KR102168162B1 - A hard layer for cutting tools and manufacturing method for the same - Google Patents

Abstract

The present invention relates to a hard film formed on a hard base material such as a cemented carbide or cermet used in a cutting tool.
The hard film according to the present invention is a hard film formed by the PVD method on the surface of a hard substrate, and the hard film includes an alternating and repeating layer in which one or more layers A and B are alternately stacked, and the A layer Silver Al _1-ab Cr _b Me1 _a C _x N _y (0≤a≤1, 0.01≤b≤1, x+y=1, 0≤y≤1, Me1 is V, Zr, Nb, Mo, Hf, Consists of at least one element selected from Ta, W, Y, Si), and the B layer is Me2C _w N _z (w+z=1, 0≤z≤1, Me2 is Cr, V, Zr, Nb, Mo , Hf, Ta, W, Y, Si), and is characterized in that a plurality of particles made of a material of the lower layer A are dispersed inside the layer B.

Description

Hard film for cutting tools and its manufacturing method {A HARD LAYER FOR CUTTING TOOLS AND MANUFACTURING METHOD FOR THE SAME}

The present invention relates to a hard coating for a cutting tool formed by the PVD method on a hard gas such as a cemented carbide, cermet, ceramic, and cubic boron nitride used in a cutting tool, and a manufacturing method thereof.

In order to improve cutting performance and improve life, a method of depositing a hard film such as TiN, TiAlN, AlTiN, and Al ₂ O ₃ on hard gases such as cemented carbide, cermet, end mill, and drill is used.

Specifically, until the 1980s, the cutting tool was coated with a single TiN to improve cutting performance and life, but heat is generated at about 600 ~ 700℃ during general cutting. The coating technology was changed to TiAlN, which has high oxidation resistance, and an AlTiN thin film was developed to further improve abrasion resistance and oxidation resistance. The AlTiN thin film obtained the effect of improving the high temperature oxidation resistance by forming an Al ₂ O ₃ oxide layer, but even in the case of the AlTiN thin film, when an Al content of 70% or more was added, an h-AlN phase was formed and the hardness was reduced. .

In recent years, the work piece has become increasingly harder, and the cutting process for difficult-to-cut materials having low thermal conductivity and severe welding with tools is increasing. It is difficult to cope with the existing single thin film structure in order to obtain excellent cutting performance and longevity in high-speed cutting processing for such high-hardness workpieces and high-speed cutting processing for difficult-to-cut materials, and by forming a multilayer structure by depositing thin films having various properties in a complex manner. , It implements the required physical properties.

As an example, in the following patent document, in forming an AlCrBN multi-coating layer deposited by the PVD method, two or more AlCrBN individual layers are combined with two or more TiAlN individual layers in at least a portion of the total thickness of the multi-coating layer, and the AlCrBN The individual layers of and TiAlN are alternately deposited up and down, the thickness of the AlCrBN individual layer is thicker than the thickness of the TiAlN individual layer, the residual stress of the multi-coating layer is lower than that of the AlCrBN single layer, and the multi-coating layer The hardness of the corresponding AlCrBN single layer is greater than or equal to the hardness, thereby preventing interlayer delamination and a method of realizing excellent wear resistance properties.

However, in the case of a multilayer structure, it is a problem to secure good bonding between thin films because materials with different chemical properties are compounded, and various methods such as gradient composition or residual stress control are used to solve this problem, but still improve bonding strength. There is a limit to ordering.

Korean Patent Publication No. 2012-0113790

An object of the present invention is to solve the problem that the hard film formed on the cutting tool is easily worn or peeled off due to high friction with the work material when processing high hardness and difficult to cut materials, and the laminated shape of the hard film is It is intended to provide a hard film and a method for manufacturing the same, which can improve the adhesion between thin films and improve overall wear resistance, chipping resistance, and heat resistance of the tool.

One aspect of the present invention for solving the above problem is a hard film formed by a PVD method on the surface of a hard substrate, wherein the hard film includes an alternating and repeating layer in which one or more layers A and B are alternately stacked. And, the A layer is Al _1-ab Cr _b Me1 _a C _x N _y (0≤a≤1, 0.01≤b≤1, x+y=1, 0≤y≤1, Me1 is V, Zr, Nb , Mo, Hf, Ta, W, Y, made of one or more elements selected from Si), the B layer is Me2C _w N _z (w+z=1, 0≤z≤1, Me2 is Cr, V, For cutting tools consisting of at least one element selected from Zr, Nb, Mo, Hf, Ta, W, Y, and Si), and a plurality of particles composed of the material of the lower layer A are dispersed inside the layer B It is to provide a hard coating.

Another aspect of the present invention for solving the above problem is a method of forming a hard film by repeatedly stacking the A layer and the B layer alternately one or more times by the PVD method on the surface or adjacent portions of the hard substrate, (a ) Forming a layer A such that a plurality of droplets are formed on the surface; (b) forming a B layer on the A layer; (c) etching the layer B to expose at least a portion of the plurality of droplets; (d) forming a layer A such that a plurality of droplets are formed on the etched layer B; And alternately repeating the steps (a) to (d) one or more times; wherein the layer A includes Al _1-ab Cr _b Me1 _a C _x N _y (0 ≤ a ≤ 1, 0.01 ≤ _b ≤ 1, x+y=1, 0≤y≤1, Me1 consists of at least one element selected from V, Zr, Nb, Mo, Hf, Ta, W, Y, and Si), and the B layer is Me2C _w Hard coating for cutting tools made of N _z (w+z=1, 0≤z≤1, Me2 is at least one element selected from Cr, V, Zr, Nb, Mo, Hf, Ta, W, Y, Si) It is to provide a method of manufacturing.

The hard coating for a cutting tool according to the present invention has a multilayer structure that is alternately stacked in the form of AB, and by dispersing a plurality of particles connected to the A layer inside the B layer (especially inside the B layer) By forming a bridge structure connected to the layer A), adhesion between the thin films is improved, and the properties of the thin film are improved through dispersion strengthening while suppressing the compressive stress.

In addition, according to the manufacturing method of the hard film for cutting tools according to the present invention, in the AB alternately stacked structure, a plurality of bridge structures formed of a material of layer A inside the layer B and integrated with the layer A and dispersed is formed. can do.

1 shows the structure of a hard film according to an embodiment of the present invention.
2 shows a manufacturing process of a hard film according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings with respect to an embodiment of the present invention will be described the configuration and operation. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, when a part'includes' a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

The hard coating for a cutting tool according to the present invention is formed by the PVD method on the surface or adjacent portions of the hard substrate (when the underlying layer is interposed), as shown in FIG. 1, and the hard coating is an A layer and a B layer. It includes an alternating and repeating layer that is repeatedly stacked alternately with one or more, and the A layer is Al _1-ab Cr _b Me1 _a C _x N _y (0≤a≤1, 0.01≤b≤1, x+y=1 , 0≤y≤1, Me1 is made of at least one element selected from V, Zr, Nb, Mo, Hf, Ta, W, Y, Si), and the B layer is Me2C _w N _z (w+z= 1, 0≤z≤1, Me2 is composed of one or more elements selected from Cr, V, Zr, Nb, Mo, Hf, Ta, W, Y, Si), and the A layer below the inside of the B layer It is characterized in that a number of particles made of a substance of are dispersed.

Further, according to an embodiment of the present invention, at least some of the plurality of particles may be integrally formed with the layer A formed under the layer B.

In addition, according to an embodiment of the present invention, at least some of the particles are formed integrally with the layer A formed under the layer B, and at the same time, when the layer A is formed on the layer B, the layer A It is possible to form a bridge (bridge) structure that is connected integrally.

In addition, the plurality of particles may have a wedge shape whose size decreases toward the top.

In addition, according to an embodiment of the present invention, the hard substrate may be a cemented carbide containing tungsten carbide, a cermet containing titanium carbonitride, ceramic, or cubic boron nitride.

In addition, when the total thickness of the alternating and repeating layer is less than 0.2 µm, it is difficult to exhibit the original characteristics of the thin film, and if it exceeds 10 µm, the compressive stress accumulated in the thin film due to the manufacturing characteristics of the thin film by the PVD method is reduced to the thickness and time of the thin film. Considering that it is proportional to, since the risk of peeling increases, the thickness is preferably in the range of 0.2 to 10 μm, and the more preferable thickness is 2 to 8 μm.

In addition, if the unit thickness of the layer A constituting the alternating and repeating layer is less than 5 nm, the deposition period is short, making it difficult to generate droplets, and if it exceeds 4 μm, the possibility of single layer peeling increases, so a range of 5 nm to 4 μm is preferable. Do.

In addition, when the unit thickness of the layer B constituting the alternate repeating layer is less than 2 nm, the deposition period is short, making it difficult to form droplets and control the thickness, and when it exceeds 1.3 μm, it is difficult to form a bridge structure beyond the droplet height of layer A. Therefore, a range of 5 nm to 1.5 μm is preferable.

In addition, the alternating and repetitive layers may include 2 layers of AB, 3 layers of ABA, 4 layers of ABAB and more micro-multilayers (when the thickness of the unit layer is 1 μm or more) or nano-multilayers (unit layer thickness is 1). If it is less than ㎛) can be made of a structure.

In addition, the A layer is Al _1-ab Cr _b Me1 _a C _x N _y (0≤a≤1, 0.01≤b≤1, x+y=1, 0≤y≤1, Me1 is V, Zr, Nb , Mo, Hf, Ta, W, Y, Si is preferably made of at least one element selected from the aspect of forming a droplet.

In addition, the B layer is Me2C _w N _z (w+z=1, 0≤z≤1, Me2 is at least one element selected from Cr, V, Zr, Nb, Mo, Hf, Ta, W, Y, Si ) Is preferable in terms of increasing the physical properties of the thin film.

In addition, the method of manufacturing a hard film according to the present invention is a method of forming a hard film by repeatedly stacking the A layer and the B layer alternately one or more times by the PVD method on the surface or adjacent portions of the hard substrate, (a ) Forming a layer A such that a plurality of droplets are formed on the surface; (b) forming a B layer on the A layer; (c) etching the layer B to expose at least a portion of the plurality of droplets; (d) forming a layer A such that a plurality of droplets are formed on the etched layer B; And alternately repeating the steps (a) to (d) one or more times; wherein the layer A includes Al _1-ab Cr _b Me1 _a C _x N _y (0 ≤ a ≤ 1, 0.01 ≤ _b ≤ 1, x+y=1, 0≤y≤1, Me1 consists of at least one element selected from V, Zr, Nb, Mo, Hf, Ta, W, Y, and Si), and the B layer is Me2C _w N _z (w+z=1, 0≤z≤1, Me2 is characterized by consisting of at least one element selected from Cr, V, Zr, Nb, Mo, Hf, Ta, W, Y, and Si).

In addition, when the maximum height (H) of the droplets formed during the deposition process of the layer A is less than 0.02 μm, it is difficult to control the layer B, and when it exceeds 1.5 μm, it gives shape to the thickness of the entire thin film. desirable.

In addition, the density of the droplet is most ideal when it is less than 1.0×10 ⁴ ea/mm2 per unit area, and if it exceeds 5×10 ⁷ ea/mm2, it affects the surface roughness, so 1.0×10 ⁴ ea/mm2 ~ 5 It is preferably x10 ⁷ ea/mm2.

In addition, the ratio (T/H) of the thickness (T) of the B layer to the height (T) of the droplets formed on the surface of the thin film is preferably 0.1 to 0.9.

In addition, the formation and height of the droplets may be controlled by controlling the nitrogen content and cathode current during the deposition of the layer A thin film.

In addition, in the step (b), the layer B is formed in a thickness thinner than the maximum height of the droplets of the layer A formed in the lower layer, a bridge made of the material of the layer A inside the layer B. It is preferable because it is easy to form a structure.

[Example]

Preparation of hard film

First, an insert made of a hard gas based on WC-Co (Hankook Metallurgy Model No.: CNMA120408) was prepared.

On the insert, a hard film having the structure shown in Table 1 was formed.

number rescue Thin film composition Thin film thickness
(㎛) Thin film hardness
(GPa) Remark 1-1 Single layer TiN 2.5㎛ 25.2 Gpa Comparative example 1-2 AlTiN 3.1㎛ 31.3 Gpa Comparative example 1-3 AlCrN 2.8㎛ 29.8 Gpa Comparative example 2-1 Micro
Multilayer AlCrN+CrSiN
Stacked 6 times 2.5㎛ 32.5Gpa Comparative example 2-2 AlCrN+CrSiN
Stacked 10 times 4.1㎛ 33.8Gpa Comparative example 2-3 AlCrN+AlCrVN
Stacked 6 times 2.6㎛ 31.9Gpa Comparative example 2-4 AlCrN+AlCrVN
Stacked 10 times 3.95㎛ 31.1Gpa Comparative example 2-5 AlCrN+CrMoN
Stacked 6 times 2.2㎛ 30.5Gpa Comparative example 2-6 AlCrN+CrMoN
Stacked 10 times 3.85㎛ 32.1Gpa Comparative example 2-7 AlCrN+AlTaN
Stacked 6 times 3.0㎛ 28.5Gpa Comparative example 2-8 AlCrN+AlTaN
Stacked 10 times 4.2㎛ 30.2Gpa Comparative example 3-1 bridge
rescue AlCrN+CrSiN
Stacked 6 times 2.28㎛ 32.0Gpa Example 3-2 AlCrN+CrSiN
Stacked 10 times 4.5㎛ 34.6Gpa Example 3-3 AlCrN+AlCrVN
Stacked 6 times 2.48㎛ 32.0Gpa Example 3-4 AlCrN+AlCrVN
Stacked 10 times 3.8㎛ 31.6Gpa Example 3-5 AlCrN+CrMoN
Stacked 6 times 2.05㎛ 30.4Gpa Example 3-6 AlCrN+CrMoN
Stacked 10 times 3.6㎛ 31.5Gpa Example 3-7 AlCrN+AlTaN
Stacked 6 times 2.9㎛ 29.2Gpa Example 3-8 AlCrN+AlTaN
Stacked 10 times 4.15㎛ 29.8Gpa Example

Single-layer TiN, AlTiN, and AlCrN thin films used as comparative examples were formed through a conventional PVD method.

In addition, the ①AlCrN/CrSiN micro multilayer thin film and ②AlCrN/AlCrVN micro multilayer thin film, ③AlCrN/CrMoN micro thin film, and ④AlCrN/AlTaN micro multilayer thin film used as comparative examples were alternately and repeatedly stacked without an etching process.

The AlCrN film according to an embodiment of the present invention is deposited using an arc-type PVD deposition facility, and a nitrogen (N ₂ ) gas is injected into the chamber and a plasma is generated through an arc using an AlCr target. Was formed using a method of reacting with nitrogen (N) to form an AlCrN thin film on the surface. At this time, a large amount of drop nets were formed on the surface of the AlCrN film.

Also, ①CrSiN film and ②AlCrVN film, ③CrMoN film, ④AlTaN formed on a surface of a AlCrN coating Cr to be deposited using a PVD deposition equipment of the arc type, with nitrogen (N ₂₎ gas into the chamber and comprises a respective ①Si It is formed by using a method of generating plasma through an arc using a target and an AlCr target containing ②V, a ③CrMo target, and a ④AlTa target so that the generated plasma reacts with nitrogen (N) to form each thin film on the surface. I did.

In addition, by etching the ①CrSiN film, ②AlCrVN film, ③CrMoN film, and ④AlTaN film, there are two methods of exposing the dropnet generated in the process of forming the AlCrN film on the surface of the ①CrSiN film, ②AlCrVN film, ③CrMoN film, and ④AlTaN film. You can use either.

The first is the argon plasma etching method, which is a method of making argon in the chamber plasma, and then accelerating the argon plasma to collide with the ①CrSiN film, ②AlCrVN film, ③CrMoN film, and ④AlTaN film.

The second is the metal plasma etching method. This method is to make the metal ions in the chamber into plasma, and then accelerate the metal plasma to collide with the ①CrSiN film, ②AlCrVN film, ③CrMoN film, and ④AlTaN film.

Evaluation of hard film properties

The peeling resistance and abrasion resistance of the composite multilayer film composed of the structure of Table 1 were evaluated under the following evaluation conditions.

(1) Peel resistance evaluation: Abnormal wear due to tearing of thin film

Work material: STS304

Sample model number: CNMG120408-MM

Cutting speed: 120m/min

Cutting feed: 0.2mm/ rev

Cutting depth: 1.5mm

(2) Wear resistance evaluation: Insert clearance and slope wear

Workpiece: SCM440

Sample model number: CNMG120408-HS

Cutting speed: 200m/min

Cutting feed: 0.2mm/rev

Cutting depth: 2mm

The results evaluated under the above conditions are shown in Table 2 below.

number rescue Furtherance Peeling resistance Wear resistance Remark Processing length
(m) Wear type Processing length
(Km) Wear type Remark 1-1 Single layer TiN single layer 47.5 Chipping and breaking 0.95 Excessive wear and tear Comparative example 1-2 AlTiN single layer 190 Welding/Chipping 2.85 Breakage after wear 1-3 AlCrN single layer 220 Welding/Chipping 2.85 Breakage after wear 2-1 Micro
Multilayer AlCrN+CrSiN
Stacked 6 times 238 Welding/Chipping 3.8 Chipping after wear Comparative example 2-2 AlCrN+CrSiN
Stacked 10 times 332 Welding/Chipping 4.75 Chipping after wear 2-3 AlCrN+AlCrVN
Stacked 6 times 238 Welding/Chipping 2.85 Chipping after wear 2-4 AlCrN+AlCrVN
Stacked 10 times 238 Welding/Chipping 3.35 Chipping after wear 2-5 AlCrN+CrMoN
Stacked 6 times 380 Welding/Chipping 2.85 Chipping after wear 2-6 AlCrN+CrMoN
Stacked 10 times 332 Welding/Chipping 3.35 Chipping after wear 2-7 AlCrN+AlTaN
Stacked 6 times 190 Welding/Chipping 2.85 Chipping after wear 2-8 AlCrN+AlTaN
Stacked 10 times 220 Welding/Chipping 3.35 Chipping after wear 3-1 bridge
rescue AlCrN+CrSiN
Stacked 6 times 238 Welding/Chipping 3.8 Chipping after wear Example 3-2 AlCrN+CrSiN
Stacked 10 times 380 Welding/Chipping 4.75 Chipping after wear 3-3 AlCrN+AlCrVN
Stacked 6 times 238 Welding/Chipping 2.85 Chipping after wear 3-4 AlCrN+AlCrVN
Stacked 10 times 238 Welding/Chipping 3.35 Chipping after wear 3-5 AlCrN+CrMoN
Stacked 6 times 410 Welding/Chipping 2.85 Chipping after wear 3-6 AlCrN+CrMoN
Stacked 10 times 332 Welding/Chipping 3.35 Chipping after wear 3-7 AlCrN+AlTaN
Stacked 6 times 220 Welding/Chipping 2.85 Chipping after wear 3-8 AlCrN+AlTaN
Stacked 10 times 220 Welding/Chipping 3.35 Chipping after wear

As can be seen in Table 2, the embodiment having the laminated structure according to the present invention can improve peeling resistance and/or abrasion resistance compared to the comparative example of a single layer or a micro-multilayer structure in which simple alternating and repeatedly stacking. Able to know.

In particular, despite the film having the same composition as Comparative Example Samples 2-1 to 2-8 and Example Samples 3-1 to 3-8, due to the structural difference (simple lamination and bridge structure), peeling resistance, abrasion resistance, and There is a remarkable difference in chipping resistance, and it can be seen that the bridge structure according to the present invention has the effect of improving the bonding strength between the multilayers of the thin film and improving the hardness and toughness. On the other hand, it can be seen that in the same thin film structure, differences in wear resistance and chipping resistance exist according to the type of Me element and the number of repeated laminations.

That is, the hard film having the composition, hardness, and laminated structure according to the present invention can implement improved peeling resistance, abrasion resistance, and chipping resistance as compared to the hard film having a conventional simple repeating alternating laminated structure.

Claims (6)

It is a hard film formed by PVD on the surface of a hard gas.
The hard coating includes an alternating and repeating layer in which one or more layers A and B are alternately stacked and repeatedly stacked,
The layer A is Al _1-ab Cr _b Me1 _a C _x N _y (0≤a≤1, 0.01≤b≤1, x+y=1, 0≤y≤1, Me1 is V, Zr, Nb, Mo , Hf, Ta, W, Y, and at least one element selected from Si),
The B layer is Me2C _w N _z (w+z=1, 0≤z≤1, Me2 is at least one element selected from Cr, V, Zr, Nb, Mo, Hf, Ta, W, Y, Si) Done,
A plurality of particles made of the material of the lower layer A are dispersed inside the layer B,
The plurality of particles are droplets generated in the process of forming the layer A and form a structure protruding from the upper surface of the layer A into the interior of the layer B,
At least some of the plurality of particles are integrally connected with the layer A formed under the layer B,
The height of the plurality of particles protruding from the upper surface of the layer A to the inside of the layer B is 0.02 ~ 1.5㎛, a hard coating for cutting tools. delete The method of claim 1,
At least a portion of the plurality of particles is integrally connected with the layer A formed under the layer B, and at the same time, when the layer A is formed on the layer B, a bridge structure is formed integrally with the layer A above, Hard coating for cutting tools. The method of claim 1,
The hard substrate is a cemented carbide containing tungsten carbide, a cermet containing titanium carbonitride, a ceramic or cubic boron nitride, a hard coating for cutting tools. It is a method of forming a hard film by repeatedly stacking the A layer and the B layer alternately one or more times by the PVD method on the surface or adjacent portions of the hard gas,
(a) forming a layer A to form a plurality of droplets on the surface;
(b) forming a B layer on the A layer;
(c) etching the layer B to expose at least a portion of the plurality of droplets;
(d) forming a layer A such that a plurality of droplets are formed on the etched layer B; And
Including; alternately repeating the steps (a) to (d) one or more times,
The layer A is Al _1-ab Cr _b Me1 _a C _x N _y (0≤a≤1, 0.01≤b≤1, x+y=1, 0≤y≤1, Me1 is V, Zr, Nb, Mo , Hf, Ta, W, Y, and at least one element selected from Si),
The B layer is Me2C _w N _z (w+z=1, 0≤z≤1, Me2 is at least one element selected from Cr, V, Zr, Nb, Mo, Hf, Ta, W, Y, Si) Consisting of, a method for producing a hard film for cutting tools. The method of claim 5,
In the step (b), the film formation of the layer B is performed to a thickness thinner than the maximum height of the droplets of the layer A formed in the lower layer, the method of manufacturing a hard film for a cutting tool.

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