JP2861832B2 - Surface coated tungsten carbide based cemented carbide cutting tool with excellent interlayer adhesion with hard coating layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hard coating layer having excellent interlayer adhesion and, therefore, exhibits excellent cutting performance over a long period of time when used for cutting, for example, mild steel having a large cutting resistance. The present invention relates to a surface-coated tungsten carbide based cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, as described in, for example, JP-B-57-1585 and JP-B-59-52703, a tungsten carbide-based cemented carbide substrate as a whole, For example, a tungsten carbide-based cemented carbide substrate having a surface portion having a relatively high content of Co or the like as compared with the inside of the substrate, that is, a tungsten carbide-based cemented carbide substrate having a binder phase enriched zone on the surface portion (hereinafter, collectively referred to as a cemented carbide substrate) ), A first layer of titanium nitride (hereinafter, referred to as TiN), a second layer of titanium carbonitride (hereinafter, referred to as TiCN), and titanium carbonate ( Less than,
TiCO) or titanium carbonitride (hereinafter TiC)
NO), a fourth layer of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ), and, if necessary, a hard coating layer of a fifth layer of TiN with an average layer thickness of 3 to 30 μm. It is well known that the coated carbide cutting tool formed by the above is mainly used for cutting or milling of alloy steel or cast iron.

[0003]

On the other hand, in recent years, the use of FA in cutting machines has been remarkable, and in conjunction with the demand for labor saving in cutting work, cutting tools tend to be required to be versatile. For carbide cutting tools, there is no problem if this is used for cutting alloy steel or cast iron, etc.
Particularly when used for cutting mild steel with high cutting resistance, the interlayer adhesion of the hard coating layer is not sufficient, so that the hard coating layer is liable to delamination and chipping, which causes a relatively short service life. At present.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoint, the above-mentioned conventional coated carbide cutting tool was focused on, and a study was conducted to improve the interlayer adhesion of the hard coating layer constituting the cutting tool. In the hard coating layer constituting the cutting tool, the adhesion of the first TiN layer to the cemented carbide substrate is extremely high, but the adhesion between the constituent layers is low, so that delamination or chipping occurs. It is easy to occur. (B) In the hard coating layer constituting the conventional coated carbide cutting tool, the first TiN layer and the second TiCN layer
The layer, the third layer TiCO layer and the TiCNO layer, and the fifth layer TiN layer formed as required, all have a granular crystal structure, and the fourth layer Al ₂ O ₃ layer has an alpha type crystal structure. In addition, the TiCN layer of the second layer has a vertically elongated crystal structure, and the Al ₂ O ₃ layer of the fourth layer has a structure mainly composed of copper-type crystals, preferably, the copper-type crystal is 50% by volume or more. And the remainder is a mixed structure composed of an alpha-type crystal, and more desirably, a structure substantially composed of a kappa-type crystal.
an iN layer, a third TiCO layer, and a TiCNO layer; and a third TiCO layer, TiCN for the fourth layer.
The adhesion between the O layer and the fifth TiN layer is significantly improved. (C) After forming the second TiCN layer, 10 to 100 to
rr in a hydrogen atmosphere, temperature: 1 to 5 at 850 to 1100 ° C
When the heat treatment is performed under the condition of holding time, at least W and Co components among the components constituting the cemented carbide substrate are diffused and moved to the grain boundaries of the first and second layers by a capillary phenomenon. At least W and Co are contained in the grain boundaries of, and as a result, the interlayer adhesion is further improved in combination with the improvement of the intercrystalline adhesion. The research results shown in (a) to (c) above were obtained.

The present invention has been made on the basis of the above research results, and includes a first TiN layer, a second TiCN layer, a third TiCO layer or a third TiN layer on a surface of a cemented carbide substrate. A coated cemented carbide cutting tool comprising a TiCNO layer, a fourth Al ₂ O ₃ layer, and, if necessary, a hard coating layer comprising a fifth TiN layer with an average layer thickness of 3 to 30 μm, (A) The first layer, the third layer, and the fifth layer have a granular crystal structure, the second layer has a vertically-grown crystal structure, and the fourth layer has a structure mainly composed of copper-type crystals. (B) The grain boundaries of the first layer and the second layer contain at least W and Co of the components constituting the cemented carbide substrate, and the hard coating is performed by the above (a) and (b). Coated carbide cutting with excellent interlayer adhesion Again and again it has the characteristics.

[0006] The TiCN layer having a vertically elongated crystal structure of the second layer of the hard coating layer constituting the coated carbide cutting tool of the present invention is, for example, as described in JP-A-6-8010. A) TiCl ₄ : 1 to ₄ in terms of reaction gas composition and volume%
_{%, CH 3 CN: 0.1~5%} , N 2: 0~35
%, H ₂ : remaining, (a) Reaction temperature: 850 to 950 ° C., (c) Atmospheric pressure: preferably 30 to 200 torr. On the other hand, TiC having a granular crystal structure
The N layer is usually composed of (a) a reaction gas composition, volume%, TiCl ₄ : 1 to 5
_{%, CH 4: 2~7%,} N 2: 15~30%,
H ₂ : remaining, (a) reaction temperature: 950 to 1050 ° C., (c) ambient pressure: 30 to 200 torr. Further, the Al ₂ O ₃ layer having a structure mainly composed of a copper-type crystal has the following characteristics.
0 minutes, AlCl ₃ : 1 to 20%, H ₂ : remaining, or AlCl ₃ : 1 to 20%, HCl: 1 to 20% and / or H ₂ S: 0.05 to 5%, H ₂ : After that, it is assumed that AlCl ₃ : 1 to 20%, CO ₂ : 0.
5~30%, H _2: remainder, or,, AlCl _3: 1~2
_{0%, CO 2: 0.5~30%} , HCl: 1~20
% And / or H ₂ S: 0.05 to 5%, H ₂ : remaining, (a) reaction temperature: 850 to 1000 ° C., (c) atmosphere pressure: 30 to 200 torr.

[0007] The hard coating layer constituting the coated cemented carbide cutting tool of the present invention is formed on the surface of the cemented carbide substrate by the chemical vapor deposition method and / or the physical vapor deposition method under the above-mentioned conditions and ordinary conditions. First, a first TiN layer is deposited, and then a second TiN layer is deposited.
From the TiCN layer of the layer to the Al ₂ O ₃ layer of the fourth layer, the fifth layer of TiN is further formed as necessary, if necessary. In some cases, the C component in the cemented carbide substrate diffuses and forms a solid solution in the TiN layer. In this case, part or all of the first layer is TiCN.

Further, the average thickness of the hard coating layer is 3 to
The reason why the thickness is set to 30 μm is that if the average layer thickness is less than 3 μm, it is not possible to secure desired excellent wear resistance, while if the average layer thickness exceeds 30 μm, the chipping resistance sharply decreases. The average thickness of the first TiN layer is 0.1 to 5 μm, that of the second TiCN layer is 3 to 20 μm, and that of the third TiCO layer or TiCNO layer is 0.1 μm. 01 to 2 μm, Al of the fourth layer
The average thickness of the ₂ O ₃ layer is preferably 0.1 to 15 μm, and the average thickness of the fifth TiN layer is 0.1 to 5 μm.

[0009]

Next, the coated carbide cutting tool of the present invention will be described in detail with reference to examples. As raw material powder, medium-grain WC powder having an average particle diameter of 3 μm, coarse WC powder having an average particle diameter of 5 μm
Powder, 1.5 μm (Ti, W) C (weight ratio, same hereafter, TiC / WC = 30/70) powder, 1.2 μm
(Ti, W) CN (TiC / TiN / WC = 24/2)
0/56) A powder and a Co powder of 1.2 μm were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and dried.
SO ・ CNMG120408 (for cemented carbide substrates A to D)
And SEEN42AFTN1 (for cemented carbide substrate E)
Each of the compacts was press-molded into a green compact having the shape specified in Table 1, and the green compact was vacuum-sintered under the conditions shown in Table 1 to produce cemented carbide substrates A to E, respectively. Further, the cemented carbide substrate B was maintained at a temperature of 1400 ° C. for 1 hour in a CH ₄ gas atmosphere at 100 torr, and then subjected to a slow cooling carburizing treatment. By removing with acid and barrel polishing, 1
Maximum Co content at 0 μm: 15% by weight, depth: 4
A 0 μm Co-enriched zone was formed on the substrate surface. Also,
In the cemented carbide substrates A and D, a Co-enriched zone having a maximum Co content of 9% by weight and a depth of 20 μm was formed on the surface portion at a position of 15 μm from the surface while being sintered, The remaining cemented carbide substrates C and E had no formation of the Co-enriched zone and had an overall homogeneous structure. Further, Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the cemented carbide substrates A to E.

Next, the surfaces of these cemented carbide substrates A to E are honed, and the compositions and the compositions shown in Tables 3 to 6 are obtained by using an ordinary chemical vapor deposition apparatus under the conditions shown in Table 2. A hard coating layer having a crystal structure and an average thickness is formed. During the formation of the second layer, a heat treatment is performed in a hydrogen atmosphere of 35 torr at a temperature of 1050 ° C. for a predetermined time within a range of 1 to 5 hours after forming the second layer. Thus, the coated carbide cutting tools 1 to 7 of the present invention were manufactured, and the conventional coated carbide cutting tools 1 to 7 were respectively manufactured without performing the heat treatment. The resulting first and second hard coating layers constituting the various coated carbide cutting tools were observed with a transmission electron microscope (TEM) to identify five grain boundaries as appropriate for each layer. Then, the W and Co contents of this specific grain boundary were quantitatively analyzed by an energy dispersive X-ray measuring apparatus. These results are shown in Tables 3 to 6 as average values.

Further, the coated carbide cutting tools of the present invention 1 to 5
For the conventional coated carbide cutting tools 1 to 5, work material: mild steel round bar, cutting speed: 335 m / min., Feed: 0.26 mm / rev., Depth of cut: 2 mm, cutting time: 20 minutes. And continuous cutting test of mild steel, and work material: square bar of mild steel, cutting speed: 305 m / min., Feed: 0.26 mm / rev., Depth of cut: 1.5 mm, cutting time: 25 minutes. In each cutting test, the flank wear width of the cutting edge was measured. Tables 4 and 6 show the measurement results. Further, regarding the coated carbide cutting tools 6 and 7 of the present invention and the conventional coated carbide cutting tools 6 and 7, a work material: a square bar of mild steel, a cutting speed: 305 m / min., A feed: 0.36 mm / tooth, and a cutting depth : 2.5 mm, Cutting time: 30 minutes, Mild steel was milled, and the flank wear width of the cutting edge was measured. The measurement results are also shown in Tables 4 and 6.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

[Table 6]

[0018]

According to the results shown in Tables 3 to 6, the coated carbide cutting tools 1 to 7 according to the present invention show that delamination or chipping of the hard coating layer occurs in the hard coating layer despite the cutting of mild steel having high cutting resistance. While showing no abrasion and excellent wear resistance,
Conventionally, the coated carbide cutting tools 1 to 7 clearly show that the interlayer adhesion in the hard coating layer is insufficient, and delamination and chipping occur in the cutting of mild steel, resulting in a relatively short service life. is there. As described above, the coated cemented carbide cutting tool according to the present invention has a hard coating layer having excellent interlayer adhesion, so that it can cut not only alloy steel and cast iron, but also mild steel having a high cutting resistance. Even when used for cutting, excellent cutting performance is exhibited over a long period of time.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C23C 28/04 C23C 28/04 (56) References JP-A-6-57429 (JP, A) JP-A-8-71814 (JP, A) JP-A-6-17229 (JP, A) JP-A-5-123904 (JP, A) Patent 2800571 (JP, B2) JP-B 7-32962 (JP, B2) JP-B 7-100858 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B23B 27/14 B23P 15/28 C23C 14/06 C23C 16/30 C23C 28/04

Claims (2)

(57) [Claims] 1. A first layer of titanium nitride, titanium carbonitride on a surface of a generally homogeneous tungsten carbide based cemented carbide substrate or a tungsten carbide based cemented carbide substrate having a binder phase enriched zone on its surface. Surface-coated tungsten carbide-based cemented carbide formed by forming a hard coating layer consisting of a second layer of titanium, a third layer of titanium carbonate or titanium carbonitride, and a fourth layer of aluminum oxide with an average layer thickness of 3 to 30 μm. (A) The first and third layers have a granular crystal structure, the second layer has a vertically-grown crystal structure, and the fourth layer has a structure mainly composed of copper-type crystals. b) The hard coating layer, characterized in that at least W and Co of the components constituting the base are diffused and contained in the crystal grain boundaries of the first and second layers, have excellent interlayer adhesion. Surface coated tan carbide Gusten-based cemented carbide cutting tool. 2. A first layer of titanium nitride, titanium carbonitride on a surface of a tungsten carbide based cemented carbide substrate which is entirely homogeneous, or a tungsten carbide based cemented carbide substrate having a binder phase enriched zone on its surface. A third layer of titanium carbonate or titanium oxycarbonitride, and a fourth layer of aluminum oxide.
Layer and a fifth hard layer of titanium nitride.
In a cutting tool made of a surface-coated tungsten carbide-based cemented carbide formed with an average layer thickness of ３０30 μm, (a) the first layer, the third layer, and the fifth layer are a granular crystal structure, and the second layer is Is a vertically-grown crystal structure, and the fourth layer is a structure mainly composed of a copper-type crystal. (B) At least one of the components constituting the base is provided at the crystal grain boundaries of the first layer and the second layer. W and Co are diffused and contained. A cutting tool made of a surface-coated tungsten carbide-based cemented carbide having a hard coating layer having excellent interlayer adhesion.