JP2002167608A - Coated cemented carbided member and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the chipping resistance of the coated cemented carbide member without deteriorating its wear resistance as that of a cutting tool. SOLUTION: The coated cemented carbide member is obtained by forming a single coating layer or plural coating layers of one or more kinds selected from the compound of the group 4a, 5a and 6a metals in the Periodic Table, and Al2O3 on the surface of a cemented carbide base material using one or more kinds of iron group metals as a bonding phase and a compound containing the group 4a, 5a and 6a metals in the Periodic Table such as Zr, Ta, Ti and Nb as a hard phase. In the member, the atoms of Zr, Ta, Ti and Nb are reduced in the surface region of the base material compared with those in the inside region. Further, the reduction ratio of the Ta, Ti and Nb atoms is smaller than that of the Zr atoms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated cemented carbide member and a method for producing the same, and more particularly to a coated cemented carbide member having excellent toughness and wear resistance used for cutting tools and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Coated cemented carbide obtained by depositing a coating layer such as titanium carbide on the surface of cemented carbide has both the toughness of the base material and the wear resistance of the surface. Many are used.

In recent years, the cutting efficiency of cutting tools has been increasing. The cutting efficiency is determined by the product of the cutting speed (V) and the feed amount (f). When the cutting speed (V) is increased, the tool life is rapidly reduced. Therefore, cutting efficiency has been improved by increasing the feed amount (f). In order to improve the cutting efficiency by increasing the feed amount (f), it is required to use a tough material that can cope with high cutting stress as a base material of the cutting tool.

[0004] In cutting tools, several proposals have been made in the past to improve the cutting characteristics by making the contradictory characteristics of wear resistance and fracture resistance compatible. For example, a cemented carbide has a layer (boundary phase-enriched layer) in which the amount of iron group metal is larger than that of the inside of the member on the outermost surface, and the outermost surface of the cemented carbide consists only of WC and the binder phase metal. Layer (removal β layer)
It has been proposed to improve wear resistance and fracture resistance by using each of the base materials having the following. Further, as a technique for supplementing them, a β-removed layer is also formed on the surface of the ridge line portion of the cutting edge (JP-A-6-7356).
No. 0: Conventionally, no β-removed layer was formed on the ridgeline of the cutting edge), and a binder phase-reducing layer was provided on the surface rather than the binder phase-enriched layer (Japanese Patent No. 2762745).

[0005]

However, as cutting conditions have become severe, it has become impossible to provide a tool having wear resistance and toughness merely by providing a β-removed layer on the surface. That is, Ti, Ta,
Alternatively, there are layers in which a hard phase component such as an Nb compound is reduced with respect to the inside, but such a reduction in the hard phase component has a disadvantage of lowering the heat resistance of the cemented carbide.

As a method of improving the strength of a cemented carbide, there is a method of increasing the amount of a binder component in a base material.
However, although the toughness is improved when the amount of the binder phase component in the base material is increased, the cutting edge temperature is increased under the condition of a high cutting speed, so that there is a problem that the cutting edge is plastically deformed.

[0007] The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a coated cemented carbide member having improved fracture resistance without deteriorating wear resistance, and a member thereof. It is to provide a manufacturing method. Another object of the present invention is to provide a coated cemented carbide member having both wear resistance and toughness even in high-efficiency cutting, and a method of manufacturing the same.

[0008]

In order to achieve the above object, in the coated cemented carbide member according to the present invention, one or more iron group metals are used as a binder phase, and Zr, Ta, Ti and Nb are used. Periodic Tables 4a, 5a, and 4a, 5a, and 6a are provided on the surface of a cemented carbide base material having a hard phase as a hard phase.
a selected from the group consisting of a group 6a metal compound and Al ₂ O ₃
A coated cemented carbide member having a coating layer composed of at least one kind of single or multiple layers, wherein the Zr, Ta, Ti and N
The b atoms are reduced in the surface region from the inner region of the base material, and the reduction ratio of the Ta, Ti and Nb atoms is smaller than the reduction ratio of the Zr atoms.

In the coated cemented carbide member, the thickness of the surface region is desirably 5 to 200 μm.

[0010] In the coated cemented carbide member, it is preferable that the binder phase is reduced in a surface region rather than in an inner region of the base material.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a coated cemented carbide member, wherein one or more iron group metals and Zr, Ta, Ti
And a compound containing a group 4a, 5a or 6a metal such as Nb and the like in the periodic table and sintering to form a cemented carbide base material. In the method for producing a coated cemented carbide member for forming a coating layer composed of one or more single or multiple layers selected from a metal compound or Al ₂ O ₃ , 135
The method is characterized in that the method includes a step of setting a heating rate at 0 ° C. or less to 5 ° C./min or less.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A coated cemented carbide member according to each claim and a method for manufacturing the same will be described below. The coated cemented carbide member of the present invention is mainly composed of a binder phase composed of one or more iron group metals and a hard phase composed of a compound of the periodic table 4a, 5a, or 6a metal.

The iron group metals constituting the binder phase include Co, N
There are i, Fe and the like, and Co and Ni are often used in relation to the solubility of the hard phase component. The addition amount is 2 to 2
0 wt% is appropriate.

The periodic table 4a, 5a, 6 constituting the hard phase
Group a metal compounds include carbides, nitrides, carbonitrides, oxides, carbonates, oxynitrides, and carbonitrides of one or more of W, Ta, Ti, Nb, and Zr. In order to improve the wear resistance and toughness, WC is preferably used as a main component. Further, carbide, nitride, carbonitride, oxide, carbonate, nitride oxide, carbonitride, or the like made of at least one of V, Cr, and Mo may be used.

[0015] The hard phase contains one or more Zr compounds. The Zr compound includes, for example, ZrC, ZrCN, Zr
rO, (Zr, W) C, (Zr, Ti, W) C, (Z
r, Ti, Ta, W) C or (Zr, Ti, T)
a, Nb, W) There is at least one selected from carbides, nitrides, carbonitrides, oxides, carbonates, nitrides, and carbonitrides containing Zr, such as C. 0.2-Zr compound
It is desirable to add 10 wt%. When the amount added is 0.
If it is less than 2 wt%, the effect of improving the cutting performance by adding Zr is lost, and if it exceeds 10 wt%, problems such as poor sintering occur and the strength of the alloy itself is reduced.

The surface of the cemented carbide base material has a periodic table 4
A surface region is formed in which the hard phase composed of the compound of the group a, 5a or 6a metal is reduced with respect to the inside. Hard phase elements that decrease with respect to the interior include Zr, Ta, Ti, Nb,
V, Cr and the like.

The thickness of this surface region is preferably 5 to 200 μm. If the thickness of this surface region is 5 μm or less, the β layer remains near the surface, and the β layer becomes a source of destruction, resulting in a decrease in strength. On the other hand, when it is larger than 200 μm, the absence of the β layer near the surface lowers the heat resistance of the cutting edge. The thickness of this surface region changes depending on the firing conditions described later.

In the present invention, Zr, Ta, Ti and Nb
It is characterized in that atoms are reduced in the surface region rather than the inner region of the base material, and the reduction ratio of Ta, Ti and Nb atoms is smaller than the reduction ratio of Zr atoms. Here, the internal region is a sufficiently internal region that is not affected by the β-removed layer from the surface of the base material.
When it is 00 μm, it is about 1000 to 2000 μm. These values are based on firing conditions (heating rate, firing atmosphere),
It changes depending on the amount of nitride added.

The Ta, Ti, and Nb compounds have an advantage that the heat resistance of the base material can be improved as compared with the Zr compound. However, if they are present on the surface of the base material in the form of a β layer, there arises a problem that the strength becomes a source of destruction and the strength is reduced. Therefore, these compounds are dissolved in the β-removed layer to strengthen the β-removed layer.
It was found that the presence of more a, Ti, and Nb compounds than the Zr compound that hardly affected the heat resistance increased the effect.

Here, the layer in which the compound of the group 4a, 5a, or 6a metal is reduced with respect to the inside of the periodic table, and the reduction ratio of the Zr, Ti, Ta, and Nb compounds in the layer with respect to the inside is XMA (X-ray Microanalysis) or the like. Here, the analysis was performed with a WDS (wavelength dispersive X-ray microanalyzer) analyzer (JXA-8600M manufactured by JEOL Ltd.) with higher accuracy. The analysis area was set to have a range of about 250 μm in parallel with the surface in order to eliminate variation in the measurement, and the analysis was performed in the depth direction. As for the analysis points, at least four or more points of the same sample were measured, and the average value thereof was used. The sample is C
After grinding the NMA120412 tool by about 2,000 μm from the rake face side with a surface grinder or the like, the ground face was mirror-finished and analyzed. The results of the analysis are shown in FIG.
That is, FIG. 1 shows the results of analysis by WDS, and shows the distribution of atoms in the depth direction from the surface to the inside. Horizontal axis 0μ
m represents the surface of the base material, and the horizontal axis represents the depth from the surface.
The vertical axis is the ratio of the count value to the inside.

In a preferred embodiment of the coated cemented carbide member according to the present invention, the region of the surface of the cemented carbide base material in which the compound of the group 4a, 5a, or 6a group metal is reduced with respect to the inside. The thickness is 5 to 200 μm. If the thickness is less than 5 μm, the effect as a β layer is removed (the β layer remains up to the surface, and the β layer becomes a source of destruction and the strength is reduced).
This is because when the thickness is larger than 200 μm, the heat resistance of the cutting edge decreases.

Further, in the conventional β-removed layer, the presence of the binder phase-enriched layer has a problem that the cutting edge is plastically deformed under the condition that the cutting edge temperature becomes high at a high cutting speed. This problem can be solved in a way that reduces the amount of iron group metal in the alloy. The binder-phase-enriched layer referred to here is a layer having a large amount of iron group metal with respect to the inside, and these analysis methods can be obtained by the XMA. FIG. 1 shows the results of this analysis.

A coating layer is provided on the surface of the cemented carbide base material.
The coating layer is made of a carbide of a metal of Group 4a, 5a or 6a in the periodic table,
It is composed of one or more single layers or multiple layers selected from nitrides, carbonitrides, oxides, borides and Al ₂ O ₃ (aluminum oxide), and is formed by chemical vapor deposition such as CVD, PVD, or PCVD. It is formed by a method or a physical vapor deposition method. With this coating layer, wear resistance and chipping resistance in high-speed cutting can be improved in a well-balanced manner.

The base material of the cemented carbide is 1400 to 1600
Firing is performed by maintaining the temperature at about 5 ° C. for about 5 to 15 minutes. During this firing, the rate of temperature rise at 1350 ° C. or less may be 5 ° C./min or less. Zr is Co at high temperature
The solubility of Co at low temperatures is lower than that of Ta and Ti, whereas the solubility of Co is lower than that of Ta and Ti. . In the present invention, a Zr compound is added at the time of preparation, and a rate of temperature rise at 1350 ° C. or lower is set to 5 ° C./min or less to form a β-desorbed layer. , Ti, or Nb compound can be formed into a layer including a layer having a small reduction ratio with respect to the inside, preferably, a layer in which the binder phase component (iron group metal) also decreases with respect to the inside. Thereafter, a coating layer is formed on the surface of the cemented carbide base material.

[0025]

Embodiments of the present invention will be described below. The raw material powder having the composition (% by weight) of 1 to 5 shown in Table 1 was subjected to IS
After shaping into a chip having the shape of O standard CNMG120408 and degreased, the temperature was raised to 1350 ° C. under the heating rate conditions shown in Table 1, and then 12.5 ° C.
The temperature was raised at a rate of 1 minute, held for 1 hour, and then cooled.
Thus, Samples 1 to 5 shown in Table 1 were produced.

[0026]

[Table 1]

Samples 1 and 2 (products of the present invention) shown in Table 1
Ta, Ti, N
There was a layer in which the reduction ratio of b atoms to the inside was small.
The magnitude of this layer thickness and the ratio of the amount of reduction of those atoms is expressed by W
Measured by DS. The results are shown in Table 1 in terms of the magnitude of the reduction ratio.

Sample 3 shown in Table 1 (product of the present invention)
With respect to the reduction ratio with respect to the inside of the Zr atom, Ta, Ti,
There is a layer in which the reduction ratio of Nb atoms to the inside is small,
In addition, there was a Co reduction layer. The magnitude of the ratio between the thickness of the layer and the reduction amount of the atoms was measured by WDS.

In samples 4 and 5 (conventional products) in Table 1,
With respect to the reduction ratio with respect to the inside of the Zr atom, Ta, Ti,
The reduction ratio of Nb atoms to the inside is increasing.

After performing a honing treatment on the ridge of the cutting edge of each of these sintered bodies, a total of 9 μm of Ti nitride and carbonitride are formed on the surface of the sintered body by the ordinary CVD method, and aluminum oxide is formed on the outer layer. To form a coating layer with a thickness of 3 μm.

Using these samples, a chipping resistance test and a wear resistance test during cutting were performed under the following conditions. Table 2 shows the test results. 1. Chipping resistance test: Cutting speed 350 m / min Work material FC250 feed 0.5 mm / rev Depth of cut 2.0 mm Cutting time 2 sec Wear resistance test: Cutting speed 500 m / min Work material FC250 feed 0.5 mm / rev Depth 2. 0mm Cutting time 1.2min

[0032]

[Table 2]

From the results shown in Table 2, the samples in which the ratio of the decrease of Ta, Ti, and Nb atoms to the inside was smaller than that of the inside of Zr atoms was prepared in a preferable range (samples No. 1, 2, and 3). Are the other samples (Sample No.
It can be seen that both the chipping resistances are superior to those of 4, 5).

Further, from the results in Table 2, it can be seen that the sample including the layer in which Co is reduced with respect to the inside (Sample No. 3) has a higher abrasion resistance than the other samples (Sample No. 2). It turns out that it is excellent.

[0035]

As described above, in the coated cemented carbide member according to the first aspect, the atoms of Zr, Ta, Ti and Nb are reduced in the surface region from the inner region of the base material, and the Ta and Ti atoms are reduced. Since the reduction ratio of Nb atoms is smaller than the reduction ratio of Zr atoms, it is possible to minimize a decrease in heat resistance of the cemented carbide.

In the coated cemented carbide according to claim 2,
Since the thickness of the surface region is 5 to 200 μm, this surface layer can sufficiently act as a β-removing layer, and the heat resistance of the cutting edge can be improved.

In the coated cemented carbide according to claim 3,
Since the binder phase is reduced in the surface region rather than the internal region of the base material, it is possible to prevent the cutting edge temperature from increasing as much as possible even at a high cutting speed, and thus to prevent plastic deformation of the cutting edge.

Further, according to the method for producing a coated cemented carbide according to claim 4, one or more iron group metals and Zr, Ta, T
When baking a mixture with a compound containing a Group 4a, 5a, or 6a metal such as i and Nb in the periodic table, a step of setting the temperature rise rate at 1350 ° C. or less to 5 ° C./min or less is performed. The composition in the layer can be controlled so that the reduction rate of Ta, Ti and Nb atoms is smaller than the reduction rate of Zr atoms, and the reduction in heat resistance of the cemented carbide can be minimized.

[Brief description of the drawings]

FIG. 1 shows a wavelength dispersion type X of a coated cemented carbide member according to the present invention.
It is a figure showing the analysis result by a line microanalyzer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 1/05 C22C 1/05 F 29/08 29/08

Claims (4)

[Claims] 1. The method of claim 1, wherein at least one iron group metal is used as a binder phase.
periodic tables 4a, 5a, such as r, Ta, Ti and Nb;
On the surface of a cemented carbide base material having a compound containing a group 6a metal as a hard phase, one or more single or multiple layers selected from compounds of the periodic table 4a, 5a, 6a metal or Al ₂ O ₃ In the coated cemented carbide member having a coating layer formed of, the Zr, Ta, Ti, and Nb atoms are reduced in the surface region from the inner region of the base material, and the Tr is reduced.
A coated cemented carbide member characterized in that the reduction rate of a, Ti and Nb atoms is smaller than the reduction rate of Zr atoms. 2. The coated cemented carbide member according to claim 1, wherein the thickness of the surface region is 5 to 200 μm. 3. The coated cemented carbide member according to claim 1, wherein the binder phase is reduced in a surface region of the base material than in an inner region of the base material. 4. One or more iron group metals and Zr, Ta, Ti
And a compound containing a group 4a, 5a or 6a metal such as Nb and the like in the periodic table and sintering to form a cemented carbide base material. In the method for producing a coated cemented carbide member for forming a coating layer composed of one or more single or multiple layers selected from a metal compound or Al ₂ O ₃ , 135
A method for producing a coated cemented carbide member, comprising a step of setting a temperature rising rate at 0 ° C. or less to 5 ° C./min or less.