.5-0.65, and the average grain size is 0.05-0.2 mu m. Tc (422) +TC (311) is less than or equal to 5.5. Compared with the conventional MTCVD TICN, has smooth surface, achieves the effect of smoothness, the heat crack resistance and the spalling resistance in milling are improved, the thickness is controlled to be 2-7 mu m, and the milling tool is used for milling gray iron and spheroidal graphite cast iron. However, the grains are too fine, resulting in a decrease in cutter strength.

In recent years, the machining working condition in the field of machining is improved, automation is widely applied, and a cutting tool with high stability and high wear resistance is required.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a coated cutting tool with excellent hardness, wear resistance, impact resistance, stripping resistance and high quality stability and a preparation method thereof. The CVD coating cutter has the advantages of optimizing the microstructure and the performance, and realizing excellent cutting performance in general cutting of steel, cast iron and stainless steel materials.

In order to solve the technical problems, the invention adopts the following technical scheme.

A coated cutting tool comprises a tool substrate and a multilayer coating coated on the surface of the tool substrate, wherein the multilayer coating at least comprises a MTCVD TICN coating layer with a columnar crystal structure, the MTCVD TICN coating layer has a preferred texture orientation of a (220) crystal face, a texture coefficient Tc (220) is more than or equal to 3, a diffraction angle 2 theta of the (220) crystal face is 60.75-61.05 degrees (in X-ray diffraction analysis using CuKa radiation line), and the crystal grain size of the MTCVD TICN coating layer is 0.1-0.4 mu m.

Preferably, tc (220) of the MTCVD TICN coating layer of the coated cutting tool is not less than 4.

Preferably, tc (220) of the MTCVD TICN coating layer of the coated cutting tool is more than or equal to 5.

In the coated cutting tool, preferably, the MTCVD TICN coating layer has a diffraction angle 2θ of a (220) crystal plane of 60.85 ° to 60.95 ° in X-ray diffraction (X-ray diffraction) analysis using CuKa radiation.

In the above coated cutting tool, preferably, the grain size of the MTCVD TICN coating is 0.15 μm to 0.3 μm.

In the above coated cutting tool, preferably, the MTCVD TICN coating layer has a thickness of 5 μm to 20 μm.

In the above coated cutting tool, more preferably, the MTCVD TICN coating has a thickness of 7 μm to 15 μm.

According to the coated cutting tool, preferably, a hard substrate layer is further arranged between the MTCVD TICN coating and the tool substrate, the hard substrate layer comprises at least one layer of a TiN layer, a TiCN layer and a TiC layer, and the thickness of the hard substrate layer is 0.1-1.0 mu m.

In the above coated cutting tool, preferably, the surface of the MTCVD TICN coating is provided with an Al ₂O₃ coating, and the thickness of the Al ₂O₃ coating is 2 μm to 15 μm.

In the coated cutting tool, the thickness of the Al ₂O₃ coating is preferably 3-10 mu m, and the Al ₂O₃ coating is an alpha-Al ₂O₃ coating or a k-Al ₂O₃ coating.

In the above coated cutting tool, preferably, the thickness of the Al ₂O₃ coating is 4 μm to 7 μm.

According to the coated cutting tool, preferably, an intermediate layer is arranged between the MTCVD TICN coating and the Al ₂O₃ coating, the intermediate layer is formed by combining two or more layers of a TiN layer, a TiCN layer, a TiCNO layer, a TiAlNO layer and a TiCO layer, the outermost layer of the intermediate layer is one of the TiCNO layer, the TiAlNO layer and the TiCO layer, and the thickness of the intermediate layer is 0.3-1.0 mu m.

In the above coated cutting tool, preferably, a color layer is provided on the surface of the Al ₂O₃ coating, where the color layer includes one or more of TiN layer, zrN layer, tiC layer and TiB layer, and the thickness of the color layer is 0.2 μm to 2.0 μm.

The invention also provides a preparation method of the coated cutting tool, which comprises the following steps of:

(1) Preparing a cutter matrix;

(2) And depositing the TiCN coating by adopting an MTCVD process to obtain the MTCVD TICN coating, wherein the process conditions comprise a deposition temperature of 870-950 ℃ and a pressure of 40-100 mbar, taking TiCl ₄-CH₃CN-HCl-N₂-H₂ as a deposition atmosphere system, wherein the reaction gas comprises 10.0-50.0 mol% of N ₂, 1.0-4.0 mol% of TiCl ₄, 0.2-1 mol% of CH ₃ CN, 0-5 mol% of HCl and the balance of H ₂ gas, and the molar ratio of TiCl ₄ to CH ₃ CN is 4-7:1.

The preparation method of the coated cutting tool preferably further comprises a step of depositing a hard substrate layer between the step (1) and the step (2), wherein the hard substrate layer is deposited on the tool substrate by adopting a CVD process, then a MTCVD TICN coating is deposited on the hard substrate layer, the hard substrate layer comprises at least one layer of a TiN layer, a TiCN layer and a TiC layer, and the thickness of the hard substrate layer is 0.1-1.0 mu m.

In the preparation method of the coated cutting tool, preferably, the step (2) further comprises a step of depositing an intermediate layer on the MTCVD TICN coating by adopting a CVD process, wherein the intermediate layer comprises one or a combination of a plurality of layers of TiN layer, tiCN layer, tiCNO layer, tiAlNO layer and TiCO layer, and the thickness of the intermediate layer is 0.3-1.0 μm.

In the preparation method of the coated cutting tool, preferably, the step of depositing the Al ₂O₃ coating after depositing the intermediate layer further comprises the step of depositing the Al ₂O₃ coating on the intermediate layer by adopting a CVD process, wherein the thickness of the Al ₂O₃ coating is 2-15 mu m.

In the preparation method of the coated cutting tool, preferably, the step of depositing a color layer is further included after depositing the Al ₂O₃ coating, wherein the color layer is deposited on the Al ₂O₃ coating by adopting a CVD process and comprises one or a combination of a plurality of layers of a TiN layer, a ZrN layer, a TiC layer and a TiB layer, and the thickness of the color layer is 0.2-2.0 mu m.

The preparation method of the coated cutting tool comprises the following steps of:

(1) Preparing a cutter matrix;

(2) Depositing a hard base layer on the tool substrate using a CVD process;

(3) Depositing TiCN coating on the hard substrate layer by adopting an MTCVD process to obtain MTCVD TICN coating, wherein the process conditions comprise a deposition temperature of 870-950 ℃ and a pressure of 40-100 mbar, taking TiCl ₄-CH₃CN-HCl-N₂-H₂ as a deposition atmosphere system, and reacting gas comprising 10.0-50.0 mol% of N ₂, 1.0-4.0 mol% of TiCl ₄, 0.2-1 mol% of CH ₃ CN, 0-5 mol% of HCl and the balance of H ₂ gas, wherein the molar ratio of TiCl ₄ to CH ₃ CN is 4-7:1;

(4) Depositing at least one of a TiCNO layer and a TiAlNO layer on the MTCVD TICN coating by adopting a CVD process as an intermediate layer;

(5) Depositing an Al ₂O₃ coating on the intermediate layer by adopting a CVD process;

(6) A CVD process is used to deposit a color layer on the Al ₂O₃ coating.

In the present invention, the texture coefficient Tc (hkl) of MTCVD TICN coating is defined as follows:

Wherein I (hkl) is the measured intensity of the (hkl) crystal plane diffraction peak, I ₀ (hkl) is the intensity of the standard powder diffraction peak according to PDF card number 42-1489 of ICDD, n is the number of crystal plane diffraction used in the calculation, and the (hkl) crystal plane diffraction peak used is (111) (200) (220) (311) (331) (420) (422) (511). Tc (hkl) maximum does not exceed 8.

In the invention, the texture coefficient Tc (220) of the MTCVD TICN coating is more than or equal to 3, preferably TC (220) is more than or equal to 4, and more preferably Tc (220) is more than or equal to 5.

The inventors have found that by controlling MTCVD TICN deposition conditions, tc (220) increases, which increases Tc (220) advantageously increases MTCVD TICN coating hardness and tool wear resistance.

In the invention, the MTCVD TICN coating has a grain size of 0.1-0.4 μm, preferably 0.15-0.3 μm. The coating grains are too fine, the breakage is easy to occur, the coating grains are too coarse, and the wear resistance is insufficient.

In the invention, in an X-ray diffraction diagram obtained by X-ray diffraction analysis of the MTCVD TICN coating, the diffraction angle 2 theta of a (220) crystal face is 60.75-61.05 degrees, and the position of the diffraction angle is related to the atomic ratio C/(C+N) of the sum of carbon and nitrogen in the coating. The higher the C/(C+N) in the coating, the lower the diffraction angle 2 theta value of the (220) crystal plane. The offset of the instrument for the diffraction angle 2 theta of the MTCVD TICN coating (220) crystal face is corrected by adopting the offset delta 2 theta of the diffraction angle 2 theta of the WC (110) crystal face in the matrix. The offset Δ2θ is defined as:

Δ2θ=2θWC(110)-2θ₀WC(110)

2θTiCN(220)=2θ₀TiCN(220)+Δ2θ

2θ WC (110) is the diffraction angle 2θ measurement position of the WC (110) crystal plane in the matrix X-ray diffraction pattern.

2Θ ₀ WC (110) is the diffraction angle 2θ position of the PDF card 25-1047 WC (110) crystal plane according to ICDD.

The 2 theta TiCN (220) is the diffraction angle 2 theta measurement position of the (220) crystal face in the TiCN coating X-ray diffraction diagram.

The 2 theta ₀ TiCN (220) is the diffraction angle 2 theta position of the PDF card 42-1489 TiCN (220) crystal face according to ICDD.

In the invention, the MTCVD TICN coating thickness is 5-20 μm. The increased coating thickness can improve tool wear resistance.

According to the invention, other coatings, such as an Al ₂O₃ coating, tiN coating and the like, are coated on the surface of the MTCVD TICN coating, the Al ₂O₃ coating can improve the oxidation and abrasion resistance, the usability of high-temperature working conditions such as high-speed processing of a cutter and the like, and the color layer can improve the use recognition function of the cutter.

In the invention, an intermediate layer is arranged between the MTCVD TICN coating and the Al ₂O₃ coating, and comprises one or a plurality of layers of TiN layer, tiCN layer, tiCNO layer, tiAlNO layer and TiCO layer, and the intermediate layer can improve the bonding strength of the outer Al ₂O₃ coating and avoid peeling.

In the invention, a hard basal layer, a MTCVD TICN layer, an intermediate layer and an Al ₂O₃ layer are sequentially deposited on the surface of the basal body. The thickness of the hard base layer is 0.1-1.0 μm, and the thickness of MTCVD TICN-20 μm, preferably 7-15 μm. The thickness of the intermediate layer is 0.3-1.0 μm, the thickness of the Al ₂O₃ layer is 2-15 μm, preferably 3-10 μm, more preferably 4-7 μm, and the Al ₂O₃ layer can be a k-Al ₂O₃ layer or an a-Al ₂O₃ layer. The intermediate layer comprises a TiCO layer, a HTCVD TICN layer can be selectively deposited between the MTCVD TICN layer and the TiCO layer, and the HTCVD TICN layer is 0.2-0.5 mu m thick. And a color layer can be selectively deposited on the surface of the Al ₂O₃ layer, wherein the color layer can be one or a plurality of layers selected from a TiN layer, a ZrN layer, a TiC layer and a TiB layer, and the thickness of the color layer is 0.2-2.0 mu m.

In the invention, the tool matrix is mainly composed of cemented carbide, cermet, ceramics or superhard materials (superhard materials such as cubic boron nitride, polycrystalline diamond, etc.).

Compared with the prior art, the invention has the main advantages that:

(1) The coated cutting tool disclosed by the invention comprises MTCVD TICN coating layers, the texture coefficient of preferred orientation is high, tc (220) is more than or equal to 3 (more preferably more than or equal to 5), the hardness of the coating layers is improved, and the wear resistance of the tool is increased. MTCVD TICN the coating has fine crystal grains, smooth deposition surface and grain size of 0.1-0.4 mu m (preferably 0.15-0.3 mu m), the coating is easily broken due to too fine crystal grains, and the coating has too coarse abrasion resistance. The coated cutting tool has the advantages of high hardness, good wear resistance, fine grains, smooth surface, high strength, good stability and the like.

(2) The preparation process disclosed by the invention has the advantages of high coating deposition efficiency, good deposition uniformity, high product quality stability, and excellent hardness, wear resistance and strength, and meanwhile, a coating with extremely high surface smoothness is obtained.

Drawings

FIG. 1 is an X-ray diffraction chart of sample 1 in example 1 of the present invention.

FIG. 2 is an X-ray diffraction chart of sample 2 in example 2 of the present invention.

FIG. 3 is an X-ray diffraction pattern of comparative sample 1.

FIG. 4 is an X-ray diffraction pattern of comparative sample 2.

FIG. 5 is a SEM photograph of the surface morphology of sample 1 of example 1 of the present invention.

FIG. 6 is a SEM photograph of the surface morphology of sample 2 of example 1 of the present invention.

Fig. 7 is a SEM photograph of the surface morphology of comparative sample 1.

Fig. 8 is a SEM photograph of the surface morphology of comparative sample 2.

FIG. 9 is a SEM photograph of the cross-sectional morphology of sample 4 of example 2 of the present invention.

Fig. 10 is an SEM photograph of the indentation exfoliation morphology of sample 5 in example 4 of the present invention.

FIG. 11 is an SEM photograph of the indentation exfoliation morphology of comparative sample 5 of example 4 of the present invention.

Detailed Description

The invention is further described below in connection with the drawings and the specific preferred embodiments, but the scope of protection of the invention is not limited thereby. The materials and instruments used in the examples below are all commercially available.

Example 1

The invention relates to a coated cutting tool, in particular to a sample 1 and a sample 2, which comprise a tool substrate and a multi-layer coating covered on the surface of the tool substrate, wherein the multi-layer coating at least comprises a MTCVD TICN coating with a columnar crystal structure, and the MTCVD TICN coating has a (220) crystal face preferred texture orientation.

In sample 1 according to the present invention:

The texture coefficient Tc (220) was 6.01, the diffraction angle 2 theta of the (220) crystal face was 60.96 DEG, the grain size of MTCVD TICN coating was 0.25 μm, and the thickness of MTCVD TICN coating was 12.0 μm.

A hard basal layer is also arranged between the MTCVD TICN coating and the cutter basal body, the hard basal layer is a TiN layer, and the thickness is 0.1 mu m.

In inventive sample 2:

The texture coefficient Tc (220) was 3.1, the diffraction angle 2 theta of the (220) crystal face was 61.01 DEG, the grain size of MTCVD TICN coating was 0.36 μm, and the thickness of MTCVD TICN coating was 7.0 μm.

A hard basal layer is also arranged between the MTCVD TICN coating and the cutter basal body, and the hard basal layer is a TiN layer with the thickness of 0.5 mu m.

The preparation method of the coated cutting tool comprises the following steps:

(1) A cemented carbide cutting tool substrate with a blade model of CNMG120408 is selected, and the substrate comprises 6wt% of Co, 0.2wt% of Ti and Ta cubic carbonitride and the balance of WC. The coating is performed in a BPX pro 530L CVD coating apparatus, before the coating, the substrate is subjected to wet blasting treatment, the substrate surface cleanliness and smoothness are improved, and the blade edge is rounded into an approximate circular arc structure with a radius of 25-45 μm.

(2) A layer of TiN coating is deposited on a tool substrate as a hard substrate layer by adopting a mixed gas of 38.5mol% of N ₂, 1.5mol% of TiCl ₄ and the balance of H ₂ at 870-930 ℃ and 160mbar, and the thickness is 0.1-1 mu m.

(3) MTCVD TICN coatings of inventive sample 1 and sample 2 and MTCVD TICN coatings of comparative sample 1 and comparative sample 2 were prepared according to StepA, stepB, stepD, stepE in table 1, respectively.

MTCVD TICN the coating was analyzed using X-ray diffraction of CuKa radiation. XRD diffraction spectra of MTCVD TICN coatings of inventive sample 1 and inventive sample 2 are shown in FIGS. 1 and 2, with the (220) diffraction peak being highest. The XRD diffraction spectra of MTCVD TICN coatings of comparative sample 1 and comparative sample 2 are shown in FIGS. 3 and 4, with (220) diffraction peaks below (311) or (422) diffraction peaks. The results of the texture coefficient Tc (hkl) of the coating of the invention MTCVD TICN and the texture coefficient Tc (hkl) of the coating of comparative example MTCVD TICN are shown in table 2. The texture coefficients Tc (220) of the sample 1 and the sample 2 are minimum 3.10 and maximum 6.01, and the texture ratio of Tc (220) reaches 44.29-85.86%. The texture coefficient Tc (220) is higher than the texture coefficients Tc (220) of comparative example 1 and comparative example 2.

TABLE 1 MTCVD TICN coating deposition parameters for inventive and comparative samples

TABLE 2 comparative tables of texture coefficients Tc (hkl) of MTCVD TICN coatings of inventive and comparative samples

The SEM morphologies of the MTCVD TICN coating surfaces of the sample 1 and the sample 2 are shown in figure 5 and figure 6 respectively. SEM morphologies of MTCVD TICN coating surfaces of the comparative sample 1 and the comparative sample 2 are shown in fig. 7 and 8, respectively. The grain sizes of MTCVD TICN coatings of the samples 1 and 2 of the invention are thinner than those of the comparative sample 1 and slightly thicker than those of the comparative sample 2.

The diffraction angle 2 theta values, thicknesses, grain sizes and nano hardness results of the (220) crystal faces of the MTCVD TICN coating layers of the inventive sample 1, the comparative sample 2 and the comparative sample 1 are shown in table 3. Diffraction angles 2 theta of (220) crystal faces of MTCVD TICN coatings of the sample 1 and the sample 2 are 60.96 degrees and 61.01 degrees respectively, and grain sizes are 0.25 mu m and 0.36 mu m respectively. The grain size is measured by taking the sample as a metallographic sample of the cross section of the coated product, the surface normal of the cross section being perpendicular to the surface normal of the substrate, and by taking the average of the widths of the grains on a straight line parallel to the substrate surface at a position intermediate the upper and lower interfaces of the MTCVD TICN coating on the cross section.

The nano hardness values of MTCVD TICN coatings of the sample 1 and the sample 2 are 27.9GPa and 27.1GPa respectively, the nano hardness of the coatings is detected by adopting a nano indentation method, the maximum load is 30.00mN, the loading rate is 60.00mN/min, the unloading rate is 60.00mN/min, and the residence time is 10.0s.

The comparative sample 1 had a grain size of 0.61 μm, TC (220) of 2.11 and a nano-hardness of 25.5GPa, and samples 1 and 2 of this example had a higher Tc (220) and a finer coating grain size than comparative sample 1.

The diffraction angle 2 theta of the (220) crystal face of comparative sample 2 was 61.07 deg., TC (220) was 0.44, and the grain size was 0.19 μm. The nano hardness was 20.3GPa, and the grain sizes of sample 1 and sample 2 of the present example were comparable to those of comparative sample 2, tc (220) was high, and diffraction angle 2. Theta. Was low.

The coating hardness of this example was high compared to comparative sample 1 and comparative sample 2.

TABLE 3 comparison of 2 theta, grain size and nano hardness of MTCVD TICN coatings of inventive and comparative samples

Sample of	2θ₂₂₀(°)	Grain size (mum)	Nanometer hardness (GPa)
				Inventive sample 1	60.96	0.25	27.9
Inventive sample 2	61.01	0.36	27.1
				Comparative sample 1	60.99	0.61	25.5
Comparative sample 2	61.07	0.19	20.3

Example 2

The invention relates to a coated cutting tool, in particular to a sample 3 and a sample 4, which comprise a tool substrate and a multi-layer coating coated on the surface of the tool substrate, wherein the multi-layer coating at least comprises a MTCVD TICN coating with a columnar crystal structure, and the MTCVD TICN coating has a (220) crystal face preferred texture orientation.

In sample 3 according to the present invention:

The texture coefficient Tc (220) was 5.54, the diffraction angle 2 theta of the (220) crystal face was 60.89 DEG, the grain size of the MTCVD TICN coating was 0.20 μm, and the thickness of the MTCVD TICN coating was 9.1. Mu.m.

The cutter substrate is sequentially provided with a hard basal layer, MTCVD TICN coating, an intermediate layer and an alpha-Al ₂O₃ coating.

The hard underlayer was a TiN layer with a thickness of 0.3 μm.

The thickness of the α -Al ₂O₃ coating was 5 μm.

The middle layer comprises an HT TiCN layer and a TiCO layer, the outer layer is a TiCO layer, and the total thickness of the middle layer is 0.5 mu m.

In inventive sample 4:

The texture coefficient Tc (220) was 4.1, the diffraction angle 2 theta of the (220) crystal face was 61.02 DEG, the grain size of the MTCVD TICN coating was 0.33 μm, and the thickness of the MTCVD TICN coating was 8.5. Mu.m.

The hard underlayer was a TiN layer with a thickness of 0.2 μm.

The thickness of the α -Al ₂O₃ coating was 5 μm.

(1) A cemented carbide cutting tool substrate with a blade model of CNMG120408 is selected, and the substrate comprises 6wt% of Co, 0.2wt% of Ti and Ta cubic carbonitride and the balance of WC. The coating is performed in a BPX pro 530L CVD coating apparatus, and before the coating, the cutter substrate is subjected to wet sand blasting treatment, so that the surface cleanliness and smoothness of the substrate are improved, and the cutting edge of the blade is rounded into an approximate circular arc structure with the radius of 25-45 mu m.

(2) A layer of TiN coating is deposited on a tool substrate by using a mixed gas of 38.5mol% of N ₂, 1.5mol% of TiCl ₄ and the balance of H ₂ at 870-930 ℃ and 160mbar, and the thickness is 0.1-1 mu m.

(3) The MTCVD TICN coatings of inventive sample 3, sample 4 and the MTCVD TICN coatings of comparative sample 3, comparative sample 4 were prepared according to StepA, stepB, stepD, stepE in table 1.

(4) And depositing an intermediate layer on the MTCVD TICN coating, wherein the intermediate layer is deposited in two steps, firstly depositing an HT TiCN layer according to Step H of table 4, and then depositing a TiCO layer according to Step I, wherein the total thickness of the HT TiCN layer and the TiCO layer is 0.5 mu m.

(5) Al ₂O₃ coating was deposited on the intermediate layer, al ₂O₃ coating was deposited in three steps, first oxidizing the TiCO layer according to StepJ of Table 4, then depositing an Al ₂O₃ layer according to Step K and Step L, with a thickness of 5 μm and Tc (006) of 2.5.

The cross-sectional SEM morphology of sample 4 of the present invention is shown in FIG. 9, which is a TiN layer, MTCVD TICN layer, intermediate layer, al ₂O₃ layer in this order from the cemented carbide tool substrate.

TABLE 4 deposition parameters of the intermediate layer and Al ₂O₃ coating of inventive and comparative samples

TABLE 5 comparative tables of texture coefficients Tc (hkl) of MTCVD TICN coatings of inventive and comparative samples

As shown in Table 5, the texture coefficients Tc (hkl) of the MTCVD TICN coatings of inventive samples 3, 4 and comparative samples 3, 4 were higher for inventive samples 3, 4 than for comparative samples 3, 4 (220).

Example 3

The hardness of MTCVD TICN and Al ₂O₃ layers of inventive samples 3,4 and comparative samples 3,4 of example 2 were analyzed using nano-hardness, as shown in Table6, the MTCVD TICN coating thicknesses of inventive samples 3,4 were 9.1 μm and 8.5 μm, respectively, the nano-hardness was 28.2GPa, 27GPa, the Al ₂O₃ layer was about 5 μm, and the nano-hardness was about 27.0GPa, respectively. The MTCVD TICN coating thickness of comparative samples 3,4 were 8.3 μm and 9.5 μm, respectively, the nano-hardness was 25.1GPa and 21.3GPa, respectively, and the thickness of the Al ₂O₃ layer was about 5 μm, and the nano-hardness was about 27Pa.

TABLE 6 comparison of the thickness and nanohardness of MTCVD TICN coatings for example 2 and comparative samples

The wear resistance of the coating product is evaluated by adopting an gray iron turning experiment, the wear resistance of the blade is evaluated by taking the wear value VB=0.3 mm of the blade rear blade surface as a blade failure judging standard and the cutting time (the service life of the blade) of the blade when the wear value VB=0.3 mm of the blade rear blade surface is used, and the longer the service life of the blade is, the better the wear resistance is. Inventive samples 3, 4 and comparative samples 3, 4 were subjected to cutting tests under different cutting conditions, the results are shown in table 7 below, the cutting test conditions are as follows:

work piece material, grey cast iron HT300

Processing mode of dry turning

Cutting speed of 600m/min,500m/min

Depth of cut 1.0mm

Feed amount 0.2mm/r

Table 7 comparison of coated tool cutting life for example samples versus comparative samples

Tests show that the service lives of the coated blade sample 3 and the coated blade sample 4 are obviously prolonged compared with the comparative sample 3 and the comparative sample 4 in the high-speed processing process of the gray cast iron HT300, and the service lives of the coated blade sample 3 and the coated blade sample 4 are obviously prolonged compared with the comparative sample 3 and the comparative sample 4 in the low-speed processing process of the gray cast iron HT 300.

Compared with the comparative blade, the service life of the coated blade is obviously prolonged, and the wear resistance of the coated blade is better than that of the comparative blade.

Example 4

The coated cutting tool comprises a tool substrate and a multi-layer coating covered on the surface of the tool substrate, wherein the multi-layer coating at least comprises a MTCVD TICN coating layer with a columnar crystal structure, and the MTCVD TICN coating layer has a preferred texture orientation of a (220) crystal face.

In inventive sample 5:

the texture coefficient Tc (220) was 3.76, the diffraction angle 2 theta of the (220) crystal face was 60.79 DEG, the grain size of MTCVD TICN coating was 0.14 μm, and the thickness of MTCVD TICN coating was 8.0 μm.

The hard underlayer was a TiN layer with a thickness of 0.2 μm.

The thickness of the α -Al ₂O₃ coating was 5.0 μm.

The middle layer comprises an HT TiCN layer and a TiCO layer which are arranged from bottom to top, and the total thickness of the middle layer is 0.5 mu m.

(1) A hard alloy cutting tool matrix with the blade model of CNMG120408 is selected, and the matrix comprises 6wt% of Co, 5.5wt% of Ti and Ta cubic carbonitride and the balance of WC. The coating is performed in a BPX pro 530L CVD coating apparatus, and before the coating, the cutter substrate is subjected to wet sand blasting treatment, so that the surface cleanliness and smoothness of the substrate are improved, and the cutting edge of the blade is rounded into an approximate circular arc structure with the radius of 25-45 mu m.

(3) The MTCVD TICN coating of inventive sample 5 and the MTCVD TICN coating of comparative sample 5 were prepared according to Step C, step F in table 1.

(6) A layer of TiN coating was deposited as a colour layer on Al ₂O₃ at 870-930℃under 160mbar using a mixture of 38.5mol% N ₂, 1.5mol% TiCl ₄ and the remainder H ₂ to give inventive sample 5 and comparative sample 5.

The orientations of MTCVD TICN coatings of inventive and comparative samples 5 are shown in table 8, and diffraction angle 2θ values, exfoliation levels, grain sizes, and nano hardness results of (220) crystal planes are shown in table 9. The (220) crystal face of sample 5 of the present invention had a diffraction angle 2 theta of 60.79, a TC (220) of 3.76, a grain size of 0.14 μm and a nano hardness of 29.1GPa. The (220) crystal face of comparative sample 5 had a diffraction angle 2 theta of 60.71, a TC (220) of 0.73, a grain size of 0.13 μm and a nano hardness of 22.1GPa. Compared with the comparative sample 5, the sample 5 of the present invention has high Tc (220) and high diffraction angle 2 theta.

The indentation peeling method is adopted to analyze the peeling resistance of the coating, the higher the indentation peeling grade is, the lower the peeling resistance is, the indentation peeling morphology of the sample 5 and the comparative sample 5 is shown in fig. 10 and 11 respectively, and the comparison of the indentation peeling results shows that the peeling resistance of the sample 5 is good.

TABLE 8 comparative tables of texture coefficients Tc (hkl) of MTCVD TICN coatings of inventive and comparative samples

TABLE 9 comparative Table of the properties of MTCVD TICN coatings of inventive and comparative samples

Example 5

The wear resistance of the sample 5 and the comparative sample 5 of the invention under different cutting conditions is evaluated by adopting a 45# steel turning experiment, the wear resistance of the blade is evaluated by taking the blade back face wear value VB=0.3 mm as a blade failure judgment standard and the blade cutting time (blade life) when the blade back face wear value VB=0.3 mm, and the longer the blade life, the better the wear resistance. The cutting test results are shown in table 10 below, and the cutting test conditions are as follows:

Work piece material 45#

Processing mode of dry turning

Cutting speed of 350m/min

Depth of cut 1.0mm

Feed amount 0.2mm/r

Table 10 comparative table of cutting life of coated tool for inventive and comparative samples

Sample of	Blade life (min)
		Inventive sample 5	35
Comparative sample 5	28

Tests show that in the turning process of the 45# steel, compared with a comparative blade, the coated blade has long service life and good wear resistance.

Example 6

The impact resistance of the coating product is evaluated by adopting a 45# steel four-groove round bar turning impact experiment, the cutter point collapse is used as a blade failure judgment standard, the impact resistance of the blade is evaluated by using the blade impact times, and the impact resistance is better when the impact times are more. The test results are shown in table 11 below, and the cutting test conditions are as follows:

Workpiece material 45# steel four-groove round bar

Processing mode of dry turning

Cutting speed 220r/min

Depth of cut 1.0mm

Feed amount 0.2mm/r

Table 11 comparative table of impact test of coated tool for inventive and comparative samples

Sample of	Number of impacts
		Inventive sample 5	4400
Comparative sample 5	1085

Tests have shown that the coated blade of the present invention has significantly better impact resistance than the comparative blade.

In conclusion, the MTCVD TICN coating of the coated cutting tool is controlled by controlling the orientation, grain size, composition and other tissue structures, the texture coefficient Tc (220) is more than or equal to 3, the diffraction angle 2 theta of the (220) crystal face is 60.75-61.05 degrees, and the grain size of the MTCVD TICN coating is 0.1-0.4 mu m. Compared with the prior art, the hardness of the coating is obviously improved, the wear resistance of the coated cutter is improved, the impact resistance and the spalling resistance of the coated blade are improved, and the stability is improved.

The above description is only of the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. While the invention has been described in terms of preferred embodiments, it is not intended to be limiting. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention or equivalent embodiments using the method and technical solution disclosed above without departing from the spirit and technical solution of the present invention. Therefore, any simple modification, equivalent substitution, equivalent variation and modification of the above embodiments according to the technical substance of the present invention, which do not depart from the technical solution of the present invention, still fall within the scope of the technical solution of the present invention.

Claims

1. The coated cutting tool is characterized by comprising a tool substrate and a multilayer coating coated on the surface of the tool substrate, wherein the multilayer coating at least comprises a layer MTCVD TICN coating with a columnar crystal structure, the MTCVD TICN coating has a preferred texture orientation of a (220) crystal face, a texture coefficient Tc (220) is more than or equal to 3, a diffraction angle 2 theta of the (220) crystal face is 60.75-61.05 degrees, and the crystal grain size of the MTCVD TICN coating is 0.1-0.4 mu m.

2. The coated cutting tool of claim 1, wherein Tc (220) of the MTCVD TICN coating is ≡4 or more.

3. The coated cutting tool of claim 2, wherein Tc (220) of the MTCVD TICN coating is ≡5 or more.

4. The coated cutting tool of claim 1, wherein the MTCVD TICN coating has a diffraction angle 2-theta of the (220) crystal plane in 60.85 ° to 60.95 ° in X-ray diffraction analysis using CuKa radiation.

5. The coated cutting tool of claim 1, wherein the MTCVD TICN coating has a grain size of 0.15 μm to 0.3 μm.

6. The coated cutting tool of claim 1, wherein the MTCVD TICN coating has a thickness of 5 μm to 20 μm.

7. The coated cutting tool of claim 6, wherein the MTCVD TICN coating has a thickness of 7 μm to 15 μm.

8. The coated cutting tool according to any one of claims 1-7, wherein a hard base layer is further provided between the MTCVD TICN coating and the tool body, the hard base layer comprises at least one of a TiN layer, a TiCN layer and a TiC layer, and the thickness of the hard base layer is 0.1 μm to 1.0 μm.

9. The coated cutting tool of claim 8, wherein the MTCVD TICN coating has a surface provided with an Al ₂O₃ coating, and the Al ₂O₃ coating has a thickness of 2-15 μm.

10. The coated cutting tool of claim 9, wherein the Al ₂O₃ coating has a thickness of 3-10 μm and the Al ₂O₃ coating is an a-Al ₂O₃ coating or a k-Al ₂O₃ coating.

11. The coated cutting tool of claim 10, wherein the Al ₂O₃ coating has a thickness of 4 μιη to 7 μιη.

12. The coated cutting tool according to any one of claims 9 to 11, wherein an intermediate layer is provided between the MTCVD TICN coating and the Al ₂O₃ coating, the intermediate layer is formed by combining two or more layers of TiN layer, tiCN layer, tiCNO layer, tiAlCNO layer and TiCO layer, the outermost layer of the intermediate layer is one of TiCNO layer, tiAlCNO layer and TiCO layer, and the thickness of the intermediate layer is 0.3 μm to 1.0 μm.

13. The coated cutting tool of claim 12, wherein the surface of the Al ₂O₃ coating is provided with a color layer comprising a combination of one or more of TiN layer, zrN layer, tiC layer and TiB layer, the color layer having a thickness of 0.2-2.0 μm.

14. A method of producing a coated cutting tool according to any one of claims 1 to 7, comprising the steps of:

(1) Preparing a cutter matrix;

15. The method of claim 14, further comprising the step of depositing a hard base layer between the step (1) and the step (2), wherein the hard base layer is deposited on the tool base body by a CVD process, and then the MTCVD TICN coating is deposited on the hard base layer, wherein the hard base layer comprises at least one of a TiN layer, a TiCN layer, and a TiC layer, and the thickness of the hard base layer is 0.1 μm to 1.0 μm.

16. The method of claim 15, further comprising the step of depositing an intermediate layer on the MTCVD TICN coating by a CVD process after step (2), wherein the intermediate layer comprises one or more of a TiN layer, a TiCN layer, a TiCNO layer, a TiAlCNO layer, and a TiCO layer, and the intermediate layer has a thickness of 0.3 μm to 1.0 μm.

17. The method of claim 16, further comprising the step of depositing an Al ₂O₃ coating after the step of depositing an intermediate layer, wherein the Al ₂O₃ coating is deposited on the intermediate layer by a CVD process, and wherein the Al ₂O₃ coating has a thickness of 2 μm to 15 μm.

18. The method of claim 17, further comprising the step of depositing a color layer on the Al ₂O₃ coating by CVD, wherein the color layer comprises one or more of a TiN layer, a ZrN layer, a TiC layer, and a TiB layer, and the color layer has a thickness of 0.2 μm to 2.0 μm.