JPH01295702A - Ceramics-coated cutting tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention consists of Mf'' layers or more made by alternately combining crystalline layers and amorphous layers. This relates to cutting tools.

[Prior Art] Cutting tools made of carbide, cermet, and ceramic base materials are coated with hard ceramic films to improve their wear resistance. Among these, alumina or silicon nitride films, which are chemically stable and have high high-temperature hardness, are often used directly on the base material C or coated on titanium nitride or carbide films. These films are often heated to 900°C from the viewpoint of adhesion to the base material and coating efficiency.
The coating treatment is performed as described above, and coating is performed by a thermal CVO method (chemical vapor deposition method).

A CVD-coated crystal film of alumina, silicon nitride, or a composite composition thereof has high hardness and excellent wear resistance, but tends to form columnar crystals. These columnar crystals are crystal grains that grow at an angle close to perpendicular to the base material surface, and when tensile stress is generated during cutting, cracks easily grow along the grain boundaries, and the cracks become a source of stress concentration. As a result, a relatively high stress leads to the loss of the force. That is, by coating the tool with a ceramic film having the composition -1- in order to obtain wear resistance, the strength of the tool itself is reduced.

This tendency increases rapidly as the thickness of this coating layer increases. For this reason, CvD coated tools have a coating thickness of several μm.
The use is limited to the following and for continuous cutting that is not subjected to repeated impact loads.

Lowering the treatment temperature is effective in avoiding this columnar crystallization, but lowering the treatment temperature tends to result in an amorphous film, resulting in a decrease in film hardness and wear resistance.

Another method for avoiding columnar crystallization is to alternately provide films with different compositions to form a multilayer film. For example, Japanese Patent Publication No. 61-54114 reports a multilayer film comprising alternating layers of oxycarbonitrides such as Tf, Zr, and Hf and An oxides.

However, in order to apply films with different compositions alternately, it is necessary to switch the raw material gas system, which not only complicates the operation, but also reduces the adhesion strength between layers, requiring interrupted cutting such as milling, and cutting of multiple small parts. As in the case of , small peeling of the coating is likely to occur in the living room in applications where the material is subject to repeated impact loads as well as repeated thermal stress due to heat generation during cutting and cooling during non-cutting.

[Problems to be Solved by the Invention] The present invention provides a CVD film of oxides, nitrides, and oxynitrides of An and Si, which are highly hard and chemically stable, but tend to form columnar crystals. The purpose of the present invention is to provide a cutting tool with excellent wear resistance and strength, which does not have a significant decrease in hardness compared to a film, does not exhibit significant columnar crystallization, and therefore has an excellent tool life even in interrupted cutting. It is something.

[Means for Solving Problem X1] If an attempt is made to form a crystal containing one or more of An, Sj oxides, nitrides, and oxynitrides by the CVD method, columnar crystals will be formed. As the film thickness increases, the columnar crystals become more pronounced and the strength of the tool decreases. In contrast, the present invention proposes that the above-mentioned problems can be solved by inserting thin amorphous layers with these compositions during the formation of crystals with these compositions to form alternating layers of crystal and amorphous. .

That is, the cutting tool of the present invention is a tool in which a carbide, cermet, or ceramic base material is coated with a film containing one or more of oxides, nitrides, and oxynitrides of ^l, Sj. is an amorphous layer with a thickness of 1.0JJI11 or less and a crystalline layer with a thickness of 2.0U or less, a total of at least 4 layers, preferably a thickness of 6JJI
It is characterized by consisting of l+ or more alternating layers.

[Operation] The amorphous layer can be inserted by temporarily lowering the CvD temperature to a temperature lower than the crystallization temperature. By inserting this amorphous layer, crystal growth is interrupted. Next, when crystals are grown again on the amorphous layer, many crystal nuclei are generated on the amorphous layer, and fine crystals begin to grow. By controlling the thickness of this crystal layer to be sufficiently small, a structure consisting of layered fine crystals instead of a prominent columnar structure can be obtained. This coating is less prone to cracking than conventional columnar crystals, even when tensile stress is applied, and even if cracks do occur, the amorphous layer suppresses the propagation of the cracks, minimizing the reduction in tool strength caused by the coating. It can be done. Although the amorphous layer has a lower hardness than a crystalline layer of the same composition, by making this layer sufficiently small, the hardness of the entire film can be made close to that of the crystalline layer alone.

In this way, the coated tool of the present invention has both excellent wear resistance and strength, and can be applied not only to continuous cutting but also to interrupted cutting where repeated impact loads are applied, and to cutting a large number of small parts. Furthermore, since the crystalline layer and the amorphous layer have the same components, their adhesion is good, and there is little peeling between the layers, which tends to occur in the case of multilayer coatings with different component systems.

[Details of the invention] Next, the reasons for the limitations of the present invention will be described.

When the thickness of the amorphous layer exceeds 1 μm, the proportion of the amorphous layer in the film increases, and the hardness of the film decreases. In addition, in order to reliably interrupt crystal growth, the
．． It is desirable that the thickness is 1 μm or more.

When the thickness of the crystal layer exceeds 2.0 μm, a remarkable columnar structure is exhibited and the strength of the tool is reduced. The thinner the crystal layer is, the better it is from the point of view of strength, but it is necessary to use a very large number of layers in order to achieve the desired thickness, so the thickness of 0.2μ is preferable.
It is desirable that it is more than m.

The minimum number of layers for the coating of the present invention is a four-layer structure consisting of two crystalline layers and two amorphous layers. It is desirable to have a multi-layered structure.

Furthermore, it is also possible to directly coat carbide, cermet, and ceramic base materials with a multilayer film consisting of one or more crystalline layers of Al, Si oxides, nitrides, and oxynitrides, and an amorphous layer. In order to increase the adhesion strength with Ti, it is desirable to coat the bottom of the stiff multilayer film with a layer of one or more Ti carbides, nitrides, or carbonitrides.

The total thickness of this alternating layer of crystalline and amorphous layers is 6
Even if the number of layers is less than m, the desired effect of the present invention can be fully exhibited, but by stacking a large number of these alternating layers to obtain a Jg of 6AJ11 or more and l151, wear resistance is further improved and excellent tool life is achieved. This leads to the following. Even if the thickness is large, it does not interfere with the tool life, but from the viewpoint of manufacturing cost, it is preferable to make it less than Ion utn.

[Example] (Example 1) ff[ffi! Ii Terot Co, 5tTiC-5
% (TaC+I'1bc), 84't VC was used as a base material, and it was set in a CVD reactor. In this CVD reactor, the initial volume ratio was 3: CQ4.9*
A gas consisting of C114 and the remainder H2 was introduced and heated to 1000°C.
, and treated for 30 minutes at 150 Torr. Next, replace C;14 with NH,9! I; (volume ratio) was introduced and treated for 20 minutes. The above process is a process for coating TiC and TiN as an undercoat of alternating layers of crystalline and amorphous layers of alumina, which will be described below.

Next, 5 volume ratio TeAQci35'Ji, (:059G
, a gas with residual H2 was introduced into the CVD reactor, and 10
00℃.

After processing for 12 minutes at 150 Torr, the same gas composition,
It was treated under gas pressure at 750°C for 8 minutes. This 1000℃,
The procedure of 12 minutes at 750°C for 8 minutes was repeated six times. 100
Repeating 0℃ and 750℃ is 1000 times inside the CVD reactor.
The test was carried out by providing zones maintained at 750°C and 750°C, and moving a holder carrying the base material between the zones. The coating layer treated by CVD in this manner has the structure shown in FIG.

This coated tool has superior transverse rupture strength compared to the comparative coated tool made of a crystalline alumina layer shown in FIG. Furthermore, the hardness of the alumina layer is higher than that of the coated tool made of an amorphous alumina layer shown in FIG. In addition, the results of cutting tests conducted under the following conditions showed that the tool life was superior to both comparison tools. These results are shown in Table 1.

Cutting test conditions> Work material: 545C Depth of cut +2mm Transmission: (1,18ff1m/rev.

-〇Speed + 180 m/+++ Cutting time per one opening: 0.8 Win life standard: v
a = 500 um or tool loss Table 1 (Example 2) At weight t, 7! A Si3N4 sintered material containing tiAlz03 as a sintering aid was used as a base material, and the following coating treatment was performed in a CVD reactor. Initially the volume ratio 15')-5iCQ
4. 5! A gas consisting of li Nil, , and residual H2 was introduced into the reactor, and after being treated at 50 Torr and 1100°C for 12 minutes, it was heated to 1350°C with the same gas composition ratio and gas pressure.
Processed for 0 minutes. This treatment at 1100°C and 1350°C was repeated 5 times. As a result, the amorphous silicon nitride layer, crystalline Si, and 10 N4 layers, totaling 2.8 u, are shown in Figure 4.
A multilayer film tool consisting of m was obtained.

Furthermore, by repeating the treatment at 1100°C and 1350°C 18 times under the same conditions, the amorphous silicon nitride layer and crystalline Si shown in
, N, a multilayer film tool consisting of 36 layers with a total volume of 11.2 μl was obtained.

These multilayer coated tools according to the present invention and comparative crystalline Si,
Table 2 shows a comparison of hardness, transverse rupture strength, and tool life with N4 and amorphous silicon nitride single-layer coated tools. The tool of the present invention has higher strength than a crystalline single layer film, and higher hardness than an amorphous single layer film. Also, the tool life is better than that of comparative drawing tools. Invention 3 with particularly thick coating
's tools are the best. The cutting test at this time was conducted under the following conditions.

Cutting test conditions> Work material: Fe12 Depth of cut: 1.5am Transmission: 0.12 arm/rev.

Speed: 300 m/l1in Cutting time per piece: 0.5 win life standard: V
B = 500 μI or tool loss table 2 (Example 3) TiC75 at weight t! k, Ni 1.5);
A cermet containing Co5 was used as a base material, and the following coating treatment was performed in a CvO reactor. First, the volume ratio Al (:R3
5! Then, a gas consisting of 5% Go, NH321 and residual H2 was introduced into the CVD reactor at 1020°C and 100T.
After processing for 10 minutes under the conditions of
After repeating ℃ 10 minutes → 700'' CIO minutes 3 times, NH
, the volume ratio AQ13596, Co5! !
, gas composition consisting of residual H2 at 1020°C 1O min → 70
The treatment at 0°C for 10 minutes was repeated twice. C used in this example
The VD furnace differs from the previous two examples in that it heats the base material holding table using high-frequency waves, and is a so-called cold wall type device that allows the processing temperature to be changed in a short period of time.

As a result, as shown in FIG. 6, AM20. and AiN crystal layer and amorphous layer and At20. A multilayer film consisting of a crystalline layer and an amorphous layer was obtained. Crystal layer thickness is 0.3~0
．． 41Jm, amorphous layer thickness is 0.1~0.151J
The total thickness is 2.7 μl at a+~0.2 μm.

The film hardness, transverse rupture strength, and tool life of this tool are shown in Table 3. The cutting test was conducted under the same conditions as in Table 1, and the tool life was superior to that of the comparative tools shown in Table 1.

Table 3 [Effects of the Invention] As mentioned above, the present invention coats a carbide, cermet, or ceramic base material with a high hardness film by alternately coating crystal layers and amorphous layers without reducing strength. It shows excellent tool life even in multiple cuts of small parts and interrupted cuts.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the coating layer of a coated tool of the present invention, in which a carbide base material is coated with TiC and TiN layers, and then 12 layers of crystalline AQaO:+ and amorphous alumina are alternately coated. FIG. 2 is a schematic cross-sectional view of the coating layer of a comparative coated tool in which a carbide base material is coated with TiC and TiN layers and then coated with crystal ^QzOs. Figure 3 is a schematic cross-sectional view of the coating layer of a comparative coated tool in which a carbide base material is coated with a Ti (:, TiN layer) and then amorphous alumina. Figure 4 is a sintered Si, crystalline Si3N4 and amorphous A schematic cross-sectional view of the coating layer of a coated tool of the present invention in which 10 layers of silicon nitride are alternately coated. Figure 5 shows a coating of the present invention in which sintered Si3N4 is alternately coated with 36 layers of crystalline Si, N4, and amorphous silicon nitride. Schematic cross-sectional diagram of the coating layer of the tool. Figure 6 shows crystals on the cermet I material.
t of the coating layer of a tool in which 6 layers of N and "j゛morphous AQ-0-N are alternately coated, and -F is coated with 4 layers of crystalline AQzO,v and amorphous alumina alternately, for a total of 10 layers. @Metamenshiki diagram.

Claims (1)

[Claims] 1. Al in the carbide, cermet, and ceramic base material
, a tool coated with a film containing one or more of Si oxides, nitrides, and oxynitrides, in which the film has an amorphous layer with a thickness of 1.0 μm or less and an amorphous layer with a thickness of 2.0 μm.
A ceramic-coated cutting tool comprising at least four or more alternating layers of the following crystal layers. 2. The thickness of the alternating layers of amorphous layers and crystal layers made of one or more of oxides, nitrides, and oxynitrides of Al and Si is 6 μm or more, according to claim 1. cutting tools.