JPH0317251A - Wear resistant film - Google Patents

Abstract

PURPOSE:To form the film having the high adhesive property to the tools and excellent wear resistance and to improve the performance and life of working tools consisting of high-speed steels and cemented carbide steels by forming a specifically composed Ti carbonitride layer and carbonitride layer of Al and Ti on the surface of the working tools by a PVD method. CONSTITUTION:The carbonitride layer of Ti expressed by TiCXN1-X (0<=X<=0.6 in this case) is first formed at 0.3 to 6mum thickness by an ion plating method or sputtering method, etc., on the surface of the working tools consisting of the high-speed steels and cemented carbide steels used for milling, cutting, boring, etc. The carbonitride layer of Ti and Al having the compsn. expressed by (AlYTi1-Y) (N2C1-Z), (0.05<=Y<=0.75, 0.8<=Z<=1 in this case) is then formed at 0.6 to 8mum thickness via an intermediate layer therein. The intermediate layer of the mixed compsn. of the compsns. of these two layers or the intermediate layer of the compsn. continuously changing to the compsns. of the two layers is interposed between these two layers. The film having the high adhesive property to the base metal of the tools and the excellent wear resistance is formed. The working performance and service life of the tools are thus improved.

Description

[Detailed description of the invention] [A field of application] The present invention is applicable to milling. Coat the surface of machine tools used for cutting, drilling, etc.

[Prior art] When manufacturing high-speed tool steel, cemented carbide tool steel, etc., nitrides such as Ti or other substances are added to the surface of the tool base material in order to improve performance such as wear resistance. The use of a wear-resistant film made of carbide is being practiced. CVD (chemical vapor deposition) and PVD (physical vapor deposition) are conventionally known methods for forming a wear-resistant film on the surface of a substrate. However, the former method exposes the base material to high-temperature treatment, which may result in deterioration of the base material properties, so the latter method tends to be preferred for tools where base material properties are also important.

Therefore, high frequency discharge plasma CVD method and reactive ion blating method, which can perform coating treatment under relatively low temperature conditions, are recommended. Sputtering methods and the like have come to be adopted.

TiN and TiC formed by ion plating are commonly used as wear-resistant films for tools and the like, and in particular, TtN films, which have excellent high-temperature oxidation resistance (heat resistance), have been widely put into practical use. That is, since TIN has better heat resistance than TiC, it exhibits the function of protecting the tool rake face from crater wear, which increases in temperature due to machining heat and frictional heat during cutting. However, Ti
Nitrogen is rather vulnerable to flank wear that occurs on the flank surface in contact with the work material, which has a lower hardness than TiC, and TiC exhibits higher durability against flank wear. In recent years, there has been a demand for higher cutting speeds, and cutting conditions tend to become more severe, so the conventional TiN coatings described above are no longer able to meet this demand. Therefore, as a film with even better heat resistance and hardness, TiAIN, which is produced by ion blating method or sputtering method,
Films such as TiAIC or TiAICN have been proposed [
Japanese Patent Publication No. 62-56565, J. Vac. Scl.
Technol. A No. 4 (6) @, 1981
i year 1 page 27l7. and J. of Sold
Stateft+em1stry, 70. 1987. pp. 318-322].

[Problems to be Solved by the Invention] Since the PVD method is a low-temperature coating method that utilizes the energy of ions, there is no thermal diffusion layer between the base material surface and the film as seen in the CVD method. Therefore, PVD
Films formed by the CVD method generally have poorer adhesion than films formed by the CVD method.

On the other hand, in recent years, there has been a tendency to make films thicker in order to improve wear resistance and extend service life, but as the film becomes thicker, the internal stress of the film increases, causing cracks to occur in the film. IiI adhesion decreases and causes film peeling. As mentioned above, (AI, Tt) (N, C) based coatings have been proposed as highly wear-resistant coatings that can replace TiN coatings, but these coatings have lower internal stress than TiN coatings. Since the thickness is more than twice as high, it is put into practical use by forming the thickness as thin as possible than when forming a TtN film.

For these reasons, it is desired to improve the film formation technology, which can fully exhibit the excellent properties of (AI, Ti) (N, C) based films. The present invention was developed in view of these circumstances, and it is possible to form a film under relatively low temperature conditions, yet it has excellent adhesion and film strength, and is resistant to crater abrasion and flank abrasion. The purpose of this invention is to provide an excellent wear-resistant coating.

[Means for Solving the Problems] The present invention that achieves the above object is based on TiCxNl-. (
However, a film layer having a chemical composition of O≦X≦0.6) and having a layer thickness of 0.3 to 6 μm is formed on the surface of the substrate, and (A I , T i +−y) (N c+-i
(However, 0.05≦y≦0.75, 0.6≦Z≦1) Consisting of the chemical composition shown, a film layer with a layer thickness of 0.6 to 8 μm is formed as the top layer, and consists of at least two layers. It is a wear-resistant film with a key point.

[Operation] The present invention is configured as described above, but in short, T i C
．． Nl-. (However, 0 ≦
I, Ti tyN Nz c. −． ) (However, 0.05
Chemistry m expressed by ≦y≦0.75, 0.6≦Z≦1)
The present invention was completed based on the discovery that a wear-resistant film with excellent film strength could be realized by forming a skin layer made of cylindrical lili as the top layer. In addition, in the film of the present invention, between the above two skin layers, a chemical composition containing a mixture of precepts that compose the respective film layer compositions, or continuously over the two film layer compositions, is added. It is preferable to interpose an intermediate layer having a changed chemical composition, and by interposing this intermediate layer, the effects of the present invention become even more remarkable.

In forming each of the above-mentioned film layers, a method of ionizing metal components by arc discharge using a cathode as an evaporation source, that is, a PVD method typified by an ion blating method, a sputtering method, etc. can be used.

Among these methods, for example, what about the ion blating method? Let's take a look at it and explain it.

In this method, ionized metal components as described above are reacted in an N2 atmosphere or N2/CH4 atmosphere to coat nitrides and nitride carbides. As a cathode, Ti
When the purpose is to form a (C,N)-based film, Ti may be used; on the other hand, when the purpose is to form an (At,Ti)(C.N)-based film, Ti and AI may be used separately. Although it can also be used, A consisting of the target composition itself
I. Ti. By targeting (2), it is easy to control the film composition.

Since the evaporation of each alloy component is carried out in a large current range of several tens of amperes or more, there is almost no deviation in the composition of the cathode material. Moreover, it has high ionization efficiency and high reactivity, and by applying a bias voltage to the substrate, a film with excellent adhesion can be obtained.

The solid solution amount of C in the formed film can be determined by X-ray analysis, Auger analysis, etc., and by knowing the correlation between the analysis value and the CH4 flow rate, more accurate composition control can be performed. In the present invention, the composition of the film layer formed on the surface of the base material (hereinafter sometimes referred to as the first film layer) is
is TtC. N1-. (However, O≦X≦O.Ii) It is necessary to be transparent. The reason why the chemical composition of the first film layer is limited as described above is to take into consideration the adhesion to the surface of the base material. Note that the first coating layer may also be TiN (when x=O), which has a lower internal stress than the (AI, Tt) (N, C) coating.5Although the effects of the present invention can be achieved, even higher wear resistance can be achieved. In order to exhibit this, it is desirable to use a Ti (C.N) based skin I1i (where x≠O and @). The reason is as follows.

TiC has a room temperature hardness (Hv) of 3100 kg/a
TiN has a high oxidation resistance and low heat resistance, but has the disadvantage of lacking heat resistance and being easily oxidized.On the other hand, TiN has good oxidation resistance at high temperatures and can easily form a film layer with good adhesion even at relatively low temperatures. However, the disadvantage is that the Hv is rather low at less than 2000 kg/mm2.

On the other hand, in the TfN-TiC solid solution film layer with the chemical composition represented by the general formula TtCXN+-x, by appropriately adjusting the amount of C solid solution (X), it has good adhesion and excellent oxidation resistance. It is possible to obtain the high hardness of TIC while having the properties of TiN. In other words, the first skin U has the properties of TiN, but increases in hardness as the solid solution amount of C increases (as x increases), and exhibits excellent performance in terms of flank wear resistance. As X increases, the hardness of the skin rFA layer increases, flank wear disappears, and the color of the film starts to turn from golden to reddish, and as Ci increases, the color changes further from red to gold, improving adhesion and Regarding oxidation resistance, performance that satisfies this is maintained. On the other hand, when X exceeds 0.6, adhesion and oxidation resistance deteriorate,
Minute film peeling occurs at the edge portions of tool members, etc., making it easy to cause crater wear. Further, the membrane velocity decreases as the amount of C solid solution increases, and the decrease is significant in the region where X exceeds 0.6. For the above reasons, in the tree invention, the range of X is 0
~0.6.

The thickness of the first film layer must be 0.3 to 6 μm.
When the layer thickness is less than 0.3 μm, skin 11I is formed on the top layer.
The internal stress of Fj cannot be appropriately relaxed, while P
When JJg exceeds 6 μm, the strength of the film itself decreases.

Next, the chemical composition of the film layer (hereinafter sometimes referred to as the surface layer) formed on the top layer is (A I, Ti+-yH Nt C,-,) However, 0
．． It is necessary that 05≦y≦0.75, 0.6≦2≦1, preferably 0,6≦y≦0.
It is 7.

The solid solution having the above surface layer composition will be described as a nitride-based solid solution. This solid solution has an edge composition of AIN-TiNft, and as a result of investigating various component ranges, as shown in Figure 1, the internal stress (compressive stress) is T
t N(7) 1.9 x 1 0 "dyne/cm'
Compared to (A ly T ! i-y) N ( :J
is 0.05 or more) Teha y = 0.6 1 Teha average 4.
It can be seen that the value is as high as 7 x 10 I0dyne/cm'. Further, as the AIN component increases, the internal stress decreases accordingly, and at y = 0.7, the crystal structure changes from NaCl type (B14IIll structure) to ZnS (wurtzite type), and the internal stress becomes 2.8x. 1 0
"dyne/cm".

FIG. 2 is a graph showing changes in hardness when changing y in the (A 1 y Ti t-y)N film layer.

As is clear from Fig. 2, as y increases from 0, the H V 4 2 0 0 0 kg/m of TiN decreases.
The hardness increases from , and when y is 0.6, H'v 'v
The maximum value is about 3000 kg/am', and as y becomes larger from 0.6, the hardness decreases due to changes in the crystal structure. When y becomes 0.75, Ti
Hardness is almost equal to that of H, and if it exceeds 0.75, TiN
hardness. That is, the AIN solid solubility (y) is 0.
If it exceeds 75, the coating layer composition approaches AIN, resulting in softening of the coating layer, making it impossible to obtain sufficient hardness and easily causing flank wear.

From the above results, in the present invention, considering both wear resistance and internal stress, the value of y (A I N hardness) is set to 0.
．． It was set as 0.05 to 0.75. A more preferable range of y is 0.6 to 0.7.

In addition, in the present invention, Tic
High hardness (room temperature hardness Hv: approx. 3100 kg/mn+2
). That is, in the composition formula of the present invention, as the value of 2 decreases, the hardness increases and the wear resistance improves.

Figure 3 shows (A 1 o.asT l O.35) (N-
CI-z) [However, Z-tension 0.4, 0.6,
0.8, 0.9.1] to a thickness of 3 μm, and the work material S50
The results of measuring the amount of crater wear after 15 minutes when C was cut at a cutting speed of 170 m/a+In, a feed rate of 0.25 n++o/rev, and a depth of cut of 0.1 mm are shown.

As seen in these results, when 2 is less than 0.6, oxidation resistance decreases and crater wear becomes more likely to occur. 2≧0
．． Within the range of 6, no significant decrease in oxidation resistance is observed. Therefore, in the present invention, the range of 2 is set as 0.6 to 1.0. As will be made clear in the examples described later, when the thickness of the surface layer is 0
．． If it is less than 6 μm, the wear resistance will be insufficient due to the effect mainly due to the first coating layer, while if it exceeds 8 μm, cracks will easily occur in the film itself, resulting in insufficient strength. Therefore, in the present invention, the layer thickness of the surface layer is 0.6 to 8 μm.
In the present invention, it is preferable to interpose an intermediate layer between the first coating layer and the surface layer, which has a mixed or graded composition of both coating layer components. This intermediate layer includes a Ti cathode for forming a first film layer, an AI for forming a surface layer, a Ti cathode for forming a first film layer, and a Ti cathode for forming a surface layer in a vacuum chamber. , N2 or N2/CH. In the atmosphere
It can be formed by creating an arc discharge simultaneously or with controlled power. By interposing such an intermediate layer between the first skin layer III and the surface layer, it is possible to realize a wear-resistant film that has excellent adhesion to the base material while alleviating the internal stress of the surface layer.

Also, by adopting such a configuration, T I I
-y N t C +-g The total thickness can be made larger than that of a single film, resulting in a film with better heat resistance and abrasion resistance.

As is clear from the examples described later, the thickness of the intermediate layer is
A stress relaxation effect is recognized with a thickness of about 0.2 μm, and a maximum thickness of 0.5 μm is sufficient.

Examples will be described below, but the present invention is not limited to the following examples, and it is within the technical scope of the present invention to make appropriate design changes in accordance with the spirit of the above and below.

[Example] Example 1 Ti cathode electrode and AI y T'try
A cemented carbide chip (WC-10% Co
) was installed. The Naoki equipment was equipped with nine base material rotation mechanisms and a heater to ensure uniformity in the formation of the wear-resistant film. During film formation, the substrate temperature was maintained at 450°C using a heater, and the substrate was heated to -7°C.
While applying a bias voltage of 0 V, high-purity N2 gas was introduced into the device up to 5 x 10-'' Torr, arc discharge was started, and T I (CX Nl -
* ) system film layer (first film layer), intermediate layer and (A 1
yT t +-yN NIL c,-,)-based skin g layers (surface layers) were laminated in this order to form various films. The layer thickness was measured by breaking one of the substrates attached to the substrate holder at the same time and observing the layer cross section with a scanning electron microscope. Further, to quantify the layer composition, the layer depth direction was analyzed using Auger spectroscopy on the base material attached at the same time. As a result, the concentration remained constant with no change in the thickness direction of the first film layer and the surface layer. An example of the analysis results is shown in FIG. 4 above. The metal component ratio T i /A l in the film did not deviate from the cathode component ratio and could be said to be almost the same.

For each film obtained, the cutting conditions were as follows:
The flank wear width was measured when subjected to a cutting test for 1 minute.

Cutting conditions: Work material S50C Cutting speed 1 70,200m/Ilin feed rate 0.25 mm/rev depth of cut 0.1
mm The results are shown in Table 1 along with the composition and layer thickness of each layer.

Table 1 shows comparative samples, (AI, Ti) (C, N) monolayer films formed in the same manner as in Example 1 (Nos. 8 to 10), and Even if the first film layer is outside the scope of the present invention (No. 11), its composition,
Layer film and flank wear width are shown.

As is clear from Table 1, all of the examples of the present invention were superior in wear resistance compared to the comparative examples.

An example of application to a carbide drill is shown below.

Example 2 Various coatings were formed in the same manner as in Example 1 on a 61φ (WC-9.5% Co-based carbide drill) drill.

Each of the obtained films was cut under the following conditions.

Cutting conditions: Work material 350C, 13mm' (HB230~250) Cutting speed 80m/nin Feed rate 0.2 mIII/rev Lubrication
The results of the number of holes punched using Emulge B are shown in Table 2 along with the composition and layer thickness of each film layer.

As is clear from Table 2, the tool obtained by the method of the present invention is
A significant increase in the number of processed pieces was observed compared to the comparative example, and the wear resistance was good. An example of application to a high speed steel drill is shown below.

Example 3 Various coatings were formed on a 6mIIlφ high-speed steel drill in the same manner as in Example 1.

Each of the obtained films was cut under the following conditions.

Cutting conditions: Rigid material: S50C, 10mmt Cutting speed: 30m/in Feed rate: 0.18mm/rev Lubrication The results of the number of holes drilled using emulsion are shown in Table 3, along with the composition and layer thickness of each coating layer. .

As is clear from Table 3, the tool obtained by the method of the present invention is
There was a significant increase in the number of processed pieces compared to the comparative example, and the wear resistance was good.

[Effects of the Invention] Since the present invention is configured as described above, it has the good adhesion to the base material inherent to the Ti(C,N)-based film based on TiN, and the surface layer has III b Since the film layer is a solid solution of Tt in AIN, which is a nitride of the group, it has high heat resistance. It exhibits excellent properties similar to AIN in terms of thermal conductivity, etc.

[Brief explanation of drawings]

Figure 1 is a graph showing changes in internal stress when changing y in the (A ly T i + -y) N-based coating layer, and Figure 2 is a graph showing (A 1 y T i + -y)
A graph showing changes in hardness when changing y in the N-based film layer, Figure 3 is (A 1 o. ssT j
0. 35) A graph showing the amount of crater wear during cutting of the hardness tip when changing the hardness of 2 in the (N-CI-x) based coating. It is a graph showing an example of a analysis result. Figure 1 AIN (mol%) in TiN (Al,Ti)N Figure 3 Z (Alo.65Tio35) (N2C1-2)
Figure 2: Z solid solubility TiN AIN Sputtering time (min) Sputtering time (rron)

Claims (2)

[Claims] (1) TiC_xN_1_-_x (however, 0≦x≦0.
6), with a layer thickness of 0.3 to 6μ
A film layer of m is formed on the surface of the base material, and (Al_yTi_1_-_y)(N_zC_1_-_z
) (However, 0.05≦y≦0.75, 0.6≦z≦1) A film layer having the chemical composition shown and having a layer thickness of 0.6 to 8 μm is formed as the uppermost layer, and at least two layers A wear-resistant film characterized by: (2) The method according to claim (1), wherein an intermediate layer having a chemical composition that is a mixture of the respective film layer compositions or a chemical composition that continuously changes over the two film layer compositions is interposed between the two film layers. Abrasion resistant coating as described.