JPS6229507B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical field The present invention relates to improvements in coated cemented carbide used for cutting tools and wear-resistant parts. (B) Background technology A coated tool that uses cemented carbide as a base material and coats the inner layer with TiC and TiN, and then coats the outer layer with 1 to 3 μm of Al ₂ O ₃ has both the wear resistance of the surface and the toughness of the base material. It is widely used as an excellent cutting tool. However, the required cutting conditions are becoming more severe year by year, and the cutting speed is now 200 m/200 m/s.
It is becoming more common for speeds to exceed 300 m/min. In such a high-speed cutting range, even the alumina-coated tools described above have a short life, and alumina-coated tools with higher performance are now required. This high performance can be achieved by increasing the thickness of the alumina film on the surface layer, making full use of the oxidation resistance, heat resistance, and wear resistance properties of Al ₂ O ₃ . It is possible that However, the growth rate of the Al ₂ O ₃ film is slow with the ordinary chemical vapor deposition method, and it is currently difficult to obtain a high-quality thick Al ₂ O ₃ layer. In order to increase the growth rate in chemical vapor deposition, methods such as increasing the temperature or adding doping agents are used, but _the grain size of Al ₂ O _{3 becomes} coarser.
This is not preferable because it has drawbacks such as a decrease in membrane purity and performance deterioration. In addition, physical vapor deposition methods such as sputtering and plasma chemical vapor deposition methods have high crystal growth rates but low adhesive strength, and are not suitable for high-speed cutting tools. (C) Disclosure of the Invention The present invention solves the above-mentioned problems and provides a coated cemented carbide for thick-film alumina-coated tools that has good performance for high-speed cutting. The characteristics of the product of the present invention are that Ti carbide, nitride, carbonitride, SiC, and Ti carbide, nitride, carbonitride, SiC, and
Si ₃ N _{4 is coated with one or more types of Si 3 N 4} , and on top of that, fine crystallized Al ₂ O ₃ of up to 2 μm is coated as an outer layer by chemical vapor deposition, and the surface is coated with plasma chemical vapor deposition and chemical vapor deposition. amorphous by repeating
This coating tool has a layered structure of a mixed layer of Al ₂ O ₃ or amorphous Al ₂ O ₃ and crystallized Al ₂ O ₃ and a layer of only crystallized Al ₂ O ₃ . The coating thickness is 1 to 10μ for the inner layer, 3 to 10μ for the outer Al ₂ O ₃ layer, and the outer layer up to 2μ adjacent to the inner layer is microcrystallized Al ₂ O ₃ by chemical vapor deposition, and the thickness of the outer layer is 3 to 10μ. The outermost layer _{of Al2O3} (1~8μ) is _{amorphous Al2O3} and _{crystallized Al2O3}
It is characterized by being laminated with. The alumina film closest to the inner layer is alumina produced by chemical vapor deposition, so it has high adhesion strength, and the alumina produced by the subsequent plasma chemical vapor deposition has a high growth rate, so the thickness of the Al ₂ O ₃ film must be increased. I can do it. In addition, the Al _{2 O 3} closest to the inner layer of the outer layer and the Al ₂ O ₃ on the outer surface have extremely good adhesion, which prevents phenomena such as separation from the lower layer when using only _the conventional plasma chemical vapor deposition method. I couldn't see it at all. In addition, thick-film Al ₂ O ₃ coated tools with an Al ₂ O ₃ film thickness of several microns or more have excellent wear resistance, but because the Al ₂ O ₃ film is a brittle material, the strength of the cutting edge is low, resulting in damage to the cutting edge, There was a problem with tool life due to chipping, etc., but the present invention solves this problem by alternately repeating chemical vapor deposition and plasma chemical vapor deposition to produce amorphous and crystalline or crystalline and amorphous materials. By creating a coating layer with a laminated structure with a mixed layer of high quality, they succeeded in significantly increasing the strength of the cutting edge. In addition, the alumina on the outer surface can be amorphous or a mixture of amorphous and crystallized alumina to reduce the thickness to 1μ.
It was found that the following fine Al ₂ O ₃ layer could be obtained. Crystalline Al ₂ O ₃ can also be obtained under certain conditions in the plasma chemical vapor deposition method, but if it is made entirely of crystallized alumina, the film will have coarse grains and its wear resistance will be slightly inferior, but the heat resistance and chemical Stability is not compromised and falls within the scope of the present invention. The inner layer is made of TiC, TiN, TiCN, SiC, and other materials that have better adhesion to the cemented carbide base material than alumina.
_Si3N4 was selected _. The film thickness is 1 to 10μ; if it is less than 1μ, it is difficult to improve adhesion;
The above is not effective in improving adhesion. Also, the outer layer
When Al ₂ O ₃ exceeds 10μ, the toughness decreases, and when it is less than 3μ, the advantage of using the continuous process of the chemical vapor deposition method and plasma chemical vapor deposition method of the present invention is lost, and the performance as a high-speed cutting tool is lost. Can not. Furthermore, if the thickness of the alumina film formed by chemical vapor deposition that is closest to the inner layer is 2 μm or more, adhesion that can withstand high-speed cutting cannot be obtained. This will be explained below using examples. Example 1 SNG432 chip made of ISO, P30 cemented carbide
5% TiCl ₄ , 5% CH ₄ , 40% N ₂ balance H ₂ at 1000 °C
It was maintained in an atmosphere of 60 Torr for 1 hour and coated with 3μ of TiCN. This surface was coated with 1μ of Al ₂ O ₃ by the same chemical vapor deposition method at 950°C in an atmosphere of 5% AlCl ₃ , 10% CO ₂ , residual H ₂ , and 30 Torr for 3 hours, and then 5% AlCl _3. Under reduced pressure of 5% CO ₂ , 90% H ₂ and 2 Torr, apply high frequency power of 200 W at 13.56 MHz for 30 minutes, then turn off the high frequency power and reduce the reaction pressure.
After holding at 30 Torr for 2 hours, high frequency power of 200 W was applied again and holding for 30 minutes. When the coating layer of the obtained coated cemented carbide was subjected to X-ray analysis and structure observation, it was found that 2μ of amorphous Al 2 O 3 and 1μ of amorphous Al ₂ O ₃ from the outer surface.
α-Al ₂ O ₃ , 2μ amorphous Al ₂ O ₃ , 1μ
of α-Al ₂ O ₃ and 3μ of TiCN were generated. Let this be A. Further, in 3% AlCl ₃ , 10% CO ₂ , 87% H ₂ , 2 Torr, high frequency power of 400 W was similarly applied for 30 minutes, the power was turned off for 2 hours, and then 200 W of power was maintained for 30 minutes. The coating layer obtained by this method has a thickness of 2μ from the outer surface.
Al ₂ O ₃ (of which 80% is amorphous Al ₂ O ₃ ), 1 μ α-Al ₂ O ₃ , 2 μ Al ₂ O ₃ (20% is amorphous Al 2 O 3 )
Al ₂ O ₃ ), 1.5 α-Al ₂ O ₃ and 3 μ TiCN. Let this be B. For comparison, 5 μ of α-Al ₂ O ₃ was used as the outer layer, and 3
C
shall be. Table 1 shows the results of testing the above samples under the following cutting conditions. Work material: FC30 Cutting speed: 300m/min. Depth of cut: 0.5mm Feed: 0.4mm/rev.

[Table] Example 2 A chip of SNG432 made of ISO, M10 cemented carbide was exposed to 5% SiCl ₄ , 5% CH ₄ , residual H ₂ ,
3μ SiC in 60Torr atmosphere for 3 hours
5% AlCl ₃ at 950℃, 10
% CO ₂ , balance H ₂ , 30 Torr for 1.5 hours and coated with 0.5 μ of α-Al ₂ O ₃ . Furthermore, in the same manner as in Example 1, 1μ of amorphous Al ₂ O ₃ and 2μ of Al ₂ O ₃ (20% a-
Al ₂ O ₃ , 80% α-Al ₂ O ₃ ) laminated coating (designated as D)
and an amorphous Al ₂ O ₃ coating (E
). Also, as a comparison material, 3.5μ α-
One with Al ₂ O ₃ as the outer layer and 3μ SiC as the inner layer (F)
was prepared by chemical vapor deposition and tested under the same cutting conditions as in Example 1. The results are shown in Table 2.

[Table] Example 3 A chip of SNG432 made of ISO M10 cemented carbide was exposed to 5% TiCl ₄ , 5% CH ₄ , residual H ₂ ,
It was kept in an atmosphere of 60 Torr for 2 hours, and a thickness of 3 μm was obtained.
TiC was generated. At the same temperature, 5% _TiCl4 , 40%
In an atmosphere of N ₂ , residual H ₂ and 60 Torr, 3 μm TiN was stored for 2.5 hours, and 5% SiCl ₄ was removed at 1100°C.
It was held for 5 hours in an atmosphere of 10% NH ₃ , 30% N ₂ , residual H ₂ and 60 Torr to produce 3 μm Si ₃ N ₄ . The surface was exposed to 5% AlCl ₃ , 20% CO ₂ and residual H ₂ at 950°C.
5 μm α-
Coated _{with Al2O3} . Furthermore, in the same manner as in Example 1, a 2 μm mixed layer of amorphous Al ₂ O ₃ and α-Al ₂ O ₃ and a 0.5 μm layer were formed on this surface.
m of α-Al ₂ O ₃ was produced. This was tested under the same cutting conditions as in Example 1. At this time, as a comparison product, a 3 μm TiC surface coated with 3 μm α-Al ₂ O ₃ was used. The test results are shown in Table 3.

【table】

Claims (1)

[Claims] 1 The base material is cemented carbide, the outer layer is Al ₂ O ₃ , and the inner layer is
It consists of one or more of Ti carbides, nitrides, carbonitrides, SiC, and Si ₃ N ₄ , and the Al ₂ O ₃ layer of 2μ or less that is closest to the inner layer of the outer layer is crystallized Al ₂ O ₃ . Yes, the outer layer with a thickness of 2 μm or more consists of three layers of amorphous Al _{2 O} or a mixed layer of amorphous Al ₂ O ₃ and crystallized Al ₂ O ₃ , and three layers of crystallized Al ₂ O ₃ alternately. A coated cemented carbide characterized by being formed by laminating the above layers.