JPH11138308A - Surface coated cemented carbide cutting tool with excellent chipping resistance with hard coating layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of a surface-coated cemented carbide in which a hard coating layer has excellent chipping resistance. SOLUTION: Al ₂ O is formed on the surface of a WC-based cemented carbide substrate.
Hard coating layers including _three layers, such as TiC layer, TiN layer, T
A hard coating layer composed of one or two or more of Ti compound layers including an iCN layer, a TiO ₂ layer, a TiCO layer, a TiNO layer, and a TiCNO layer, and an Al ₂ O ₃ layer is used.
In a surface-coated cemented carbide cutting tool formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of ２５25 μm, the Al ₂ O ₃ layer constituting the hard coating layer is divided into an upper portion and a lower portion (substrate side). ) Having a different crystallographic structure, wherein the upper portion is a parallel texture of columnar singular polyhedral crystals of longitudinal growth in which adjacent cross-sectional shapes and cross-sectional dimensions in the longitudinal direction are equalized, and the lower portion is parallel texture of columnar diversification polyhedral crystal Vertical growth there are large differences in cross-sectional shape and cross-sectional dimension of the adjacent one another longitudinally composed of the Al ₂ O ₃ layer having a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hard coating layer having excellent chipping resistance and, therefore, to a severe cutting such as high-speed cutting of steel or cast iron and heavy cutting such as high-speed and high feed and high cutting. Surface coated cemented carbide cutting tool (hereinafter referred to as coated cemented carbide tool) that exhibits excellent cutting performance over a long period of time without chipping (small chipping) of the cutting edge even when used under various conditions Things.

[0002]

2. Description of the Related Art Conventionally, in general, a hard coating layer including an aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ) layer, for example, Ti, is formed on a surface of a tungsten carbide-based cemented carbide substrate (hereinafter, referred to as a cemented carbide substrate). Carbide (hereinafter, referred to as TiC) layer, nitride (hereinafter, also referred to as TiN) layer, carbonitride (hereinafter, referred to as TiCN) layer, oxide (hereinafter, referred to as TiO ₂ ) layer, carbonate (hereinafter, referred to) , TiCO) layer, a nitrided oxide (hereinafter referred to as TiNO) layer, and one or more Ti compound layers including a carbonitride (hereinafter referred to as TiCNO) layer, and Al ₂ 2. Description of the Related Art Coated carbide tools are known in which a hard coating layer composed of an O ₃ layer is formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of 10 to 25 μm. Used for continuous and intermittent cutting of steel And it is also known. Further, it is also known that the Al ₂ O ₃ layer constituting the hard coating layer has a granular crystal structure, and the surface of the Al ₂ O ₃ layer is further subjected to X-ray diffraction using Cuκα ray as a radiation source. as illustrated in the X-ray diffraction pattern of FIG. 6, Al ₂ O ₃
31.1 degrees (indicated by A in the figure) at which the peak of
The peak height at a diffraction angle (2θ) of 7.7 degrees (indicated by B in the drawing) is 3 at the diffraction angle of 37.7 degrees.
It is also known that the peak height, which is relatively higher than the peak height at a diffraction angle of 1.1 degrees, shows a small X-ray diffraction pattern.

[0003]

On the other hand, in recent years, high performance and high output of a cutting device have been remarkable, and there is a strong demand for labor saving. Accordingly, cutting has been performed at a high speed and a high feed rate and a high depth of cut have been required. However, in the above-mentioned conventional coated carbide tools, the Al ₂ O ₃ layer among the hard coating layers constituting the same is particularly excellent in oxidation resistance and thermal stability, and has a higher hardness. Although it has hardness, it is relatively low in strength compared to the other constituent layer Ti compound layer, and because it is brittle, for example, under severe conditions such as high-speed cutting and high-speed high-feed cutting of steel and cast iron In the above cutting, chipping easily occurs on the cutting edge, and as a result, the service life can be reached in a relatively short time at present.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, attention was paid to the Al ₂ O ₃ layer constituting the hard coating layer of the coated carbide tool, and a study was conducted to improve the strength and toughness of the Al ₂ O ₃ layer. The Al ₂ O ₃ layer having a granular crystal structure constituting the hard coating layer of the tool (hereinafter, referred to as a granular Al ₂ O ₃ layer) comprises: (a) a reaction gas composition volume%, AlCl ₃ : 1 to 20%; CO ₂ : 0.5 to
30% optionally HCl: 1 to 20% and / or _{H 2 S: 0.05~5%, H} 2: remainder, (b) the reaction temperature: 950 to 1050 ° C., (c) reaction pressure: 30 (A) When forming the Al ₂ O ₃ layer, (1) the conditions at the start of the reaction are: (a) AlCl ₃ : 1 to 20 in terms of the reaction gas composition volume% %, CO ₂ : 0.5 ~
2%, H _2: remainder, (b) the reaction temperature: 900 to 950 ° C., (c) reaction pressure: and, 30~200torr, (2) Then, the reaction pressure without changing the H ₂ S as a reaction gas In addition, CO ₂ was increased over a predetermined period of time, and the temperature was raised to the following temperature. (A) Composition of reaction gas by volume, AlCl ₃ : 1 to 20%, CO ₂ : 10 to 3
_{0%, H 2 S: 0.1~2} %, H 2: remainder, (b) the reaction temperature: 950~1000 ℃, (c) reaction pressure: the the Al ₂ O ₃ layer with 30～200Torr, and the conditions When formed, as shown in the structure photograph of the longitudinal fracture surface of FIG. 1 by a scanning electron microscope and the surface structure photograph of the same by a scanning electron microscope in FIG. large differences is parallel texture columnar diversification polyhedral crystal portrait grows "the Al ₂ O ₃ layer having a (hereinafter, referred to as the longitudinal grains diverse tissues) (hereinafter, the Vertical diversification the Al ₂ O ₃ layer After forming a vertically diversified Al ₂ O ₃ layer having a predetermined layer thickness under the above conditions, (B) Al ₂ O ₃
The conditions for forming the O ₃ layer are as follows: (a) Composition of reaction gas by volume, AlCl ₃ : 1 to 20%, CO ₂ : 5 to 15
_{%, H 2 S: 0.05~1%} , H 2: remainder, (b) the reaction temperature: 900~950 ℃, (c) reaction pressure: 30～200Torr, to, i.e. CO ₂ and in the reaction gas H ₂ S was halved and the reaction temperature was relatively lowered.
_After the formation of the ₂ O ₃ layer, as shown in the micrograph of the longitudinal fracture surface of FIG. 1 by a scanning electron microscope and the micrograph of FIG. 3 by the same scanning electron microscope,
Al having "parallel texture of columnar singular polyhedral crystals of longitudinal growth with equalized cross-sectional shapes and cross-sectional dimensions in adjacent longitudinal directions" (hereinafter referred to as "vertical crystal singularized structure")
_{A 2} O ₃ layer (hereinafter, referred to as a vertically elongated unified Al ₂ O ₃ layer) is formed. Thus, the lower portion has a vertically elongated crystal diversified structure, and the upper portion has a vertically elongated single crystal structure. Composed Al
_{The 2} O ₃ layer is formed by the coexistence of these two structures.
_Since it has higher strength and toughness as compared with the ₂ O ₃ layer, the hard coating layer containing the same has excellent chipping resistance.
_{The 2} O ₃ layer is formed as usual with an average layer thickness of _{3 to} 15 μm, and it is desirable that 20 to 80% of the average layer thickness be the vertically elongated unified Al ₂ O ₃ layer. The resulting coated carbide tool has excellent cutting performance for a long time without chipping of the cutting edge even in severe conditions such as high-speed cutting and high-speed heavy cutting of steel and cast iron. The research result that it becomes like that was obtained.

The present invention has been made based on the results of the above-mentioned research, and comprises a hard coating layer including an Al ₂ O ₃ layer, for example, a TiC layer, a TiN layer, a TiC layer
N layer, TiO ₂ layer, TiCO layer, TiNO layer, and T layer
One or two of Ti compound layers made of iCNO layer
And a hard coating layer composed of an Al ₂ O ₃ layer
In the coated cemented carbide tool formed with an average layer thickness of ２５25 μm, the Al ₂ O ₃ layer constituting the hard coating layer has different crystal structures in an upper portion and a lower portion (substrate side). The upper part is a vertical crystal unitized structure (parallel texture of columnar unified polyhedral crystals of longitudinal growth with equalized cross-sectional shapes and cross-sectional dimensions in adjacent longitudinal directions), and the lower part is a vertical crystal A hard structure composed of an Al ₂ O ₃ layer having a diversified structure (parallel texture of columnar diversified polyhedral crystals grown longitudinally having a large difference in the cross-sectional shape and cross-sectional dimension in the longitudinal direction of adjacent ones) The present invention is characterized by a coated carbide tool having a coating layer having excellent chipping resistance.

[0006] In the coated carbide tool of the present invention,
The longitudinally unified Al ₂ O ₃ layer and the vertically diversified Al ₂ O ₃ layer constituting the upper part and the lower part of the Al ₂ O ₃ layer of the hard coating layer, respectively, use Cuκα rays for the surface as a source. In the X-ray diffraction used, FIG. 1 (vertical unified Al ₂ O ₃
Layers) and 2 (as shown in Vertical diversification the Al ₂ O ₃ layer), 31.1 ° peak appears in Al ₂ O ₃ (A in the figure shown) and 37.7 degrees (figure B Display) Diffraction angle (2
θ), the peak height at a diffraction angle of 31.1 degrees is relatively higher than the peak height at a diffraction angle of 37.7 degrees, and the peak height is higher. It shows an X-ray diffraction pattern having a large difference in height, which is different from the X-ray diffraction pattern of the granular Al ₂ O ₃ layer shown in FIG.

The thickness of the upper portion of the Al ₂ O ₃ layer in the hard coating layer of the coated carbide tool according to the present invention is 3 to 3 which is the average thickness of the ordinary Al ₂ O ₃ layer as described above. 15 μm 2
It is desirable to set the ratio to 0 to 80%, but the ratio is 2%.
If it is less than 0% or exceeds 80%, the layer thickness of the lower portion of the Al ₂ O ₃ layer becomes relatively too thick or too thin, and the mutual coexistence balance of these two becomes insufficient. This is because it is impossible to secure the desired excellent chipping resistance to the hard coating layer because the hard coating layer breaks, and the average layer thickness of the hard coating layer is set to 8 to 25 μm because If the thickness is less than 8 μm, it is not possible to secure desired excellent wear resistance, while if the thickness exceeds 25 μm, the chipping resistance is reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide tool of the present invention will be specifically described with reference to examples. As raw material powder, fine WC powder having an average particle size of 1.5 μm, coarse W having the same particle size of 5 μm
C powder, 1.2 μm (Ti, W) CN (by weight ratio,
Hereinafter, the same, TiC / TiN / WC = 24/20/56)
Powder, 1.3 μm of (Ta, Nb) C (TaC / Nb)
C = 90/10) powder, 1 μm Cr powder and 1.2 μm Co powder were prepared.
And wet-mixed with a ball mill for 72 hours, dried, and then subjected to ISO • CNMG120408.
Each of the compacts was press-molded into a green compact having the shape specified in (1), and the compact was vacuum-sintered under the same conditions as shown in Table 1 to produce carbide substrates A to E, respectively. Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the carbide substrates A to E.

Next, the surfaces of these super-hard substrates A to E are honed, and the compositions and the compositions shown in Tables 3 and 4 are obtained using ordinary chemical vapor deposition equipment under the conditions shown in Table 2. By forming a hard coating layer composed of a Ti compound layer and an Al ₂ O ₃ layer having an average thickness, coated carbide tools 1 to 12 of the present invention and conventionally coated carbide tools 1 to 12 were produced, respectively. The resulting coated carbide tools 1 to 5 of the present invention obtained as described above
No. 12 shows A among the hard coating layers constituting the
The l ₂ O ₃ layer shows the same fracture structure as the fracture surface structure of the coated carbide tool 8 of the present invention shown in FIG. 1, and the vertically diversified Al ₂ O ₃ layer on the lower side and the longitudinal single layer on the upper side in tissue observation and X-ray diffraction by scanning electron microscope for each of the surfaces of the Ichika the Al ₂ O ₃ layer, the same as the surface structure photographs and X-ray diffraction pattern of the present invention coated carbide tool 8 shown in FIGS. 2-5 The results are shown. FIG. 6 shows a conventional coated carbide tool 8.
The X-ray diffraction pattern of the granular Al ₂ O ₃ layer constituting the hard coating layer of FIG.
_{The 2} O ₃ layer also showed the same X-ray diffraction pattern.

Next, the coated carbide tools 1 to 12 according to the present invention will be described.
Workpiece: FC300 (hardness: HB180) round bar, Cutting speed: 400 m / min. , Depth of cut: 3 mm, feed: 0.4 mm / rev, cutting time: 20 minutes, wet continuous high-speed high-feed cutting test of cast iron, and work material: JIS SCM440 (hardness: HB220) Round bar, cutting speed: 350 m / min. Infeed: 3 mm. , Feed: 0.4 mm / rev, cutting time: 10 minutes, a dry continuous high-speed high-feed cutting test of the alloy steel was performed, and the flank wear width of the cutting edge was measured in each cutting test. Table 5 shows the results of these measurements.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

According to the results shown in Tables 3 to 5, the upper part of the Al ₂ O ₃ layer in the hard coating layer is vertically elongated and unitized Al ₂ O.
_The coated carbide tools 1 to 12 according to the present invention, which are composed of _three layers and the lower part is composed of a vertically diversified Al ₂ O ₃ layer, are entirely composed of granular Al.
Compared to the conventional coated carbide tools 1 to 12 composed of ₂ O ₃ layers, the above-described vertically elongated unified Al ₂ O ₃ layer and vertically elongated diversified Al ₂ O
_{Due to} the coexistence of the _three layers, it has extremely high strength and toughness compared to the granular Al ₂ O ₃ layer, so chipping is performed on the cutting edge even in high-speed high-feed cutting of cast iron and steel, which is severe cutting conditions. While excellent cutting performance is exhibited over a long period of time without generation of cracks, conventional coated carbide tools 1-1
In No. 2, it is apparent that chipping of the cutting edge is inevitable due to the granular Al ₂ O ₃ layer, and in any case, the service life is shortened in a relatively short time. As described above, the coated cemented carbide tool according to the present invention is characterized in that the Al ₂ O ₃ layer of the hard coating layer that constitutes the upper part of the vertically elongated unified Al ₂ O ₃ layer and the vertically diversified Al ₂ O ₃ It is designed to have excellent chipping resistance by being formed at the lower side of the layer, so that it can be used not only for continuous cutting and interrupted cutting under ordinary conditions such as steel and cast iron, but also for high speed cutting and high speed Even when used for cutting under severe conditions such as feed and high-speed high-cut cutting, the cutting edge does not generate chipping and exhibits excellent cutting performance over a long period of time. And can contribute to labor saving.

[Brief description of the drawings]

FIG. 1 is a micrograph (magnification: 4000 times) of a longitudinal fracture surface of a coated carbide tool 8 of the present invention, taken by a scanning electron microscope.

[2] The present invention coated carbide tool 8 Vertical diversification the Al ₂ O ₃ layer surface structure photograph by a scanning electron microscope in the Al ₂ O ₃ layer constituting the hard coating layer of (magnification: 5000 times).

FIG. 3 is a surface texture photograph (magnification: 5000 times) of a vertically elongated unified Al ₂ O ₃ layer in an Al ₂ O ₃ layer constituting a hard coating layer of the coated super hard tool 8 of the present invention by a scanning electron microscope. .

4 is a diagram showing an X-ray diffraction pattern of the present invention Vertical diversification the Al ₂ O ₃ layer in the Al ₂ O ₃ layer constituting the hard coating layer of the coated cemented carbide tool 8.

5 is a diagram showing an X-ray diffraction pattern of the longitudinal unification the Al ₂ O ₃ layer in the present invention constituting the hard layer of the coated cemented carbide tool 8 the Al ₂ O ₃ layer.

FIG. 6 is a view showing an X-ray diffraction pattern of a granular Al ₂ O ₃ layer constituting a hard coating layer of the conventional coated carbide tool 8.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C23C 16/40 C23C 16/40

Claims (3)

[Claims] 1. A hard coating layer containing an aluminum oxide layer having a thickness of 8 to 25 μm is formed on the surface of a tungsten carbide-based cemented carbide substrate.
In a surface-coated cemented carbide cutting tool formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of m, the aluminum oxide layer constituting the hard coating layer is different between the upper part and the lower part (substrate side). Having a crystal structure, wherein the upper portion is a parallel texture of columnar monolithic polyhedral crystals of longitudinal growth in which the cross-sectional shapes and cross-sectional dimensions in the longitudinal direction of the adjacent ones are equalized; Excellent chipping resistance of the hard coating layer, which is composed of an aluminum oxide layer with a parallel texture of columnar diversified polyhedral crystals grown longitudinally with large differences in longitudinal cross-sectional shape and cross-sectional dimensions Surface coated cemented carbide cutting tool having 2. The method according to claim 1, wherein the surface of the tungsten carbide-based cemented carbide substrate comprises a Ti carbide layer, a nitride layer, a carbonitride layer, an oxide layer, a carbonate layer, a nitride oxide layer, and a carbonitride layer. Hard coating layer composed of one or more of the Ti compound layers described above and an aluminum oxide layer is 8 to 25 μm.
In a surface-coated cemented carbide cutting tool formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of m, the aluminum oxide layer constituting the hard coating layer is different between the upper part and the lower part (substrate side). Having a crystal structure, wherein the upper portion is a parallel texture of columnar monolithic polyhedral crystals of longitudinal growth in which the cross-sectional shapes and cross-sectional dimensions in the longitudinal direction of the adjacent ones are equalized; Excellent chipping resistance of the hard coating layer, which is composed of an aluminum oxide layer with a parallel texture of columnar diversified polyhedral crystals grown longitudinally with large differences in longitudinal cross-sectional shape and cross-sectional dimensions Surface coated cemented carbide cutting tool having 3. An X-ray diffraction using Cuκα rays as a radiation source on the upper surface and the lower surface of the aluminum oxide layer, wherein an aluminum oxide peak appears.
The peak height at a diffraction angle of 31.1 degrees is higher than the peak height at a diffraction angle of 37.7 degrees at 1.1 and 37.7 degrees. 3. The surface-coated cemented carbide cutting tool according to claim 1, wherein the cutting tool is relatively high, and the difference in peak height is large.