KR20060102658A - Cemented carbide cutting tool having multicoated layer - Google Patents

Abstract

  The present invention forms a laminated titanium compound layer by chemical vapor deposition and a titanium aluminum nitride layer or aluminum titanium nitride layer by physical vapor deposition on the surface of a coated cemented carbide base material used as a tool material for metal cutting, thereby increasing bonding strength and tensile residual stress. The present invention relates to a cutting tool and a method of manufacturing the same, alleviating and increasing the service life by improving wear resistance and oxidation resistance.

TiN layer or TiC layer is laminated on the surface of the base material, and the TiN layer, TiC layer, TiCN is included on the laminated upper surface, at least including the TiCN layer according to MTCVD (Moderate Temperature CVD) regardless of the stacking order. A single layer of the same material or a TiAlN layer or an AlTiN layer on the upper surface of at least three layers and at least three layers stacked on a boundary where materials are not overlapped with each other by selecting one or more of the layers. The cemented carbide cutting tool is characterized by being laminated with an outer layer 3 of a composite layer.

Chemical vapor deposition. Physical vapor deposition. Cutting tools

Description

Cemented carbide cutting tool having multicoated layer

1 is a milling insert applied to the CVD and PVD composite coating of the present invention

2 to 8 are cross-sectional views in which the coating layer of the present invention is shown, showing several preferred embodiments in which a CVD and PVD composite coating layer is formed on the base material surface.

3 to 16 are cross-sectional views in which a coating layer showing another embodiment of the present invention is stacked.

Explanation of reference numerals for main parts of drawings

1: WC-Co alloy base material 2: inner layer 3: outer layer

The present invention relates to a coated cemented carbide tool used as a tool material for metal cutting, and more particularly to a laminated titanium compound layer by chemical vapor deposition and a titanium aluminum nitride layer or aluminum titanium nitride layer by physical vapor deposition. The present invention relates to a cutting tool having a longer service life due to an increase in bonding strength with a base material and relaxation of tensile residual stress, and an improvement in wear resistance and oxidation resistance.

The cutting tool for cutting the workpiece consists of cemented carbide such as iron, steel (alloy steel), etc., and chemical vapor deposition (CVD: chemical vapor deposition of compounds such as various oxides and carbides on the surface of the tool steel base material in order to increase wear resistance and toughness. coating) and physical vapor deposition (PVD).

CVD coated carbide tools are generally coated with chemical vapor deposition at a temperature of 800 ℃ or higher by coating TiC, TiN, TiCN, and Al ₂ O ₃ layers on a light alloy base material, which is a P-based grade containing a second carbide such as TiC and TaC. As a result, a high bonding strength between the uniform coating layer and the base material can be obtained. The CVD coated cutting tool has excellent bonding strength, and particularly excellent wear resistance and heat resistance, thus exhibiting excellent characteristics in turning inserts.

However, the CVD coating has a disadvantage in that the coating proceeds by a high temperature chemical reaction, and thus, a brittle eta phase is easily formed between the base material and the coating, it is difficult to obtain a sharp cutting edge, and tensile stress occurs on the coating surface.

On the other hand, PVD-coated carbide tools are applied to milling tools that require high impact resistance by coating TiN, TiCN and TiAiN at low temperatures by physical vapor deposition. Unlike CVD coating, compression stress is generated, which is advantageous for interrupted machining. . In addition, the PVD coating has an advantage in that the adhesion strength of the coating layer is lower than that of the CVD coating, but the chipping resistance can be increased and a sharp cutting edge can be obtained.

As such, two types of cutting tool coating techniques are widely used to suit their purpose, taking advantage of their respective advantages and disadvantages. Recently, attempts to combine these two coating technologies have been conducted. Such an attempt is a method in which TiN, TiCN by CVD coating, and TiN coating by PVD method are combined with P-based cemented carbide base material containing a second carbide such as TiC, TaC, NbC, Cr ₃ C, etc. (US Patent) 5,364,209). This method takes advantage of the characteristics of CVD TiCN. On the other hand, another attempt is to coat a variety of second carbide and then CVD coating k-Al ₃ O ₃ of 0.1 ~ 5㎛ again (US Patent 6,565,957 B2).

 In the case of the existing composite coating base materials, not all WC-Co grades are used but P-type grades including TiC, TaC, etc., and the reason is CVD + PVD composite coating layer suitable for the base material WC-Co grade. It is difficult to develop. This is because the CVD coating technology for the P-based base material is relatively common, and further, PVD coating to obtain a new improved performance of the composite coating layer can be referred to the above-mentioned US patent.

The present invention is to obtain a new concept of the coating cutting tool by compensating the respective disadvantages by complexing the above CVD and PVD coating, Al ₂ O ₃ layer in the case of CVD coating in the conventional patent, including the United States patent But in the case of the present invention does not comprise an Al ₂ O ₃ layer. The Al ₂ O ₃ layer has excellent abrasion resistance at high temperature but is brittle and easily causes coating layer peeling and chipping. Therefore, without introducing this coating layer, TiAlN coating with excellent properties such as high temperature abrasion resistance, oxide wear and chipping resistance can be used as monolayer or multinano. As a structure, the coating having excellent wear resistance and toughness can be obtained by replacing the role of the Al ₂ O ₃ layer.

That is, the present invention newly developed a CVD + PVD composite coating layer exhibiting excellent cutting characteristics using the WC-Co base material.

      The present invention is to complement the disadvantages of each of the CVD coating and PVD coating widely used in conventional cutting tools and maximize the advantages, to increase the bonding strength with the cutting tool base material and to reduce the tensile residual stress, and to improve wear resistance and oxidation resistance In order to obtain a new cutting tool with an increased service life, a Ti-based ceramic layer is used as the CVD coating layer to obtain a rigid coating layer having excellent bonding force with the base material, and a hard TiAlN layer using the PVD coating layer is applied to the CVD layer. The purpose of the present invention is to provide a new cutting tool having a longer service life by improving oxidation resistance, such as relieving tensile residual stress of the CVD coating layer to improve wear resistance.

That is, the present invention newly developed a CVD + PVD composite coating layer exhibiting excellent cutting characteristics using the WC-Co base material.

The present invention for achieving the above object is composed of a cutting tool consisting of a plurality of lamination according to the chemical vapor deposition method and a lamination structure according to the physical vapor deposition method on the surface of the WC-Co binary alloy base material. 1 illustrates a perspective view of an insert cutting structure, and FIGS. 2 to 8 show embodiments of various laminated coating structures laminated to the insert base material surface.

The present invention is a superhard base material, for example, the inner layer (2) (Inner layer) and the physical vapor deposition method (PCD) forming a plurality of layers of titanium compound by chemical vapor deposition (CVD) on a substrate, for example, WC-Co base material (1) It is composed of an outer layer (out layer) structure having a monolayer or a multilayer layer made of titanium aluminum nitride or aluminum titanium nitride laminated according to the same material.

 2 to 16 illustrate various embodiments of the present invention, in which a TiN layer or a TiC layer is stacked on the surface of the base material 1, and TiCN according to MTCVD (Moderate Temperature CVD) regardless of the stacking order. At least one of the TiN layer, the TiC layer, and the TiCN layer includes at least one of the inner layers (2) and the outermost layer of the inner layer, which are stacked at a boundary not overlapping with each other, as a TiAlN layer or an AlTiN layer. Cemented carbide cutting tool, characterized in that the outer layer (3) made of a single layer or a composite layer of the same material is laminated.

2 to 16 showing an embodiment of the present invention, as shown in Figure 2, as shown in Figure 2, the TiN layer sequentially on the surface of the WC-Co base material (1) containing 3 to 15% by weight cobalt (Co) MTC (TiCN layer, TiC layer, TiCN layer, TiN layer according to Moderate Temperature CVD, the inner layer (2) is laminated by chemical vapor deposition (CVD), physical vapor deposition (PVD) on top of the TiN continuously forming the outermost layer ) Coating to form a TiAlN or AlTiN layer.

In addition, as shown in FIG. 3, the TiN layer, the TiCN layer, the TiCN layer, the TiC layer, and the TiN layer according to Moderate Temperature CVD (MTCVD) are sequentially stacked on the base material 1 by chemical vapor deposition (CVD). In order to form a TiAlN or AlTiN layer according to physical vapor deposition (PVD) on the top of the outermost layer in succession to the inner layer (2).

In addition, the present invention, as shown in Figure 4, the TiN layer, the TiCN layer, TiC layer, TiN layer according to the Moderate Temperature CVD (MTCVD), the upper layer of the base material (1) sequentially stacked by chemical vapor deposition (CVD) Continuously coated with (2) to the TiAlN or AlTiN layer according to physical vapor deposition (PVD) on the top of the outermost layer.

In addition, the present invention, as shown in Figure 5, the inner layer (2) in which the TiN layer, the TiC layer, the TiCN layer according to the Moderate Temperature CVD (MTCVD) sequentially stacked on the base material 1 by the chemical vapor deposition (CVD) It is coated with a TiAlN or AlTiN layer according to the physical vapor deposition method (PVD) on the top forming the outermost layer in succession.

In addition, in the present invention, as shown in Figure 6, the TiN layer, the TiCN layer according to the Moderate Temperature CVD (MTCVD), the TiC layer is stacked on the base material 1, the inner layer (2) by the chemical vapor deposition (CVD), Continuously coating on the top of the outermost layer to be a TiAlN or AlTiN layer according to physical vapor deposition (PVD).

In the present invention, the laminated structure shown in FIGS. 2 to 6 is preferable.

In addition, the present invention can also be implemented with respect to Figures 7 to 16 described below, which is not shown in Figures 2 to 6 as described above, as shown in Figure 7, the TiC layer, TiN layer, TiCN layer, TiAlN or AlTiN according to physical vapor deposition (PVD) on top of the outer layer in succession with the inner layer (2) in which the TiCN layer according to the Moderate Temperature CVD (MTCVD) sequentially stacked by chemical vapor deposition (CVD) Coating to layer.

In addition, as shown in FIG. 8, the TiC layer, the TiN layer, and the TiCN layer according to the Moderate Temperature CVD (MTCVD) layer on the base material 1 are successively laminated with the inner layer 2 sequentially deposited by chemical vapor deposition (CVD). The uppermost layer forming the outermost layer is coated so that the TiAlN or AlTiN layer according to physical vapor deposition (PVD).

In addition, as shown in Fig. 9, the outermost layer in succession with the inner layer (2) in which the TiC layer on the base material (1), the TiCN layer by MTCVD (Moderate Temperature CVD) is sequentially laminated by chemical vapor deposition (CVD) Coating on the top to form a TiAlN or AlTiN layer according to physical vapor deposition (PVD).

In addition, as shown in FIG. 10, an inner layer 2 in which a TiN layer, a TiCN layer, a TiCN layer, and a TiC layer are sequentially stacked by chemical vapor deposition (CVD) on the base material 1. It is coated with a TiAlN or AlTiN layer according to the physical vapor deposition method (PVD) on the top forming the outermost layer in succession.

In addition, according to the present invention, as shown in FIG. 11, the TiN layer, the TiCN layer, and the TiCN layer according to the Moderate Temperature CVD (MTCVD) layer on the base material 1 are sequentially stacked by chemical vapor deposition (CVD). It is coated with a TiAlN or AlTiN layer according to the physical vapor deposition method (PVD) on the top forming the outermost layer in succession.

 In addition, as shown in FIG. 12, the TiC layer, the TiCN layer, and the TiCN layer according to the Moderate Temperature CVD (MTCVD) layer on the base material 1 are successively laminated with the inner layer 2 sequentially deposited by chemical vapor deposition (CVD). The uppermost layer forming the outermost layer is coated so that the TiAlN or AlTiN layer according to physical vapor deposition (PVD).

 In addition, as shown in FIG. 13, an inner layer 2 in which a TiC layer, a TiCN layer, a TiCN layer according to Moderate Temperature CVD (MTCVD), and a TiN layer are sequentially stacked by chemical vapor deposition (CVD) on the base material 1. It is coated with a TiAlN or AlTiN layer according to the physical vapor deposition method (PVD) on the top forming the outermost layer in succession.

 In addition, as shown in FIG. 14, an inner layer 2 in which a TiC layer, a TiCN layer, a TICN layer, and a TiN layer are sequentially stacked by chemical vapor deposition (CVD) on the base material 1. It is coated with a TiAlN or AlTiN layer according to the physical vapor deposition method (PVD) on the top forming the outermost layer in succession.

 In addition, as shown in FIG. 15, the TiC layer, the TiCN layer according to the Moderate Temperature CVD (MTCVD), and the TiC layer are successively stacked on the base material 1 on the inner layer 2 sequentially deposited by chemical vapor deposition (CVD). The uppermost layer forming the outermost layer is coated so that the TiAlN or AlTiN layer according to physical vapor deposition (PVD).

 In addition, as shown in FIG. 16, the TiC layer, the TiCN layer according to the Moderate Temperature CVD (MTCVD), and the TiN layer were sequentially stacked on the base material 1 on the basis of the chemical vapor deposition (CVD). The uppermost layer forming the outermost layer is coated so that the TiAlN or AlTiN layer according to physical vapor deposition (PVD).

Except for the TiCN layer according to the Moderate Temperature CVD (MTCVD) in the laminated structure constituting the inner layer (2) it is carried out according to the high temperature chemical vapor deposition method (800 ~ 1000 ℃). MTCVD (Moderate Temperature CVD) in the inner layer is to be coated in the range of 400 ~ 700 ℃, when the coating at a high temperature is a problem between the coating layer and the base material, resulting in the degradation of the base material structure and the generation of altered layer In order to improve the etc, this coating can improve the problems of the high-temperature coating as the coating proceeds at a lower temperature than the conventional one.

TiC and TiN in the laminated structure is a coating layer introduced to increase the bonding force between the base material and the coating layer or coating layer, MT TiCN and TiCN is a coating layer introduced to increase the toughness and wear resistance.

In the present invention, it is preferable that the total thickness of the inner layer 2 is in the range of 2 to 20 m, and the total thickness of the outer layer 3 is in the range of 0.5 to 10 m.

Co content of the cemented carbide base material WC-Co binary alloy used in the composite coating of the present invention is preferably used in the range of 5 to 13% by weight, the binary alloy composition used in the present invention is TiC, TaC, etc. Compared to other cemented carbides such as P series, the strength and toughness are excellent, and excellent characteristics are expected under cutting conditions requiring impact resistance.

 In the outer layer 3 constituting the TiAlN or AlTiN layer constituting the outer layer 3 in the above structure, the TiAlN or AlTiN layer is a monolayer or a layer in which a mutinano layer, that is, a nano-sized TiAlN layer is superimposed. In the case of such a composite layer, it can be said that it is useful in cutting applications such as intermittent cutting because the stability of the cutting tool edge resistance and the like is greatly improved in high speed machining.

In applying the physical vapor deposition method to have the outer layer 3, it is carried out in the range of 400 ~ 600 ℃.

The following is described according to the embodiment.

The carbide base material applied to the present invention as shown in Table 1 was WC-Co binary alloy having a Co content of 5 to 13% by weight without the addition of a second carbide.

The raw material powder having the composition was pulverized and mixed for 50 to 80 hours by a wet ball milling method, and dried to form cutting tools of each specification at a molding pressure of 150 to 200 Mpa. The molded body was carried out in a vacuum atmosphere at a sintering temperature of 1350 to 1450 ° C. for 30 to 60 minutes to obtain a coating base material.

Example 1

The surface of the cemented carbide (Wc-Co containing 3% by weight of Co) obtained above was cleaned to remove foreign substances, and then a coating layer having a structure as shown in Table 1 was obtained by CVD coating.

Table 1

CVD coating layer    Thickness (㎛)     Reaction gas    TiN   0.3 to 0.8 H ₂ , N ₂ , TiCl ₄    TiC   0.8 to 1.5  Same as above   MTCVD TiCN   3.0 to 6.0 H ₂ , N ₂ , TiCl _4, CH ₃ CN    TiN   0.3 to 0.8 H ₂ , N ₂ , TiCl ₄                          WC-Co Base Material

As shown in Table 1, it has a laminated structure in the order of TiN / MTCVD (TiCN / TiC / TiN) from the base material surface. The thickness of such a multi-coating layer has a range of 4 ~ 9㎛ and has an average thickness of about 6㎛. Unlike the CVD structure including a conventional Al ₂ O ₃ layer, such CVD coating is composed of a pure Ti-based ceramic layer, TiCxN1-x of 0.2 ~ 1.0㎛ between TiCN and TiC, TiC and TiN in combination of these layers A transition layer is included.

Therefore, since the coating layer structure has similar properties and physical properties between the coating layers, the bonding strength between the coating layers is not only firm, but also excellent hard coating effect can be expected. Such a CVD coating layer is evaluated to have excellent properties as an inner layer (Inner layer) of the CVD + PVD composite coating layer.

Example 2

This embodiment is an outer layer to the inner layer (Inner layer) obtained in Example 1, two monolayers or a composite layer (Multinano layer) by PVD coating as shown in Table 2 The TiAlN (or AlTiN) coating layers having a structure were each independently obtained to obtain a composite layer.

Table 2

PVD coating layer    Thickness (㎛)  PVD temperature (℃) Monolayer-TiAlN or AlTiN    2.5 to 4.5  400-600 Multinanolayer-TiAlN or AlTiN    5.0 to 7.0  400-600                          CVD layer (Inner layer)

       As shown in Table 2, the outer layer according to the PVD coating formed on the inner layer obtained in Example 1 has a TiAlN layer of mono or nano structure depending on the crystal structure. The average thickness of the mono-TiAlN coating layer is about 3.5㎛, and the average thickness of the Nano-TiAlN coating layer is about 6㎛.

The TiAlN coating layer of the outer layer is expected to greatly improve the chipping resistance of the cutting tool while mitigating the tensile stress generated on the surface of the CVD inner layer. In addition, TiAlN coating layer is expected to greatly improve the wear resistance of the cutting tool due to excellent oxidation resistance and wear resistance at high temperature as well as room temperature.

Example 3

The cutting performance test was performed for the cutting tool through Example 2.

The cutting tool specifications were manufactured with SPKN1203EFTR milling inserts and the results of comparing the cutting performance with the typical CVD or PVD coated cutting tools for conventional cast iron machining are shown in (Table 3).

In the milling test, cast iron (Gray cast iron) and ductile cast iron (FCD), which are 90 × 90 × 200 mm sized workpieces, were used, and the cutting edges of each cutting tool (Flank) under cutting conditions in which conventional coated cutting tools are used. Abrasion was evaluated as the distance to reach 0.25mm, and the tool life was evaluated when the cutting was difficult due to chip edge defect or chipping during cutting.

Table 3 and Table 4 show the results of milling comparison test of cast iron and ductile cast iron, respectively, compared with conventional coated cutting tools.

Table 3

Base alloy Co%       CVD      PVD    Cutting result Cutting length remarks Invention A   6 TiN / MT TiCN / TiC / TiN Mono-TiAlN   6.4 B   6 TiN / MT TiCN / TiC / TiN Multinano-TiAlN   6.9 Comparative invention C   6 MT TiCN / Al ₂ O ₃ / TiN       -   5.2 Chipping D   6           - Mono-TiAlN   4.5                       Workpiece: F25 (Gray Cast Iron, HB 190) Cutting Condition: V = 400, f = 0.25, d = 2.0, Dry

Table 4

Base School Scholarship Co%     CVD      PVD       Cutting result Cutting length remarks Invention A   6 TiN / MT TiCN / TiC / TiN Mono-TiAlN    4.3 B   6 TiN / MT TiCN / TiC / TiN Multinano-TiAlN    3.8 Comparative invention C   6 MT TiCN / Al ₂ O ₃ / TiN       -    2.7 Chipping D   6         - Mono-TiAlN    2.9                         Workpiece: F25 (Gray Cast Iron, HB 200) Cutting Condition: V = 150, f = 0.25, d = 3.0, Dry

As shown in the results of Tables 3 and 4, it can be seen that the coated cutting tool of the present invention has superior cutting performance compared to conventional CVD or PVD coated cutting tools in FC and FCD cutting. Therefore, stable cutting is possible with excellent tool life compared to other cutting tools in cutting under the same conditions.

In particular, the chipping resistance of the cutting edge is superior to the conventional CVD-coated cutting tool, which enables more reliable milling. In addition, compared to the conventional TiAlN PVD-coated cutting tools, not only has excellent toughness, such as PVD coating, but also shows excellent tool life due to excellent wear resistance.

From the cutting performance comparison test results, the CVD + PVD-coated cutting tool of the present invention can be seen that the tool life is significantly improved compared to the conventional CVD or PVD-coated cutting tool.

As described above, the new CVD + PVD coated cutting tool of the present invention solves the problems of the conventional CVD or PVD coated cutting tool, thereby obtaining cutting performance superior to that of the conventional coated cutting tool. It is expected to be able to greatly improve the tool life compared to the conventional coated cutting tool because the Co binary composition has excellent toughness and shows excellent performance not only in cutting of steel but also in gray and ductile cast iron.

Claims (8)

Titanium aluminum material according to inner layer and physical vapor deposition (PVD) forming a plurality of layers of titanium compound according to chemical vapor deposition (CVD) on the surface of WC-Co cemented carbide base material containing 3 to 15% by weight of cobalt (Co) Cemented carbide cutting tool, characterized in that the outer layer (Outlayer) consisting of a single layer or a composite layer made of a compound or aluminum titanium nitride is sequentially stacked. The method of claim 1, A TiN layer or a TiC layer is laminated on the base material surface, and at least one TiCN layer according to MTCVD (Moderate Temperature CVD) regardless of the stacking order, and at least one of the TiN layer, the TiC layer, and the TiCN layer. The inner layer 2 having at least three or more layers laminated at a boundary where the materials do not overlap with each other, and a single layer of a TiAlN layer or an AlTiN layer or a composite layer of the same material on the upper surface of the outermost layer of the inner layer. Cemented carbide cutting tool, characterized in that the outer layer (3) is laminated. The method of claim 2, TiCN layer / TiC layer / TiCN layer / TiN layer, TiC layer / TiCN layer / TiCN layer / TiC layer / TiN by TiN layer / TiC layer according to Moderate Temperature CVD (MTCVD) Layer, TiN layer / TiC layer / TiN layer, TiN layer / TiC layer, TiCN layer, TiN layer / Moderate Temperature CVD (MTCVD) A cemented carbide cutting tool comprising an inner layer (2) of one selected from TiCN and TiC layers. The method of claim 2, TiCN layer, TiC layer, TiC layer, TiN layer, MTCVD (TiCN layer, TiC layer, TiC layer, TiCN layer, ModeC temperature (CVD) according to TiC layer, TiN layer, MTCVD (Moderat Temperature CVD) TiCN layer according to Moderat Temperature CVD, TiC layer / TiCN layer according to Moderat Temperature CVD (MTCVD), TiN layer / TiCN layer / TiCN layer / TiC layer according to Moderat Temperature CVD (MTCVD). TiCN layer, TiC layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, TiCN layer, Moderate Temperature CVD TiCN layer, TiCN layer, TiC layer, TiC layer, TiC layer, TiC layer, TiC layer, TiC layer, Moderate Temperature CVD (MTCVD) Cemented carbide cutting tool, characterized in that consisting of the inner layer (2) of the selected one of the TiCN layer / TiN layer. The method according to claim 1 or 2, The total thickness of the inner layer is 2-20 占 퐉, and the total thickness of the outer layer Carbide cutting tool, characterized in that the thickness of 0.5 ~ 10㎛. The method according to any one of claims 1 to 5, The cemented carbide cutting tool, characterized in that the TiCN layer according to the MTCVD (Moderate Temperature CVD) in the inner layer is coated at a temperature of 400 ~ 700 ℃, the remaining titanium compound layer is coated at a temperature of 800 ~ 1000 ℃. The method according to any one of claims 1 to 5. Cemented carbide cutting tool, characterized in that the outer layer is coated at a temperature of 400 ~ 600 ℃. The method of claim 6,  Cemented carbide cutting tool, characterized in that the outer layer is coated at a temperature of 400 ~ 600 ℃.

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