JP2023134119A - Surface coated cutting tool - Google Patents

Abstract

To provide a coated tool of a TiCN cermet base body having superior abrasion resistance.SOLUTION: A base body includes a hard phase of TiCN and TiWMCN (M is one kind or more of Zr, Hf, V, Nb, Ta, Cr, Mo), and an average thickness from a boundary surface of a coated layer to an internal part of the base body exceeds 0.1 μm and is less than 10 μm. The base body includes a binding phase component enrichment region where (mass% of Co+mass% of Ni) is 1.4-6.0 times relative to the same sum of the internal part of the substrate. In the same region, a binding phase contacting the boundary surface contains 5-15 atomic% of W, (Co atomic%+Ni atomic%)/W atomic% is 0.9-9.0 and is 1.4 times or more relative to an atomic% of W in the binding phase at a position of 20 nm depth from the boundary surface, a W enrichment region with an average thickness of 1-10 nm is contained, and a sum λa of lengths by which a respective binding phase contacting the boundary surface is in contact with the coated layer, and a sum λb of lengths by which the hard phases respectively contacts the coated layer satisfy 0.10≤λa/(λa+λb)≤0.40.SELECTED DRAWING: Figure 1

Description

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

Conventionally, coated tools have been known in which a coating layer is formed on a base material of, for example, tungsten carbide-based cemented carbide, titanium carbonitride-based cermet alloy (hereinafter referred to as TiCN cermet), or the like.
Proposals have been made to improve the cutting performance of the base itself by modifying the structure, composition, etc. of the base.

For example, in Patent Document 1, the support contact surface in contact with the support is composed of a sintered skin that is not covered with a coating layer, and the outermost surface of the support contact surface is coated with Co, Ni, etc. A metal exudation layer consisting of a single phase mainly composed of one or two species is formed with a thickness of 0.1 μm or more and 5 μm or less and a surface occupation rate of 60 area % or more, while the flank surface and chip It describes a coated tool based on TiCN cermet that does not have the metal exudation layer on the surface of the breaker, and it is said that the coated tool can suppress the occurrence and progression of cracks and damage from the support contact surface. .

Further, for example, Patent Document 2 describes a cutting tool whose base material is TiCN cermet in which the metal exudation layer contains 20 to 90% by mass of metal components, and the cutting tool has wear resistance and chipping resistance. It is said to be excellent in

JP2012-245581A Japanese Patent Application Publication No. 4-146006

The present invention was made in view of the above-mentioned circumstances and the above-mentioned proposals, and an object of the present invention is to provide a surface-coated cutting tool having excellent wear resistance and having TiCN cermet as a base material.

The surface-coated cutting tool according to the embodiment of the present invention includes:
It has a base and a coating layer on the base,
The substrate has a hard phase containing TiCN and TiWMCN (M is one or more of Zr, Hf, V, Nb, Ta, Cr, and Mo) and a bond mainly composed of one or two of Co and Ni. has a phase,
The base body has an average thickness of more than 0.1 μm and 10 μm or less from the interface of the coating layer toward the inside of the base body, and (mass % of Co + mass % of Ni) is within the interior of the base body. Having a binder phase component enriched region that is 1.4 times or more and 6.0 times or less with respect to the sum of the same mass %,
In the binder phase component enriched region,
The binder phase in contact with the interface contains W at 5 at % or more and 15 at % or less, and [(Co at % + Ni at %)/W at %] is 0.9 or more and 9.0 or less, and , including a W-enriched region that is 1.4 times or more atomic % of W in the binder phase existing at a depth of 20 nm from the interface, and has an average thickness of 1 nm or more and 10 nm or less, and The sum of lengths λa of each of the binder phases in contact with the interface with the coating layer and the sum λb of the lengths of each of the hard phases in contact with the coating layer are 0.10≦λa/(λa+λb)≦ It is 0.40.

The surface-coated cutting tool has excellent wear resistance.

FIG. 1 is a schematic diagram of a longitudinal section of a surface-coated cutting tool according to an embodiment of the present invention.

The present inventor studied a metal exudation layer produced on the surface of a TiCN cermet substrate by sintering. Here, the metal exudation layer refers to the components of the binder phase such as Ni and Co that may ooze out onto the surface of the sintered body when a TiCN-based cermet cutting insert is manufactured by sintering. It refers to a metal layer mainly composed of components.

As a result of the review, the following items were found.
(1) The cutting tool described in Patent Document 1 has a metal seepage layer on the contact surface of the through-hole with the support, so although it suppresses the occurrence and progression of cracks and damage from the same surface, metal seepage does not occur. Flank surfaces and chip breaker areas where no layer exists have low toughness.
(2) Although the cutting tool described in Patent Document 2 has toughness due to the metal extrusion layer, boundary wear occurs when subjected to high-speed cutting processing, resulting in poor durability; If a coating layer is formed on top, the adhesion strength of the coating layer will be low and the coating layer will easily peel off.

In other words, although the presence of a metal seeping layer improves fracture resistance, it cannot suppress boundary wear during high-speed cutting, and the adhesion with the coating layer is low, making it difficult to obtain a coated tool with high durability. I found out that I can't do it.

Here, high-speed cutting refers to cutting in which the cutting speed is 30% or more faster than normal cutting; for example, in steel cutting, the cutting speed is 2.0 mm or less, 0.5 mm/rev. This refers to cutting conditions that meet the following feed rates and cutting speeds of 200 m/min or more.

Therefore, in order to obtain a coated tool that achieves the above-mentioned objective, the present inventor conducted further intensive studies and focused on W present in the binder phase.
W may be added to strengthen the binder phase as a solid solution, or may be added to adjust the alloy carbon content, or may be unintentionally mixed as an unavoidable impurity. In either case, the W that cannot be solidly dissolved in the binder phase surrounds the hard phase TiCN to form an intermediate layer in the form of TiWMCN. Additionally, when the W content increases, W has a lower affinity for nitrogen than Ti, so the amount of nitrogen in the alloy tends to decrease, leading to problems such as a decrease in the notch wear resistance of TiCN-based cermets. A point occurs. Therefore, it has been found that in order to improve the life during high-speed cutting, a state in which W is excessively contained in the hard phase and the binder phase is not very desirable.

In addition, the present inventor has determined that from the interface between the coating layer and the substrate toward the inside of the substrate, the sum of the mass % of Co and Ni expressed as (mass % of Co + mass % of Ni) is has a region (bond phase component enriched region) that is a predetermined value compared to the sum of mass %,
Then, at the interface between the binder phase part and the coating layer in this region, the ratio of the sum of Co atomic % and Ni atomic % to the W atomic %, that is, [(Co atomic % + Ni atomic %)/W atomic %] is within a predetermined range, and there is a W enriched region that is 1.4 times or more of the atomic % of W in the binder phase existing at a depth of 20 nm from the interface,
It was found that the adhesion between the coating layer and the substrate is improved, and the decrease in wear resistance can be minimized.

Below, a coated tool according to an embodiment of the present invention will be explained in more detail.
In this specification and claims, when a numerical range is expressed as "L to M" (L and M are both numerical values), it is synonymous with "L or more, M or less", and the range is the upper limit. It includes a value (M) and a lower limit value (L), and when a unit is written only for the upper limit value (M), the unit for the lower limit value is also the same.

FIG. 1 schematically shows a cross-sectional view of a coated tool according to an embodiment of the present invention (a cross section perpendicular to the surface of the base, which is treated as a horizontal plane, ignoring minute irregularities on the surface of the base). As is clear from FIG. 1, the coated tool according to this embodiment has a coating layer (2) on a base (1). The substrate (1) has an interior of the substrate (3), a binder phase component enriched region (4), and an interface between the substrate (1) and the coating layer (2) in the binder phase component enriched region (4). There is a W-enriched region (5) in the vicinity of (6). These will be explained in order below.

1. Substrate The substrate preferably has a hard phase containing TiCN and TiWMCN (M is one or more of Zr, Hf, V, Nb, Ta, Cr, and Mo) and a binder phase containing Co and Ni.
There is no particular restriction on the ratio of TiCN mass to TiWMCN mass, but in order to ensure a W-enriched region, W inside the substrate (at a vertical distance of 400 μm inward from the interface of the coating layer) is It is preferable to mix so that the concentration of is 5% by mass to 25% by mass.

In the bonded phase, it is preferable that the ratio of the number of Co atoms to the sum of the numbers of Co and Ni atoms, Co/(Co+Ni), is 0.4 or more. Note that this ratio may be 1.0 (all Co).
Here, the bonded phase has an fcc structure, and the total of Co and Ni accounts for 50 atomic % or more of all components constituting the phase.
The binder phase may contain Ti, W, M, C, N, and other unavoidable impurities that are components of the hard phase. When these are present in the binder phase, they are presumed to be in a solid solution state in the binder layer.

Moreover, the hard phase is one in which the total of Ti, W, M, C, and N occupies 50 atomic % or more of all the components constituting the phase.
The hard phase may contain Co, Ni, and other unavoidable impurities that are components of the binder phase.

2. Binding phase component enriched region From the interface of the coating layer to the inside of the substrate,
The average thickness is more than 0.1 μm and less than 10 μm,
It is preferable to have a binder phase component enriched region in which (mass % of Co+mass % of Ni) is 1.4 times or more and 6.0 times or less the sum of the same mass % inside the substrate.

The reason why the average thickness of the binder phase component enriched region is set to the above range is that crack growth is suppressed by the presence of the binder phase component enriched region (average thickness exceeding 0.1 μm), but on the other hand, This is because when the average thickness exceeds 10 μm, the plastic deformation resistance of the base surface decreases, resulting in a decrease in cutting performance.

In the binder phase component enriched region, (mass % of Co+mass % of Ni) is preferably 1.4 times or more and 6.0 times or less with respect to the sum of the same mass % inside the substrate. This is because if it is less than 6.0 times, a sufficient effect on fracture resistance cannot be obtained, whereas if it exceeds 6.0 times, the surface hardness will decrease and the cutting performance of the coated tool will deteriorate.

Here, in the claims and specification, when discussing the average thickness of a layer, it refers to the average value of the thicknesses measured as follows.
First, the interface between the substrate surface and the coating layer is defined as follows.
1) Line analysis is performed on the substrate and the coating layer in the vertical direction on a cross section (sometimes referred to as a vertical cross section) perpendicular to a plane that is treated as horizontal, ignoring minute irregularities on the surface of the substrate.

2) As a result of the line analysis, a point where 25 atomic % or more of a component contained only in the coating layer, such as Al, is detected is determined as an interface point between the substrate and the coating layer.
3) Connect these interface points and approximate the average with a straight line to define the interface. and,
The direction perpendicular to this interface is determined as the direction in which the average thickness is measured.

The contents of Co and Ni are measured using SEM-EDS. The distance in the vertical direction from the interface is defined as the measurement depth, and measurements are performed in a region up to a measurement depth of 15 μm and a measurement depth region of 400 μm (treated as the inside of the substrate in terms of Co and Ni contents).

For regions up to a measurement depth of 15 μm, a rectangular measurement region of 20 μm parallel to the interface and 0.2 μm perpendicular to the interface is set (this measurement region contains at least one of the bonded phase and the hard phase). The center of the short side (length 0.2 μm) is the measurement depth position, and the measurement depth is 15 μm from the interface to the substrate at 0.1 μm intervals up to a measurement depth of 3.0 μm, and at 0.5 μm intervals beyond that. Measure the area inside. Inside the base, a rectangular measurement area of 20 μm in parallel to the interface and 15 μm in the vertical direction is set, and the center of the short side (20 μm in length) of the rectangle is measured as the measurement depth position.

The average thickness of the binder phase enriched layer is calculated based on the measurement results. The mass proportion occupied by Co and Ni in the measurement region up to a measurement depth of 15 μm, that is, (mass% of Co + mass% of Ni) of the substrate measured as described above for each depth (for each measurement interval described above). Divide by the mass percentage occupied by Co and Ni inside. Thereby, it is possible to calculate the ratio to the mass percentage occupied by Co and Ni inside the base in the depth direction in the measurement region up to a measurement depth of 15 μm. At this time, the thickness of the region in the range of 1.4 to 6.0 times is defined as the average thickness of the binder phase enriched layer.

2. W enriched region A binder phase component enriched region in which the binder phase in contact with the interface contains W at 5 atomic % or more and 15 atomic % or less, and with respect to the W atomic % at a point at a depth of 20 nm from the interface. have a W concentration of 1.4 times or more, and have a W enriched region where [(atomic % of Co + atomic % of Ni)/atomic % of W] is 0.9 or more and 9.0 or less. is preferred.
The average thickness of the W-enriched region is preferably 1 nm or more and 10 nm or less, more preferably 2 nm or more and 4 nm or less.

Although the reason is not clear, the presence of the W-enriched region having this average thickness improves the adhesion between the coating layer and the substrate, ensuring chipping resistance and abrasion resistance.

The presence of the W enriched region is confirmed by TEM-EDS line analysis, and the thickness is measured. Five TEM-EDS line analyzes are performed in a direction perpendicular to the tangent line for a portion (contact point) where any binder phase and coating layer are in contact with each other. The W enriched region contains W at 5 atomic % or more and 15 atomic % or less, and the W concentration is 1.4 times or more the atomic % of W in the bonding phase at a position 20 nm from the contact point to the base material side. and the atomic % of (Co atomic % + Ni atomic %)/W is 0.9 or more and 9.0 or less, and the range that satisfies this condition on the analysis line is defined as the W-enriched region. The thickness shall be .

3. The ratio of the sum of the lengths of each of the hard phase and the bonding phase in contact with the coating layer The sum of the lengths of each of the bonding phases in contact with the coating layer λa and the sum of the lengths of each of the hard phases in contact with the coating layer λb are: It is preferable that 0.10≦λa/(λa+λb)≦0.40.
The reason for this is that when λa/(λa+λb) is less than 0.10, crack growth cannot be sufficiently suppressed by the binder phase component-enriched region, and the contact area between the coating layer and the W-enriched region is small. On the other hand, when λa/(λa+λb) exceeds 0.40, the ratio of the binder phase at the interface between the coating layer and the substrate increases, and the As a result, the rate of plastic deformation of the binder phase that occurs when stress is applied to the coating layer increases, making it easier for the coating layer to peel off from the base.

To measure λa and λb, the interface is two-dimensionally observed in cross section, and the sum of the lengths of contact between the coating layer and the hard phase and the sum of the lengths of contact between the coating layer and the binder phase are measured. For example, a SEM image or SEM-EDS image and image processing software (eg, Image-J) are used. Observe the interface at an appropriate magnification (for example, 15,000 times), calculate λa and λb using image software, and obtain λa/(λa+λb).

4. Coating Layer The coating layer of this embodiment is not limited as long as it is a known coating layer. For example, a composite nitride layer of Al, Ti, and Si and a composite nitride layer of Al and Cr are laminated alternately, a single layer of a composite nitride layer of Al, Ti, and Si, a composite nitride layer of Al and Cr, or a composite nitride layer of Al and Cr. A composite nitride layer of Ti and Ti can be used. It is preferable to use the PVD method as a means for forming these nitride layers.

5. Manufacturing method The method for manufacturing the surface-coated tool according to the present embodiment includes, for example, forming a coating layer using an AIP device after bombarding a titanium-based cermet substrate made using WC as one of the raw material powders. There is a way to do it.

Next, examples will be described, but the present invention is not limited to the following examples.

TiCN powder, TiC powder, TiN powder, ZrC powder, NbC powder, WC powder, Mo ₂ C powder, Co powder, and Ni powder were prepared as raw material powders, and these raw material powders were mixed into A and B shown in Table 1. It was blended into two types of formulation compositions. Each of the raw material powders contained trace amounts of unavoidable impurities.

Further, wax was added to each of these two types of blends, mixed in an attritor for 11 hours in alcohol, dried, and then pressed to obtain molded bodies. These molded bodies were degreased, heated to 1200°C in a nitrogen atmosphere under a reduced pressure of 500 Pa, further heated to 1400°C in a vacuum, then heated to 1500°C in a nitrogen atmosphere under a reduced pressure of 1000 Pa, The sample was kept as it was for 1 hour, and then cooled to 1450° C. in an argon atmosphere of 100 Pa at a rate of 4° C./min, and then rapidly cooled to room temperature. The obtained sintered body was ground and the cutting edge was honed to produce substrates A to D having insert shapes conforming to ISO standard CNMG120408-FP.

Next, these substrates A and B are ultrasonically cleaned in acetone in order to form a coating layer using an AIP apparatus having a direct current (DC) sputtering deposition source. It was mounted along the outer periphery at a predetermined distance in the radial direction from the central axis on the inner rotary table. Further, as a cathode electrode (evaporation source), a Ti--Al target, a Ti--Al--X (X=Si, Nb) target, and an Al--Cr target were arranged according to the composition of the coating layer.

In order to form a W-enriched region at the interface between the substrate and the coating layer, bombardment treatment was performed at a bias of -130 V to -200 V for 30 to 120 minutes. The bombardment process is performed by heating the inside of the AIP device to 400 to 1000° C. with a heater while evacuating the inside of the AIP device and maintaining a vacuum of 10 ⁻² Pa or less, and then placing it in an Ar gas atmosphere of 0.1 to 2.0 Pa. A DC bias voltage was applied to the substrate rotating while rotating on the rotary table, and treatment was performed with argon ions.

Next, nitrogen gas is introduced as a reaction gas into the AIP apparatus, the pressure of the nitrogen gas is adjusted to a predetermined reaction atmosphere within the range of 1.0 to 5.0 Pa, and the substrate is rotated on a rotary table. A predetermined current within the range of 80 to 200 A shown in Table 2 is applied between the Ti-Al target, Ti-Al-X target, or Al-Cr target for forming the coating layer, which is the cathode electrode, and the corresponding anode electrode. The coating layers shown in Table 3 were formed on the base by vapor deposition, thereby producing Example Tools 1 to 5.

On the other hand, for comparison, the compositions shown in Table 1 were mixed in the same manner as above, substrates C and D were prepared using the same equipment as above, and bombardment was performed using the same equipment as above. Then, each film was deposited under the conditions shown in Table 2 to produce Comparative Example Tools 1 and 2 shown in Table 3.

The average thickness of the binder phase enriched layer, the average thickness of the W enriched layer, and λa/(λa+λb) of the substrate were measured by the method described above. When measuring the average thickness of the W-enriched layer, the interval between the aforementioned interface points was 10 nm, and the number of measurement points was 5.

The average composition and average thickness of the coating layer are determined based on the vertical cross section of the coating layer (cross section perpendicular to the substrate) perpendicular to the surface of the substrate of Example Tools 1 to 5 and Comparative Example Tools 1 to 2 prepared above. The width in the direction parallel to the surface was 10 μm, and the field of view was set to include the entire thickness region of the coating layer using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an energy dispersive type. It was determined by cross-sectional observation using X-ray spectroscopy (EDS).

Specifically, the average thickness of the coating layer was calculated by enlarging the observed cross section 5000 times and determining the thickness at five points at intervals of 1 μm in a direction parallel to the surface of the substrate. The average composition of the coating layer was analyzed using EDS at five points on the cross section of the coating layer, in a square area with one side having a length of 30% to 80% of the average thickness, and the content ratio of each component was determined. The values were measured and averaged.

Next, a cutting test by wet outer diameter turning was conducted under the conditions shown below with Example Tools 1 to 5 and Comparative Example Tools 1 to 2 all clamped to a DCLNL2525M12 bit.

Work material: SNCM439
Cutting speed: 350m/min
Depth of cut: 0.5mm
Feed: 0.1mm/rev.
The amount of flank wear was measured 20 minutes after the start of cutting. If the amount of flank wear exceeded 0.2 mm before 20 minutes had elapsed, the time until this amount of wear was reached was measured as the life. The results are shown in Table 4.

As is clear from Table 4, all of the example tools 1 to 5 exhibited excellent wear resistance with little wear and long life. On the other hand, Comparative Examples 1 and 2 all had a large amount of wear and reached the end of their service life in a short period of time.

1 Substrate 2 Covering layer 3 Substrate interior 4 Binding phase component enriched region 5 W enriched region

Claims (1)

A surface-coated cutting tool having a base and a coating layer on the base,
The substrate has a hard phase containing TiCN and TiWMCN (M is one or more of Zr, Hf, V, Nb, Ta, Cr, and Mo) and a bond mainly composed of one or two of Co and Ni. has a phase,
The base body has an average thickness of more than 0.1 μm and 10 μm or less from the interface of the coating layer toward the inside of the base body, and (mass % of Co + mass % of Ni) is within the interior of the base body. Having a binder phase component enriched region that is 1.4 times or more and 6.0 times or less with respect to the sum of the same mass %,
In the binder phase component enriched region,
The binder phase in contact with the interface contains W at 5 at % or more and 15 at % or less, and [(Co at % + Ni at %)/W at %] is 0.9 or more and 9.0 or less, and , including a W-enriched region that is 1.4 times or more atomic % of W in the binder phase existing at a depth of 20 nm from the interface, and has an average thickness of 1 nm or more and 10 nm or less, and The sum of the lengths λa of each of the bonding phases in contact with the interface with the coating layer and the sum λb of the lengths of each of the hard phases in contact with the coating layer are 0.10≦λa/(λa+λb)≦ It is 0.40,
A surface-coated cutting tool characterized by:

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