WO2014104589A1

WO2014104589A1 - Multi-crystal diamond sintered body using titanium coated diamond powder, and method for manufacturing same

Info

Publication number: WO2014104589A1
Application number: PCT/KR2013/010751
Authority: WO
Inventors: 전휘수; 박희섭; 안보경
Original assignee: 일진다이아몬드(주)
Priority date: 2012-12-28
Filing date: 2013-11-26
Publication date: 2014-07-03
Also published as: KR20140092474A; KR101443762B1

Abstract

The present invention relates to a multi-crystal diamond sintered body using titanium coated diamond powder and to a method for manufacturing same. Specifically, the multi-crystal diamond sintered body according to the present invention includes: a carbide layer; and a multi-crystal diamond layer provided on the carbide layer and formed by sintering diamond powder coated with a conductive metal. According to the present invention, processability is improved while maintaining the quality of an existing product, and thus production efficiency of the product itself can be increased and the yield and the reliability of the product can be improved.

Description

Polycrystalline Diamond Sintered Body Using Titanium Coated Diamond Powder and Manufacturing Method Thereof

The present invention relates to a polycrystalline diamond sintered body using titanium coated diamond powder and a method of manufacturing the same, and more particularly, to a polycrystalline diamond sintered body having improved workability and a method of manufacturing the same.

As the automotive and aviation industry develops, cutting tool materials with high wear resistance are required due to the increase in high-precision and high-efficiency (environmental) machining, and traditional cutting tool materials used in the past are being replaced by new materials. Representative materials include polycrystalline diamond (PCD). The polycrystalline diamond sintered body is manufactured by sintering under high temperature and high pressure (HPHT) based on diamond powder.

Specifically, the polycrystalline diamond sintered body is wet-mixed together with a metal binder, and is manufactured at a point when the bonding between the diamond particles is completed under high temperature and high pressure and is crystallographically stable. The polycrystalline diamond sintered body thus made is applied to nonferrous and difficult-to-machine materials.

However, in order to manufacture such a polycrystalline diamond sintered body as a cutting tool, it must be processed (cut) to a desired standard. The electric discharge machining method (Wire-EDM) is used for cutting the polycrystalline diamond sintered compact. However, the electrical conductivity contributes as an absolute factor to the workability by electric discharge machining. In the case of the polycrystalline diamond sintered body, the cutting is performed due to the WC disk used with the diamond layer and the metal binders added to increase the bonding strength. Diamonds that are not conductive have many difficulties in processing by electrostatic machining.

In order to solve this problem, a method of increasing the conductivity of the polycrystalline diamond sintered body is required. The first method can reduce the content of non-conductive diamond and relatively increase the content of highly conductive metal binder, but adversely affects the most important wear resistance of the polycrystalline diamond sintered body. The second method is to reduce the size of the diamond particles to increase the amount of cobalt (Co) leached out of the WC disc, which is a material assembled together. However, the polycrystalline diamond sintered body formed of large particles is used for roughing processing, and the polycrystalline diamond sintered body formed of small particles is used for fine surface roughness, thereby reducing the width of the application field.

The present invention provides a polycrystalline diamond sintered body and a method of manufacturing the same, which have higher conductivity than existing polycrystalline diamond sintered bodies and are easy for electric discharge machining (processability).

In another aspect, the present invention provides a polycrystalline diamond sintered body that can satisfy the processability and product quality simultaneously by minimizing the content of the metal binder and determining the size of the particles to suit the purpose.

Polycrystalline diamond sintered body according to the present invention is a cemented carbide layer; And a polycrystalline diamond layer provided on the cemented carbide layer and formed by sintering diamond powder coated with a conductive metal.

In addition, the conductive metal may be titanium (Ti).

Furthermore, the coating film of the conductive metal may be formed to a thickness of 200 to 300nm.

In addition, the coating film formed by the conductive metal may include a titanium carbide (TiC) component.

In addition, the polycrystalline diamond layer may further include a metal binder.

Furthermore, the metal binder may be cobalt (Co).

On the other hand, the polycrystalline diamond sintered body manufacturing method according to the present invention comprises a first step of producing a diamond powder; Coating a conductive metal on the diamond powder; A third step of mixing the coated diamond powder; A fourth step of filtering foreign matter from the mixed diamond powder; A fifth step of performing heat treatment to reduce metal components and remove foreign substances in the diamond powder; And a sixth step of sintering the heat treated diamond powder.

In addition, in the second step, the conductive metal may be coated by a sputtering method.

In addition, in the third step, the diamond powder may be dried simultaneously with mixing using a dry mixing method.

Furthermore, in the third step, drying and mixing may be performed by a ball mill using a ball made of tungsten carbide (WC) material.

According to the present invention, by increasing the conductivity of the polycrystalline diamond sintered body, it is possible to improve the workability due to the electrical discharge machining.

In addition, according to the present invention, it is possible to maintain the quality of the product by not affecting the content of the metal binder and the particle size of the diamond powder despite improving the workability.

That is, according to the present invention, by improving the processability while maintaining the quality of the existing product has the effect of increasing the production efficiency of the product itself and improve the yield and reliability of the product.

1 is a flowchart illustrating a method of manufacturing a polycrystalline diamond sintered body according to an embodiment of the present invention.

Figure 2 is a photograph of the diamond powder for producing a polycrystalline diamond sintered body according to a comparative example by a scanning electron microscope.

3 is a photograph of a diamond powder for preparing a polycrystalline diamond sintered body according to the present embodiment with a scanning electron microscope.

4 is a graph showing the results of the XRD peak of the diamond powder for producing a polycrystalline diamond sintered body according to the present embodiment.

5 is a graph showing the results of XRD peaks of the polycrystalline diamond sintered body according to the present example and the polycrystalline diamond sintered body according to the comparative example.

6 is a photograph for each component of a polycrystalline diamond sintered body according to a comparative example by a scanning electron microscope (SEM).

7 is a photograph for each component of the polycrystalline diamond sintered body according to the present embodiment by a scanning electron microscope (SEM).

8 is a photograph showing a state of a cut surface according to the electric discharge machining of the polycrystalline diamond sintered body according to the comparative example.

9 is a photograph showing a state of a cut surface according to the electric discharge machining of the polycrystalline diamond sintered body according to the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Unless otherwise defined or mentioned, terms indicating directions used in the present description are based on the states shown in the drawings. In addition, the same reference numerals throughout the embodiments indicate the same member.

The polycrystalline diamond sintered body is produced by sintering using a diamond powder and a metal binder on a cemented carbide substrate. Polycrystalline diamond sintered body according to the present invention

Compared with the general polycrystalline diamond sintered body, there is a difference in that the surface of the diamond powder used for sintering is coated with a conductive metal.

Titanium (Ti) may be used as the conductive metal. Titanium metal is one of the hardest materials as ferromagnetic. Other metal materials can be used to fabricate PCDs, but they can adversely affect the wear resistance that is inherent to polycrystalline diamond sintered bodies. In addition, the combination of diamond and Ti produces a material called TiC. TiC is weaker than C (diamond), but has higher electrical conductivity and higher hardness than cobalt (Co), which is mainly used as a metal binder.

In other words, although titanium is used as the conductive metal in the present embodiment, the present invention is not limited thereto. If the metal is ferromagnetic and easily wettable with diamond, it can be used for coating diamond instead of titanium. Ferromagnetic metals (alternative metals) include Fe, Ni, Co, Ti, Al, Ag, Au, Mo, and Nb. However, the above elements are relatively poor in wettability with diamonds, cannot be manufactured as targets, or react with diamonds at high temperatures, thereby degrading product performance or producing manufacturability compared to titanium.

Hereinafter, a method of manufacturing a polycrystalline diamond sintered body according to the present embodiment will be described with reference to FIG. 1.

First, in order to manufacture a polycrystalline diamond sintered body according to the present embodiment, diamond powder is manufactured (S10). That is, the particle size of the diamond powder is selected according to the purpose or the use of the product, and the diamond powder according to the selected particle size is prepared.

Next, the conductive metal is coated on the prepared diamond powder (S20). In this case, titanium (Ti) is used as the conductive metal as described above. Titanium is also coated on the diamond powder by sputtering. At this time, the titanium coating film is preferably formed to have a thickness of 200 to 300nm. When the coating film is formed with a thickness of 200 nm or less, it is difficult to obtain sufficient conductivity as desired, and when the coating film is formed with a thickness of 300 nm or more, the manufacturability of the product is deteriorated due to sintering problems.

* Then mix the coated diamond powder (S30). In the case of using a wet ball mill method, such as in the manufacture of a general polycrystalline diamond sintered body, there is a fear that the coated titanium may be damaged or peeled off. Therefore, in the present embodiment, the coated diamond powder is mixed using a dry ball mill method. At this time, the mixture is mixed for 3 hours at 45 rpm, and a ball mill is performed using a tungsten carbide (WC) ball.

On the other hand, this dry mixing method is accompanied by a side effect. That is, the diamond powder is dried during dry mixing, and thus, there is no need to perform a separate drying operation or process.

The mixed and dried diamond powder is filtered to filter foreign matter (S40). At this time, the material to be filtered includes fragments of tungsten carbide or other foreign substances added during the mixing process. In this embodiment, the sieve is sieved using a size of 45 μm.

Next, the diamond powder from which the foreign matter is removed is heat-treated (S50). Through the heat treatment step, the metal component contained in the coating layer of the diamond powder is reduced, and other foreign substances are removed. In the heat treatment step, the heat treatment is performed at 800 占 폚, 1.5hr, and vacuum / hydrogen atmosphere.

Next, as a previous step for sintering, the heat-treated diamond powder is assembled according to the desired shape (S60). Then, the granulated diamond powder is sintered (S70) to form a polycrystalline diamond sintered body. Sintering is about 1500? And 5 Gpa. Sintered polycrystalline diamond powder is completed by polishing.

With reference to Figures 2 to 4 it is checked whether the titanium coating layer is formed on the diamond powder by the manufacturing method as described above. FIG. 2 is a photograph of a diamond powder for preparing a polycrystalline diamond sintered compact according to a comparative example, and FIG. 3 is a photograph of a diamond powder for manufacturing a polycrystalline diamond sintered compact according to the present embodiment. 4 is a graph showing the results of XRD peaks of diamond powder for producing a polycrystalline diamond sintered body according to the present embodiment.

It is darker in the titanium coated diamond powder as shown in FIGS. 2 and 3. Titanium-coated diamond powder is believed to have a darker color because no charging occurs. Therefore, as shown in FIG. 3, it is determined that the conductivity of the titanium-coated diamond powder without charging is more excellent.

On the other hand, looking at the XRD peak of the titanium coated diamond powder as shown in Figure 4 it can be seen that the titanium carbide (TiC) is included. Titanium carbide (TiC) is a material generated by the combination of titanium and diamond, it can be seen that the coating film containing tungsten is formed in the diamond powder.

5 to 7, the components of the polycrystalline diamond sintered body according to the present example and the polycrystalline diamond sintered body according to the comparative example are compared. 5 is a graph showing the results of XRD peaks of the polycrystalline diamond sintered body according to the present embodiment and the polycrystalline diamond sintered body according to the comparative example, and FIG. 6 is a component of the polycrystalline diamond sintered body according to the comparative example by a scanning electron microscope (SEM). It is a star photograph, Figure 7 is a photograph of each component of the polycrystalline diamond sintered body according to the present embodiment by a scanning electron microscope (SEM).

As shown in FIG. 5, titanium carbide (TiC) components are also confirmed in a polycrystalline diamond sintered body manufactured at high temperature and high pressure using diamond powder coated with titanium. As described above, titanium is combined with diamond to form titanium carbide. Therefore, unlike the comparative example, the polycrystalline diamond sintered body according to the present example can confirm that there is a coating layer in which titanium and diamond are bonded by checking titanium carbide through XRD.

This can also be confirmed from the scanning electron micrographs of FIGS. 6 and 7. In the case of the polycrystalline diamond sintered body not coated with a metal as shown in FIG. 6, the Ti component was not confirmed, but in the case of the polycrystalline diamond sintered body coated with titanium as shown in FIG. It can be seen that the component forms a bonding structure.

Referring to FIGS. 8 and 9, a comparative experiment and a result of the polycrystalline diamond sintered body according to the present example and the polycrystalline diamond sintered body according to the comparative example will be described. 8 is a photograph showing a state of the cut surface of the polycrystalline diamond sintered compact according to the comparative example according to the electrical discharge machining, and FIG. 9 is a photograph showing a state of the cut surface according to the electrical discharge machining of the polycrystalline diamond sintered compact according to the present embodiment.

A polycrystalline diamond sintered body according to the present example was prepared for cutting processing comparison experiments. The polycrystalline diamond sintered body according to the comparative example was prepared in the same manner except for the metal coating. In the polycrystalline diamond sintered body according to the present example, it was confirmed that the coating film was formed by the XRD peak described above.

First, the electrical resistance value was measured through a digital multi meter (DMM) tool. DMM equipment is a machine that can measure the electrical resistivity of an object. Since electrical resistivity is the inverse of conductivity (electrical conductivity), the lower the measured value, the better the conductivity can be expected. As a result of measuring the electrical resistance values of the polycrystalline diamond sintered bodies according to the examples and the comparative examples at 1 cm intervals, the resistance of 2.6 Ω was measured in the example, while the resistance of 4.1 Ω was measured in the comparative example. As a result, it can be seen that the conductivity of the polycrystalline diamond sintered body according to the present embodiment is improved as compared with the comparative example.

Next, an electric discharge machining experiment was performed. The discharge machining experiment was performed using EDM-wire equipment, and the results are shown in Table 1 below.

As shown in Table 1, the example shows a cutting speed of 2.30 to 2.34 mm per minute, and the comparative example shows a cutting speed of 2.15 to 2.17 mm per minute. That is, as described above, in the case of the embodiment, it is determined that the cutting speed is improved by improving the electrical conductivity as compared with the comparative example.

On the other hand, in the comparative example, the direct damage zone was 19.15 μm and the indirect damage zone was measured to be 200 μm. In contrast, in the case of the example, the direct daisy zone was 17.66 μm and the indirect damage zone was 175 μm. As can be seen in FIGS. 8 and 9, in the case of the embodiment, the damage at the cut surface was further reduced despite the faster cutting speed due to the electric discharge machining.

That is, in the polycrystalline diamond sintered body according to the present invention as described above, the electrical conductivity is improved, so that the cutting speed due to electric discharge machining is improved, and the quality of the cut surface is improved. Improved cutting speeds and quality of cut surfaces result in improved production speeds, yields and quality.

Although the preferred embodiments of the present invention have been described above, the technical spirit of the present invention is not limited to the above-described preferred embodiments, and various polycrystalline diamond sintered bodies and within the scope not departing from the technical spirit of the present invention specified in the claims and It can be implemented by the manufacturing method.

Claims

Cemented carbide layer; And

And a polycrystalline diamond layer provided on the cemented carbide layer and formed by sintering diamond powder coated with a conductive metal.
The method of claim 1,

The conductive metal is titanium (Ti) polycrystalline diamond sintered body.
The method of claim 2,

The coating film of the conductive metal is a polycrystalline diamond sintered body formed to a thickness of 200 to 300nm.
The method of claim 2,

The coating film formed by the conductive metal is a polycrystalline diamond sintered body containing a titanium carbide (TiC) component.
The method of claim 1,

The polycrystalline diamond layer further comprises a metal binder.
The method of claim 5,

The metal binder is cobalt (Co) polycrystalline diamond sintered body.
A first step of preparing diamond powder;

Coating a conductive metal on the diamond powder;

A third step of mixing the coated diamond powder;

A fourth step of filtering foreign matter from the mixed diamond powder;

A fifth step of performing heat treatment to reduce metal components and remove foreign substances in the diamond powder; And

And a sixth step of sintering the heat treated diamond powder.
The method of claim 7, wherein

In the second step, the polycrystalline diamond sintered body manufacturing method of coating the conductive metal by the sputtering method.
The method of claim 7, wherein

In the third step, a method for producing a polycrystalline diamond sintered body by drying the diamond powder at the same time by mixing using a dry mixing method.
The method of claim 9,

In the third step, the method of manufacturing a polycrystalline diamond sintered body is dried and mixed by a ball mill (ball mill) using a ball of tungsten carbide (WC) material.