JPH08187604A - Cutting tool of surface coated tungsten carbide based cemented carbide with its hard coating layer having excellent inter-layer adhesion - Google Patents

Abstract

PURPOSE: To provide a cutting tool of coated cemented carbide with its hard coating layers having excellent inter-layer adhesion. CONSTITUTION: A cutting tool of coated cemented carbide comprises hard coating layers as first layer, second layer, third layer, fourth layer, and fifth layer if necessary, average layer thickness 3-30μm, by lamination, on surface of a WC based cemented carbide base. The first layer in contact with surface of the base is constituted of TiN having granular crystal structure, the second layer of TiCN having vertically-grown crystal-structure, the third layer of TiCO or TiCNO having granular structure, the fourth layer of AION having amorphous structure or granular crystal structure, and the fifth layer of TiN having granular crystal structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a hard coating layer having excellent interlayer adhesion, and therefore exhibits excellent cutting performance over a long period of time when used for cutting, for example, mild steel having a large cutting resistance. The present invention relates to a surface-coated tungsten carbide based cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Patent Publication No. 57-1585 and Japanese Patent Publication No. 59-52703, for example, an entirely homogeneous tungsten carbide based cemented carbide substrate and a binder phase forming component have been used. For example, a tungsten carbide based cemented carbide substrate having a surface portion in which the content of Co or the like is relatively high compared to the inside of the substrate, that is, a surface portion having a binder phase enriched zone (hereinafter, these are collectively referred to as cemented carbide substrate. On the surface of the titanium nitride (hereinafter referred to as TiN), the second layer of titanium carbonitride (hereinafter referred to as TiCN), and the titanium carbonate (to Less than,
TiCO) or titanium oxycarbonitride (hereinafter TiC)
A hard coating layer comprising a third layer of NO), a fourth layer of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) and, if necessary, a fifth layer of TiN, has an average layer thickness of 3 to 30 μm. It is well known that the coated cemented carbide cutting tool formed by laminating is mainly used for turning and milling of alloy steel and cast iron.

[0003]

On the other hand, in recent years, the use of FA in cutting machines has been remarkable, and in conjunction with the demand for labor saving in cutting work, cutting tools tend to be required to be versatile. For carbide cutting tools, there is no problem if this is used for cutting alloy steel or cast iron, etc.
Particularly when used for cutting mild steel with high cutting resistance, the interlayer adhesion of the hard coating layer is not sufficient, so that the hard coating layer is liable to delamination and chipping, which causes a relatively short service life. At present.

[0004]

Therefore, the present inventors have
From the viewpoints described above, as a result of focusing on the above-mentioned conventional coated carbide cutting tool and conducting a study for improving the interlayer adhesion of the hard coating layer constituting the same, (a) the above conventional coated carbide In the hard coating layer constituting the cutting tool, the adhesion of the TiN layer of the first layer to the cemented carbide substrate is extremely high, but the adhesion between the constituent layers is low, which causes delamination and chipping. It is likely to occur. (B) In the hard coating layer constituting the conventional coated carbide cutting tool, the first TiN layer and the second TiCN layer
The layer, the TiCO layer and the TiCNO layer of the third layer, and the TiN layer of the fifth layer formed as necessary all have a granular crystal structure, and the Al ₂ O ₃ layer of the fourth layer has an alpha type crystal structure. However, the second TiCN layer has a vertically elongated crystal structure, and the Al ₂ O ₃ layer of the fourth layer has an amorphous structure or a granular crystal structure (hereinafter referred to as AlON). Instead of the layer, the first TiN layer and the third TiCO layer and the TiCNO layer with respect to the second layer, the third TiCO layer and the TiCNO layer with respect to the fourth layer, and the fifth layer TiN.
As a result, the adhesion of the layers is significantly improved, so that the resulting coated carbide cutting tool does not cause delamination and chipping of the hard coating layer even when cutting work materials with high cutting resistance. To exhibit excellent cutting performance over a long period of time. The research results shown in (a) and (b) above were obtained.

The present invention has been made based on the above-mentioned research results. The first invention is provided on the surface of a cemented carbide substrate.
A coated carbide cutting tool formed by laminating a hard coating layer consisting of a layer, a second layer, a third layer, and a fourth layer, and optionally a fifth layer with an average layer thickness of 3 to 30 μm, The first layer contacting the surface of the substrate is TiN having a granular crystal structure,
The second layer is TiCN having a vertically elongated crystal structure, and the third layer is TiCO or TiCN having a granular crystal structure.
O, the fourth layer is AlON having an amorphous structure or a granular crystal structure, and the fifth layer is TiN having a granular crystal structure.
It is characterized by a coated carbide cutting tool in which the interlayer adhesion of the hard coating layer is improved by constituting the above.

The TiCN layer having the longitudinal crystal structure of the second layer of the hard coating layers constituting the coated cemented carbide cutting tool of the present invention has a reaction as described in, for example, JP-A-6-8010. gas composition: by _{volume%, TiCl 4: 1~4%,} CH
₃ CN: 0.1 to 5%, N ₂ : 0 to 35%, H ₂ : remaining, reaction temperature: 850 to 950 ° C., atmospheric pressure: 30 to 200 torr. On the other hand, a TiCN layer having a granular crystal structure usually has a reaction gas composition: volume%, TiCl ₄ : 1 to 5%, CH
_{4: 2~7%, N 2:} 15~30%, H 2: remainder, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 30～200Torr, is formed by the conditions.

The AlON layer having an amorphous structure, which constitutes the fourth layer of the hard coating layer, has a reaction gas composition: volume%, AlCl ₃ : 1 to 20%, C
O ₂ : 0.5 to 30%, NH ₃ : 0.05 to 5%, HCl: 1 to 20% if necessary, H ₂ : remaining, reaction temperature: 700 to 900 ° C., atmospheric pressure: 30 to 200 torr Are formed under the following conditions. Further, the AlON layer having the granular crystal structure which also constitutes the fourth layer has a reaction gas composition: volume%, AlCl ₃ : 1 to 20%, C
O ₂ : 0.5 to 30%, NH ₃ : 0.05 to 5%, HCl: 1 to 20% if necessary, H ₂ : remaining, reaction temperature: 900 to 1050 ° C., atmospheric pressure: 30 to 200 torr Are formed under the following conditions.

Further, the hard coating layer constituting the coated cemented carbide cutting tool of the present invention is formed on the surface of the cemented carbide substrate by the chemical vapor deposition method and / or the physical vapor deposition method under the above-mentioned conditions and ordinary conditions. First, the first TiN layer is vapor-deposited, then the second
From the TiCN layer of the fourth layer to the AlON layer of the fourth layer, and further by sequentially depositing the TiN layer of the fifth layer as necessary. When forming the second layer and the subsequent layers, the TiN layer of the first layer is formed. In some cases, the C component in the cemented carbide substrate may diffuse and form a solid solution in the layer. In this case, part or all of the first layer becomes TiCN. Further, the average layer thickness of the hard coating layer is set to 3 to 30 μm, because when the average layer thickness is less than 3 μm, desired excellent wear resistance cannot be secured, while the average layer thickness is 30 μm. This is because the fracture resistance of the TiN layer suddenly deteriorates when it exceeds 1.0, and the average layer thickness of the TiN layer of the first layer is 0.1.
˜5 μm, that of the second TiCN layer is 3-20 μm,
The third layer of TiCO layer or TiCNO layer is 0.01-2.
The average thickness of the AlON layer of the fourth layer is 0.1 to 15 μm, and the thickness of the TiN layer of the fifth layer is 0.1 to 5 μm.

[0009]

Next, the coated carbide cutting tool of the present invention will be described in detail with reference to examples. As the raw material powder, a medium-grain WC powder having an average particle diameter of 3 μm and a coarse-grain WC having the same particle diameter of 5 μm
Powder, 1.5 μm (Ti, W) C (weight ratio, same below, TiC / WC = 30/70) powder, 1.2 μm
(Ti, W) CN (TiC / TiN / WC = 24/2)
0/56) powder and Co powder of 1.2 μm were prepared, these raw material powders were compounded to the compounding composition shown in Table 1, wet-mixed for 72 hours with a ball mill, dried, and then I
SO / CNMG120408 (for cemented carbide substrates A to D)
And SEEN42AFTN1 (for cemented carbide substrate E)
Cemented carbide base bodies A to E were manufactured by press-molding into a green compact having the shape defined in 1. and vacuum sintering the green compact under the conditions shown in Table 1. Further, the above cemented carbide substrate B was kept at a temperature of 1400 ° C. for 1 hour in a CH ₄ gas atmosphere of 100 torr and then subjected to carburizing treatment by slow cooling. After the treatment, carbon and Co attached to the substrate surface were removed. 1 from the surface by removing with acid and barrel polishing
Maximum Co content at 0 μm: 15% by weight, depth: 4
A Co enriched zone of 0 μm was formed on the substrate surface. Also,
In the cemented carbide substrates A and D, as-sintered, a Co-enriched zone having a maximum Co content of 9 wt% and a depth of 20 μm was formed on the surface at a position of 15 μm from the surface, The remaining cemented carbide substrates C and E did not have the Co-enriched zone formed and had an overall homogeneous structure. Further, Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the cemented carbide substrates AE.

Then, the surfaces of these cemented carbide substrates A to E were subjected to honing, using a conventional chemical vapor deposition apparatus, under the conditions shown in Table 2 under the conditions shown in Table 2 and the compositions shown in Tables 3 to 6 The coated carbide cutting tools 1 to 7 of the present invention and the coated carbide cutting tools 1 to 7 of the related art were manufactured by forming a crystal structure and a hard coating layer having an average layer thickness.

Next, regarding the various coated carbide cutting tools obtained as a result, the work material: round bar of mild steel, cutting speed: 220 m / min, feed: 0.3 mm / rev., Depth of cut: 2 mm, cutting Continuous cutting test of mild steel under the condition of time: 40 minutes, and work material: square steel of mild steel, cutting speed: 180 m / min, feed: 0.3 mm, depth of cut: 2.5 mm, cutting time: 50 minutes, Milling of mild steel was carried out under the conditions of, and the flank wear width of the cutting edge was measured. The measurement results are also shown in Tables 4 and 6.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

[Table 6]

[0018]

From the results shown in Tables 3 to 6, the coated carbide cutting tools 1 to 7 of the present invention are not susceptible to delamination or chipping of the hard coating layer despite the cutting of mild steel having high cutting resistance. While it does not occur and shows excellent wear resistance,
Conventionally, the coated carbide cutting tools 1 to 7 clearly show that the interlayer adhesion in the hard coating layer is insufficient, and delamination and chipping occur in the cutting of mild steel, resulting in a relatively short service life. is there. As described above, the coated cemented carbide cutting tool according to the present invention has a hard coating layer having excellent interlayer adhesion, so that it can cut not only alloy steel and cast iron, but also mild steel having a high cutting resistance. Even when used for cutting, excellent cutting performance is exhibited over a long period of time.

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Claims (2)

[Claims] 1. A first layer and a second layer are formed on the surface of an entirely homogeneous tungsten carbide based cemented carbide substrate or a tungsten carbide based cemented carbide substrate having a binder phase enriched zone in the surface layer portion.
3 to 3 hard coating layers consisting of a layer, a third layer, and a fourth layer
In a surface-coated tungsten carbide based cemented carbide cutting tool formed by laminating with an average layer thickness of 0 μm, the first layer in contact with the substrate surface is titanium nitride having a granular crystal structure, and the second layer is a vertically grown crystal. Titanium carbonitride having a structure, the third layer is composed of titanium carbonate or titanium oxycarbonitride having a granular crystal structure, and the fourth layer is composed of aluminum oxynitride having an amorphous structure or a granular crystal structure. A surface-coated tungsten carbide-based cemented carbide cutting tool having a hard coating layer with excellent interlayer adhesion. 2. The first layer, the second layer, and the second layer on the surface of the tungsten carbide-based cemented carbide substrate which is wholly homogeneous, or the tungsten carbide-based cemented carbide substrate which has a binder phase enriched zone in the surface layer portion.
A surface-coated tungsten carbide-based cemented carbide cutting tool comprising a hard coating layer formed of a layer, a third layer, a fourth layer, and a fifth layer, each having an average layer thickness of 3 to 30 μm. The contacting first layer is titanium nitride having a granular crystal structure, the second layer is titanium carbonitride having a vertically elongated crystal structure, and the third layer is titanium carbonate or titanium oxycarbonitride having a granular crystal structure. A surface coating having excellent interlayer adhesion with a hard coating layer, characterized in that four layers are composed of aluminum oxynitride having an amorphous structure or a granular crystal structure, and the fifth layer is composed of titanium nitride having a granular crystal structure. Cutting tool made of tungsten carbide based cemented carbide.