KR20110105980A - Cutting tool having multi coating layers with improved oxidation resistance and high hardness - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer coated cutting tool, wherein chemical vapor deposition (hereinafter referred to as "CVD") and physical vapor deposition ("PVD") are formed on a base material formed of cemented carbide, cermet or ceramic. The invention relates to a cutting tool in which a hybrid multi-layer coating is deposited in parallel to improve wear resistance, oxidation resistance, chipping resistance, and the like.

Description

CUTTING TOOL HAVING MULTI COATING LAYERS WITH IMPROVED OXIDATION RESISTANCE AND HIGH HARDNESS}

The present invention relates to a cutting tool having high hardness and oxidation resistance, and particularly to a cutting tool having excellent hardness and oxidation resistance at high temperature. The cutting tool according to the present invention has excellent mechanical properties such as wear resistance, oxidation resistance, and chipping resistance by laminating a hybrid multilayer coating layer coated by hybridizing chemical vapor deposition (CVD) and physical vapor deposition (PVD). . The cutting tool according to the present invention can be particularly usefully applied as an indexable insert of an indexable tool.

The tool used to replace the insert is called an indexable tool, where the part responsible for the actual cutting is the insert. In general, the insert is sometimes referred to as a cutting tool, the entire indexable tool into which the insert is inserted may be referred to as a cutting tool, and both may be referred to as cutting tools. In the present invention, both the insert and the indexable tool into which the insert is inserted are called cutting tools.

Such cutting tools or inserts generally have a higher hardness than the material of the workpiece, have good abrasion resistance, and have appropriate toughness to withstand the mechanical impact generated during cutting. Carbide alloys, cermets, ceramics, and the like are known as materials that satisfy these requirements. If these materials are used as cutting tools, the life of the tool is not long due to problems such as wear. It is used as a tool by coating it on the base material.

For example, in order to improve the life of the tool, non-oxide ceramic materials such as TiN, TiC, TiCN, etc., which are harder than the base material of the cemented carbide, are used by CVD (chemical vapor deposition) or PVD (physical vapor deposition). Thus, efforts have been made to coat the surface of the base material with a single layer or multiple layers. However, in the case of cutting at high speed and high temperature and high pressure, the non-oxide-based thin film is oxidized or reacted with oxygen or plastic deformation occurs at the edge of the tool due to heat transfer. There is a problem.

In order to solve this problem, in addition to the non-oxide-based thin film, an attempt to apply a multi-layered thin film further formed Al ₂ O ₃ thin film, which is an oxide-based thin film having excellent oxidation resistance and heat blocking effect at a high temperature. There was. Such multilayer thin films have been found to dramatically increase tool life. Based on such an attempt, forming a multilayer thin film having, for example, TiCN / Al ₂ O ₃ / TiN lamination order on a base material made of cemented carbide or the like can be said to be a typical example of a multilayer ceramic thin film currently commercially available.

By the way, Al ₂ O ₃ has the advantage of excellent oxidation resistance and hardness at high temperature, but because of the brittleness of the material, when the mechanical interupt occurs during cutting, defects or chipping ( There is a disadvantage that chipping is likely to occur. The Al ₂ O ₃ thin film was formed by a CVD method. In order to form an Al ₂ O ₃ coating layer by the CVD method, a high temperature of 1000 to 1100 ° C. is generally required. After the coating process is completed, a cooling process is performed. In this cooling process, due to the difference in thermal expansion coefficient between the base material and the ceramic thin film, a tensile residual stress is generated between the surface and the inside of the coated thin film, and thermal cracking occurs. There is a disadvantage that the toughness is lowered.

As a method for solving this problem, US Pat. Nos. 5,597,272 and 5,776,588 disclose a multilayer thin film having a stacked structure of TiCN / Al ₂ O ₃ / TiN formed by MTCVD (Moderate Temperature Chemical Vapor Deposition). The surface treatment is performed by using a brush and a diamond paste on the edge portion of the formed cemented carbide cutting tool, thereby reducing or reducing the thickness of the alumina (Al ₂ O ₃ ) of the edge portion of the cemented carbide. , Methods of improving defect resistance are introduced.

In addition, European Patent EP 0,693,574, US Patent US 6,015,614, US Patent Publication US 2002/0039521, etc., Al ₂ O ₃ after the CVD process In order to alleviate the tensile residual stress generated inside, by applying a blasting process to inject a slurry of water and Al ₂ O ₃ powder of about 100 ~ 300 mesh to the CVD coated cemented carbide at a certain pressure after CVD coating A method of improving the chipping resistance and fracture resistance of a cutting tool by introducing a tensile residual stress in a thin film or by applying a compressive residual stress is introduced.

When the above method is applied, the chipping resistance and the fracture resistance of the Al ₂ O ₃ thin film are better than before, but there is a deficiency in overcoming the brittleness of the Al ₂ O ₃ thin film. In order to solve this problem, US Pat. No. 5,143,488, forms TiN, ZrN, HfN produced by the CVD method as an inner layer on a cemented carbide base material, and TiN, ZrN, HfN or TiCN, It is introduced to form ZrCN, HfCN, etc. so that these layers have compressive residual stress. In addition, Korean Patent No. 10-0665266 discloses a technique for depositing TiCN, TiC, TiN on the surface of a simple cemented carbide composed of WC and Co by MTCVD, and forming TiAlN or AlTiN on a single layer or multilayer by PVD method. have.

As described above, the hybrid multi-layer coating for forming a thin film by using a CVD method and a PVD method is TiCN / Al ₂ O ₃ formed by the MTCVD method, which is a kind of a conventional CVD method. It is one of the methods to solve the brittleness problem of Al ₂ O ₃ that a thin film having a / TiN lamination structure has. Because the PVD method has a lower coating temperature than the CVD method (around 600 ° C), the coating materials evaporated from the target in the reaction chamber are accelerated by the electromagnetic force and collide with the surface of the base material with kinetic energy to form a thin film. This is because the density of D is high and the compressive residual stress is formed on the surface and the inside of the thin film after the process, which is advantageous for tool life, so that the chipping resistance and the fracture resistance are excellent.

However, as described above, in the case of the hybrid coating in which the laminated structure is formed by forming TiCN coating on the base material by MTCVD method first and then forming AlTiN or TiAlN by PVD method, an excellent improvement effect is shown in intermittent processing such as milling. In the continuous processing-oriented processes such as turning, a slight interruption occurs, when the machining speed is high, there is a problem that there is a limit mainly to wear resistance.

Accordingly, the present invention is intended to solve the problem of brittleness of the Al ₂ O ₃ thin film formed by the CVD method described above, and at the same time solve the wear resistance problem of the conventional hybrid coating formed by using the CVD method and the PVD method. In addition, the present invention is to provide a coating that satisfies the wear resistance, oxidation resistance, chipping resistance and defect resistance required in high speed processing.

It is therefore an object of the present invention to provide a cutting tool having a coating film having excellent abrasion resistance, oxidation resistance, chipping resistance and defect resistance.

Another object of the present invention is to provide a method of manufacturing a cutting tool having a coating film having excellent wear resistance, oxidation resistance, chipping resistance and defect resistance.

In order to achieve the above object, the present invention, a cutting tool base material 300, the first coating layer 100 formed on the base material by chemical vapor deposition (CVD) and physical vapor deposition (physical vapor deposition); PVD) and the second coating layer 200 formed on the first coating layer, the second coating layer provides a cutting tool having a layer structure of at least three stages.

According to an example of the present invention, the cutting tool base material may be formed by any one selected from the group consisting of cemented carbide, cermet and ceramics.

According to an example of the present invention, the chemical vapor deposition method for forming the first coating layer is a medium temperature chemical vapor deposition (MTCVD), the thickness of the first coating layer is, for example, about 3 to 10㎛ It is possible.

According to an example of the present invention, the first coating layer comprises titanium (Ti), carbon (C) and nitrogen (N), and further includes at least one of boron (B) and oxygen (O).

According to an example of the present invention, the preferential growth orientation of the first coating layer may be 311 or 220.

In the first coating layer, the content of titanium (Ti) may be contained in an amount of 40 to 90% by weight, and the content of boron (B) may be 0 to 2% by weight.

On the other hand, the second coating layer has a layer structure of at least three steps, according to an example of the present invention, the second coating layer 200 is a first step layer 210; Second step layer 220; And a third step layer 230. According to an example of the present invention, the first step layer 210 may act as a toughening reinforcing layer, for example, the second step layer 220 may function as a wear resistant reinforcing layer, and the third step layer 230. May act as an oxidation resistance and hardness enhancement layer.

Here, the first step layer 210 has a composition of Ti _k Al _{1 - k} N, and may be 0.3 ≦ k ≦ 0.7.

According to one embodiment of the present invention, the second step layer 220 has a composition of Al _a Ti _b Si _{1 -a- b} N and has 0.3 ≦ a ≦ 0.7, 0.3 _{≦ b} ≦ 0.7 and 0 <1-ab ≦ 0.1 Phosphorus unit layer A 221; A unit layer B 222 having a composition of Ti _m Al _{1 -m} N and having 0.3 ≦ _m ≦ 0.7; And a unit layer C (223) having a composition of Al _x Ti _{1 - x} N and having 0.3 ≦ _x ≦ 0.7. Here, the unit layers A 221, the unit layers B 222, and the unit layers C 223 may be alternately stacked at least once or more times. Preferably, the unit layer A 221, the unit layer B 222, and the unit layer C 223 may be stacked in one to four cycles, respectively.

For example, the periods of the unit layers A, B, and C are in the form of [unit layer A-unit layer B-unit layer C], [unit layer A-unit layer B-unit layer C-unit layer A-unit layer B]. ], [Unit layer A-unit layer C-unit layer B-unit layer A], and the like, and can also be laminated in various forms. Further, the unit layer A 221, the unit layer B 222 and the unit Layer C 223 may be stacked in a single layer. In the stacking form of the unit layers, those skilled in the art are required to meet the object of the present invention as long as the unit layer A 221, the unit layer B 222, and the unit layer C 223 are alternately stacked at least once each. It can be carried out by adjusting the stacking form by.

Meanwhile, the third step layer 230 may include aluminum (Al), titanium (Ti), and nitrogen (N), and may further include at least one of silicon (Si) and yttrium (Y). . According to an example of the present invention, the third step layer has a composition of Al _d Ti _e (Si, Y) _1-d- N, wherein 0.3 ≦ _d ≦ 0.7, 0.3 ≦ _e ≦ 0.7, 0 <1-de It is possible to be ≤0.1.

The thickness of the first step layer 210, the second step layer 220 and the third step layer 230 may be the same or different from each other, the thickness of the step layer may be in the range of 0.1 to 5㎛ each Do.

According to one embodiment of the present invention, the preferred crystal orientation of the second coating layer may be 200.

According to an example of the present invention, an underlayer 400 formed between the base material 300 and the first coating layer 100 may be further formed. The thickness of the base layer 400 may be, for example, 0.1 to 10 μm.

The present invention also comprises the steps of preparing a base material 300 for cutting tools; Forming a first coating layer (100) on the base material by chemical vapor deposition (CVD); And forming a second coating layer 200 on the first coating layer by a physical vapor deposition (PVD) method, wherein the forming of the second coating layer includes at least three coatings. It provides a method for producing a cutting tool to perform the second coating layer has a layer structure of three or more steps.

According to one embodiment of the present invention, the chemical vapor deposition forming the first coating layer may be a medium temperature chemical vapor deposition (MTCVD).

According to one embodiment of the present invention, the step of forming the second coating layer 200 may be further subdivided to form a first step layer 210; Forming a second step layer 220; And forming a third step layer 230. As described above, the first step layer 210 may act as a toughness reinforcing layer, for example, the second step layer 220 may act as a wear resistant reinforcement layer, and the third step layer 230. ) May act as an oxidation resistance and hardness enhancement layer.

According to an example of the present invention, the forming of the second step layer 220 may have a composition of Al _a Ti _b Si _1-ab N and has 0.3 ≦ a ≦ 0.7, 0.3 ≦ _b ≦ 0.7 and 0 <1-ab Forming a unit layer A 221 of ≤ 0.1; Forming a unit layer B 222 having a composition of Ti _m Al _{1 -m} N and having 0.3 ≦ _m ≦ 0.7; It may include; _- and Al _x Ti _{1 x} N having the composition of forming the unit layer 0.3≤x≤0.7 C (223). Here, the forming of the unit layer A 221, the unit layer B 222, and the unit layer C 223 may be performed at least one or more times, and preferably, the unit layer A 221, the unit The layer B 222 and the unit layer C 223 may be stacked in one to four cycles, respectively.

According to an example of the present invention, before the forming of the first coating layer 100, the forming of the base layer 400 on the base material may be performed. The base layer 400 may be formed to have a thickness of, for example, 0.1 to 10 μm.

According to the present invention, the base material is mainly composed of Ti, such as Ti (B, C, N), Ti (C, O, N), Ti (B, C, N, O), by the CVD method, particularly the MTCVD method. By forming the first coating layer, the thin film columnar crystal grains are finer than the conventional commercially available TiCN coating layer, thereby obtaining a thin film having improved hardness and wear resistance. In addition, by forming a PVD thin film, which is a second coating layer having a three-step structure, on the first coating layer by using a PVD method, high temperature wear resistance and oxidation resistance of the conventional hybrid coating may be solved.

Among the second coating layer 200 having the three-step structure, the second step layer 220 is formed in multiple layers to increase the hardness of the thin film to act as a wear-resistant reinforcing layer, making it more suitable for continuous processing such as turning. . In addition, the third step layer 230, which is the outermost layer, is formed by adding Si or Y to AlTiN, thereby providing high temperature hardness, oxidation resistance, and high hardness, and thus having higher wear resistance than conventional hybrid coatings in high-speed turning processing in which high temperature is generated. And chipping resistance and oxidation resistance.

In addition, the second coating layer having the three-step laminated structure is characterized in that it has a compressive residual stress, TiCN / Al ₂ formed by the MTCVD method of the conventional CVD thin film by forming the second coating layer on the first coating layer containing Ti as a main component Compared with a thin film having a laminated structure of O ₃ / TiN, a toughness improving effect of remarkably improving chipping resistance and fracture resistance can be obtained.

1 is a schematic representation of a cross section of a cutting tool according to an example of the present invention.
2 is a schematic representation of a cross section of a cutting tool according to another example of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a cross section of a cutting tool according to an example of the present invention, and FIG. 2 is a cross section of a cutting tool according to another example of the present invention, and the cutting tool according to FIG. 2 further includes an underlayer 400.

According to an example of the present invention, the TiCN-based thin film, which is the first coating layer 100, is first formed on the surface of the base material 300 made of cemented carbide, or the like, followed by the AlTiN series, which is the second coating layer 200 by the PVD method. A thin film of was formed.

Here, in order to further improve wear resistance of the multilayer thin film, a TiCN-based thin film, which is the first coating layer 100, is formed by MTCVD, and in this process, CO gas and BCl ₃ gas are used to improve hardness and abrasion resistance due to fine particles. Doping at the same time or one by one.

That is, the MTCVD process is carried out at a temperature of about 800 ~ 900 ℃ and a pressure of 70 ~ 100mbar and used as the reaction gas TiCl ₄ , CH ₃ CN, H ₂ , N ₂ , wherein, in the CO gas and BCl ₃ gas At least one additionally doped. The doped BCl ₃ gas may be about 0.1 to 0.2% by volume of the total reaction gas flow rate, CO gas may be about 4 to 6% by volume of the total reaction gas flow rate. Coating time for forming the first coating layer is maintained for about 100 ~ 300 minutes. The doping flow rate of the BCl ₃ gas and the doping flow rate of the CO gas are effective even if introduced at the same time or flowed alone.

The TiCN-based thin film, which is the first coating layer 100 formed by the above method, is, for example, Ti (B, C, N), Ti (C, O, N), or Ti (B, C, O, N) or the like. The first coating layer may have a thickness of about 3 ~ 10㎛, preferential growth orientation (311) or (220) is possible. Here, the element composition is 0 <B, C, N, O ≤ 60% by weight, the content of B is preferably 0 <B ≤ 2% by weight.

A second coating layer 200 having a three-step thin film structure is formed on the first coating layer by using a PVD method.

Step layer 210 1 toughness enhancement layer of Ti Al _{k 1 - k} and the N atom 0.3≤k≤0.7 composition, and its thickness is preferably 0.1 ~ 5㎛.

The second step layer 220 is a wear-resistant reinforcing layer, _a unit layer A (221) made of Al _a Ti _b Si _{1 -a- b} N, a unit layer B (222) made of Ti _m Al _{1 - m} N, and Al _x Ti _{1 -} a unit layer C (223) to _x N is at least one layer is a composite multi-layered thin film alternately laminated in at least each. At this time, the atomic composition of Al _a Ti _b Si _{1 -a- b} N, which is the unit layer A 221, is 0.3 ≦ a ≦ 0.7, 0.3 _{≦ b} ≦ 0.7, 0 <1-ab ≦ 0.1, and unit layer B (222). ), The atomic composition of Ti _m Al _{1 - m} N is 0.3 ≦ y ≦ 0.7, and the atomic composition of Al _x Ti _1-x N, which is the unit layer C (223), is 0.3 ≦ _x ≦ 0.7. It is preferable that the thickness of a said 2nd step layer is 0.1-5 micrometers.

The third step layer is Al _d Ti _e (Si, Y) _1-d- N, which is an oxidation resistance and hardness strengthening layer, and the atomic composition is 0.3 ≦ _d ≦ 0.7, 0.3 ≦ _e ≦ 0.7, 0 <1-de ≦ 0.1 The thickness is in the range of 0.1 to 5 mu m.

In order to form the second coating layer 200 made of a PVD thin film having a three-step structure as described above, AlTiSi, TiAl, AlTi, or AlTiY alloy is used as a deposition target, and an arc ion plating method, which is a physical vapor deposition method, is used. Coating.

Initial vacuum degree of the coating process was reduced to 8.5 × 0 ^-5 Torr or less and N ₂ was injected into the reaction gas. Gas pressure for the coating is 30 × 0 ^-5 Torr or less, preferably 20 × 0 ^-5 Torr or less, the coating temperature is adjusted to 400 ~ 550 ℃, the substrate bias voltage during coating is -20 ~ -150V Was applied. Of course, the working conditions may vary depending on the equipment characteristics and conditions.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

&Lt; Examples and Comparative Examples &

Cutting tools according to Examples 1 to 3 and Comparative Examples 1 to 6 were prepared in the following Table 1. For reference, the composition content of each component applied to the coating examples and comparative examples is disclosed in Table 2 of the following Test Example 1.

Base material Base layer
(CVD)
(0.5 ~ 1㎛) First coating layer
(MTCVD)
(8 ~ 10㎛) Second coating layer (PVD) Stage 1
(1 ~ 3㎛) Tier 2
(2 ~ 4㎛) Tier 3
(0.5 ~ 3㎛) Example 1 94WC
-0.5WTiC
-5.5 Co TiN Ti (B, C, N) TiAlN AlTiSiN / TiAlN / AlTiN AlTi (Si, Y) N Example 2 Ti (C, O, N) Example 3 Ti (B, C, O, N) Comparative Example 1 Ti (C, N) TiAlN monolayer Comparative Example 2 Ti (C, N) AlTiN monolayer Comparative Example 3 Ti (B, C, N) AlTiN monolayer Comparative Example 4 Ti (C, N) TiAlN AlTiSiN / TiAlN AlTi (Si, Y) N Comparative Example 5 Ti (B, C, N) TiAlN AlTiSiN / TiAlN
/ AlTiN Comparative Example 6 Ti (C, N) CVD method Al ₂ O ₃ / TiN

&Lt; Example 1 >

A cemented carbide having a composition of Tungsten Carbide (WC) 94%, Co 5.5%, and 0.5% WTiC was used as the base material. On the base material, 0.5-1 μm TiN was first formed using the CVD method as the base layer 400.

Next, using the MTCVD method, H ₂ , N ₂ , TiCl ₄ , CH ₃ CN gas and BCl ₃ gas were used as B doping source at a temperature of about 850-900 ° C. and a pressure of 85-95 mbar. The first coating layer 100 was formed by coating for 360 minutes to form a thin film of Ti (B, C, N) having a thickness of 8 ~ 10㎛. The BCl ₃ gas was introduced into the reaction chamber under the condition of 50-100 ml / min. The preferential growth direction of the first coating layer is (311) or (220).

After the first coating layer was formed, the second coating layer 200 was formed by forming a PVD thin film having a three-layer laminated structure by using a PVD arc ion plating method.

In forming the PVD thin film, three types of alloys of AlTiSi alloy, AlTi alloy, and TiAl alloy were used, and the initial vacuum in the reaction chamber was reduced to 8.5 × 0 ^-5 Torr or lower, and N ₂ was reacted as a reaction gas. Injected. Gas pressure during the PVD coating process was adjusted to 20 × 0 ^-5 Torr or less, the coating temperature was adjusted to 450 ~ 550 ℃, the bias voltage applied to the base material during the coating process was adjusted to -100 ~ -110V.

The first coating layer of the thin film having a three-step structure to form the second coating layer is a toughened layer Ti _k Al _{1 - k} N and the atomic composition is 0.3≤k≤0.7, 0.3≤1-k≤0.7, The thickness was formed in 1-3 micrometers. The second step layer is an abrasion resistant reinforcement layer, wherein the unit layer (A) Al _a Ti _b Si _{1 -a- b} N film, the unit layer (B) Ti _m Al _{1 -m} N film, and the unit layer (C) Al _x Ti _{1 - x} N film as a composite multi-layer thin film structure in which several lamination cycle by more each, and the thickness was formed to 2 ~ 4㎛. The third stage layer is an oxidation resistant layer and a hardened layer, Al _d Ti _e (Si, Y) _{1-d- e} N and atomic composition of 0.3≤d≤0.7, 0.3≤e≤0.7, 0 <1-de≤0.1 It was formed so that the thickness might be 0.5-3 micrometers. The preferred crystal orientation of each of the first to third stage layers forming the second coating layer has a (200) plane. Specific contents of each component are shown in Table 2.

<Example 2>

In comparison with Example 1, the same process as in Example 1 was performed except that Ti (C, O, N) was formed instead of Ti (B, C, N) when the first coating layer was formed. In order to form the Ti (C, O, N), the coating temperature and pressure, the coating time, the flow rate of H ₂ , N ₂ , TiCl ₄ , CH ₃ CN gas is the same as in Example 1, BCl ₃ as a doping gas Instead, CO was used to flow into the reaction chamber at a flow rate of 2.0-2.5 l / min.

<Example 3>

When compared with Example 1, it carried out similarly to Example 1 except forming Ti (B, C, O, N) instead of Ti (B, C, N). In order to form Ti (B, C, O, N), coating temperature and pressure, coating time, and the flow rate of H ₂ , N ₂ , TiCl ₄ , CH ₃ CN gas were same as in Example 1 and BCl ₃ as doping gas. Both and CO were used, but BCl ₃ gas was introduced into the reaction chamber under the conditions of 50-100 ml / min, and CO was allowed to enter the reaction chamber at a flow rate of 2.0-2.5 l / min.

Comparative Example 1

After forming TiN having a thickness of 0.5 to 1 μm on the cemented carbide base material having the same composition as used in Example 1 to form a base layer, TiCN having a thickness of 8 to 10 μm was formed using the MTCVD method. To form a first coating layer. Thereafter, TiAlN was formed in a single layer with a thickness of about 3 to 5 μm using a PVD arc ion plating method to form a second coating layer.

Comparative Example 2

In comparison with Comparative Example 1, an AlTiN single layer was formed instead of a single TiAlN layer as the second coating layer.

Comparative Example 3

Except for forming Ti (B, C, N) by the MTCVD method as a first coating layer was prepared in the same manner as in Comparative Example 2.

<Comparative Example 4>

Compared with Example 1, the same TiCN as in Comparative Example 1 was formed as the first coating layer, and the same as in Example 1 except that AlTiSiN / TiAlN was formed as the second step layer 220 of the second coating layer 200. It was carried out.

Comparative Example 5

Compared with Example 1, it was carried out in the same manner as in Example 1 except that the three-stage layer of the second coating layer was not formed.

Comparative Example 6

Compared with Comparative Example 1, it was carried out in the same manner as in Comparative Example 1 except that the Al ₂ O ₃ layer was formed by the CVD method as a second coating layer, and TiN was formed by the CVD method as a top layer thereon.

<Test Example 1>

The coating layer of the cutting tools prepared in Examples 1 to 3 and Comparative Examples 1 to 6 by energy diffraction X-ray spectroscopy (EDX) and plasma discharge component analysis (GDOES, Glow Discharge Optical Emission Spectroscopy) The composition of the thin film to form a was analyzed. The composition of the thin film is shown in Table 2.

CVD thin film composition analysis
(EDX + GDOES, wt%) PVD (CVD) thin film composition analysis
(EDX + GDOES, at.%) Ti B C N O Al Ti Si Y N O Example 1 54.5 1.2 20.9 23.4 31.5 17.2 1.8 0.2 49.3 Example 2 50.2 16.2 23.1 10.5 30.4 18.1 1.5 0.1 49.1 Example 3 50.5 1.4 16.9 21.9 9.3 31.2 18.2 1.7 0.3 48.6 Comparative Example 1 53.6 22.9 23.5 24.4 23.5 - - 52.1 Comparative Example 2 52.7 21.4 25.9 29.4 19.5 - - 51.1 Comparative Example 3 54.2 1.3 20.8 23.7 28.2 20.4 - - 51.4 Comparative Example 4 52.4 23.2 25.4 30.3 18.2 1.6 0.2 48.9 Comparative Example 5 54.1 1.2 21.6 23.1 30.4 19 1.7 48.9 Comparative Example 6 53.1 22.6 24.3 52.1 1.3 0.8 45.8

<Test Example 2>

Thin film thickness was analyzed by Energy Diffraction X-ray Spectrometer (EDX) and Glow Discharge Optical Emission Spectroscopy (GDOES), and the results are shown in Table 3.

In addition, Table 3 also shows the results of the preferential crystal orientation, room temperature thin film hardness and deterioration hardness test by X-ray diffraction analysis (XRD).

First, using the 2θ method using Cu ka line for specimens in which each thin film was deposited on a cemented carbide base material polished with a diamond abrasive of 1 μm for the cutting tools prepared in Examples 1 to 3 and Comparative Examples 1 to 6, respectively. X-ray diffraction analysis (XRD) was performed.

In addition, the thin film hardness showed the results of micro hardness test using Fischerscope (HP100C-XYP; German HELMUT FISCHER GMBH, ISO14577), and the hardness value after the heat treatment, that is, the thermal hardness, was carried out in a heat treatment furnace at 900 ° C. for 30 minutes. The value was measured. The results are shown in Table 3.

Comparing Examples 1 to 3 and Comparative Examples 1 to 6, when the thin film structure of the second coating layer, which is a PVD layer, is formed of a multilayer, it has excellent hardness characteristics due to the strengthening effect compared to a single layer. In the case of a multilayer thin film, compared to a single layer, the thin film interface layer repeatedly laminated suppresses dislocation movement, thereby obtaining an effect of improving hardness. In addition, as shown in Examples 1 to 3, if the outermost layer suppresses the reduction of deterioration hardness due to oxidation, it is possible to maintain excellent high temperature hardness properties of the intermediate layer even at high temperatures.

During the deterioration test, the oxidation reaction of the thin film due to the high temperature occurs in Examples 1 to 3 and Comparative Examples 1 to 6.

In Examples 1 to 3 of the present invention, the outermost layer (oxidation layer), which is the third step layer 230 of the second coating layer, has Al ₂ O ₃ and SiO _{2 ,} Two oxide layers of Y ₂ O ₃ layers are formed. As a result, Examples 1-3 have especially oxidation-resistant characteristics superior to the TiAlN and AlTiN thin films which are Comparative Examples 1-3. In general, the SiO ₂ layer and the Y ₂ O ₃ layer form an oxide layer that is more stable and faster than the TiO ₂ and Al ₂ O ₃ oxide layers, thereby suppressing atomic diffusion of Al and Ti as solid solutions and depleting the solid solution in the hard thin film. Suppresses the hardness deterioration caused by the decrease in hardness.

On the other hand, as shown in the results of Table 3 it can be seen that the CVD layer of Examples 1 to 3 has a superior room temperature hardness than the comparative example. It is believed that the thin film columnar structure is further refined due to the B or O element added to the MTCVD layer, thereby increasing the thin film hardness.

On the other hand, as can be seen from the results of confirming the degradation hardness of the CVD layer (CVD + MTCVD) in Examples 1 to 3 and Comparative Examples 1 to 6, it can be seen that the decrease in the degradation hardness of the CVD layer is not large. The oxide layer is formed in the outermost portion of the thin film PVD layer, it can be seen that the degradation does not proceed to the CVD inner layer.

The hardness deterioration phenomenon is a major factor that greatly affects the wear resistance during high speed and high feed cutting. If the hardness deterioration is suppressed as described above it will be possible to maintain excellent cutting performance and cutting life during cutting.

Thin film thickness (㎛) Preferred Crystal Direction (XRD) Room temperature
Thin Film Hardness (GPa) Degradation Hardness (GPa)
900 ℃, 30min CVD layer PVD layer CVD layer
CVD + MTCVD PVD layer
(CVD layer) CVD layer
CVD + MTCVD PVD layer
(CVD layer) CVD layer
CVD + MTCVD PVD layer
(CVD layer) Example 1 10.2 3.5 (311) (200) 28 39 27 39 Example 2 10.3 3.2 (220) (200) 26 41 26 38 Example 3 10.6 3.1 (311) (200) 27 40 26 39 Comparative Example 1 10.1 3.3 (220) (200) 23 30 23 24 Comparative Example 2 10.8 3.4 (220) (200) 22 36 21 29 Comparative Example 3 10.5 3.1 (311) (200) 28 36 26 28 Comparative Example 4 10.4 3.2 (220) (200) 22 40 22 38 Comparative Example 5 10.3 3.4 (311) (200) 28 38 27 37 Comparative Example 6 10.7 3.5 (220) (220) 22 30 21 30

Test Example 3 Wear Resistance Test

Wear resistance was compared with respect to the cutting tools manufactured in Examples 1-3 and Comparative Examples 1-6. The wear resistance evaluation conditions are as follows.

Cutting speed (Vc) = 400 m / min

Feedrate (fn) = 0.35mm / rev

Depth of cut (ap) = 2.0mm

Coolant: Wet

Workpiece material: GC250 (Gray Cast Iron, Φ300, Cylinder Type)

Processing method: Continuous processing

Table 4 summarizes the results of the wear resistance evaluation performed under the above conditions.

As a result of the evaluation, Examples 1 to 3 to which the thin film of the present invention was applied can be confirmed that the tool life was greatly improved as compared with Comparative Examples 1 and 2 to which the conventional thin film was applied.

In the results of Examples 1 to 3 and Comparative Example 3, it can be seen that the PVD thin film according to the present invention having the second coating layer 200 having a three-stage stacking structure has superior tool life than the PVD thin film of the conventional single layer.

As a result of the comparison between Examples 1 to 3 and Comparative Example 4, it can be seen that the MTCVD TiBCN of the present invention forming the first coating layer 100 has an effect of improving tool life compared to conventional MTCVD TiCN.

As a result of the comparison between Examples 1 to 3 and Comparative Example 5, the third step layer 230, which serves to improve the oxidation resistance and the high temperature hardness, of the second coating layer 200 of the present invention is effective to improve the wear resistance. You can check it.

In the comparison between Examples 1 to 3 and Comparative Example 6, the coating layer having the laminated structure according to the present invention has an improved effect compared to Al ₂ O ₃ / TiN formed by the conventional CVD method, replacing Al ₂ O ₃ formed by the CVD method. You can see that it is a technology that can be done.

<Test Example 4> high temperature wear resistance and oxidation resistance test

In order to confirm that the cutting tool having the coating layer according to the present invention exhibits a somewhat improved effect in high temperature wear resistance and oxidation resistance in cutting, compared to a conventional cutting tool, a high temperature is generated in the local region of the edge portion during cutting. Difficult-to-work material evaluation was performed.

Evaluation conditions were as follows.

Cutting speed (Vc) = 70 m / min

Feedrate (fn) = 0.15mm / rev

Depth of cut (ap) = 1.5mm

Coolant: Wet

Workpiece material: Inconell 718 (Heat-resistant alloy, Φ100, Cylinder type)

Processing method: Continuous processing

The evaluation results are shown in Table 4.

Evaluation Results Examples 1 to 3 may confirm that the oxidation resistance and high temperature wear resistance of the edge portion were significantly improved as compared with Comparative Examples 1 and 2 of the prior art.

In addition, when comparing Examples 1 to 3 and Comparative Example 3, it can be seen that the PVD thin film having a three-step laminated structure, which is the second coating layer of the present invention, exhibits an excellent lifespan as compared to the conventional PVD thin film.

In the comparison between Examples 1 to 3 and Comparative Example 4, it can be seen that Ti (B, C, O, N) forming the first coating layer of the present invention has superior wear resistance than conventional TiCN.

Comparing Examples 1 to 3 and Comparative Example 5, it can be confirmed that the effect of improving the high temperature wear resistance and oxidation resistance of the third step layer 230 of the second coating layer of the present invention is effective.

When comparing Examples 1 to 3 and Comparative Example 6, the coating layer according to the present invention in terms of high temperature wear resistance and oxidation resistance is superior to the conventional thin film formed to have a laminated structure of TiCN / Al ₂ O ₃ / TiN formed by the CVD method It could be confirmed that.

Test Example 5 Defect Resistance Test

In order to evaluate and evaluate the fracture resistance of the coating layer thin film, Examples 1 to 3 and Comparative Example 6 were evaluated under the following cutting conditions. However, Comparative Example 6 applied wet blasting, a commercially available surface treatment method, to compensate for chipping resistance and fracture resistance, to mitigate tensile residual stress present in CVD multilayer thin films, and to apply compressive residual stress. .

Vc = 200 m / min

fn = 0.25 mm / rev

ap = 2.0mm

Coolant: Dry

Workpiece material: SCM440 4-hole

Conventional commercialized CVD thin films in the machining conditions in which mechanical interruption (impact) occurs severely in the cutting process cannot be chipped and fracture resistant compared to the coating layers formed in Examples 1 to 3 even when the surface treatment of wet blasting is applied. It has been confirmed that the performance is indicative. In view of this, it can be seen that the hybrid thin film applied with the MTCVD and PVD methods is a technology that can significantly improve the chipping resistance and the fracture resistance.

Tool life Wear resistance
(Test Example 3) Oxidation Resistance + High Temperature Hardness
(Test Example 4) Fault tolerance
(Test Example 5) Example 1 33 minutes 18 minutes 152 seconds Example 2 31 minutes 19 minutes 148 seconds Example 3 30 minutes 19 minutes 155 seconds Comparative Example 1 17 minutes 7 minutes Comparative Example 2 18 minutes 8 minutes Comparative Example 3 20 minutes 12 minutes Comparative Example 4 25 minutes 15 minutes Comparative Example 5 23 minutes 14 minutes Comparative Example 6 29 minutes 6 minutes 37 seconds

<Description of Drawing>
100: first coating layer 200: second coating layer
210: first stage layer 220: second stage layer
221: unit layer A 222: unit layer B
223: unit layer C 230: third layer
300: base material 400: base layer

Claims (12)

Cutting tool base material 300;
A first coating layer (100) formed on the base material by chemical vapor deposition (CVD); And
And a second coating layer 200 formed on the first coating layer by physical vapor deposition (PVD).
Here, the second coating layer 200, the first step layer 210, the second step layer 220 and the third step layer 230; includes,
The first step layer 210 has a composition of Ti _k Al _{1 - k} N, where 0.3 ≦ k ≦ 0.7,
The second step layer 220
A unit layer A 221 having a composition of Al _a Ti _b Si _{1 -a- b} N, wherein 0.3 ≦ a ≦ 0.7, 0.3 _{≦ b} ≦ 0.7, and 0 <1-ab ≦ 0.1;
A unit layer B 222 having a composition of Ti _m Al _{1 -m} N and having 0.3 ≦ _m ≦ 0.7; And
And a unit layer C (223) having a composition of Al _x Ti _{1 - x} N and wherein 0.3 ≦ _x ≦ 0.7.
The unit layers A 221, the unit layers B 222, and the unit layers C 223 are alternately stacked at least once each,
The third step layer 230,
Aluminum (Al), titanium (Ti) and nitrogen (N); Also
Further comprising at least one of silicon (Si) and yttrium (Y),
Its composition is Al _d Ti _e (Si, Y) _{1-d- e} N, 0.3≤d≤0.7, 0.3≤e≤0.7, 0 <1-de≤0.1
Cutting tool, characterized in that. According to claim 1, The cutting tool base material is a cutting tool, characterized in that formed by any one selected from the group consisting of cemented carbide, cermet and ceramics. The cutting tool of claim 1, wherein the chemical vapor deposition method for forming the first coating layer is a medium temperature chemical vapor deposition (MTCVD) method. The cutting tool according to claim 1, wherein the first coating layer has a thickness of 3 to 10 μm. The method of claim 1, wherein the first coating layer,
Titanium (Ti), carbon (C) and nitrogen (N);
Cutting tool, characterized in that it further comprises at least one of boron (B) and oxygen (O). The cutting tool according to claim 5, wherein the titanium (Ti) content is 40 to 90% by weight. The cutting tool according to claim 5, wherein the boron (B) content is 0 to 2% by weight. The cutting tool according to claim 1, wherein the thicknesses of the first step layer, the second step layer, and the third step layer may be the same or different from each other, and the thickness ranges from 0.1 to 5 μm. The cutting tool according to claim 1, further comprising an underlayer (400) formed between the base material (300) and the first coating layer (100). Preparing a base material 300 for cutting tools;
Forming a first coating layer (100) on the base material by chemical vapor deposition (CVD); And
And forming a second coating layer 200 on the first coating layer by physical vapor deposition (PVD).
Here, the forming of the second coating layer 200 may include forming a first step layer 210; Forming a second step layer 220; And forming a third step layer 230,
The first step layer 210 has a composition of Ti _k Al _{1 - k} N, where 0.3 ≦ k ≦ 0.7,
Forming the second step layer 220
Forming a unit layer A 221 having a composition of Al _a Ti _b Si _{1 -a- b} N, wherein 0.3 ≦ a ≦ 0.7, 0.3 _{≦ b} ≦ 0.7, and 0 <1-ab ≦ 0.1;
Forming a unit layer B 222 having a composition of Ti _m Al _{1 -m} N, wherein 0.3 ≦ _m ≦ 0.7; And
Forming a unit layer C (223) having a composition of Al _x Ti _{1 - x} N, wherein 0.3≤x≤0.7;
Forming the unit layer A 221, forming the unit layer B 222, and forming the unit layer C 223 are alternately performed at least one or more times, respectively.
The third step layer,
Aluminum (Al), titanium (Ti) and nitrogen (N);
Further comprising at least one of silicon (Si) and yttrium (Y),
Its composition is Al _d Ti _e (Si, Y) _{1-d- e} N, 0.3≤d≤0.7, 0.3≤e≤0.7, 0 <1-de≤0.1
Method for producing a cutting tool, characterized in that. The method of claim 10, wherein the chemical vapor deposition method for forming the first coating layer is a medium temperature chemical vapor deposition (MTCVD) method. 11. The method of claim 10, wherein the step of forming a base layer (400) before the step of forming the first coating layer (100).

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