CN104507603A - Polycrystalline cubic boron nitride (pcbn) body made with distinct layers of pcbn - Google Patents

Abstract

A polycrystalline cubic boron nitride (PcBN) is fabricated using a process of overlaying layers of cubic boron nitride (cBN) powder, where the layers have cBN mixed with various concentrations of a ceramic. The process of fabricating the PcBN includes depositing, in a refractory capsule, a carbide, a cubic boron nitride (cBN), and a mixture of cBN and a ceramic, then applying a high pressure and high temperature (HPHT) to the content of the refractory capsule. During the depositing step of the process, the concentration of cBN in the mixture of the cBN and ceramic is lower than the concentration of cBN that is in the layer below it. Upon applying HPHT, the carbide first diffuses across the cBN layer, and then diffuses across the layer with the mixture of the cBN and ceramic. After HPHT ends and the content of the refractory capsule cools, the process yields a PcBN having layers with various concentrations of cBN, and at least one cBN layer with a ceramic material.

Description

Polycrystalline cubic boron nitride (PcBN) bodies fabricated using different PcBN layers

Cross References to Related Applications

This application claims priority to provisional application 61/670676, filed July 12, 2012.

technical field

The invention relates to a polycrystalline cubic boron nitride (PcBN) body. More particularly, the present invention relates to a PcBN body manufactured using a method comprising overlaying a layer or pre-compacted disk of cubic boron nitride (cBN) powder, wherein the The layers have cBN mixed with different concentrations of ceramics.

Background technique

In the discussion that follows, reference is made to specific structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not constitute prior art against the present invention.

In conventional polycrystalline cubic boron nitride manufacturing methods, the substrate adjoins a PcBN layer which is made in its entirety of a single grade (ie, cBN is the predominant material in the layer). Due to desirable and often competing characteristics in the grades, optimization for one characteristic, such as toughness, may result in a deterioration of another characteristic, such as welding stability or wear resistance.

Therefore, there is a need for an improved method of PcBN fabrication that produces a PcBN body having the desired characteristics without degrading one or more of the desired characteristics in order to enhance another characteristic.

Contents of the invention

The present invention describes an improved method of manufacturing PcBN and PcBN bodies made using the improved method.

In one embodiment, a method includes depositing in a refractory vessel: a substrate (eg, containing cobalt (Co)), cubic boron nitride (cBN), and a mixture of cBN and ceramic. Deposited cBN and mixtures of cBN and ceramic can be powder or pre-compacted discs. The deposited substrate, cBN and the mixture of cBN and ceramic constitute the content in the refractory vessel. During said depositing step, the concentration of cBN in the layer having said mixture of cBN and ceramic is lower than the concentration of cBN in the layer deposited below it. After depositing the contents, high pressure and high temperature (HPHT) is applied to the contents in the refractory vessel. When HPHT is applied, for example, Co in the substrate first diffuses through the cBN layer, ie, the cBN layer is swept by the Co. In some embodiments, the Co may also be swept across the layer with a mixture of cBN and ceramic.

In some embodiments, the contents are deposited in reverse order, starting with the cBN and ceramic mixture, the cBN, and the substrate (eg, containing cobalt (Co)). During said depositing step, the concentration of cBN in the layer with the mixture of cBN and ceramic is lower than the concentration of cBN in the layer deposited thereon. After depositing the contents in reverse order, HPHT is applied to the contents of the refractory container. Upon application of HPHT, for example, the cobalt of the substrate is swept across the cBN layer. In some embodiments, the Co may also be swept across the layer with a mixture of cBN and ceramic.

In another embodiment, a polycrystalline cubic boron nitride (PcBN) body is prepared by a method comprising the following steps. Substrates (eg, containing cobalt (Co)), cubic boron nitride (cBN), and mixtures of cBN and ceramics are deposited in refractory vessels. Deposited cBN and mixtures of cBN and ceramic can be powder or pre-compacted discs. After depositing the contents, high pressure and high temperature (HPHT) is then applied to the contents in the refractory vessel. During said depositing step, the concentration of cBN in said layer with the mixture of cBN powder and ceramic powder is lower than the concentration of cBN in the layer deposited below it. Upon application of HPHT, for example, the Co of the substrate diffuses through the cBN powder. In some embodiments, the Co may also be swept across the layer with a mixture of cBN and ceramic.

In some embodiments, the deposition of the contents is applied in reverse order, starting with the cBN and ceramic mixture, the cBN, and the substrate (eg, containing cobalt (Co)).

At least Co diffuses, for example, through a first inter-diffusion layer (i.e., between the substrate and the first PcBN layer), and in some embodiments, through a second inter-diffusion layer (i.e. , between the first PcBN layer and the second PcBN layer thereon), this diffusion during sintering causes the substrate to fuse (fusion) to its adjacent PcBN layer, and to any adjacent PcBN layer Additional PcBN layer. After the application of HPHT has ended and the contents of the refractory container have cooled, the method produces a PcBN body with layers containing different concentrations of cBN and ceramic material (ie different PcBN layers). The desired characteristics of the resulting PcBN body can be controlled by adjusting the concentrations of cBN and ceramic material in each PcBN layer adjacent to the substrate.

Description of drawings

The following detailed description of the preferred embodiment can be understood with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

Figure 1 shows, by 6Ox scanning electron microscopy (SEM), a cross-section of an unpolished PcBN body fabricated using the disclosed method.

Figure 2a shows, by 6Ox SEM, a cross-section of a polished PcBN body fabricated using the disclosed method.

Figures 2b-e show, by 1000x SEM, multiple cross-sections of different layer and inter-layer interfaces of a polished PcBN body fabricated using the disclosed method.

Figures 2f-g show refractory containers (cups) that may be used to hold deposited contents according to some embodiments.

Figure 3a shows a plot of Ti K fluorescence x-ray intensity generated using energy dispersive x-ray (EDX) spectral line scans of PcBN bodies fabricated using the disclosed method.

Figure 3b shows a plot of Co K fluorescence x-ray intensity generated using energy dispersive x-ray (EDX) spectroscopic line scans of PcBN bodies fabricated using the disclosed method.

Figure 4 shows a flow chart of the steps of an improved method of making a PcBN body.

Figure 5 shows a flow chart of the steps of another improved method of making a PcBN body.

Detailed description of the invention

The purpose of the embodiments described here is to illustrate a method of PcBN fabrication, and a PcBN body produced by such a method, wherein the PcBN body produced has desirable characteristics that are not intended to enhance another obtained without degrading one or more of the desired characteristics.

Accordingly, embodiments relate to methods of fabricating polycrystalline cubic boron nitride (PcBN) bodies that substantially eliminate One or more problems due to limitations and deficiencies in the related art are addressed.

Figure 1 shows an EDM cut section of an unpolished PcBN body 101 fabricated using a modified method. This section shows the resulting material after HPHT sintering. Next to the cemented carbide (WC/Co) substrate 102 there is a cBN layer 103 (high cBN material), and an adjoining layer 104 of a mixture of cBN and ceramic (low cBN layer). The cBN layer 103 has a lower ceramic concentration than the low cBN layer 104 .

The method of making this unpolished PcBN body 101 involves depositing the following in a refractory vessel: a substrate 102, cubic boron nitride (high cBN) powder, and a mixture layer of cBN and ceramic powder (low cBN), and then depositing the The contents of the refractory container are subjected to high pressure and high temperature (HPHT). Suitable examples of substrate 102 include metallic cobalt (Co), cemented carbide (WC/Co), cermets ((W,Ti)(C,N)/(Co,Ni)), silicon (Si), or nickel (Ni ). In some embodiments, the high cBN deposited layer and the low cBN layer may be a powder or a pre-compacted disc.

In some embodiments, pre-compacted discs, also known as pre-sintered bodies, may be fabricated using one or more of the following methods, which are disclosed in US Patent 6,676,893 B2, issued January 13, 2004, "Porous Cubic Boron Nitride Based MaterialSuitable for Subsequent Production of Cutting Tools and Method for itsProduction" (applicable to the subsequent production of cutting tools based on porous cubic boron nitride material and its production method), which is incorporated herein by reference .

In some embodiments, the refractory vessel may be formed from tantalum (Ta) or molybdenum (Mo) foil sheet/wrap, or any other transition metal of grades IV-VI. Embodiments of tantalum refractory containers (cups) are shown in Figures 2f-g. Figure 2f illustrates a tantalum metal container (cup) with a non-collared top. Figure 2g illustrates a tantalum refractory container (cup) with a folded top.

In some embodiments, the concentration of cBN in the low cBN powder is lower than the concentration in the high cBN powder.

The ceramic powder may for example comprise titanium nitride (TiN) or aluminum oxide (Al ₂ O ₃ ) or Ti ₂ AlN. Other ceramics may also be used without departing from the scope of the described embodiments. For example, ceramics such as AlN, TiC, TiCN, ZrN, ZrO ₂ , HfO ₂ or any other transition metal of groups IV-VI such as Me(C,N,O) may be used.

The high cBN powder has, for example, a high cBN content of about 90%. Layer 103 contains about 90% cBN and about 10% of one or more of some other material, which may include the ceramic. In some embodiments, the cBN layer 103 may also contain a relatively low concentration of ceramics, such as TiN or Al ₂ O ₃ , for example, about 10%. Furthermore, the low cBN layer 104 may, for example, have a cBN content of about 50%. Layer 104 may also comprise a relatively high content of ceramics, such as TiN or Al ₂ O ₃ , for example about 50%.

When HPHT is applied to the contents 102-104 of the refractory vessel to initiate sintering, the Co of the substrate 102 first diffuses through the cBN powder layer 103, and then, in some embodiments, diffuses through the cBN powder and the ceramic powder layer 104 of the mixture. Thus, in some embodiments, two intermediate diffusion layers may be formed. A first intermediate diffusion layer between the substrate 102 and the high cBN layer 103 and a second intermediate diffusion layer between the high cBN layer 103 and the low cBN layer 104 . Diffusion of the substrate material (e.g., Co) through the two intermediate diffusion layers, for example, results in fusion of the substrate 102 to the high cBN layer 103 adjoining it, and to one or more further PcBN layers adjoining the cBN layer 103 layer, such as the low cBN layer 104.

After the end of HPHT and cooling of the contents in the refractory vessel, the process produces a PcBN body with layers having different concentrations of cBN and ceramic material (ie, different PcBN layers). The desired characteristics of the resulting PcBN body can be controlled by adjusting the concentrations of cBN and ceramic material in each PcBN layer adjacent to the base layer 102 . In some embodiments, the high cBN layer 103 has about 86-99% cBN and 88-96% cBN by volume, and a metal binder with a ceramic content of about 2-8%. In some embodiments, the low cBN layer 104 has about 35-85% by volume cBN and a binder of ceramic character after HPHT.

In a cross-section of an unpolished PcBN body 101 produced using a modified method, the first amount, corresponding to the layer thickness of the substrate 102, may for example be approximately between 0.0 mm and 8 mm. The second amount corresponds to the thickness of the high cBN layer 103, for example between about 0.3 mm and 3.2 mm, and between about 0.5 mm and 1.0 mm. The third amount, corresponding to the thickness of the low cBN layer 104, may, for example, be between about 0.2 mm and 3.2 mm, and between about 0.3 mm and 1.0 mm.

Figure 2a shows a cross-section of a polished PcBN body 201 fabricated using the modified method using a 6Ox scanning electron microscope (SEM). As shown, the polished PcBN body 201 has a first WC/Co cemented carbide base layer 202 , a second high cBN layer 203 , and a third low cBN layer 204 . In this embodiment, the carbide base layer 202 (its entirety not shown) has a thickness of about 4 mm. The second cBN powder layer 203 has a thickness of about 0.6 mm. The third low cBN layer 204 has a thickness of about 0.4 mm. A polished PcBN body 201 was fabricated using the method described previously. After HPHT, EDM cuts the body 201 and polishes the cross section to facilitate microscopic examination. Polishing is accomplished using standard metallographic methods.

Figures 2b-e show multiple cross-sections of different layer and interlayer interfaces of a PcBN body 201 fabricated using the improved method by SEM at a higher magnification of 100Ox. In particular, Figure 2b shows the substrate 202-high cBN layer 203 interface 205; Figure 2c shows the second layer 203 at a higher magnification 206; Figure 2d shows the high cBN layer 203-low cBN layer 204 interface 207; and Fig. 2e shows 208 of the low cBN layer 204 at a higher magnification.

The grain structure of the carbides, the Co (metallic binder) and the light gray vitrified binder (cBN grains in black) are easily seen at 1000× magnification. Substrate 202 has a visible light contrast (see Figure 2b) due to its WC and Co content. The second layer 203 is shown at 206 in Fig. 2e at a higher magnification. The black grains are cBN and the bright contrast in the binder phase is due to Co interdiffuse from the substrate, also known as sweeping. The third layer 204 is shown 208 at a higher magnification. The black grains are cBN and the gray phase is the ceramic binder without Co interdiffusion. Both the interface 205 of the base layer 202 to the second layer 203 and the interface 207 of the second layer 203 to the third layer 204 are abrupt (see Figures 2b and 2d). No cracks or pores were shown in the PcBN body (see Fig. 2b-e), implying good bonding characteristics.

Figures 2f-g show a refractory container (cup) 210 that may be used to hold deposition contents according to some embodiments. Fig. 2f illustrates a refractory container 210 made of tantalum and having a non-collared top. Figure 2g illustrates a refractory container made of tantalum with a folded top. Other refractory vessel types than Figure 2f or Figure 2g may be used without departing from the scope of the described embodiments.

Figure 3a shows a plot of the Ti K fluorescence x-ray intensity generated using energy-dispersive x-ray (EDX) spectroscopy of a PcBN body fabricated using the disclosed method. Graph 310 is a line scan (along white line 302) of the PcBN body, qualitatively illustrating the concentration of Ti through the thickness of the PcBN body. Line scan 301 is taken from top to bottom along white line 302 . Ti, which can be bonded as ceramic TiN, does not show any evidence of diffusion, as the interface 303 of the second to third layer corresponds to the open arrow in diagram 301 . TiN is present in the third layer 204 towards the top/intended working surface of the PcBN body, this presence is to increase the chemical stability of the PcBN layer and strengthen the PcBN body for its use, e.g. Used as cutting tools in hard component turning applications. A higher cBN content in the second layer 203 imparts higher toughness and hardness to the material.

Figure 3b shows a graph 305 of Co K fluorescence x-ray intensity generated using energy dispersive x-ray (EDX) spectroscopy for PcBN bodies fabricated using the disclosed methods. The graph 305 is a line scan of PcBN qualitatively illustrating the concentration of cobalt (Co) through the thickness of the PcBN body. Line scan 306 is taken along white line 305 from top to bottom.

Line scans of the PcBN body were obtained in a scanning electron microscope in which electrodes produced a characteristic x-ray fluorescence proportional to the Co concentration in the PcBN body. In this example, Co metal from the substrate 202 is enriched at the first interface 308 between the substrate layer and the second layer, and diffuses through the second layer 203 across the interface 308, but not across the first interface 308. The second interface 307 enters the third layer 204 .

Figure 4 shows a flowchart 400 of steps 401-404 of an improved method of making polycrystalline cubic boron nitride (PcBN body). The method comprises: depositing a first amount of substrate 401 in a refractory vessel; depositing a second amount of at least cubic boron nitride (cBN) 402 in said refractory vessel; depositing a third amount in said refractory vessel a mixture 403 of cBN and ceramic; and applying high pressure and high temperature (HPHT) to the contents of the refractory vessel 404, wherein the first concentration of cBN in said third amount is lower than that of cBN in said second amount and wherein upon application of HPHT, Co of the substrate first diffuses through the second amount of at least cBN, and then diffuses through the third amount of a mixture of cBN and ceramic.

One or more steps may be inserted into or substituted for each of the aforementioned steps 401-404 without departing from the scope of the present invention.

FIG. 5 shows a flowchart 500 of steps 501-504 of another improved method of making a PcBN body. The method comprises: depositing a first amount of a mixture of cubic boron nitride (cBN) and ceramic 501 in a refractory vessel; depositing a second amount of at least cBN 502 in said refractory vessel; depositing a third amount of substrate 503; and applying high pressure and high temperature (HPHT) to the contents of said refractory vessel, wherein a first concentration of cBN in said first amount is lower than in said second amount A second concentration of cBN, and wherein upon application of HPHT, Co of the substrate first diffuses through the second amount of at least cBN, and then diffuses through the mixture 504 of the first amount of cBN and ceramic. The advantage here is that the refractory container does not require an additional tantalum (Ta) layer as a capping layer.

One or more steps may be inserted into or substituted for each of the aforementioned steps 501-504 without departing from the scope of the present invention.

Although the present invention has been described in conjunction with preferred embodiments of the present invention, those of ordinary skill in the art will understand that, without departing from the spirit and scope of the present invention as defined in the appended claims, modifications not specifically described may be made. additions, deletions, changes and substitutions.

Claims (38)

1. manufacture a method for polycrystal cubic boron nitride (PcBN) cutting element, described method comprises:

Deposition:

The substrate of the first amount;

At least cubic boron nitride (cBN) of the second amount;

The cBN of the 3rd amount and the mixture of pottery; With

Apply high pressure and high temperature (HPHT).

2. method according to claim 1, wherein said substrate comprises at least one in metal and silicon.

3. method according to claim 1, wherein said deposition is to the deposition in following refractory vessel, and described refractory vessel is formed by the paillon foil material of tantalum (Ta), molybdenum (Mo) or group IV-VI transition metal or coiled material.

4. method according to claim 1, wherein said substrate comprises carbide.

5. method according to claim 1, wherein said pottery comprises and is selected from TiN, Al ₂o ₃, AlN, TiC, TiCN, ZrN, ZrO ₂and HfO ₂in at least one.

6. method according to claim 3, wherein said refractory vessel comprises: (1) described substrate, the mixture of (2) described cBN and the cBN powder described in (3) and pottery.

7. method according to claim 6, wherein said pottery comprises and is selected from TiN, Al ₂o ₃, AlN, Ti ₂alN, TiC, TiCN, ZrN, ZrO ₂and HfO ₂in at least one.

8. method according to claim 1, described method also comprises the step terminating to apply HPHT.

9. method according to claim 1, first concentration of the cBN wherein in described 3rd amount is lower than second concentration of the cBN in described second amount.

10. method according to claim 4, wherein when applying described HPHT, first the carbide of described substrate diffuses through at least cBN of described second amount, and then diffuses through the cBN of described 3rd amount and the mixture of pottery.

11. methods according to claim 1, wherein said first amount is the thickness of about 0.0 to 8mm.

12. methods according to claim 1, wherein said second amount or the 3rd amount are the thickness of about 0.3 to 3.2mm.

13. methods according to claim 1, wherein said second amount is the thickness of about 0.5 to 1.0mm.

14. methods according to claim 1, wherein said 3rd amount is the thickness of about 0.3 to 1.0mm.

15. methods according to claim 1, wherein said second amount comprises and is selected from TiN, Al ₂o ₃, AlN, TiC, Ti ₂alN, TiCN, ZrN, ZrO ₂and HfO ₂in at least one.

16. methods according to claim 15, wherein in described second amount, second concentration of described cBN is greater than and is selected from TiN, Al ₂o ₃, AlN, Ti ₂alN, TiC, TiCN, ZrN, ZrO ₂and HfO ₂in the concentration of at least one.

17. methods according to claim 15, TiN or Al wherein in described second amount ₂o ₃the first concentration be less than TiN or Al in described 3rd amount ₂o ₃the second concentration.

18. methods according to claim 1, the second amount wherein deposited or the 3rd amount are in the form of the dish material of compacting in advance.

19. methods according to claim 1, the second amount wherein deposited or the 3rd amount are in the form of powder.

20. methods according to claim 1, wherein said substrate comprises the carbonitride of Me (C, N) form.

21. 1 kinds of polycrystal cubic boron nitride (PcBN) cutting elements, it comprises:

In the content that high pressure and high temperature (HPHT) apply:

The substrate of the first amount;

At least cubic boron nitride (cBN) of the second amount; With

The cBN of the 3rd amount and the mixture of pottery.

22. PcBN according to claim 21, wherein said substrate comprises at least one in metal and silicon.

23. PcBN according to claim 21, wherein said content is contained in the refractory vessel formed by the paillon foil material of tantalum (Ta), molybdenum (Mo) or group IV-VI transition metal or coiled material.

24. PcBN according to claim 21, wherein said substrate comprises carbide.

25. PcBN according to claim 21, wherein said pottery comprises and is selected from TiN, Al ₂o ₃, AlN, TiC, TiCN, ZrN, ZrO ₂and HfO ₂in at least one.

First concentration of 26. PcBN according to claim 21, the cBN wherein in described 3rd amount is lower than second concentration of the cBN in described second amount.

27. PcBN according to claim 24, wherein when applying described HPHT, first the carbide of described substrate diffuses through at least cBN of described second amount, and then diffuses through the cBN of described 3rd amount and the mixture of pottery.

28. PcBN according to claim 21, wherein said first amount is the thickness of about 0.0 to 8mm.

29. PcBN according to claim 21, wherein said second amount or the 3rd amount are the thickness of about 0.3 to 3.2mm.

30. PcBN according to claim 21, wherein said second amount is the thickness of about 0.5 to 1.0mm.

31. PcBN according to claim 21, wherein said 3rd amount is the thickness of about 0.3 to 1.0mm.

32. PcBN according to claim 21, wherein said second amount comprises and is selected from TiN, Al ₂o ₃, AlN, TiC, Ti ₂alN, TiCN, ZrN, ZrO ₂and HfO ₂in at least one.

33. PcBN according to claim 25, wherein in described second amount, second concentration of described cBN is greater than and is selected from TiN, Al ₂o ₃, AlN, Ti ₂alN, TiC, TiCN, ZrN, ZrO ₂and HfO ₂in the concentration of at least one.

34. PcBN according to claim 25, TiN or Al wherein in described second amount ₂o ₃the first concentration be less than TiN or Al in described 3rd amount ₂o ₃the second concentration.

35. PcBN according to claim 21, the second amount of wherein said content or the 3rd amount are in the form of the dish material of compacting in advance.

36. PcBN according to claim 21, the second amount of wherein said content or the 3rd amount are in the form of powder.

37. PcBN according to claim 21, wherein said substrate comprises the carbonitride of Me (C, N) form.

The method of 38. 1 kinds of manufacture polycrystal cubic boron nitride (PcBN) cutting elements, described method comprises:

Deposition:

The cubic boron nitride (cBN) of the first amount and the mixture of pottery;

At least cBN of the second amount;

The substrate of the 3rd amount; With

Apply high pressure and high temperature (HPHT).