JPH10180506A - Coated hard metal tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain growth of abnormal grain so as to provide a coated hard metal tool of excellent chipping resistance and improved wear resistance by adding Ni to a super hard base material, and alternately laminating a plurality of TiN layers and TiCN layers on the surface of the super hard base material. SOLUTION: Ni is contained in the metallic bond phase of a super hard base material, and a plurality of TiN layers and TiCN layers are alternately laminated on the surface of the super hard base material so as to form a coated hard metal tool. In the case of metallic bonding agent under about 3wt.%, it loses toughness and is apt to be broken off, meanwhile, in the case of over about 25wt.%, hardness becomes too low so as to deteriorate wear resistance. The thickness of a coating film is desiable to be about 3μm- about 20μm. In the case of thickness of the coating film under about 3μm, it is feared that wear resistance deteriorates, meanwhile, in the case of over about 20μm, it is feared that the restraining effect on abnormal grain growth reduces, and further wear resistance and film strength become insufficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool such as a turning tool, which is made of a cemented carbide material, and in particular, forms a hard coating film on a cemented carbide tool base material having improved fracture toughness. To coated cemented carbide.

[0002]

2. Description of the Related Art In a cutting tool, a hard coating film made of a nitride or carbide such as Ti is formed on the surface of a tool base material in order to improve wear resistance of a cermet tool or a carbide tool. There is something.

As the method, TiN, TiN are formed by a CVD method (chemical vapor deposition method) and a PVD method (physical vapor deposition method).
Coatings such as AlN, TiAlC, or TiAlCN have been performed.

Japanese Patent Publication No. 4-53642 discloses an invention related to such a coated cutting tool.
On the surface of the base member composed of iCN-based cermet,
(Ti, Al) C, (Ti, Al) N, and (Ti,
Al) A hard coating layer consisting of one single layer or two or more coatings of CN is formed by a CVD method, a PVD method, or the like.
The surface-coated tool had excellent wear resistance and was deposited with an average layer thickness of 0.5 to 10 μm.

[0005]

However, in recent years, there has been a demand for higher cutting speeds, and cutting conditions tend to be more severe, so that the cutting tools are more excellent in chipping resistance than conventional cutting tools. There is a need for a cutting tool with improved wear resistance.

[0006]

In view of the above, the present inventors have improved the fracture resistance, that is, the fracture toughness value, of the base metal of the conventional coated cemented carbide, and As a result of intensive studies on a hard coating film having excellent wear resistance suitable for a material, the following was found.

[0007] That is, by adding Ni to the cemented carbide base material, the fracture toughness value can be increased and the fracture resistance can be enhanced. Further, when such a base material contains Ni, TiN or Al ₂ O can be obtained. _An abnormal grain growth tends to occur in these layers when an attempt is made to form a coating film composed of layers such as ₃ ; however, abnormal grain growth is caused by alternately laminating a plurality of TiN layers and TiCN layers on the surface of the carbide base material. Growth can be suppressed,
As a result, it has been found that a coated carbide tool having a coating film excellent in wear resistance can be provided on the cemented carbide base material excellent in fracture resistance.

[0008] The present invention has been made based on the above-mentioned research results, and includes Ni in the metal bonding phase of the cemented carbide base material.
And a TiN layer and a TiC
A coated carbide tool comprising a plurality of N layers alternately stacked is characterized.

The composition of the cemented carbide base material includes nickel as a metal binder, optionally 3 to 25% by weight of cobalt, iron and their alloys, and titanium carbide, tantalum carbide and the like as transition metal carbides. 0.05 to carbide
The one containing 25 wt% and the balance of tungsten carbide is preferred. If the amount of the metal binder is less than 3% by weight, the toughness is lost and chipping is liable to occur, while if it exceeds 25% by weight, the hardness becomes too low and the abrasion resistance may deteriorate. Further, if the content of the transition metal is less than 0.05 wt%, the hardness becomes low, and the abrasion resistance may be deteriorated. On the other hand, if it exceeds 25 wt%, the alloy strength may be lowered and the toughness may be deteriorated.

[0010] Ni is required as the metal binder, but other metals such as cobalt, iron and alloys thereof are optional and need not be used.

In addition, TiC can be used as the transition metal, and in this case, TaC need not always be used.

Next, the thickness of the coating film is 3 μm to 20 μm.
μm is preferred. If the thickness of the coating film is less than 3 μm, the abrasion resistance may be deteriorated.
When m is exceeded, the effect of suppressing abnormal grain growth is small, and the abrasion resistance and the film strength may be insufficient. Also, T
The iN layer and the TiCN layer are alternately stacked two or more times.
N, suppresses abnormal grain growth of Al ₂ O _3, and most preferably 4 times in terms of wear resistance, it is preferred to 5 times 3 times.
In addition, the effect of suppressing abnormal grain growth may be reduced by two times, while the thickness of each layer may be reduced and the wear resistance may be deteriorated by six times or more.

The outermost layer is made of Ti
N and Al ₂ O ₃ are preferable from the viewpoint of wear resistance, and in particular, those in which an Al ₂ O ₃ layer and a TiN layer are sequentially layered on the outer side of the alternately stacked TiN layer and TiCN layer are excellent. .

[0014]

Next, the coated cutting tool of the present invention will be specifically described with reference to examples.

Example 1 87 wt% WC, 2 wt% TiC, 5 wt% ZrC, 2 wt% N
A raw material having a composition of bC, 4 wt% Co, and 4 wt% Ni was fired to obtain a base material of a cemented carbide sintered body. Baking at 400 ° C
Dewaxing is performed for 3 hours in a 50 torr nitrogen atmosphere. Next, the nitrogen powder is stopped, the temperature in the furnace is raised to 1600 ° C. in a vacuum atmosphere, and then vacuum sintering is performed under the same condition for about 1 hour. Thereafter, vacuum cooling was performed as it was, and then rapid cooling was performed in a 50 torr nitrogen atmosphere.

When the hardness Hv and the fracture toughness value of the base material were measured, they were 1350 kg / mm ² and 14.4 kg, respectively.
MN / m ^1.5 was a very excellent value.

The base material is formed by a known CVD method.
(Base material) → TiN → TiCN → TiN → TiCN → Ti
N → TiCN → TiN → TiCN → Al ₂ O ₃ → TiN
A coating film having a thickness of 7.5 μm was formed in the order of (surface).

Example 2 87 wt% WC, 2 wt% TiC, 5 wt% ZrC, 2 wt% N
A raw material having a composition of bC and 8 wt% Ni was fired by the method of Example 1 to obtain a base material of a cemented carbide sintered body. Hardness H of the base material
v and the fracture toughness value were measured,
g / mm ² and 16.1 MN / m ^1.5 .

This base material is formed by a known CVD method.
(Base material) → TiN → TiCN → TiN → TiCN → Ti
N → TiCN → TiN → TiCN → Al ₂ O ₃ → TiN
A coating film having a thickness of 12 μm was formed in the order of (surface).

Example 3 The base material of Example 2 was subjected to a known CVD method (base material) → TiN → TiCN → TiN → TiCN → TiN →
A coating film having a thickness of 20 μm was formed in the order of TiCN → TiN → TiCN → Al ₂ O ₃ → TiN (surface).

Example 4 The base material of Example 1 was subjected to a known CVD method (base material) → TiN → TiCN → TiN → TiCN → TiN →
A coating film having a thickness of 14 μm was formed in the order of TiCN → TiN → TiCN → Al ₂ O ₃ → TiN (surface).

Experimental Example 1 (Evaluation of wear)
4) were evaluated for wear under the following conditions.

The cutting conditions · V = 230 m / min · d = 2.0 mm · f = 0.3 mm / rev · wet · Workpiece: SCM435-chip shape: CNMG120408HS - Cutting Time: 16 min 57 sec results example product 1 example product 2 example product _{3 · V B 0.164 0.269 · V} BMAX 0.220 0.385 deficiency · Nose 0.166 0.234 · R 0.08 0.08 experimental example 2 (Continuous Intermittent Evaluation) The continuous intermittent evaluation was performed on the above Examples 1 and 2 under the following conditions.

Cutting conditions : V = 200 m / min. D = 1.5 mm. F = 0.4 mm / rev. Wet. Work material: SCM440. Tip shape: CNMG120408HS. Honing R 0.07-0. 09 Result Example product 1 Approx. 1800 times Example product 2 Approx. 1400 times As described above, very excellent results were obtained.

[0025]

As described above, according to the present invention, the fracture toughness value is increased by adding Ni to the cemented carbide base material,
The fracture resistance can be improved, and abnormal grain growth in the coating film due to the base material containing Ni can be prevented by alternately stacking a plurality of TiN layers and TiCN layers on the surface of the cemented carbide base material. This has an extremely excellent effect that a coated carbide tool having a coating film excellent in wear resistance can be provided on the cemented carbide base material excellent in fracture resistance.

Claims (2)

[Claims] 1. A coated carbide tool in which a plurality of TiN layers and TiCN layers are alternately laminated on the surface of a cemented carbide base material containing Ni in a metal bonding phase. 2. The method according to claim 1, wherein the TiN layer and the TiC layer are alternately stacked.
Coated cemented carbide tool according to claim 1, characterized in that sequentially particle course the the Al ₂ O ₃ layer and the TiN layer on the outside than the N layer.