JP2000317705A - Cutting tool made of surface coating tungsten carbide group cemented carbide alloy having hard coating layer exhibiting excellent abrasion-resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of a surface coating tungsten carbide group cemented carbide alloy with a hard coating layer having excellent abrasion-resistance. SOLUTION: This cutting tool is obtained by carrying out chemical vapor deposition and/or physical vapor deposition on a hard coating layer having 5 to 25 μm thickness in total average. The hard coating layer is composed of (a) a Ti compound layer consisting of a TiC layer, a TiN layer and a TiCNO layer which all have thickness of 0.1 to 5 μm in average as well as granular crystalline structures, respectively. Further, the hard coating layer includes (b) a Ti-Zr-based carbonitride layer consisting of a ZrCN thin layer having a longitudinal grown crystalline structure, a TiCN thin layer having the longitudinal grown crystalline structure on the surface side, a (Ti, Zr) CN layer which is an intermediate main body layer sandwiched therebetween and similarly has the longitudinal grown crystalline structure. In addition, the Ti-Zr system carbonitride layer has the longitudinal grown crystalline structure extending from the (Ti, Zr) CN layer to the TiCN thin layer and has an average layer thickness of 5 to 15 μm in these three layers. Furthermore, the hard coating layer has (c) an Al2O3 layer having a layer thickness of 0.5 to 10 μm in average and the granular crystalline structure, and these layers are laminated on a tungsten carbide cemented alloy substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cutting tool made of a surface-coated tungsten carbide-based cemented carbide (hereinafter referred to as coated super-hard alloy) in which a hard coating layer exhibits excellent wear resistance and exhibits excellent cutting performance over a long period of time. Hard tool).

[0002]

2. Description of the Related Art Conventionally, a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) generally has (a)
Each of which has an average layer thickness of 0.1 to 5 μm and a granular crystal structure, a titanium carbide (hereinafter referred to as TiC) layer, a titanium nitride (hereinafter also referred to as TiN) layer, and a titanium carbonitride (hereinafter referred to as TiCN). ) Layer, titanium carbonate (hereinafter, T
(b) a Ti compound layer comprising one or more of an iCO) layer, a titanium oxynitride (hereinafter, shown as TiNO) layer, and a titanium carbonitride (hereinafter, shown as TiCNO) layer; A titanium carbonitride (hereinafter referred to as 1-TiCN) layer having an average layer thickness of 5 to 15 μm and a vertically grown crystal structure, and (c) an aluminum oxide having an average layer thickness of 0.5 to 10 μm and a granular crystal structure ( Hereinafter, Al
And ₂ O indicated by ₃₎ layer, in configured hard coating layer 5 to 2
A coated carbide tool formed by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 5 μm is known, and it is also known that this coated carbide tool is used for continuous or interrupted cutting of steel, cast iron, and the like. Have been. It is also well known that, generally, those having an α-type crystal structure, those having a κ-type crystal structure, and the like are widely and practically used as the Al ₂ O ₃ layer constituting the hard coating layer of the coated carbide tool. Further, the above-mentioned 1-TiCN layer is known, for example, from JP-A-6-8010 and JP-A-7-328808.
It is formed by chemical vapor deposition in a normal chemical vapor deposition apparatus at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride as a reaction gas.

[0003]

On the other hand, in recent years, there is a strong demand for labor saving, energy saving, and further cost reduction in cutting, and with this trend, cutting tools are required to have a longer service life. However, in the conventional coated carbide tool described above, the relatively thick l-TiCN layer, which is a constituent layer of the hard coating layer, has excellent toughness but has insufficient hardness, so that it is not practically used. At present, the wear of the cutting edge progresses relatively quickly, and the above requirements cannot always be met satisfactorily.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
In view of the above, attention has been paid to a relatively thick l-TiCN layer, which is a constituent layer of the hard coating layer of the conventional coated carbide tool, and research has been conducted to further improve the wear resistance thereof. As a result, (a) a carbon-nitride solid solution of Ti and Zr having a vertically elongated crystal structure by replacing a part of Ti in the l-TiCN layer constituting the hard coating layer with a Zr component [hereinafter, l − (T
i, Zr) CN] layer, the l-
The hardness of the (Ti, Zr) CN layer is significantly improved by partial replacement of Ti with Zr, and the abrasion resistance is improved. In this case, the 1- (Ti, Zr) CN layer is represented by a composition formula : (Ti ₁ -xZrx) C ₁ -yNy, where x and y values are represented by atomic ratio, x: 0.1
0.6, y: It is desirable to set it to 0.3 to 0.6. In the above composition formula, the value of x is set to 0.1 to 0.6. If the value is less than 0.1, the desired hardness improving effect cannot be obtained. This is because the toughness suddenly decreases, which causes chipping and chipping of the cutting edge. The reason why the y value is set to 0.3 to 0.6 is that the value is
When it is less than 0.3, the proportion of carbon relatively increases, the proportion of nitrogen decreases, the hardness increases, but the toughness sharply decreases,
On the other hand, if the value exceeds 0.6, the proportion of carbon decreases, the proportion of nitrogen increases, the toughness increases, but the hardness decreases sharply, and the wear resistance decreases. This is because it causes a decrease.

(B) The 1- (Ti, Zr) CN layer is
Zirconium carbonitride having a vertically-growing crystal structure prior to its vapor deposition formation, because grains grow easily during the formation of their own layer, and in particular, the grain growth in the case of thickening is remarkable, which inevitably reduces the strength. A thin layer (hereinafter referred to as 1-ZrCN) is preferably formed with an average layer thickness of 0.1 to 2 μm, and the ZrCN layer itself has a fine structure. When the l- (Ti, Zr) CN layer is formed thereon, the l- (Ti, Zr) CN layer is formed.
The (Ti, Zr) CN layer is formed as a continuous layer of a fine l-ZrCN thin layer (seed crystal). As a result, the growth is remarkably suppressed and a fine vertically-grown crystal structure is obtained. When the l-ZrCN thin layer in this case is also represented by the composition formula: ZrC1-yNy, the y value is
For the same reason as the (Ti, Zr) CN layer,
y: Desirably 0.3 to 0.6.

(C) On the other hand, the above-mentioned hard l- (Ti, Z
r) The CN layer is, in particular, a TiCO layer, a TiNO layer, and a T
Since the adhesion to the iCNO layer and further to the Al ₂ O ₃ layer is inferior, the l-
If a thin layer of the TiCN layer is desirably formed with an average thickness of preferably 0.1 to 2 μm and having the same vertically-grown crystal structure continuous with the l- (Ti, Zr) CN layer,
- (Ti, Zr) CN layer TiCO layer via the l-TiCN thin layer, TiNO layer, and TiCNO layer, become more firmly adhered and the Al ₂ O ₃ layer, insufficient adhesion is caused Chipping or chipping is prevented from being generated on the cutting edge, and the l- (Ti, Zr) layer has a vertically elongated crystal structure that is continuous with the l- (Ti, Zr) CN layer. ) The toughness of the surface of the CN layer is significantly improved. Also in this case,
When the TiCN thin layer is also represented by the composition formula: TiC1-yNy, the y value is represented by an atomic ratio of y: 0.3 to 0.3 for the same reason as in the above-described l- (Ti, Zr) CN layer. It is desirable to set it to 0.6.

(D) The l-ZrCN thin layer shown in (a) to (c) above and l- (T
An i, Zr) CN layer and the above-mentioned l-TiCN thin layer are composed of three layers having different compositions, but a vertically-grown crystal Ti-Zr-based carbonitride layer having a continuous vertically-grown crystal structure is formed into a hard coating layer Coated carbide tools exhibit excellent wear resistance and excellent cutting performance over a long period of time. The research results shown in (a) to (d) above were obtained.

The present invention has been made on the basis of the above-mentioned research results, and (a) TiC having an average layer thickness of 0.1 to 5 μm and a granular crystal structure on the surface of a cemented carbide substrate. Layer, TiN layer, TiCN layer, TiCO layer,
One or two of a TiNO layer and a TiCNO layer
And (b) three compositionally different layers, the three layers being an l-ZrCN thin layer on the substrate side, an l-TiCN thin layer on the surface side, and both of these thin layers. An l- (Ti, Zr) CN layer as an intermediate main body layer sandwiched therebetween, and the l-ZrCN thin layer
A vertically elongated crystal Ti-Zr-based carbonitride having a vertically elongated crystal structure continuous over the (Ti, Zr) CN layer and the l-TiCN thin layer, and having an average layer thickness of all three layers of 5 to 15 μm. And (c) 0.5 to 1
Al ₂ O having an average layer thickness of 0 μm and a granular crystal structure
A hard coating layer composed of _three layers, which is formed by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 5 to 25 μm,
The present invention is characterized by a coated carbide tool in which a hard coating layer exhibits excellent wear resistance.

The thin layer of l-ZrCN on the substrate side of the vertically-grown crystal Ti-Zr-based carbonitride layer constituting the hard coating layer of the coated cemented carbide tool of the present invention has a reaction gas composition of ZrCl ₄ : 0.5 to 2%,
CH ₃ CN: 0.1~3%, optionally N _2: 0.5
-20%, H2: remaining, reaction atmosphere temperature: 850-950 [deg.] C., reaction atmosphere pressure: 40-400 Torr.
The (Ti, Zr) CN layer has a composition of reactive gas: volume%, TiCl ₄ : 0.6 to 6%,
_{ZrCl 4: 0.3~3%, CH 3} CN: 0.1~3
%, Optionally N2: 0.5~20%, H _2: remainder, reaction atmosphere temperature: 850 to 950 ° C., reaction atmosphere pressure: 40～400Torr, formed in conditions, the further surface side l- TiCN lamina reaction gas composition: by volume%, TiCl _4: 0.5 to 2%,
CH ₃ CN: 0.1~3%, optionally N _2: 0.5
-20%, H2: remaining, reaction atmosphere temperature: 850-950 [deg.] C., reaction atmosphere pressure: 40-400 Torr.

Further, the average layer thickness of the constituent layers in the hard coating layer of the coated carbide tool according to the present invention is determined for the following reasons. That is, each of the Ti compound layers has a function of improving interlayer adhesion between constituent layers as a common property, and therefore, the average layer thickness is 0.1%.
If it is less than 5 μm, the desired excellent interlayer adhesion cannot be ensured. On the other hand, if the average layer thickness exceeds 5 μm, chipping or chipping of the cutting edge due to high-speed cutting, especially when a TiC layer exists as a constituent layer. When the soft TiN layer is also present, the wear of the hard coating layer is promoted.
５5 μm.

The Al ₂ O ₃ layer has the effect of improving the wear resistance of the hard coating layer, but the average thickness of the Al ₂ O ₃ layer is 0.1 mm.
When the average layer thickness is less than 5 μm, the desired excellent wear resistance cannot be secured. On the other hand, when the average layer thickness exceeds 10 μm, chipping easily occurs on the cutting edge. It was determined to be 10 μm.

Furthermore, the vertically grown crystal Ti-Zr-based carbonitride layer has high hardness in addition to the excellent toughness of the l-TiCN layer, and contributes to improvement of the wear resistance of the hard coating layer. When the average layer thickness is less than 5 μm, the effect of improving the wear resistance is insufficient, and as a result, the service life is not extended satisfactorily. On the other hand, when the average layer thickness exceeds 15 μm, the cutting edge is chipped or chipped. , The average layer thickness was determined to be 5 to 15 μm. The reason why the total average layer thickness of the hard coating layer is set to 5 to 25 μm is that the average layer thickness is 5 μm.
If it is less than m, the desired wear resistance cannot be secured,
On the other hand, if the average layer thickness exceeds 25 μm, chipping and chipping of the cutting edge are likely to occur.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a coated carbide tool of the present invention
Will be specifically described with reference to examples. As raw material powder,
Equivalent particle size: 1.5 μm fine WC powder, 3.0 μm medium particle
WC powder, 1.2 μm (Ti, W) CN (weight ratio)
And the same hereinafter, TiC / TiN / WC = 24/20/5
6) Powder (1.3 μm) of (Ta, Nb) C (TaC /
NbC = 90/10) powder, 1.2 μm ZrC powder
Powder of 1.0 μm Powder and C of 1.2 μm
o Powders were prepared, and these raw material powders were mixed as shown in Table 1.
Blend in composition, wet mix in ball mill for 72 hours, and dry
After that, this mixed powder was subjected to ISO standard CNMG16061.
Pressing into a green compact in the shape of a throw-away tip in accordance with 2.
After molding, this green compact is vacuumed at 0.10 torr.
Medium, 1 hour to a predetermined temperature in the range of 1400 to 1430 ° C
Carbide substrates A to E by vacuum sintering
Was manufactured respectively. Further, with respect to the above-mentioned carbide substrate E
In a 50 torr CH4 gas atmosphere, temperature: 140
After holding at 0 ° C for 1 hour, carburizing is performed under slow cooling conditions.
After treatment, carbon and Co adhering to the surface of
8 μm from the surface by removing by barrel polishing
Maximum Co content: 14.2% by weight, depth: 32 μm
Was formed on the surface of the substrate. Also, any
Is still sintered, and the surface of the cemented carbide substrate C
At a position of 18 μm from the maximum Co content: 9.3% by weight,
Length: Co-enriched band of 22 μm, the surface of the super-hard substrate D
12. Maximum Co content at a position 20 μm from the surface of the part:
5% by weight, depth: 27μm Co-enriched zone respectively
And the remaining carbide substrates A and B have the above Co
No formation of enriched zone, with a uniform texture throughout
Met. Further, Table 1 shows the insides of the above-mentioned carbide substrates A to E.
Hardness (Rockwell hardness A scale)
Was.

Then, in a state where these super-hard substrates A to E are processed and honed into a predetermined shape, the surfaces thereof are formed on a surface thereof by using an ordinary chemical vapor deposition apparatus under the conditions shown in Tables 2 and 3. By forming a hard coating layer having a target composition and a target layer thickness (flank of the cutting edge) shown in Tables 4 and 5, a vertically-grown crystal Ti—Zr-based carbonitride layer was formed as a constituent layer of the hard coating layer. Coated carbide tools 1 to 10 according to the present invention and conventional coated carbide tools 1 to 10 formed by forming an l-TiCN layer in place of the vertically grown crystal Ti-Zr-based carbonitride layer
10 were each manufactured. In addition, about various coating superhard tools obtained as a result, when the composition and average layer thickness of the constituent layers of the hard coating layer were measured using an electron probe microanalyzer and an optical microscope, all of them were as shown in Table 4,
The composition and the average layer thickness were substantially the same as the target composition and the target layer thickness shown in FIG.

Next, the coated carbide tools 1 to 10 according to the present invention will be described.
Workpiece: JIS SCM440 round bar, Cutting speed: 270 m / min. Infeed: 3.5 mm Feed: 0.4 mm / rev. , Cutting time: 10 minutes, Dry continuous cutting test of alloy steel under the following conditions: Work material: JIS SCM440 Lengthwise equally spaced round bar with 4 vertical grooves, Cutting speed: 300 m / min. , Notch: 0.3 mm, feed: 3.5 mm / rev. , Cutting time: 10 minutes, Dry intermittent cutting test of the alloy steel was performed under the following conditions, and the maximum flank wear width of the cutting edge was measured in each cutting test. Table 6 shows the measurement results.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

[Table 6]

[0022]

From the results shown in Tables 2 to 6, all of the coated carbide tools 1 to 10 according to the present invention in which a vertically elongated crystal Ti—Zr-based carbonitride layer is present as a constituent layer in the hard coating layer, Since the hard coating layer has a high hardness by the vertically-grown crystal Ti-Zr-based carbonitride layer, the cutting edge is excellent without chipping or chipping in any of continuous cutting and intermittent cutting. In the conventional coated carbide tools 1 to 10 in which the hard coating layer has an l-TiCN layer in place of the vertically-grown crystal Ti-Zr-based carbonitride layer while exhibiting wear resistance, In the cutting test, it is clear that the wear of the cutting edge progresses relatively quickly and the service life is reached in a relatively short time. As described above, the coated cemented carbide tool of the present invention exhibits excellent wear resistance in continuous cutting or intermittent cutting of steel or cast iron, for example, and can extend the service life of the tool. It is possible to satisfactorily cope with labor saving and energy saving of processing, and further cost reduction.

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Claims (1)

[Claims] 1. A surface of a tungsten carbide-based cemented carbide substrate, comprising: (a) a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, each having an average layer thickness of 0.1 to 5 μm and a granular crystal structure; A titanium compound layer comprising one or more of a titanium carbonate layer, a titanium oxynitride layer, and a titanium oxycarbonitride layer; and (b) three layers different in composition, wherein the three layers are A zirconium carbonitride thin layer having a vertically elongated crystal structure on the side, a titanium carbonitride thin layer having a vertically elongated crystal structure on the surface side, and a vertically elongated crystal structure as an intermediate main layer sandwiched between these thin layers It is composed of a Ti and Zr carbonitride solid solution layer, and has a vertically elongated crystal structure that is continuous from the zirconium carbonitride thin layer to the Ti and Zr carbonitride solid solution layer and the titanium carbonitride thin layer. And the average layer thickness of these three layers is 5 to 15 μm.
And (c) an aluminum oxide layer having an average layer thickness of 0.5 to 10 μm and a granular crystal structure, and a hard coating layer composed of an aluminum oxide layer having a grain structure of 0.5 to 10 μm. A cutting tool made of a surface-coated tungsten carbide-based cemented carbide having a hard coating layer exhibiting excellent wear resistance, which is formed by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 25 μm.