JP2011173212A - Surface-coated tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated tool with a stable high wear resistance, achieved by suppressing the separation of a coated layer and by improving wear resistance of the base body surface itself. <P>SOLUTION: In the surface-coated tool, the coated layer 6 is formed on the surface of the base body 1 made of a cemented carbide of a WC phase 2, a binding phase 3 made of one or more ferrous metals, and a B1-type solid solution phase 4, other than WC, made of a carbide, nitride, or carbonitride of one or more metals of group 4, 5, and 6, including Zr, in the periodic table. The surface area 7 of the base body 1 with a depth of 5-100 &mu;m from the surface is dotted with a ZrO<SB>2</SB>phase 5, but has no &eta; phase. The inside of the base body 1 with a depth deeper than 100 &mu;m from the surface has no ZrO<SB>2</SB>phase 5, or is dotted with a ZrO<SB>2</SB>phase 5 with an average particle diameter of 1/5 or less of the average particle diameter of the ZrO<SB>2</SB>phase 5 in the surface area 7. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a surface-coated tool, and particularly to a cutting tool made of a cemented carbide having excellent plastic deformation resistance, high toughness, and excellent wear resistance.

  Cemented carbides that have been widely used for metal cutting have traditionally consisted of a hard phase mainly composed of tungsten carbide and a bonded phase of an iron group metal such as cobalt. A system in which a B1-type solid solution, which is a solid solution phase of carbide, nitride, carbonitride, etc., is dispersed is known.

  For example, Patent Document 1 discloses that a Zr compound is contained in a WC-based cemented carbide base material on which a coating layer is formed, and the size of the compound is 0.02 to a depth of 50 μm from the surface of the alloy. It is described that 0.5 to 1.0 μm at a depth of 0.5 μm, 50 to 150 μm, and 1.0 to 5.0 μm at a depth of 150 μm.

  Moreover, in patent document 2, in the surface of the cemented carbide alloy containing a cubic system compound, it is the 1st which consists of tungsten carbide and the binder phase 1.2 to 3 times as much as the inside in the depth of 2-10 micrometers from the surface. A surface region and a second surface region made of tungsten carbide, a binder phase, and a cubic compound 1.5 to 5 times larger than the inside are formed at a depth of 3 to 15 μm from the interface of the first surface region. In other words, a cemented layer formed on the surface of the cemented carbide is also disclosed.

JP 2000-336489 A JP 2004-259286 A

  However, in both configurations of Patent Document 1 and Patent Document 2, when a strong impact is applied, the coating layer often peels off, and the substrate after the coating layer is peeled is exposed. When cutting is continued, there is a problem that the wear progresses very quickly and reaches the end of its life.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to suppress the peeling of the coating layer and to improve the wear resistance on the surface of the substrate itself, thereby providing a stable and high wear resistance. The object is to provide the resulting surface-coated tool.

The surface-coated tool of the present invention includes a WC phase, a binder phase composed of one or more types of iron group metals, and one or more types of carbides and nitrides of Group 4, 5, and 6 metals of the periodic table including Zr other than WC. Alternatively, a coating layer is formed on the surface of a substrate made of a cemented carbide with a B1 type solid solution phase made of carbonitride, and a ZrO layer is formed in a surface region having a depth from the surface of the substrate of 5 to 100 μm. _{The two} phases are interspersed and the η phase does not exist, and in the interior deeper than the surface region, the ZrO ₂ phase does not exist, or the average particle size with respect to the average particle size of the ZrO ₂ phase in the surface region is It is dotted with a size of 1/5 or less.

Here, the coating layer has a laminated structure, and the first layer on the substrate side is TiN, TiC.
, TiB ₂ , TiCN, or TiAlN, which is particularly effective when it is one kind of Ti compound, and the coating layer is more difficult to peel off than conventional cemented carbide.

Also, the when observed in cross-section for the surface area, the ratio of the average particle size _{d 2} of the ZrO ₂ phase average particle size _{d 1} and the B1-type solid solution phase of _(d 1 / _{d 2)} is 1.2 to It is desirable that the ratio of the ZrO ₂ phase in the surface region is 1 to 10 area%.

  Furthermore, it is desirable that the content ratio of the binder phase in the surface region is 1.2 to 2 times the inside.

According to the cutting tool of the present invention, the η phase does not exist on the surface of the cemented carbide and the ZrO ₂ phase is scattered, thereby suppressing the peeling of the coating layer due to the difference in thermal expansion between the substrate and the coating layer. Even when the coating layer is peeled off or worn, the exposed cemented carbide substrate has high wear resistance, and stable cutting as a cutting tool is possible.

It is a mapping photograph which shows the density | concentration distribution of the oxygen component by the wavelength dispersion type | mold spectral analysis in the mirror polishing cross section about an example of the cutting tool which is a suitable example of the surface coating tool of this invention. It is a scanning electron micrograph about the cutting tool of FIG. 1, and the component analysis result by energy dispersive type | mold spectral analysis about a local.

  About the cutting tool of this invention, the scanning electron micrograph of FIG. 1 and FIG. 2 which is a mapping photograph which shows the density distribution of the oxygen component by the wavelength dispersion type | mold spectral analysis in the mirror polishing cross section about the example, and the component analysis result about a local This will be explained based on the above.

A cemented carbide (substrate) 1 shown in FIGS. 1 and 2 includes a WC phase 2, a binding phase 3 composed of one or more iron group metals, and a periodic table 4th, 5th, and 6th metals including Zr other than WC. It is formed from a B1 type solid solution phase (hereinafter abbreviated as B1 type solid solution phase) 4 made of carbide, nitride, or carbonitride of at least seeds, and is further dotted with ZrO ₂ phases 5. Further, according to FIG. 1, a coating layer 6 containing Ti is formed on the surface of the substrate 1.

According to FIG. 1, the ZrO ₂ phase 5 is scattered in the surface region 7 having a depth of 5 to 100 μm from the surface of the substrate 1, and the depth from the surface of the substrate 1 is deeper than 100 μm. Then, the ZrO ₂ phase 5 does not exist. Further, the surface region 7 of the substrate 1 has no η phase, and the surface region 7 itself is not destroyed. According to the present invention, even if the average particle diameter with respect to the average particle diameter of the ZrO ₂ phase 5 in the surface region 7 is scattered within 1/5 or less in the inside of the substrate 1, the effect of the present invention is achieved. Can be demonstrated.

  With the above configuration, the peeling of the coating layer 6 due to the difference in thermal expansion between the substrate 1 and the coating layer 6 can be suppressed, and even if the coating layer 6 is peeled off or worn, the resistance of the exposed cemented carbide substrate 1 is prevented. Abrasion is high. Therefore, stable cutting is possible when used as a cutting tool.

Here, the coating layer 6 has a laminated structure, and is particularly effective when the first layer on the substrate 1 side is a Ti compound such as TiN, TiC, TiB ₂ , TiCN, or TiAlN. Compared with, the coating layer is more difficult to peel off. In addition, the coating layer is not necessarily formed by only one layer, and may have a laminated structure of two or more layers. The thermal expansion coefficient of each material is 9.4 × 10 ⁻⁶ for TiN, 7.4 × 10 ^{−6 for} TiC, and 7.6 × 1 for TiB _2.
0 ^-6, TiAlN is 7.7 × ^{10 -6,} the cemented carbide is 5~6 × ¹⁰ -6, ZrO ₂ is ^{_{10.5 × 10 -6, Al 2 O}} 3 7.5 × 10 -6, Co Is 12.4 × 10 ⁻⁶ .

Further, when the surface area 7 and cross-sectional observation, the ratio of the average particle size _{d 2} of an average particle diameter _{d 1} and the B1-type solid solution phase 4 of the ZrO ₂ phase 5 _(d 1 / _{d 2)} is 1.2 to 10 It is desirable that the toughness of the substrate 1 can be maintained and the adhesion between the substrate 1 and the coating layer 6 can be improved. For example, the average particle diameter d ₁ of the ZrO ₂ phase 5 is 1.5 to ₁₀ μm. , average particle size _{d 2} of the B1-type solid solution phase 4 is 0.2 and 1.5 .mu.m.

Furthermore, the presence ratio of the ZrO ₂ phase 5 in the entire surface region 7 to the entire structure is 1 to 10 area%, so that the toughness of the substrate 1 can be maintained and the adhesion between the substrate 1 and the coating layer 6 can be enhanced. Desirable in terms. In the observation of the structure of the substrate 1, the presence of the B1 type solid solution phase 4 in a ratio of 1 to 20 area% can increase the high temperature hardness of the substrate 1 and without reducing the toughness of the substrate 1. It is preferable for improving the plastic deformation resistance. A desirable range of the area ratio of the B1 type solid solution phase 4 in the inside of the substrate 1 is 1 to 8 area%, and a desirable range of the area ratio of the B1 type solid solution phase 4 in the surface region 7 is 1 to 10 area%. .

  Furthermore, the content ratio of the binder phase 3 in the surface region 7 is 1.2 to 2 times that in the inside, so that the hardness on the surface of the substrate 1 is not lowered so much and the wear resistance is high, and the substrate 1 and the coating layer This is desirable in that the difference in thermal expansion coefficient from 6 can be further reduced.

(Production method)
An example of the manufacturing method of the cemented carbide which comprises the cutting tool mentioned above is demonstrated. First, 5.0 to 15.0 mass% of metal cobalt (Co) powder with respect to tungsten carbide (WC) powder, and zirconium carbide powder is used as a compound powder for forming a B1-type solid solution phase. The compound powder for forming 05-1 mass% and another B1 type solid solution phase is prepared in the ratio of 0-3 mass%.

  A solvent is added to the prepared powder and mixed and pulverized for a predetermined time to form a slurry. Then, a binder is added to the slurry and further mixed, and the mixture is granulated while drying the slurry using a spray dryer or the like. I do. Next, the granulated granules are molded into a cutting tool shape by press molding. At this time, the shape of the cutting edge of the molded body itself is set to a shape with honing, or a honing process is performed on the generated shape before firing to obtain a shape with honing before firing.

Then, after degreasing in a nitrogen gas atmosphere containing 0.5 to 10% oxygen in a firing furnace, the temperature of the firing furnace is increased in a nitrogen gas atmosphere, and a temperature range of 500 to 570 ° C. is set to 20 to 20%. Hold for 45 minutes. Then, the atmosphere in the firing furnace is switched from a nitrogen gas atmosphere to a vacuum atmosphere, and the firing temperature is raised to 1450 to 1600 ° C. at a heating rate of 5 to 15 ° C./minute, and firing is performed at this temperature for 0.3 to 1 hour. In this way, a cemented carbide in which ZrO ₂ phases are scattered more in the surface region than in the interior can be produced.

Moreover, as a preparation ratio of the raw material powder for forming the B1-type solid solution phase, zirconium carbide (ZrC): 0.5 to 1.5 mass%, titanium carbide (TiC): 0 to 0.3 mass%, The composition of tantalum carbide (TaC): 0 to 0.3% by mass and chromium carbide (Cr ₃ C ₂ ): 0 to 0.3% by mass is particularly suitable.

Then, a known coating layer is formed on the surface of the cemented carbide by a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. In the present invention, in the coating layer formed by the CVD method in which the tensile stress remains in the coating layer, the effect of the conventional technique is remarkable.

  A tungsten carbide (WC) powder having an average particle diameter of 0.8 μm, a metal cobalt (Co) powder having an average particle diameter of 1.2 μm, and a compound powder shown in Table 1 having an average particle diameter of 1 to 2 μm were prepared at the ratio shown in Table 1. Then, after adding a solvent to this and mixing and pulverizing it, a shape-retaining agent was added and further mixed, and the resulting slurry was put into a spray dryer to produce a granulated powder. Next, the granulated powder is used to form a cutting tool shape (CNMA 120204) by press molding. At this time, a honing process was performed on the obtained generated shape to obtain a shape with honing before firing. And after putting a molded object in a baking furnace and performing degreasing | defatting for 2 hours at 450 degreeC in the nitrogen gas atmosphere which contains oxygen gas in the ratio shown in Table 1, it is gas at the temperature and time shown in Table 1. The atmosphere was switched and fired, and then fired under the conditions shown in Table 1 to produce a cemented carbide.

Furthermore, a 0.5 μm titanium nitride (TiN) film, a 9.0 μm titanium carbonitride (TiCN) film having a columnar crystal structure is formed on the surface of the processed cemented carbide by chemical vapor deposition (CVD), A coating layer of a 3 μm α-type aluminum oxide (Al ₂ O ₃ ) film was sequentially formed.

The resulting tool, the mirror polished surface of the cemented carbide shot 3000 times by the scanning electron microscope image, by image analysis by Luzex this, the presence or absence of the surface region, and the surface area and ZrO inside ₂ The average particle size (d ₁ , d ₂ , d ₃ , d ₄ ) and area% of the phase and the B1 type solid solution phase were calculated. In addition, the average value of arbitrary three places was made into area% of the B1 type solid solution phase contained in a cemented carbide. The results are shown in Table 2.

  Then, using this tool, a continuous cutting test and a strong interrupted cutting test were performed under the following conditions to evaluate the wear resistance and fracture resistance.

(Abrasion test)
Work material: FCD700
Tool shape: CNMA120204
Cutting speed: 300 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 1.5mm (cutting variation every 3 seconds cutting)
Cutting time: 6 minutes Cutting fluid: Mixture of 15% emulsion + 85% water Evaluation item: Observe the cutting edge with a microscope, measure the amount of flank wear and check the cutting edge condition (strongly interrupted cutting conditions)
Work material: FCD700
Tool shape: CNMA120204
Cutting speed: 150 m / min Feeding speed: 0.15-0.3 mm / rev
Cutting depth: 1.5mm
Cutting fluid: Mixture of 15% emulsion + 85% water Evaluation item: Number of samples lost within 2000 impacts (20 evaluations)
And confirmation of the cutting edge condition of the sample that was not damaged after 2000 impacts
The results are shown in Table 3.

From the results shown in Tables 1 to 3, Sample No. in which no Zr component was added as a raw material was used. In No. 8, no ZrO ₂ phase precipitation was observed, and chipping accompanied by peeling of the coating layer was observed. In addition, Sample No. with a heat treatment temperature in the N ₂ atmosphere exceeding 550 ° C. In No. 5, the η phase was precipitated on the surface of the substrate, and chipping was observed at the cutting edge. Furthermore, Sample No. No. _{2 in} which the heat treatment time in the N ₂ atmosphere is longer than 45 minutes. In No. 6, the distribution state of the ZrO ₂ phase in the cemented carbide after firing became the same between the surface and the inside, the hardness of the cemented carbide itself decreased, and the progress of wear was rapid. In addition, the sample No. _{2 in} which the oxygen content of the gas when heat-treating in an N ₂ atmosphere is less than 0.5% by volume is obtained. In No. 7, no precipitation of ZrO ₂ phase was observed, and chipping accompanied by peeling of the coating layer was observed.

  On the other hand, the sample No. having a predetermined surface area. In Nos. 1 to 6, the adhesiveness of the coating layer was high, the occurrence of chipping was suppressed, and stable cutting was possible.

1: Cemented carbide (base)
2: WC phase 3: bonded phase 4: B1-type solid solution phase 5: ZrO ₂ phase 6: coating layer 7: surface region

Claims (5)

B1 type comprising a WC phase, a binder phase composed of one or more types of iron group metals, and one or more types of carbides, nitrides or carbonitrides of Group 4, 5, 6 metals of the periodic table containing Zr other than WC A coating layer is formed on the surface of a substrate made of a cemented carbide with a solid solution phase, and ZrO ₂ phases are scattered in a surface region having a depth of 5 to 100 μm from the surface of the substrate and η There is no phase, and in the interior deeper than the surface region of the substrate, the ZrO ₂ phase does not exist, or the average particle size with respect to the average particle size of the ZrO ₂ phase in the surface region is 1/5 or less. Scattered surface coating tools. The surface-coated tool according to claim 1, wherein the coating layer has a laminated structure, and the first layer on the substrate side is one kind of Ti compound of TiN, TiC, TiB ₂ , TiCN, or TiAlN. When observed in cross-section for the surface region, the ratio of the average particle size _{d 2} of the ZrO ₂ phase average particle size _{d 1} and the B1-type solid solution phase of _(d 1 / _{d 2)} is at 1.2 to 10 The surface-coated tool according to claim 1 or 2. The surface-coated tool according to any one of claims 1 to 3, wherein the existence ratio of the ZrO ₂ phase in the surface region to the entire structure is 1 to 10 area%.   The surface-coated tool according to any one of claims 1 to 4, wherein the content ratio of the binder phase in the surface region is 1.2 to 2 times the inside.