CN116904961B - Coated cutting tool with enhanced toughness and wear resistance and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of machining cutters, and particularly relates to a coated cutter with enhanced toughness and wear resistance and a preparation method thereof, wherein the cutter comprises a cutter substrate and a coating coated on the cutter substrate; the coating at least comprises a layer of micron columnar crystal MT-TiCN and a layer of nanometer equiaxed crystal MT-TiB which are alternately deposited on the cutter substrate from inside to outside by a medium temperature CVD method_x C_y N_z O_w A layer, wherein x+y+z+w=1, 0 < x.ltoreq.0.1, 0.5.ltoreq.y.ltoreq.0.9, 0.1.ltoreq.z.ltoreq.0.5, 0 < w.ltoreq.0.1. The structure of the periodic coating refines the crystal grains of the MT-TiCN coating and increases the crack propagation path, so that the coating has higher toughness and wear resistance and can obviously prolong the service life of the cutter.

Description

Coated cutting tool with enhanced toughness and wear resistance and preparation method thereof

Technical Field

The invention belongs to the technical field of machining tools, and particularly relates to a coated tool with enhanced toughness and wear resistance and a preparation method thereof.

Background

In order to meet the requirement of improving the production efficiency, the modern machining field puts higher requirements on the performance of the cutter. The surface coating of the hard alloy cutter plays a crucial role in improving the cutter performance. CVD coating for cutting tools commonly adopts TiN/TiCN/TiAlOCN/alpha-Al₂ O₃ TiN "this composite coating structure. Wherein the TiCN coating is prepared by adopting a medium-temperature chemical vapor deposition (MT-CVD) method, and is one of important functional layers of the CVD coating of the cutterThe TiCN coating has good resistance to the abrasion of the rear cutter surface, the crystal grains of the TiCN coating are generally coarse columnar crystals, the hardness and the abrasion resistance are required to be improved, and the columnar structure easily causes cracks to penetrate to the matrix along a straight line.

Since the 90 th century MT-TiCN coating (TiCN coating prepared by a medium temperature chemical vapor deposition method) was applied to the market, in order to improve the wear resistance of the coating and the service life of the tool, the grain refinement of the MT-TiCN coating has been a research hot spot of CVD hard alloy coating. Chinese patent publication No. CN103506640a discloses a method for refining grain size of TiCN coating by boron doping. In the process of preparing the coating by CVD, a proper amount of BCl is introduced into the reaction gas₃ Boron is incorporated into the TiCN coating. The hardness and the wear resistance of the prepared TiBCN coating are obviously improved, and the cutting performance of the coated cutting tool is improved. However, the boron doped TiBCN coating has the disadvantages of larger stress and reduced coating binding force. In addition, boron is light and diffuses easily to the surface of the substrate to produce a detrimental CoWB phase. The Chinese patent with publication number CN104099580A relates to a method for preparing micron columnar crystals MT-TiCN with grain size of 50-150 nm by doping different amounts of hydrocarbon gas into TiCN process gas. The carbon doped TiCN coating has finer grain size, higher hardness and lower friction coefficient, and can remarkably improve the wear resistance and impact resistance of the cutting tool. An improper carbon doping amount easily causes formation of a discontinuous impurity phase at the interface of the film base, thereby causing a decrease in the film base bonding force. In addition, the cracking of hydrocarbon gases can easily cause carbon particles to adhere to the inner walls of the reaction chamber and the surfaces of the graphite boats, causing carbon contamination. The Chinese patent with publication No. CN100549222C provides a method for producing a high-quality ceramic by using CO and CO₂ 、ZrCl₄ Or AlCl₃ A method for effectively refining the grain size of MT-TiCN coating by doping. The method can even obtain a coating with a nano equiaxed crystal structure. The MT-TiCN coating has higher wear resistance and toughness, and is particularly suitable for cutting plastic metals such as stainless steel. However, the MT-TiCN hardness of nano-scale is rather lowered, and grain boundary slip is easily generated due to excessive grain boundaries, resulting in poor wear resistance of the coating. Can be used forAlthough the component and grain size of the MT-TiCN coating can be regulated and controlled through element doping, the hardness and wear resistance of the coating are improved, certain defects exist in various element doping methods, the improvement of the hardness of the coating inevitably leads to the reduction of the toughness of the coating, tiny collapse is easy to generate in the cutting process, and the coated cutter is caused to be failed prematurely.

Disclosure of Invention

In order to solve the problems in the prior art, the main object of the invention is to provide a coated cutting tool with enhanced toughness and wear resistance and a preparation method thereof, in particular to a MT-TiB with enhanced toughness and wear resistance_x C_y N_z O_w Coated tools and methods of making the same.

In order to solve the technical problems, according to one aspect of the present invention, the following technical solutions are provided:

a coated cutting tool with enhanced toughness and wear resistance includes a tool substrate and a coating applied to the tool substrate;

the coating at least comprises a layer of micron columnar crystal MT-TiCN and a layer of nanometer equiaxed crystal MT-TiB which are alternately deposited on the cutter substrate from inside to outside by a medium temperature CVD method_x C_y N_z O_w A layer, wherein x+y+z+w=1, 0 < x.ltoreq.0.1, 0.5.ltoreq.y.ltoreq.0.9, 0.1.ltoreq.z.ltoreq.0.5, 0 < w.ltoreq.0.1.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: micron columnar crystal MT-TiCN layer and nanometer equiaxed crystal MT-TiB_x C_y N_z O_w The transition layers with the contents of B and O elements changing in gradient are arranged between the layers.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: the thickness of the transition layer is 0.01-0.02 mu m, and the content of O and B elements in the transition layer is from the MT-TiCN layer to the adjacent MT-TiB_x C_y N_z O_w The layers exhibit a gradient and increasing variation.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: the number of the alternate depositions is 2-7.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: the monolayer nano equiaxed crystal MT-TiB_x C_y N_z O_w The thickness of the layer is smaller than 0.5 mu m, and the thickness of the single-layer micron columnar crystal MT-TiCN layer is 0.5-5.0 mu m.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: the MT-TiB_x C_y N_z O_w The average grain size of nano equiaxed crystals of the layer is smaller than 100nm, and the average grain size of micron columnar crystals of the MT-TiCN layer is 0.3-2.0 mu m.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: the microhardness of the micro columnar crystal MT-TiCN layer is not lower than 25Gpa.

As a preferred embodiment of the coated cutting tool with enhanced toughness and wear resistance according to the present invention, wherein: the material of the cutter matrix is hard alloy, titanium-based carbonitride or ceramic material, and the total thickness of the coating is 1-30 mu m.

In order to solve the above technical problems, according to another aspect of the present invention, the following technical solutions are provided:

a preparation method of a coating cutter with enhanced toughness and wear resistance comprises the steps of preparing a micro columnar crystal MT-TiCN layer at 800-950 ℃ and 50-200 mbar by TiCl₄ 、N₂ 、H₂ And CH (CH)₃ CN is a precursor, and is prepared by a medium-temperature CVD method; nano equiaxed crystal MT-TiB_x C_y N_z O_w The layers are treated with TiCl at 800-950 ℃ and 50-200 mbar₄ 、BCl₃ 、N₂ 、H_2、 CO and CH₃ CN is a precursor, and is prepared by a medium-temperature CVD method.

The beneficial effects of the invention are as follows:

the invention provides a coated cutting tool with enhanced toughness and wear resistance and a preparation method thereof, wherein the cutting tool comprises a toolA coating having a substrate and a coating applied to the tool substrate; the coating at least comprises a layer of micron columnar crystal MT-TiCN and a layer of nanometer equiaxed crystal MT-TiB which are alternately deposited on the cutter substrate from inside to outside by a medium temperature CVD method_x C_y N_z O_w A layer, wherein x+y+z+w=1, 0 < x.ltoreq.0.1, 0.5.ltoreq.y.ltoreq.0.9, 0.1.ltoreq.z.ltoreq.0.5, 0 < w.ltoreq.0.1. The structure of the periodic coating refines the crystal grains of the MT-TiCN coating and increases the crack propagation path, so that the coating has higher toughness and wear resistance and can obviously prolong the service life of the cutter.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a graph of the coating and crack propagation path of a tool according to example 1 of the present invention;

FIG. 2 is a graph of MT-TiCN coating and crack propagation path for the tool of comparative example 1.

Reference numerals illustrate:

1-first coating, 2-second coating, 3-third coating, 4-fourth coating, 5-fifth coating, 6-substrate.

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following description will be made clearly and fully with reference to the technical solutions in the embodiments, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The invention provides a coated cutting tool with enhanced toughness and wear resistance and a preparation method thereof, and according to one aspect of the invention, the invention provides the following technical scheme:

a coated cutting tool with enhanced toughness and wear resistance includes a tool substrate and a coating applied to the tool substrate;

the coating at least comprises a layer of micron columnar crystal MT-TiCN and a layer of nanometer equiaxed crystal MT-TiB which are alternately deposited on the cutter substrate from inside to outside by a medium temperature CVD method_x C_y N_z O_w A layer, wherein x+y+z+w=1, 0 < x.ltoreq.0.1, 0.5.ltoreq.y.ltoreq.0.9, 0.1.ltoreq.z.ltoreq.0.5, 0 < w.ltoreq.0.1. Nano equiaxed crystal MT-TiB_x C_y N_z O_w The existence of the layer breaks through the growth of the micron columnar crystal MT-TiCN layer, forces the micron columnar crystal MT-TiCN layer to re-nucleate and grow up, and plays a role in inhibiting the growth of crystal grains. At the same time, the columnar structure of the broken MT-TiCN layer is beneficial to increasing the path of crack propagation. The coating provided by the invention has higher toughness and wear resistance, and can obviously prolong the service life of the cutter.

Preferably, to improve the bonding force between the coatings, the micro columnar crystal MT-TiCN layer and nano equiaxed crystal MT-TiB_x C_y N_z O_w The transition layers with the contents of B and O elements changing in gradient are arranged between the layers.

Preferably, the thickness of the transition layer is 0.01-0.02 mu m, and the content of O and B elements in the transition layer is from the MT-TiCN layer to the MT-TiB above the MT-TiCN layer_x C_y N_z O_w The layers exhibit a gradient and increasing variation.

Preferably, the number of times of alternate deposition is 2-7 times.

Preferably, the monolayer nano equiaxed crystal MT-TiB_x C_y N_z O_w The thickness of the layer is smaller than 0.5 mu m, and the thickness of the single-layer micron columnar crystal MT-TiCN layer is 0.5-5.0 mu m.

Preferably, the MT-TiB_x C_y N_z O_w The average grain size of nano equiaxed crystals of the layer is smaller than 100nm, and the average grain size of micron columnar crystals of the MT-TiCN layer is 0.3-2.0 mu m.

Preferably, the microhardness of the micro columnar crystal MT-TiCN layer is not lower than 25Gpa.

Preferably, the material of the cutter matrix is hard alloy, titanium-based carbonitride or ceramic material, and the total thickness of the coating is 1-30 mu m.

Preferably, the coating can be sequentially distributed with five layers from the substrate outwards, and the first coating is a bottom layer with the thickness of 0.1-2.5 mu m; the second coating is at least one layer of micron columnar crystal MT-TiCN layer and one layer of nanometer equiaxed crystal MT-TiB which are deposited alternately from inside to outside on the cutter substrate by a medium temperature CVD method_x C_y N_z O_w The thickness of the coating layer is 1-15 mu m; the third coating is a TiAlOCN coating with the thickness of 0.1-2.5 mu m; the fourth coating is alpha-Al₂ O₃ The thickness of the coating is 1-15 mu m; the fifth coating is a top colored layer having a thickness of 0.1 to 2.5 μm.

Preferably, the first coating layer and the fifth coating layer are TiN coating layers, tiC coating layers or TiCN coating layers, preferably TiN coating layers.

According to another aspect of the invention, the invention provides the following technical scheme:

a preparation method of a coating cutter with enhanced toughness and wear resistance comprises the steps of preparing a micro columnar crystal MT-TiCN layer at 800-950 ℃ and 50-200 mbar by TiCl₄ 、N₂ 、H₂ And CH (CH)₃ CN is a precursor, and is prepared by a medium-temperature CVD method; nano equiaxed crystal MT-TiB_x C_y N_z O_w The layers are treated with TiCl at 800-950 ℃ and 50-200 mbar₄ 、BCl₃ 、N₂ 、H_2、 CO and CH₃ CN is a precursor, and is prepared by a medium-temperature CVD method.

Preferably, the TiAlOCN is coated with TiCl₄ 、N₂ 、H₂ 、CH₄ 、CO、CO₂ And AlCl₃ Is a precursor and is prepared by chemical reaction at 900-1000 ℃ and 50-500 mbar.

Preferably, the alpha-Al₂ O₃ Coating with H₂ 、AlCl₃ And CO₂ Is used as a precursor, and is prepared by mixing,by H₂ S is a catalyst, and is prepared through chemical reaction at 900-1010 ℃ and 50-200 mbar.

Preferably, the coating is post-treated using wet blasting or polishing such that the coating surface roughness Ra is less than or equal to 0.7 μm.

The technical scheme of the invention is further described below by combining specific embodiments.

Example 1

At least 5 layers of coating are sequentially coated on a WNMG 080408E blade of a hard alloy indexable blade by a CVD technology (as shown in figure 1, only part of the composition structure of a second coating 2 is shown in the figure for the convenience of drawing and display effect), the blade matrix 6 comprises 10% of Co,1.7% of cubic carbide and the balance WC, the total thickness of the 5 layers of coating is about 16 mu m, the total thickness of the 5 layers of coating comprises a first coating 1 (TiN coating and about 0.5 mu m), and the first coating 2 (a micro columnar crystal MT-TiCN layer and a nano equiaxial crystal MT-TiB layer)_x C_y N_z O_w Layers alternating 5 times to form a coating of about 9 μm total), a third coating 3 (TiAlOCN coating, about 0.5 μm), a fourth coating 4 (alpha-Al₂ O₃ Coating, about 5 μm) and a fifth coating 5 (TiN coating, about 0.5 μm).

The preparation process parameters of each coating are shown in table 1.

TABLE 1

Comparative example 1

The cemented carbide indexable insert WNMG 080408E insert was coated with at least 5 layers of coating (as shown in FIG. 2) in sequence by CVD technique, the insert base 6 composition was 10% Co,1.7% cubic carbide and the balance WC, the total thickness of the 5 layers of coating was about 16 μm, including a first coating 1 (TiN coating, about 0.5 μm), a first coating 2 (single layer columnar grain MT-TiCN coating, about 9 μm total), a third coating 3 (TiAlOCN coating, about 0.5 μm), a fourth coating 4 (α -Al)₂ O₃ Coating, about 5 μm) and a fifth coating 5 (TiN coating, about 0.5 μm).

The preparation process parameters of each coating are shown in table 2.

TABLE 2

In terms of coating properties, comparative experiments of continuous and intermittent cutting of steel pieces were performed on the tool of example 1 and the tool of comparative example 1 by turning of steel pieces. The information about cutting experiment 1 is as follows:

the operation is as follows: continuous turning

Work piece: cylindrical member

Materials: alloy steel

Blade type: WNMG 080408E

Cutting speed: 350 m/min

Feeding: 0.3 mm/rev

Cutting depth: 2.0 mm (mm)

Wet cutting

The wear values VB (unit mm) measured after cutting for 4min, 8min, 12min and 16min are shown in Table 3.

TABLE 3 Table 3

The information about cutting experiment 2 is as follows:

the operation is as follows: intermittent turning

Work piece: slotted cylinder

Materials: alloy steel

Blade type: WNMG 080408E

Cutting speed: 250 m/min

Feeding: 0.3 mm/rev

Cutting depth: 2.0 mm (mm)

Wet cutting

The wear values VB (unit mm) measured after cutting for 4min, 9min, 14min and 18min are shown in Table 4.

TABLE 4 Table 4

As can be seen from a combination of the crack propagation paths (extension lines in the coating indicated by arrows in the figures) in fig. 1-2 and experiments 1 and 2, the coated cutting insert of the present invention increased the crack propagation paths and improved the chipping resistance of the tool, and compared to the insert of comparative example 1, the insert of the present invention improved the insert lifetime, both in continuous turning and intermittent turning of the steel piece.

The tool comprises a tool matrix and a coating coated on the tool matrix; the coating at least comprises a layer of micron columnar crystal MT-TiCN and a layer of nanometer equiaxed crystal MT-TiB which are alternately deposited on the cutter substrate from inside to outside by a medium temperature CVD method_x C_y N_z O_w A layer, wherein x+y+z+w=1, 0 < x.ltoreq.0.1, 0.5.ltoreq.y.ltoreq.0.9, 0.1.ltoreq.z.ltoreq.0.5, 0 < w.ltoreq.0.1. The structure of the periodic coating refines the crystal grains of the MT-TiCN coating and increases the crack propagation path, so that the coating has higher toughness and wear resistance and can obviously prolong the service life of the cutter.

The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the content of the present invention or direct/indirect application in other related technical fields are included in the scope of the present invention.

Claims (6)

1. A coated cutting tool having enhanced toughness and wear resistance, comprising a tool substrate and a coating applied to the tool substrate;

the coating at least comprises a layer of micron columnar crystal MT-TiCN and a layer of nanometer equiaxed crystal MT-TiB which are alternately deposited on the cutter substrate from inside to outside by a medium temperature CVD method_x C_y N_z O_w A layer, wherein x+y+z+w=1, 0 < x.ltoreq.0.1, 0.5.ltoreq.y.ltoreq.0.9, 0.1.ltoreq.z.ltoreq.0.5, 0.ltoreq.w.ltoreq.0.1;

the times of the alternate deposition are 2-7 times; monolayer of the nano equiaxed crystal MT-TiB_x C_y N_z O_w Thickness of layerThe thickness of the single-layer columnar crystal MT-TiCN layer is 0.5-5.0 mu m, and the degree is smaller than 0.5 mu m; the MT-TiB_x C_y N_z O_w The average grain size of the nano equiaxed crystal of the layer is less than 100nm; the average grain size of the micron columnar crystals of the MT-TiCN layer is 0.3-2.0 mu m.

2. The coated cutting tool of claim 1, wherein the micro columnar crystal MT-TiCN layer and nano equiaxed crystal MT-TiB have enhanced toughness and wear resistance_x C_y N_z O_w The transition layers with the contents of B and O elements changing in gradient are arranged between the layers.

3. The coated cutting tool with enhanced toughness and wear resistance according to claim 2, wherein the thickness of the transition layer is 0.01-0.02 μm.

4. The coated cutting tool of claim 2 wherein the O and B element content in the transition layer is from the MT-TiCN layer to its adjacent MT-TiB_x C_y N_z O_w The layers exhibit a gradient and increasing variation.

5. The coated cutting tool of claim 1, wherein the microhardness of the microcolumnar crystalline MT-TiCN layer is no less than 25Gpa.

6. A method for preparing a coated cutting tool with enhanced toughness and wear resistance according to any one of claims 1-5, wherein the micro columnar crystal MT-TiCN layer is prepared by using TiCl under the conditions of 800-950 ℃ and 50-200 mbar₄ 、N₂ 、H₂ And CH (CH)₃ CN is a precursor, and is prepared by a medium-temperature CVD method; nano equiaxed crystal MT-TiB_x C_y N_z O_w The layers are treated with TiCl at 800-950 ℃ and 50-200 mbar₄ 、BCl₃ 、N₂ 、H_2、 CO and CH₃ CN is a precursor, throughThe preparation method comprises a medium-temperature CVD method.