JP2022126379A - Surface-coated cutter - Google Patents

Abstract

To provide a coated tool that can be used in high-speed and high-efficiency cutting of hard-to-cut materials such as a Ti-based alloy and has its coating layer to exhibit sufficient heat resistance even in such treatment, demonstrating a long life.SOLUTION: A surface-coated cutter includes a tool substrate and a coating layer on the surface of the tool substrate. The coating layer includes a composite boride layer of Ti and lanthanoid with its average layer thickness of 0.5-10.0 μm. With the average composition of the composite boride layer expressed by the formula: Ti1-zLzBx (L is one or more lanthanoid elements), the atomic ratio z is 0.01-0.20 and x is 1.0-3.5.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool).

2. Description of the Related Art Conventionally, as a coated tool, for example, a tool base made of a tungsten carbide (hereinafter referred to as WC)-based cemented carbide or the like with a coating layer formed thereon has been known.
A proposal has been made to obtain a coating layer with a higher hardness by adjusting the composition of this coating layer.

For example, in Patent Document 1, the surface of a tool substrate is coated with a boride film made of one or more metal elements selected from Al, Si, Cr, W, Ti, Nb, and Zr, and the boride The compound coating has a hexagonal crystal structure, the 011 diffraction line in X-ray diffraction has the strongest hardness, and a coated tool having a residual compressive stress of 0.1 GPa or more is described, and the coated tool has excellent adhesion and high hardness. It is said to have a long life because it has a coating of

JP 2008-238281 A

A coated tool having a boride film as a coating layer, for example, as described in Patent Document 1, has excellent cutting performance because the coating layer has excellent adhesion and high hardness. According to the inventors' studies, it was found that the heat resistance was insufficient when used for high-speed, high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys.

An object of the present invention is to provide a long-life coated tool with a coating layer having sufficient heat resistance even when subjected to high-speed, high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys. Here, high-speed, high-efficiency cutting refers to cutting in which the cutting speed is 30% or more and the amount of cutting is 30% or more as compared to ordinary cutting.

The inventor of the present invention has made intensive studies to obtain a coated tool that achieves the above object. As a result, if the coating layer contains a composite boride containing one or two or more lanthanoids (hereinafter, lanthanoids may be abbreviated as L) in addition to Ti, the high-speed, high-speed machining of difficult-to-cut materials such as Ti-based alloys can be achieved. A new knowledge was obtained that the coating layer has sufficient heat resistance even when subjected to efficient cutting, and that the coated tool has a long life.

The present invention is based on this finding and is as follows.
"A surface-coated cutting tool having a tool substrate and a coating layer on the surface of the tool substrate,
The coating layer includes a composite boride layer of Ti and lanthanide having an average layer thickness of 0.5 to 10.0 μm, and the average composition of the composite boride layer is represented by the composition formula: Ti _1-z L _z B When represented by _x (L is one or more lanthanoids), the atomic ratio z is 0.01 to 0.20 and x satisfies 1.0 to 3.5.
A surface-coated cutting tool characterized by: ”

According to the above, excellent wear resistance and chipping resistance are exhibited even when subjected to high-speed, high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys.

It is a schematic diagram of the longitudinal section of the coating layer in the surface-coated cutting tool of the present invention.

Below, the coated tool which concerns on embodiment of this invention is demonstrated in detail. In addition, in the description of the present specification and claims, when a numerical range is expressed using "A to B", the range includes the numerical values of the upper limit (B) and the lower limit (A). Also, the upper limit (B) and the lower limit (B) are in the same unit.

The layer structure of the coating layer of the coated tool according to the embodiment of the present invention is as schematically shown in FIG. A lower layer (2) may be provided between the boride layer (3) and the tool substrate (1), and an upper layer (4) may be provided on top of the boride layer.

1. Coating Layer The coating layer will be described below.

(1) Structure of coating layer The coating layer in the coated tool according to the present embodiment has a composite boride layer of Ti and L, and optionally (if necessary) a lower layer below it. It may have an upper layer on top.

(1-1) Composite boride layer of Ti and L The average composition of the composite boride layer of Ti and L is the composition formula: Ti _1-z L _z B _x (L is one or more lanthanoids ), z is preferably 0.01 to 0.20 and x is preferably 1.0 to 3.5.

The reason why the above range of z is preferable is that if it is less than 0.01, the improvement in heat resistance and mechanical properties brought about by L cannot be obtained, while if it exceeds 0.20, the hardness and toughness of the composite boride layer This is because chipping and breakage tend to occur.
The reason why the above range of x is preferable is that if it is less than 1.0, the improvement in the adhesion resistance of the composite boride phase cannot be sufficiently exhibited, while if it exceeds 3.5, the hardness of the composite boride phase decreases. This is because the wear tends to progress at an early stage.

(1-2) Average Thickness The average layer thickness of the composite boride layer of Ti and L is preferably 0.5 to 10.0 μm. The reason for this is that if it is less than 0.5 μm, the composite boride layer cannot exhibit excellent wear resistance over a long period of use, while if it exceeds 10.0 μm, the crystal grains of the composite boride layer This is because the particles tend to coarsen, and the chipping resistance cannot be improved. More preferably, the average layer thickness is 0.8 to 8.0 μm.

(2-1) Lower Layer A lower layer may be provided between the tool substrate and the composite boride layer of Ti and L.
The lower layer is a Ti or TiAl carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer so that the total average layer thickness is 0.1 to 20.0 μm. Choose one or more layers. When this lower layer is provided, the coated tool can exhibit even more excellent wear resistance and chipping resistance in conjunction with the functions provided by the layers constituting the lower layer.

Here, the reason why the total average layer thickness of the lower layer is set in the above range is that when the thickness is less than 0.1 μm, the lower layer does not work sufficiently, while when it exceeds 20.0 μm, the crystal grains of the lower layer become coarse. The reason for this is that the coating layer is likely to be chipped.

(2-2) Upper Layer As the upper layer, an aluminum oxide layer having an average layer thickness of 1.0 to 25.0 μm may be provided. The provision of a top layer results in a coated tool with better wear resistance and thermal stability.

Here, the reason why the average layer thickness of the aluminum oxide layer is within the above range is that if the thickness is less than 1.0 μm, the upper layer does not work sufficiently, while if it exceeds 25.0 μm, the crystal grains of the upper layer become coarse. This is because it becomes easy to cause chipping in the coating layer.

Also, a TiN layer may be provided as an upper layer. When this TiN layer is provided, since the TiN layer itself has a golden color tone, for example, whether the coated tool is unused or used can be determined by the change in color tone. Identification layer can be utilized as The average layer thickness of the TiN layer as the identification layer may be, for example, 0.1 to 1.0 μm.

2. Method for measuring average layer thickness In the present embodiment, the average layer thickness of each layer constituting the coating layer is measured using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). A longitudinal section using energy dispersive X-ray spectroscopy (EDS) (when inserting, when treating as a flat surface ignoring minute irregularities on the tool base surface, perpendicular to this surface It can be obtained by observing a cross section (a cross section perpendicular to the shaft in the case of a shaft tool such as a drill).

Here, the surface of the tool substrate is observed in longitudinal section, and the interface between the tool substrate and the composite boride layer of Ti and L (the lower layer when the lower layer is provided) is determined by elemental mapping. Arithmetically find the mean line of the interface roughness curve thus obtained, and use this as the surface of the tool substrate.

3. Tool Substrate (1) Material The tool substrate used in the present embodiment can be any material as long as it is a conventionally known tool substrate material, as long as it does not hinder the achievement of the above-mentioned object. For example, cemented carbide (WC-based cemented carbide, containing Co in addition to WC, and further containing carbonitrides such as Ti, Ta, Nb, etc.), cermet (TiC, TiN, TiCN, etc. as a main component, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cBN sintered body, or diamond sintered body is preferable. .

(2) Shape The shape of the tool base is not particularly limited as long as it is a shape used as a cutting tool, examples of which include the shape of an insert and the shape of a drill.

4. Manufacturing Method The coating layer of the coated tool of the present embodiment can be manufactured, for example, using a film forming apparatus having a vapor deposition source for high-power pulse sputtering, which is a type of PVD. In addition, as the target, when providing the TiN layer which is the lower layer, a Ti or TiAl target is used, and when a composite boride layer of Ti and L is provided, a Ti _(1-z) L _z B _x target is used as the upper layer. When providing an aluminum oxide layer, it is possible to form a film by using an Al target, respectively

Next, examples will be described.
Here, as an example of the coated tool of the present invention, an insert cutting tool using a WC-based cemented carbide as a tool substrate will be described. The same applies to drills, end mills, etc. as the shape of the tool base as described above.

First, Co powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and WC powder were prepared as raw material powders, and these raw material powders were blended in the composition shown in Table 1, and further Wax is added and wet-mixed in a ball mill for 72 hours, dried under reduced pressure, and then press-molded at a pressure of 100 MPa. Tool substrates 1 to 3 made of WC-based cemented carbide and having an insert shape were produced.

Next, in order to form a coating layer on the tool substrates 1 to 3 using a film forming apparatus having a high-power sputtering deposition source and a direct current (DC) sputtering deposition source, ultrasonic cleaning is performed in acetone, and in a dried state, A tool substrate was mounted along the outer periphery at a position radially away from the central axis of the rotary table in the apparatus. Also, Ti, Al, and an alloy target of Ti, L, and boron were arranged as a cathode electrode (evaporation source).

Subsequently, while the inside of the film forming apparatus was evacuated and maintained at a vacuum of 10 ⁻² Pa or less, the inside of the apparatus was heated to 500° C. with a heater, then set to an Ar gas atmosphere of 1.0 Pa, and placed on the rotary table. A DC bias voltage of -1000 V was applied to the tool substrate rotating while rotating at , and the surface of the tool substrate was bombarded with argon ions for 30 minutes.

Ar gas having a partial pressure within the range of 0.1 to 1.0 Pa shown in Table 2 was introduced into the film forming apparatus as a reaction gas for a predetermined time, and the temperature inside the furnace was maintained at the temperature shown in Table 2. A tool substrate that rotates while rotating on a table is subjected to high-power pulse sputtering under predetermined pulse sputtering conditions shown in Table 2 for a time corresponding to the layer thickness, and the coated tool of the present invention shown in Table 2 (hereinafter referred to as " Examples 1 to 9 were produced.

On the other hand, for comparison, a coating layer was deposited on tool substrates 1 to 3 under the conditions shown in Table 3 using the same film forming apparatus as above, and coated tools of comparative examples shown in Table 3 (hereinafter, , referred to as “comparative examples”) 1 to 5 were produced.

The average layer thickness of the coating layer and the average composition of the coating layer are parallel to the surface of the tool substrate with respect to the vertical cross section of the coating layer perpendicular to the surface of the tool substrate of Examples 1 to 9 and Comparative Examples 1 to 5 prepared above. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS) were performed on a field of view that was 10 µm wide in the direction of the polarities and was set to include the entire thickness region of the coating layer. ) was obtained by cross-sectional observation using.

Specifically, the average layer thickness of each layer was calculated by magnifying an observed section (longitudinal section) by 5000 times and obtaining the film thickness at five points. The average content ratio of each component in each layer was obtained by performing five TEM-EDS line analyzes in the thickness direction.

Next, a single-edge face milling test was performed on the inventive tools 1 to 9 and the comparative example tools 1 to 5 using a cutter of SE445R0506E. A wet high-speed cutting test was performed on the Ti-6Al-4V alloy under the following cutting conditions.

Cutting conditions:
Work material: Block material of width 110 mm x length 250 mm Cutting speed: 105 m/min.
Notch: 1.3mm
Feed: 0.12 mm/tooth.
Cutting was performed up to a cutting length of 1.8 m, the flank wear width was measured, and the wear state of the cutting edge was observed.
Table 4 shows the results of the cutting test.

According to the results in Table 4, in Examples 1 to 9, abnormal damage such as chipping and peeling did not occur, and both wear resistance and chipping resistance were excellent.
On the other hand, in Comparative Examples 1 to 5, it is clear that chipping occurs or flank wear progresses, leading to the end of life in a short period of time.

REFERENCE SIGNS LIST 1 tool substrate 2 lower layer 3 composite boride layer of Ti and lanthanide 4 upper layer

Claims (1)

A surface-coated cutting tool having a tool substrate and a coating layer on the surface of the tool substrate,
The coating layer includes a composite boride layer of Ti and lanthanide having an average layer thickness of 0.5 to 10.0 μm, and the average composition of the composite boride layer is represented by the composition formula: Ti _1-z L _z B When represented by _x (L is one or more lanthanoids), the atomic ratio z is 0.01 to 0.20 and x satisfies 1.0 to 3.5.
A surface-coated cutting tool characterized by:

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