JP2000071108A - Surface coated cemented carbide cutting tool of hard coating layer displaying excellent delamination-proof property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the surface coated cemented carbide cutting tool of a hard coating layer displaying excellent delamination-proof property. SOLUTION: A surface coating cemented carbide cutting tool, which is made by chemical evaporation and/or physical evaporation on the surface of a WC base cemented carbide substrate in an average layer thickness of 3 to 20 μm of a hard coating layer composed of a Ti compound layer composed of two or more layers among a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, a TiNO layer and a TiCNO layer, an α type Al2O3 layer and/or a κ type Al2O3 layer, and a TiCN layer including a longitudinally grown crystaline structure, is formed of a minute hole dispersion zone covering [the depth within the range of 1 μm to (average layer thickness of the longitudinally grown crystaline structure TiCN layer × 0.5) μm] from the surface along the Al2O3 layer existing lateral of the longitudinally grown crystaline structure TiCN layer by structural observation using a scanning type electron microscope of a square polished section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool made of a surface-coated cemented carbide in which a hard coating layer exhibits excellent delamination resistance even when it is used for high-speed continuous cutting of steel, for example. (Hereinafter referred to as coated carbide tool).

[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
a Ti compound layer composed of two or more of the following layers; an α-type aluminum oxide (hereinafter, referred to as α-Al ₂ O ₃ ) layer and / or a κ-type aluminum oxide (also referred to as α-Al ₂ O ₃ ) having a granular crystal structure. Hereinafter, referred to as κ-Al ₂ O ₃ ) layer and a mixed gas containing an organic carbonitride as a reaction gas, as described in, for example, JP-A-3-87369 and JP-A-6-8008. Use 70
A hard coating layer composed of a titanium carbonitride (hereinafter referred to as l-TiCN) layer having a vertically elongated crystal structure formed by performing chemical vapor deposition in a medium temperature range of 0 to 950 ° C. has an average of 3 to 20 μm. Known is a coated carbide tool formed by chemical vapor deposition and / or physical vapor deposition at a layer thickness. It is also known that this coated carbide tool is used for continuous or interrupted cutting of steel, cast iron, and the like. I have.

[0003]

On the other hand, in recent years, there has been an increasing demand for labor saving and energy saving of the cutting work, and with this, the cutting speed has been increased and the hard coating layer has been used for the purpose of extending the service life. Al ₂ O ₃ layer and l-
The TiCN layer tends to be thick, but in the above-mentioned conventional coated carbide tool, when this is used for high-speed continuous cutting of steel, for example, where heat is remarkable, the Al ₂ O ₃ layer and the l-T
There is a large difference in thermal expansion between the iCN layers, that is, the former has a small thermal expansion coefficient and the latter has a large thermal expansion coefficient, so that separation between these two layers is likely to occur.
_{At present, the more the 2} O ₃ layer and the 1-TiCN layer are made thicker, the more they appear, and as a result, the service life is relatively short.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoint, attention is paid to the hard coating layer of the conventional coated carbide tool, and the Al ₂ O ₃ layer and the 1-T
As a result of conducting a study to improve the delamination resistance with the iCN layer, along the side surface of the 1-TiCN layer where the Al ₂ O ₃ layer is present, the structure of the perpendicular-polished cross section was observed with a scanning electron microscope. When a band in which micropores are dispersed over a depth in the range of 1 μm to (the average layer thickness of the l-TiCN layer × 0.5) μm is provided, the micropore band becomes
Since the difference in thermal expansion between the Al ₂ O ₃ layer and the 1-TiCN layer is sufficiently absorbed, the A
l ₂ O ₃ layer and l-TiCN without occurrence of peeling between layers, the delamination improvement of the Al ₂ O ₃ layer and l-TiCN
The research results showed that even if the layer was thickened, it did not change.

The present invention has been made on the basis of the above research results, and a TiC layer and a T
a Ti compound layer composed of two or more of an iN layer, a TiCN layer, a TiCO layer, a TiNO layer, and a TiCNO layer; an α-Al ₂ O ₃ layer and / or a κ-Al ₂ O ₃ layer; Hard coating layer composed of 3 to 2 layers
In a coated cemented carbide tool formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of 0 μm, the structure of a right-angled polished cross section is observed by a scanning electron microscope along the side surface on which the Al ₂ O ₃ layer is present in the 1-TiCN layer. And from the surface 1μm ~
(Average layer thickness of the l-TiCN layer × 0.5) μm, and a micropore dispersion zone is formed over a depth of
The present invention is characterized by a coated carbide tool in which a hard coating layer exhibits excellent delamination resistance.

[0006] In the coated carbide tool of the present invention,
The depth from the surface of the microvoid dispersion zone formed along the side surface of the 1-TiCN layer forming the hard coating layer along the Al ₂ O ₃ layer-existing side is 1 μm to (the average layer thickness of the 1-TiCN layer ×
0.5) μm because the depth is less than 1 μm
The difference in thermal expansion between the Al ₂ O ₃ layer and the l-TiCN layer due to heat generation cannot be sufficiently absorbed, and as a result, separation between these two layers cannot be avoided. If the average thickness exceeds 0.5 μm, the excellent toughness of the l-TiCN layer cannot be maintained.

[0007] Further, the minute void in the l-TiCN layer.
The pore dispersion zone is the same as that used in ordinary chemical vapor deposition and physical vapor deposition equipment.
And the reaction gas composition (in% by volume)-TiCl_Four : 1 to 5%, N
_Two : 2 to 15%, CH _ThreeCN: 1-4%, H_Two : The remaining reaction atmosphere temperature: 800 to 950 ° C., reaction atmosphere pressure: 30 to 100 Torr.
CH in gas_ThreeThe content ratio of CN is relatively 6-15%.
The reaction atmosphere pressure is increased to 150 to 500 To
Under the condition where rr is increased (the other conditions are the same), l-
Dispersion and appearance of microvoids in TiCN layer
Formed by

Further, the average thickness of the hard coating layer is 3 to 20.
The reason why the thickness is set to μm is that if the layer thickness is 3 μm, the desired excellent wear resistance cannot be secured, while the layer thickness is 20 μm.
If the thickness exceeds μm, chipping and chipping of the cutting edge are likely to occur.

[0009]

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 surface of each of the superhard substrates A to E was honed, and an ordinary chemical vapor deposition apparatus was used.
TiC having a vertically elongated crystal structure described in Japanese Patent Publication No. 0
Under the conditions shown in Tables 3 and 4 to form micropores in the 1-TiCN layer of the hard coating layer by forming a hard coating layer having the composition and target thickness shown in Tables 3 and 4. The coated carbide tool of the present invention having a dispersion zone formed therein.
No. 0 and conventional coated carbide tools 1 to 10 having no formation of the micropore dispersion zone were produced. It should be noted that the l-T constituting the hard coating layer of the coated carbide tools 1 to 10 according to the present invention described above.
Observation of the right-angle polished cross section of the iCN layer with a scanning electron microscope confirmed the presence of a microvoid dispersion zone in a tissue in which micropores were dispersed and distributed over the depths shown in Table 3, respectively.

Next, the coated carbide tools 1 to 10 according to the present invention will be described.
Workpiece: JIS SCM440 round bar, Cutting speed: 600 m / min. Infeed: 2 mm Feed: 0.3 mm / rev. The cutting speed was 10 minutes, and a dry high-speed continuous cutting test of the alloy steel was performed under the following conditions, and the flank wear width of the cutting edge was measured. Table 5 shows the results of these measurements.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

From the results shown in Tables 3 to 5, the coated carbide tools 1 to 10 according to the present invention, in which the micropore dispersion zone is present in the 1-TiCN layer of the hard coating layer, all have remarkable heat generation. Al ₂ O forming hard coating layer even in high-speed continuous cutting of steel
_Since the large thermal expansion difference generated between the _three layers and the l-TiCN layer is sufficiently absorbed by the microvoid dispersion zone,
No separation occurs between these layers, and excellent cutting performance is exhibited over a long period of time. On the other hand, in the conventional coated carbide tools 1 to 10 having no formation of the micropore dispersion zone, cutting is not performed. It is evident that the large thermal expansion that sometimes occurred between the Al ₂ O ₃ layer and the 1-TiCN layer caused delamination between the two layers, resulting in a relatively short service life. As described above, the coated cemented carbide tool of the present invention performs not only continuous cutting and interrupted cutting under ordinary conditions such as steel and cast iron, but also particularly involves continuous heat cutting at a high speed, for example, with remarkable heat generation. Even when used in such a case, the hard coating layer exhibits excellent delamination resistance, exhibits excellent cutting performance over a long period of time, and contributes to labor saving and energy saving in cutting.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Atsushi Sugawara 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. BA18 BA35 BA36 BA38 BA41 BA43 BB01 BB03 BB06 BB11 BB12 CA03 JA01 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, each having a granular crystal structure; (B) a titanium carbonitride layer having a vertically-grown crystal structure, and (c) an α-type and / or κ-type aluminum oxide layer having a granular crystal structure. A) a surface-coated cemented carbide cutting tool obtained by chemical vapor deposition and / or physical vapor deposition of the hard coating layer composed of (c) to (3) to 20 μm in total thickness of 3 to 20 μm; Observation of the structure of the right-angled polished cross section along the side surface on which the aluminum oxide layer exists in the titanium nitride layer by scanning electron microscopy revealed that from the surface, 1 μm to (from the titanium carbonitride layer having the above-described vertically grown crystal structure) Surface coated cemented carbide having a hard coating layer exhibiting excellent delamination resistance, characterized in that a micropore dispersion zone is formed over a depth in the range of (average layer thickness × 0.5) μm. Cutting tools.