JP2000096235A - Cutting tool made of surface coated cemented carbide, having hard coating layer excellent in chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of surface coated cemented carbide, having a hard coating layer excellent in chipping resistance. SOLUTION: A hard coating layer, consisting of the undermentioned (a) and (b), is formed on the surface of a base material composed of WC-based cemented carbide to 5-30 μm total average layer thickness by chemical vapor deposition and/or physical vapor deposition: (a) one or >=2 layers of Ti compound layers consisting of TiC layer, TiN layer, TiCN layer, TiCO layer, TiNO layer, and TiCNO layer and each having 0.1-15 μm average layer thickness; (b) one or more layers of Al2O3 dispersed layers of 3-20 μm average layer thickness, having a structure where, from the observation on the structure under an optical microscope, slender Al2O3 phases having a crystal structure grown longer in a longitudinal direction with respect to the surface of a base material are dispersedly distributed parallelly to each other and a binding phase composed of TiCO or TiCNO exists between mutual slender Al2O3 phases and also these slender Al2O3 phases are contained by 61-90 area %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hard coating layer having excellent chipping resistance, and particularly to cutting of steel, cast iron or the like at a high speed with a thick hard coating layer. The present invention relates to a cutting tool made of a surface-coated cemented carbide (hereinafter, referred to as a coated cemented carbide tool) that exhibits excellent cutting performance for a long time without occurrence of chipping (minute chipping) on a blade.

[0002]

2. Description of the Related Art Conventionally, a titanium carbide (hereinafter referred to as TiC) layer and a titanium nitride (hereinafter referred to as TiC) layer each having a granular crystal structure are generally provided on the surface of a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate). Hereinafter, also denoted by TiN) layer,
Titanium carbonitride (hereinafter referred to as TiCN) layer, titanium carbonate (hereinafter referred to as TiCO) layer, titanium oxynitride (hereinafter referred to as TiCO)
TiNO) layer and titanium carbonitride (hereinafter referred to as T
One or more of the Ti compound layers composed of iCNO) and an aluminum oxide (hereinafter, Al ₂ O ₃₎ such as an α-type aluminum oxide layer or a κ-type aluminum oxide layer having the same granular crystal structure. A coated super hard tool is known which is obtained by chemically and / or physically vapor-depositing a hard coating layer composed of a hard coating layer having an average thickness of 3 to 20 μm. It is also known to be used for continuous cutting and interrupted cutting of steel, cast iron, and the like. Further, among the hard coating layers of the coated cemented carbide tool, the TiCN layer having a granular crystal structure formed at a high temperature of 1000 ° C. or higher using a normal chemical vapor deposition apparatus is disclosed in No. 87369 and JP-A-Hei-6
As described in JP-A-8008 and the like, a mixed gas containing an organic carbonitride is used as a reactant gas.
A TiCN layer having a vertically elongated crystal structure by performing chemical vapor deposition in a medium temperature range of 50 ° C. is also known, and the toughness of the hard coating layer is improved by applying the TiCN layer having the vertically elongated crystal structure, thereby providing a cutting edge. A coated carbide tool is also known which suppresses the occurrence of chipping or chipping (small chipping) in a portion.

[0003]

On the other hand, in recent years, there has been a strong demand for labor-saving and energy-saving cutting, and in accordance with this, not only the cutting tends to be faster, but also the service life has to be extended. From among the hard coating layers, Al ₂
O ₃ layer tends to thicken, but thus Al ₂ O ₃
Using a coated carbide tool with a layer thickened to an average layer thickness of 10 μm or more, for example, when intermittent cutting of steel is performed under high-speed conditions, the thickened Al ₂ O ₃ layer is not sufficient in toughness. In addition, chipping tends to occur in the cutting edge portion, and as a result, the service life can be reached in a relatively short time at present.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, the inventors focused on the hard coating layer of the coated carbide tool and conducted research to improve the chipping resistance. (A) Among the hard coating layers of the coated carbide tool, Al ₂ O ₃
The layers are inferior in toughness but have good oxidation resistance and thermal stability, and also have high hardness, while the TiCO and TiCNO layers have relatively poor abrasion resistance but good toughness, Thus, a mixture of these two layers will have the useful properties of each layer, namely, excellent wear resistance and toughness. (B) Reaction gas composition (% by volume, the same applies hereinafter) —TiCl ₄ , for example, which is a condition for forming a TiCO layer in a normal chemical vapor deposition apparatus:
0.6~6%, CO: 0.6~6%, H 2: remainder, ambient temperature: 900 to 1100 ° C., atmospheric pressure: 30～250Torr, also the formation conditions of the TiCNO layer, the reaction gas composition -TiCl ₄ : 0.6 to 6%, CO: 0.
_{3~3%, N 2: 5~50%} , H 2: remainder, ambient temperature: 900 to 1100 ° C., atmospheric pressure: relatively 30～250Torr, in the AlCl ₃ was added as a reaction gas, and the atmospheric pressure raised condition, i.e., the reaction gas composition -TiCl _4: 0.3~3%, AlCl
₃ : 2 to 20%, CO: 1 to 10%, A if necessary
r: 1~30%, H _2: remainder, ambient temperature: 900 to 1100 ° C., atmospheric pressure: 100～600Torr, and the conditions, as well as the reaction gas composition -TiCl _4: 0.3~3%, AlCl
_{3: 2~20%, CO: 0.5~8} %, N 2: 5~45
%, If necessary, Ar: 1 to 35%, H ₂ : remaining, ambient temperature: 900 to 1100 ° C., atmospheric pressure: 100 to 600 Torr. The elongated Al ₂ O ₃ phases having a crystal structure that has grown vertically in the longitudinal direction with respect to the surface of the superhard substrate are distributed and distributed in parallel with each other, and the elongated Al ₂ O ₃ phases are made of TiCO or TiCNO. Al ₂ showing the structure in which the binder phase was present
To become that as O ₃ dispersed layer is formed. (C) above the Al ₂ O ₃ dispersion layer (b), also in the cross-sectional structure observation with an optical microscope, Al ₂ O ₃ phase TiC
It indicates a structure existing in a ratio of 61 to 90 area% by a ratio to a total amount of a binder phase composed of O or TiCNO, and an average thickness of one or more layers and an average layer thickness per layer is 0.1%. The coated carbide tool in which the hard coating layer is formed in the presence of one or two or more Ti compound layers having a thickness of 15 μm to 15 μm has an average layer thickness of 10 μm or more per Al ₂ O ₃ dispersed layer. The film should be formed and exhibit excellent wear resistance without chipping at the cutting edge even when used for high-speed interrupted cutting of steel, for example. The research results shown in (a) to (c) above were obtained.

The present invention has been made based on the above research results.
And (a) Ti
C layer, TiN layer, TiCN layer, TiCO layer, TiNO
And a TiCNO layer, and the average of each
One of the Ti compound layers having a thickness of 0.1 to 15 μm
Or two or more layers, and (b) cross-sectional structure observation with an optical microscope
The crystal that grew long in the vertical direction with respect to the substrate surface
Slender Al structure_Two O_Three The phases are distributed parallel to one another,
Slender Al _Two O_Three TiCO or TiCN between the phases
O, and the elongated Al_Two O_Three phase
Average layer thickness indicating a tissue occupying 61 to 90 area%: 3 to
20 μm Al_Two O_Three A hard layer comprising at least one dispersion layer
Chemical vapor deposition of the coating layer with a total average layer thickness of 5-30 μm and
// The hard coating layer formed by physical vapor deposition has excellent chip resistance.
Features of surface coated cemented carbide cutting tool with pingability
Have

Next, the overall average thickness of the hard coating layer of the coated cemented carbide tool of the present invention, and the Al ₂ O ₃
The reason why the average layer thickness per one layer of the dispersion layer and the Ti compound layer is limited as described above will be described. That is, both the Al ₂ O ₃ dispersed layer and the Ti compound layer constituting the hard coating layer contribute to the improvement of the wear resistance. Among them, the Al ₂ O ₃ dispersed layer has a relatively higher effect of improving the wear resistance. , And Al
_{Since the} binder phase of the ₂ O ₃ dispersion layer is made of TiCO or TiCNO, it has excellent adhesion to the Ti compound layer.
Since the i-compound layer has excellent interlayer adhesion, any of the constituent layers enables the formation of a strong hard coating layer. Therefore, the average layer thickness per Al ₂ O ₃ dispersed layer If the average thickness of the Ti compound layer is less than 0.1 μm, the interlayer adhesion of the hard coating layer becomes insufficient. Excellent wear resistance from the results
In addition, formation of a hard coating layer having sufficient interlayer adhesion requires a total average layer thickness of at least 5 μm, and Al ₂ O ₃
The average layer thickness per one layer of the dispersion layer and the Ti compound layer and the overall average layer thickness of the hard coating layer are each Al ₂ O ₃
Distributed layer: 20 [mu] m, Ti compound layer: 15 [mu] m, and the hard coating layer: exceeds 30 [mu] m, since the chipping even cutting edge in any case is likely to occur, the average layer thickness of each, Al ₂ O ₃ dispersion Layer: 3 to 20 μm, preferably 5 to 15 μm, Ti compound layer: 0.1 to 15 μm, preferably 3 to 10 μm, hard coating layer: 5 to 30 μm, preferably 8 to 20 μm.

Further, the ratio of the Al ₂ O ₃ phase in the Al ₂ O ₃ dispersed layer constituting the hard coating layer of the coated carbide tool according to the present invention is set to 61 to 90 area% because the ratio is 61 area. %
If the ratio is less than 90%, the desired excellent wear resistance of the Al ₂ O ₃ phase cannot be sufficiently exhibited by high-speed intermittent cutting. On the other hand, if the ratio exceeds 90 area%, the binder phase relatively composed of TiCO or TiCNO Is too small, the toughness rapidly decreases, and chipping is likely to occur at the cutting edge portion in high-speed interrupted cutting, and is desirably 70 to 85% by area. Is good.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide tool of the present invention will be specifically described with reference to examples. As the raw material powder, WC powder having a predetermined average particle diameter in the range of 0.5 to 5 μm, (Ti, W) C (hereinafter, the same in terms of weight ratio, T
iC / WC = 30/70) powder, (Ti, W) CN (T
iC / TiN / WC = 24/20/56) powder, (T
a, Nb) C (TaC / NbC = 90/10) powder, C
An r ₃ C ₂ powder and a Co powder were prepared, and these raw material powders were blended into the blending composition shown in Table 1, and then mixed with a ball mill.
2 hours wet mixed, dried, and pressed into a green compact, the green compact in a vacuum of 10 ^-2 Torr, 1350
By sintering at a predetermined temperature in the range of ℃ 1500 ° C. for one hour, the carbide substrates A to E of a throw-away chip type having the shape specified in ISO · CNMG120408 were manufactured. In addition, the said super-hard substrate A,
In B and C, a Co-enriched zone in which the content of Co, which is a binder phase forming component, is relatively high as compared with the inside of the base body at an arbitrary depth position from the base body surface while being sintered. Arbitrary width and formed along the surface of the substrate, the remaining carbide substrates D and E have no formation of the Co-rich zone,
It had an overall homogeneous structure.

Then, the surfaces of these superhard substrates A to E are honed, and a conventional chemical vapor deposition apparatus is used.
TiC having a vertically elongated crystal structure described in Japanese Patent Publication No. 0
Under the conditions shown in Table 3, a hard coating layer having the composition shown in Tables 4 and 5 and the target layer thickness (thickening conditions) was formed, whereby the coating of the present invention was obtained. Hard tools 1 to 11 and conventional coated coated super hard tools 1 to 11 were manufactured, respectively. In addition, the present coated carbide tools 1 to 11
And, among the hard coating layers of the conventional coated coated super hard tools 1 to 11, the Ti compound layer was formed under the same conditions of the same composition and target layer thickness, and corresponded. In addition, the cross section of the hard coating layer formed under the condition of increasing the thickness of each of the coated super hard tools 1 to 11 of the present invention and the conventional coated super hard tools 1 to 11 was observed by an optical microscope (magnification: 1000 times). When the average layer thickness of each of the constituent layers was measured, all the average layer thicknesses were substantially the same as the target layer thickness. Further, an Al ₂ O ₃ dispersion layer (in Table 4 which constitutes a hard coating layer of each of the coated carbide tools 1 to 11 of the present invention,
The Al ₂ O ₃ dispersion layers formed under the conditions of symbols A to A in Table 3 are respectively denoted by “symbols A to S”, and the cross-sectional structure was observed with an optical microscope (magnification: 1000 times). When the ratio of the Al ₂ O ₃ phase in the Al ₂ O ₃ dispersion layer was measured using an image analyzer, each showed substantially the same value as the target content ratio. FIG. 1 is a schematic diagram showing the result of observing the longitudinal section structure of the surface of the coated carbide tool 4 of the present invention with an optical microscope (magnification: 1000 times).

Next, the coated carbide tools 1 to 11 according to the present invention will be described.
Workpiece: JIS SCM440 (hardness: HB 230) with four longitudinal grooves at regular intervals in the longitudinal direction, and cutting speed: 400 m / min. Infeed: 2 mm Feed: 0.3 mm / rev. , Cutting time: 5 minutes, dry high-speed interrupted cutting test of alloy steel under the following conditions (referred to as condition A), and work material: JIS SCM440 (hardness: HB220), four equally spaced in the length direction Flute round bar, Cutting speed: 500m / min. Infeed: 2 mm Feed: 0.3 mm / rev. A cutting time: 3 minutes, a dry high-speed intermittent cutting test of alloy steel was performed under the following conditions (referred to as condition B), and the flank wear width of the cutting edge was measured in each of the cutting tests. Table 6 shows the measurement results.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

[Table 6]

[0017]

According to the results shown in Tables 4 to 6, the hard coating
Crystal structure in which the layer grows long in the vertical direction to the substrate surface
Slender Al_Two O_Three The phases are distributed parallel to each other,
Al_TwoO_Three TiCO or TiCNO between the phases
Showing a structure in which a bonded phase consisting of_TwoO_ThreeDispersion layer
The present invention comprises at least one layer and at least one Ti compound layer.
The coated carbide tools 1 to 11 are made of the Al_TwoO_ThreeThick dispersion layer
Even with excellent wear resistance and toughness,
Chipping on the cutting edge even at high-speed intermittent cutting of steel, which is a severe cutting condition
Demonstrates excellent cutting performance over a long period
On the other hand, the hard coating layer_TwoO_ThreeLayer and Ti compound
At least one material layer, and_TwoO_ThreeAverage layer
Layer thickness: Conventional coated carbide tools 1 to 10 μm thick
In No. 11, Al_TwoO_ThreeDue to insufficient toughness of the layer
Chipping is likely to occur on the blade, and
It is clear that the service life is reached. As mentioned above, this
The coated carbide tool according to the present invention has a hard coating layer of A
l _TwoO_ThreeExcellent wear resistance even when the dispersion layer is thick
And toughness, such as steel and cast iron
In addition to continuous cutting and interrupted cutting under the conditions of
High-speed intermittent cutting conditions that make these cutting conditions extremely harsh
No chipping on the cutting edge
It demonstrates excellent cutting performance over
Contribute sufficiently to labor saving and energy saving of processing
It is.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the result of observing the longitudinal section structure of the surface of a coated carbide tool according to the present invention with an optical microscope (magnification: 1000 times).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Nakamura 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Inside Mitsubishi Materials Research Institute (72) Inventor Kunihiro Endo 1-297 Kitabukurocho, Omiya City, Saitama Mitsubishi Materi F-term in AL Research Institute (for reference) BB03 BB12 BB13 CA03 DA03 JA01 JA06 JA20 LA01 LA22

Claims (1)

[Claims] 1. A surface of a tungsten carbide-based cemented carbide substrate comprising: (a) a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carbonate layer, a titanium oxynitride layer, and a titanium carbonitride oxide layer. And the average layer thickness of each is 0.1 to
(B) Observation of a cross-sectional structure by an optical microscope shows that elongated aluminum oxide phases having a crystal structure that has grown long in the longitudinal direction with respect to the substrate surface are parallel to each other. Average layer thickness showing a structure in which a binder phase composed of titanium carbonate or titanium carbonitride exists between the elongated aluminum oxide phases in a dispersed state and the elongated aluminum oxide phase occupies 61 to 90 area%. : Hard coating layer formed by chemical vapor deposition and / or physical vapor deposition of a hard coating layer comprising at least one layer of an aluminum oxide dispersion layer of 3 to 20 μm and a total average layer thickness of 5 to 30 μm has excellent chipping resistance. Surface coated cemented carbide cutting tool.