JPH04128378A - Coated cemented carbide - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of the film of the coated cemented carbide and to greatly prolong the tool life by forming the boundary face of the hard phase of the cemented carbide base material to constitute the film of the 1st layer and the forming phase of an NaCl type crystal. CONSTITUTION:The part from 0.5mum to 8mum of the surface part of the base material consisting of the cemented carbide is formed of the boundary layer constituted of the hard phase of the cemented carbide and the forming phase consisting of the NaCl type crystal. The film of the above-mentioned forming phase is formed at <=15mum thickness on the front surface thereof to form the coated cemented carbide. The hard phase of the cemented carbide base material is formed of a WC phase or the WC phase and the double carbide phase or double carbonitride phase of W, Ti, Ta, and Nb. The coating with which the forming phase of the NaCl type crystal consists of one kind of TiC, Ti(C, N), TiN is preferably formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a coated cemented carbide used as a tool material,
More specifically, the present invention relates to a coated cemented carbide that has a high adhesion strength to the cemented carbide base material and has improved wear resistance and chipping resistance.

[Prior Art] Conventionally, coated cemented carbide is produced by depositing Tic, Ti on the surface of a cemented carbide base material having a sintered surface or a ground surface by a vapor phase deposition method.
Tools coated with one or more types of ceramics such as (C,N), TiN, and Al2O3 are widely used as wear-resistant tools or cutting tools.

[Problems to be Solved by the Invention] However, in coated cemented carbide, in order to coat hard ceramics with different characteristics on the surface of a cemented carbide base material with a relatively high toughness value, the coating is applied to the cemented carbide base material. It is not possible to increase the adhesion strength.

Therefore, when a coated cemented carbide with low adhesion strength is used under severe conditions, the coating on the surface of the cemented carbide base material peels off, making it impossible to obtain the desired tool life.

[Object of the Invention] The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a coated cemented carbide that can improve the adhesion of the coating of the coated cemented carbide and greatly extend the tool life. It is something.

[Means for Solving the Problems] The present invention solves the aforementioned problems by the means described below.

That is, 0.5 μm of the surface of the base material made of cemented carbide.
to 8 μm is an interfacial layer composed of a hard phase of cemented carbide and a generated phase consisting of NaCl type crystals, and a coating of the generated phase with a thickness of 15 μm or less is formed on the upper surface of the interface layer. The first aspect is the alloy, and the hard phase of the cemented carbide base material is composed of a WC phase or a WC phase and a double carbide phase or a double carbonitride phase of W, Ti, Ta, and Nb, and a generated phase consisting of NaCl type crystals. is TiC, Ti (C,N), Ti
The second gist is a coated cemented carbide made of one type of N, and the third gist is
T i C1 on the upper surface of the coated cemented carbide described above.
One or more types of coatings selected from the group consisting of Ti (C,N), TiN, and A1203 are formed, and the total thickness of these coatings is 1 μm to 15 μm.

[Operation of the invention] One of the reasons why conventional coated cemented carbide does not always have satisfactory adhesion strength between the cemented carbide base material and the coating is as follows.
Since the contact interface between the base material and the coating is smooth, it cannot withstand the stress received during cutting, and the coating is likely to peel off from the cemented carbide base material.

In order to solve the above-mentioned problems of the conventional technology, it is necessary to increase the contact area between the cemented carbide base material and the coating, and to create an interface area with geometric irregularities on the contact surface between the base material and the coating. It has been found that the adhesion strength of the coating to the base material is greatly improved by forming the coating.

That is, by forming an interfacial phase between the hard phase of the cemented carbide base material and the NaCl type crystal, which becomes the first layer coating of the base material, this first layer coating is formed on the base material. The coating exists in a rooted form on the surface of the base material and has a structure that sufficiently resists large stresses received during cutting, and the coating does not easily peel off from the base material.

In other words, the formation of the above-mentioned film on the surface of the cemented carbide base material involves dissolving and removing the bonded metal phase on the surface of the cemented carbide to form a depression or cavity, and then vapor-phase deposition. TiC with NaCl crystal structure by method,
By depositing either Ti (C, N) or TiN in the recesses or cavities on the surface of the base material and continuously coating the surface of the base material, a superhard material can be formed as shown in Figure 1. The adhesion strength of the coating to the alloy base material, which has an interfacial layer consisting of the hard phase of the cemented carbide and the generated phase of NaCl crystals on the surface of the alloy base material, and a coating consisting of the generated phase continuously coated on the surface. A coated cemented carbide with extremely high hardness can be obtained.

The reason why the surface area of the cemented carbide base material, which becomes the interfacial phase, is set to 0.5 to 8 μm is because if it is less than 0.5 μm, a film with high adhesion strength cannot be obtained, and if it exceeds 8 μm, it will have a NaCl type crystal structure. This is because it is difficult for the generated phase consisting of the above to completely enter the recess or cavity, leaving it as a bore or significantly reducing the surface roughness and lowering the surface strength.

Further, the coating thickness of the generated phase that is coated subsequent to the above-mentioned interface layer is set to be 15 μm or less (not including 0) because if it exceeds 15 μm, the surface strength will decrease.

Then, the first layer of the coating consisting of the same generated phase as the generated phase in the interface layer is replaced with Tic, Ti (C,N
), TiN was used because it has the best hardness, that is, wear resistance, among ceramic coatings, and also has good affinity with the cemented carbide base material.

TiC, Ti (C1N), Ti
The reason for using one or more selected from the group consisting of N, Al10B is that these ceramic coatings have wear resistance,
This is because it has excellent heat resistance, oxidation resistance, and friction resistance, and at the same time, it can be stably produced by vapor phase deposition and has good affinity with the first layer coating described above. be.

[Example] Example 1 Cutting tip made of cemented carbide (tip shape, ISO5
NGN120412) is formed, the Co phase on the surface is removed by electrolytic treatment in an acidic bath of pH 3 to 4, and then a TiC coating is applied by chemical vapor deposition to form the coated carbide of the present invention having an interface layer. Made an alloy. Details of these are shown in Table 1. Comparative cutting tips coated with TiC by conventional chemical vapor deposition were also made and shown in Table 1.

The composition of the cemented carbide base material of each sample described above is WC:
A cutting test was conducted using the above samples with 94% Co and 6% under the cutting conditions shown in (1) of Table 2.
The tool life until flank wear reached a maximum of 0.3 mm was determined.

Table 1 Table 2 As a result of testing using the cutting method (1) shown in Table 2, coated cemented carbide No. 11 of the present invention reached flank wear of 0.3 mm in 25 minutes, and similarly I-2: The life span was reached in 28 minutes, whereas the comparison product I-3 lost its cutting edge after a 5-minute test, and the same <r-4 lost its cutting edge after a 1-minute cutting test. has been discontinued.

Example 2 The composition of cemented carbide is WC: 90%, (W, Ti)C: 3
%, TiN: 1%, cutting tip consisting of co=6% (
Using chip shaper So 5NGN120412),
After electrolytically removing the Co phase on the surface of this chip, Ti (C,N) was coated by chemical vapor deposition to obtain a coated cemented carbide according to the present invention.

In addition, for comparison, a conventional coated cemented carbide in which a TiC film was directly coated on a cemented carbide base material by a chemical vapor deposition method was also prepared. The hard phase was converted to WCl (W,
Ti) (C, N), the generated phase is Ti (C, N), the thickness of these is 2 μm, and Ti (C, N) is formed on the upper surface.
) was coated with 8ttm.

In addition, the comparative product does not have an interface layer and has a 10 μm coating of Ti (C, N) on the surface of the cemented carbide base material. The peeling load of the coating, which is a measure of the adhesion force between the alloy base material and the coating, was determined by a scratch test method using a diamond indenter, and then Table 2 (2
) A cutting test was carried out under the cutting conditions shown in Example 1 to find the same tool life as in Example 1. As a result, the coated cemented carbide of the present invention showed a peeling load of 85 (N), and the tool life was shortened in the 12 minute test. In contrast, the comparative product reached the end of its life after a 5-minute test with a peeling load of 53 (N).

Example 3 Composition of cemented carbide: WC: 86%, (W, Ti)C: 2
%, (Ta, Nb)C: 5%, cutting tip (chip shape, ISOSNMG120412
) to electrolytically remove the CO phase on the surface of this chip, and then coated with TiC-Al2O by chemical vapor deposition to obtain a coated cemented carbide according to the present invention.

TiC-Al2 was prepared by thermal chemical vapor deposition for comparison.
A coated cemented carbide was prepared by directly coating a cemented carbide base material of the above composition with an O3 film.

The details of the above samples are that the coated cemented carbide of the present invention has a hard phase as an interface layer of Wc, (W, Ti, Ta, Nb)C
The generated phase was TiC, and these layers were coated with TiC (4 μm)-Al103 (2 μm) to a thickness of 1 μm.

In addition, the comparative product does not form an interfacial phase and has Tic (
5 μm)-A1203 (2 μm).

A cutting test was performed on the above sample under the cutting conditions shown in Table 2 (3), and the tool life similar to that in Example 1 was determined.

As a result, the coated cemented carbide of the present invention has a peeling load of 8
1 (N) and a 25-minute test was possible, whereas the comparative product had a peeling load of 45 (N) and reached the end of its life after a 15-minute test.

Example 4 Composition of cemented carbide: WC: 85%, (W, Ti)C: 5
%, TiN: 2%, CO: 8% (
After electrolytically removing the CO phase on the surface of the chip, a coated cemented carbide according to the present invention was obtained by coating TiN-Al2O3-TiN by chemical vapor deposition.

For comparison, TiNAIz○ was also produced by chemical vapor deposition.
A coated cemented carbide was also prepared in which a 3-TiN film was directly coated on a cemented carbide base material having the above composition.

The details of the above sample are such that the coated cemented carbide according to the present invention has WC as a hard phase serving as an interfacial phase, TiN as a generated phase, and has a layer thickness of 2 μm. ■TiN (
4μm), Al103 (3μm), TiN (1μm)
coated.

The surface layer of the comparative product is TiN (5 μm), A12
03 (3 μm) and TiN (1 μm).

The above-mentioned samples were tested under the cutting conditions shown in Table 2 (3), and tool life similar to that in Example 1 was determined.

As a result, the coated cemented carbide of the present invention exhibited a peeling load of 85 (N) and was capable of cutting for 30 minutes, whereas the comparative product had a peeling load of 43 (N) and could be cut for 30 minutes. The time was 18 minutes.

Example 5 The composition of the cemented carbide base material was WC: 87%, (W, Ti
) C2 2%, (Ta, Nb) C; 2%
Using a cutting tip (chip shape, ISO5NGNI 20412) consisting of , TiN: 1%, and CO: 8%, the CO phase on the surface of these was removed in the same manner as in implementation f!41, and then the surface was A coated cemented carbide of the present invention and a comparative coated cemented carbide were prepared by coating, the details of which are shown in Table 3.

Tests were conducted using each of the above samples under the cutting conditions shown in (3) of Table 2. The life measurement was the same as in Example 1.

The result of the above test is that sample V-1 of the coated cemented carbide according to the present invention can be cut for 35 minutes with a peeling load of 90 (N), and Sample V-2 can be cut for 35 minutes with a peeling load of 85 (N). However, the comparison product V3 lost its cutting edge after 6 minutes of cutting, and the V-4 had a peeling load of 55 (N).
), the flank wear of the cutting edge was 0.3 mm after 17 minutes of cutting.
Reached.

Example 6 Two drawing dies (inner diameter 130 mm, outer diameter 180 mm, height 15 mm) were prepared using cemented carbide with a composition of WC: 94% and CO: 6%, and one of them was made by chemical vapor deposition. A conventional drawing die was made by coating with Ti (C,N) to a thickness of 15 μm and, after casing, grinding the film to a thickness of 8 to 10 μm.

Another method is to adjust the CO phase on the surface of the cemented carbide to a pH of 3 to
After removal by electrolytic treatment in an acidic bath in step 4, Ti (C5N) was coated by chemical vapor deposition to separate the WC phase and Ti.
The interfacial layer consisting of (C,N) phase is 2μm, Tic,N)
A coating of 13 μm was formed, and after gauging, the coating was ground to a thickness of 8 to 10 μm to obtain a drawing die according to the present invention.

Using the above-mentioned drawing die, we tested a cold rolled steel plate of 5pc without lubrication at a machining speed of 100 mm/sec and a rate of 30 pieces per minute. On the other hand, the conventional drawing die mentioned above reached the end of its life after about 500,000 dies.

[Effects of the Invention] As described above, the coated cemented carbide of the present invention has greatly improved adhesion between the cemented carbide base material and the coating compared to conventional coated cemented carbide, and is resistant to harsh use. It is possible to prevent a decrease in tool life due to peeling of the coating under certain conditions, and provide a coated cemented carbide with a stable tool life.

4,

[Brief explanation of the drawing]

Figure 1 is a microscopic photograph of the coated cemented carbide according to the present invention. (1000x magnification) ゛Super hard 6/1 official: Mother (Niji) Procedural amendment method %formula% Display of incidents 1990 Patent Application No. 25 No. 50 person who makes corrections Relationship with the incident

Claims (3)

[Claims] (1) From 0.5 μm to 8 on the surface of the base material made of cemented carbide
μm is an interface layer composed of a hard phase of cemented carbide and a generated phase consisting of NaCl type crystals, and a coating of the generated phase of 15 μm or less is formed on the upper surface of the interface layer. coated cemented carbide. (2) The hard phase of the base material made of cemented carbide is WC phase or W
It is characterized by consisting of a C phase and a double carbide phase or a double carbonitride phase of W, Ti, Ta, and Nb, and the generated phase consisting of NaCl type crystals is composed of one type of TiC, Ti (C, N), and TiN. coated cemented carbide. (3) The coated cemented carbide according to claims 1 and 2, wherein the second or higher coating is selected from the group consisting of TiC, Ti(C,N), TiN, and Al_2O_3. A coated cemented carbide, characterized in that the total layer thickness of the coating is from 1 μm to 15 μm using one or more types.