Polycrystalline cubic boron nitride material

Abstract

The present disclosure relates to polycrystalline cubic boron nitride (PCBN) materials that include a binder matrix material containing a nitride compound, where the nitride compound is selected from HfN, VN, and / or NbN.

Description

Technical Field

[0001] The present disclosure relates to the field of sintered polycrystalline cubic boron nitride materials and to methods of making such materials. In particular, the present disclosure relates to the machining of Inconel® superalloys using sintered polycrystalline cubic boron nitride materials.

Background Art

[0002] Polycrystalline superhard materials such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) can be used in a variety of tools for cutting, machining, drilling, or crushing hard materials or abrasive materials such as rocks, metals, ceramics, composites, and wood-containing materials. Abrasive compacts are widely used in cutting, turning, grinding, milling, drilling, and other abrasive operations and generally contain superhard abrasive microparticles dispersed in a second-phase matrix. The matrix may be a metal or a ceramic or a cermet. The superhard abrasive microparticles may be diamond, cubic boron nitride (cBN), silicon carbide, or silicon nitride, etc. These microparticles may bond to each other during the commonly used high-pressure high-temperature compact manufacturing process to form a polycrystalline mass. Or, they may be bonded by a matrix of a second-phase material to form a sintered polycrystalline body. Such objects are generally known as polycrystalline diamond or polycrystalline cubic boron nitride and contain diamond or cBN, respectively, as superhard abrasives. U.S. Patent No. 4,334,928 teaches a sintered compact used in a tool consisting essentially of 20 to 80 volume % cubic boron nitride; the balance is a matrix of at least one matrix compound material selected from the group consisting of carbides, nitrides, carbonitrides, borides, and silicides of transition metals of Group IVa or Va of the periodic table, mixtures thereof, and solid solution compounds thereof. All of the methods outlined in the present invention involve combining the desired materials using mechanical grinding / mixing techniques such as ball milling, grinders, etc.

[0003] The sintered polycrystal may be "backed" by forming it on a substrate. Cemented tungsten carbide may be used to form a suitable substrate. For example, after mixing tungsten carbide fine particles / particles and cobalt and then heating and solidifying, it is formed from carbide fine particles dispersed in a cobalt matrix. To form a cutting element having a hard material layer such as PCD or PCBN, diamond fine particles or particles, or CBN particles are placed adjacent to a cemented tungsten carbide object in a refractory metal casing such as a niobium casing, and are subjected to high pressure and high temperature so that an interparticle bond occurs between the diamond particles or CBN particles to form a polycrystalline diamond or polycrystalline CBN layer. The substrate may be completely sintered before adhering to the hard material layer, or the substrate may be unsintered (not completely sintered). In the latter case, the substrate may be completely sintered during the HPHT sintering process. The substrate may be in powder form and may solidify during the sintering process used to sinter the hard material layer. Alternatively, the solid sintered polycrystal may not be backed and may be formed to stand on its own without a substrate.

[0004] Figure 1 shows an exemplary method of fabricating a sintered PCBN material. The following numbers correspond to those in Figure 1. S1. Pre-mix the matrix precursor powder. Examples of the matrix precursor powder include carbides and / or nitrides of titanium and aluminum. The typical average particle size of the matrix precursor powder is 1 μm to 10 μm. S2. Heat-treat the matrix precursor powder at over 1000 °C for at least 1 hour to initiate a pre-reaction between the matrix precursor fine particles and form a "cake". S3. Crush and screen the cake to obtain the desired particle size fraction. S4. Add cubic boron nitride (cBN) fine particles with an average particle size of 0.5 μm to 15 μm to the screened matrix precursor powder. S5. The resulting mixed powder is ball-milled to reduce the matrix precursor powder to a desired diameter (typically 50 nm to 700 nm), and the matrix precursor powder is intimately mixed with cBN microparticles. This process may take several hours and involves using a grinding medium such as tungsten carbide balls. S6. The resulting milled powder is dried at a temperature above 60 °C under vacuum or low pressure to remove the solvent, and then the surface of the metal such as aluminum is passivated by slowly introducing oxygen into the system. S7. The dried powder is sieved to prepare a pre-composite assembly. S8. The pre-composite assembly is heat-treated at a temperature above 700 °C to remove any adsorbed water or gas. S9. The gas-evolved pre-composite assembly is assembled into a capsule suitable for sintering. S10. The capsule is sintered in a high-pressure high-temperature (HPHT) process at at least 1250 °C and at least 4 GPa to form a sintered PCBN material.

[0005] In Europe, both tungsten (W) and cobalt (Co) are classified as critical raw materials (CRMs). CRMs are raw materials that are considered economically and strategically important for the European economy. In principle, they are associated with high supply risks, are critically important for major sectors in the European economy such as household appliances, environmental technologies, automotive, aerospace, defense, healthcare, and steel, and lack (feasible) substitutes. Both tungsten and cobalt are major components of two important hard materials, cemented carbide / WC-Co and PCD / diamond-Co.

Summary of the Invention

[0006] An object of the present invention is to develop a feasible alternative material for tool operation, which functions well under extreme conditions and does not require the use of a WC-Co backing.

[0007] According to a first aspect of the present invention, a polycrystalline cubic boron nitride (PCBN) material comprising: - 40 to 95% by volume of cubic boron nitride (cBN) microparticles; - a binder matrix material in which the cBN microparticles are dispersed and the content is 5 to 60% by volume of the PCBN material; and - the binder matrix material contains aluminum or its compound, and / or titanium or its compound; - the binder matrix material further contains an oxide compound, a nitride compound and / or an oxynitride compound, and the nitride compound is selected from any one or more of the following HfN, VN and / or NbN, to provide a polycrystalline cubic boron nitride (PCBN) material. Optionally, the oxynitride compound is present in an amount of 5 to 35% by volume of the PCBN material. Optionally, the oxynitride compound is present in an amount of 10 to 25% by volume of the PCBN material. Optionally, the oxynitride compound contains AlON. Optionally, the oxide compound contains Al 2 O 3 . Al 2 O 3 may be present in an amount of 10% or 25% by volume of the PCBN material. Optionally, HfN is present in an amount of 10% or 25% by volume of the PCBN material. The binder matrix material may further contain HfB 2 and / or BN. Optionally, VN is present in an amount of 10% or 25% by volume of the PCBN material. The binder matrix material may further contain AlN and / or BN. Optionally, NbN is present in an amount of 10% or 25% by volume of the PCBN material. Optionally, aluminum (Al) or its compound is present in an amount of 2 to 15% by volume, preferably 5 to 15% by volume, more preferably 5% by volume of the PCBN material. The PCBN material may contain 50 to 70% by volume of cubic boron nitride (cBN). Optionally, the PCBN material contains 60% by volume of cubic boron nitride (cBN).

[0008] According to a second aspect of the present invention, - Cubic boron nitride (cBN) powder - Oxide-containing powder - Nitride-containing powder selected from HfN, VN and / or NbN - Aluminum-containing powder and / or titanium-containing powder grinding the precursor powder of - shaping the ground precursor powder to form a green body; - sintering the green body at a temperature of 1250°C to 2200°C and a pressure of 4.0 GPa to 8.5 GPa to form a sintered PCBN material according to the first aspect of the present invention, A method for producing a polycrystalline cubic boron nitride (PCBN) material is provided, including Optionally, the oxide-containing powder contains Al 2 O 3 Optionally, the temperature is 1250°C to 1450°C. Optionally, the temperature is 1350°C. Optionally, the pressure is about 6.5 GPa. Optionally, the temperature is 1800°C to 2100°C. Optionally, the pressure is about 8 GPa.

[0009] According to a third aspect of the present invention, there is provided the use of a PCBN material according to the first aspect of the present invention for machining a heat-resistant superalloy. The heat-resistant superalloy may include Inconel (trademark), which is a kind of austenitic nickel-chromium-based superalloy. Hereinafter, non-limiting embodiments will be described through examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0010]

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Best Mode for Carrying Out the Invention

[0011] Figure 2 is a flowchart showing exemplary steps, and the following numbers correspond to those in Figure 2. S1. Grind the precursor powder to form a dense mixture and obtain the desired particle size. The precursor powder includes an oxide-containing powder, a nitride-containing powder, an aluminum powder, and a cBN powder. The mixing of the precursor powder was carried out in an organic solvent using ball milling technology and dried with a rotary evaporator. S2. Dry press the ground precursor powder to form a green body with a metal seal before putting it into the HPHT capsule. In the case of HPHT sintering, in order to reduce the dimensional change after sintering, specifically, after filling the powder into a soft mold after drying, the powder is compressed and formed by using cold isostatic pressing to form a green body with a high green density. Thereafter, the green body is cut into different heights and put into the HPHT capsule. S3. Thereafter, the dry-pressed green body is subjected to high-temperature vacuum heat treatment and then sintered in a capsule. The materials produced so far were sintered under two conditions: - A pressure of about 6.5 GPa, a temperature of 1250°C to 1450°C, typically 1350°C; - A pressure of about 8 GPa, a temperature of 1800°C to 2100°C and sintered. The sintering temperature was calibrated up to 1800°C using an S-type thermocouple. S4. After sintering, the resulting sintered product is cooled to room temperature. The cooling rate is not controlled.

Examples

[0012] Table 1 lists all of the PcBN compositions included in this study, along with reference samples of TiC and TiCN. In this section, LPLT represents low pressure and low temperature, and HPHT represents high pressure and high temperature.

Table 1

[0013] Example 1 S1. As described above, a precursor powder containing Al 2 O 3 and HfN was mixed with cBN powder and Al powder at the ratios shown in Table 1. S2. Subsequently, the precursor powder was molded to form a green body within a metal seal. S3. After placing the green body in a capsule, it was sintered. S4. The PCBN material, which was the sintered product, was cooled to room temperature, and preparations for subsequent property evaluation and application tests were made. The XRD trace in Figure 3 shows the presence of HfN, HfB 2 , Al 2 O 3 and BN in the sintered product. Figure 4 shows the resulting microstructure, and the EDS image in Figure 5 shows the analysis of the composition of the microstructure in the selected area of the sample.

[0014] Example 2 S1. As described above, a precursor powder containing Al 2 O 3 and VN was mixed with cBN powder at the ratios shown in Table 1. S2. Subsequently, the precursor powder was molded to form a green body within a metal seal. S3. After placing the green body in a capsule, it was sintered by LPLT. S4. The PCBN material, which was the sintered product, was cooled to room temperature, and preparations for subsequent property evaluation and application tests were made. The XRD trace in Figure 6 shows the presence of VN, AlN, Al 2 O 3 and BN in the sintered product. Figure 7 shows the resulting microstructure, and the EDS image in Figure 8 shows the analysis of the composition of the microstructure in the selected area of the sample.

[0015] Example 3 S1. As described above, a precursor powder containing Al2 O 3 The precursor powder containing O and VN was mixed with cBN powder. S2. Subsequently, the precursor powder was molded to form a green body. S3. The green body was cut, placed in a capsule, and then HPHT sintered. S4. The sintered PCBN material was cooled to room temperature, and then preparations for property evaluation and application tests were made. The XRD trace in Fig. 9 shows the presence of VN, AlN, Al 2 O 3 and BN in the sintered product. SEM photographs and EDS images of the samples were taken but are not included here.

[0016] Hardness The samples were further characterized using a Vickers hardness test. The Vickers hardness (HV) is calculated by introducing a diamond pyramid indenter under a predetermined load and measuring the length of the diagonal of the indentation left in the sample material (see, for example, Fig. 10). Table 2 shows the hardness of the samples sintered from powders 1 and 2 under different conditions.

Table 2

[0017] Application Tests Subsequently, tests were carried out using deformed PCBNs with different binder chemistries, mimicking machining on aged Inconel (trademark) 718 with a Rockwell hardness of HRC44 - 46. The results are shown in Fig. 11. Fig. 11 is a graph showing the surface cutting speed V C (m / min) and the wear rate (μm / min). For most samples, the wear rate was measured at three different cutting speeds. These surface cutting speeds were 280 m / min, 350 m / min, and 420 m / min. Generally, the reference TiC binder is shown in 10, and the TiCN binder in 12. 2 O 3 -VN(HPHT) is reference number 14. 2 O 3 -VN(LPLT) is reference number 16. 2 O 3 -NbN(HPHT) is reference number 18. Al 2 O 3 -HfN(HPHT) is reference number 20 and is a single data point. From FIG. 11, it is clear that all the samples in Table 1 perform better than the reference sample. Also, samples with reference numbers 14 and 16 on the graph (i.e., Al 2 O 3 -VN binder chemistry), there is a small difference in wear rate when sintered under LPLT conditions compared to sintering under HPHT conditions. Al 2 O 3 -VN (HPHT or LPLT) performs better than either sample. 2 O 3 -NbN performed second best, followed by Al 2 O 3 -HfN follows. Referring to FIG. 12, a second test similar to the first application test was conducted. The second test was conducted to examine the effect of Al on the longitudinal machining of aged Inconel 718 with a Rockwell hardness of HRC44-46. 2 O 3 -Focused on the performance of VN binder chemistry. Both LPLT and HPHT were considered. Figure 12 shows the surface cutting speed V C Figure 1 is a bar graph showing the wear rate (m / min) and wear rate (μm / min). A single surface cutting speed of 350 m / min was used. The results show that both the LPLT and HPHT variants performed significantly better than the reference TiC binder chemistry. Furthermore, it shows that the performance difference in wear rate between the LPLT and HPHT variants is minimal. Figures 13 to 15 show the resulting wear scars. 2 O3 - The wear marks related to VN binder chemistry are significantly smaller than those of the TiC reference sample. In summary, the inventors have successfully identified several materials that are suitable for use in extreme tool applications and are viable alternatives to CRM. In particular, PCBN materials are particularly suitable for machining Inconel (trademark) 718 and have several advantages over carbide products.

[0018] Definitions As used herein, the term "PCBN" material refers to a certain type of superhard material in which cBN particles are dispersed within a matrix containing a metal or ceramics. PCBN is an example of a superhard material. As used herein, it is understood that the term "binder matrix material" means a matrix material that wholly or partially fills the pores, gaps or interstices in a polycrystalline structure. The term "binder matrix precursor powder" is used to refer to the powder that becomes the matrix material when subjected to an HPHT or LPLT sintering process. Although the present invention has been specifically shown and described with reference to embodiments, those skilled in the art will understand that various changes in form and detail can be made without departing from the scope of the invention as defined in the appended claims. (Addendum) The present disclosure includes the following embodiments. <Embodiment 1> A polycrystalline cubic boron nitride (PCBN) material, comprising 40 to 95% by volume of cubic boron nitride (cBN) microparticles, a binder matrix material in which the cBN microparticles are dispersed and the content is 5% to 60% by volume of the PCBN material, and the binder matrix material contains aluminum or its compound, and / or titanium or its compound, the binder matrix material further contains an oxide compound, a nitride compound and / or an oxynitride compound, and the nitride compound is selected from HfN, VN, NbN, a polycrystalline cubic boron nitride (PCBN) material. <Embodiment 2> The PCBN material according to Embodiment 1, wherein the oxynitride compound is present in an amount of 5% to 35% by volume of the PCBN material. <Embodiment 3> The PCBN material according to Embodiment 2, wherein the oxynitride compound is present in an amount of 10% to 25% by volume of the PCBN material. <Embodiment 4> The PCBN material according to Embodiment 1, 2 or 3, wherein the oxynitride compound contains AlON. <Embodiment 5> The PCBN material according to any one of Embodiments 1 to 4, wherein the oxide compound contains Al 2 O 3 <Embodiment 6> The PCBN material according to Embodiment 5, wherein the Al is present in an amount of 10% or 25% by volume of the PCBN material. 2 O 3 <Embodiment 7> The PCBN material according to any one of Embodiments 1 to 6, wherein the HfN is present in an amount of 10% or 25% by volume of the PCBN material. <Embodiment 8> The PCBN material according to Embodiment 7, wherein the binder matrix material further contains HfB and / or BN. 2 <Embodiment 9> The PCBN material according to any one of Embodiments 1 to 8, wherein the VN is present in an amount of 10% or 25% by volume of the PCBN material. <Embodiment 10> The PCBN material according to Embodiment 9, wherein the binder matrix material further contains AlN and / or BN. <Embodiment 11> The PCBN material according to any one of Embodiments 1 to 10, wherein the NbN is present in an amount of 10% or 25% by volume of the PCBN material. <Embodiment 12> ​ The PCBN material according to any one of Embodiments 1 to 11, wherein the aluminum Al or its compound is present in an amount of 2 to 15% by volume, preferably 5 to 15% by volume, more preferably 5% by volume of the PCBN material. <Embodiment 13> The PCBN material according to any one of Embodiments 1 to 12, comprising 50 to 70% by volume of cubic boron nitride (cBN). <Embodiment 14> The PCBN material according to any one of Embodiments 1 to 13, comprising 60% by volume of cubic boron nitride (cBN). <Embodiment 15> A method for producing a polycrystalline cubic boron nitride (PCBN) material, comprising: grinding the following precursor powders together: · Cubic boron nitride (cBN) powder · Oxide-containing powder · Nitride-containing powder selected from HfN, VN, and / or NbN · Aluminum-containing powder and / or titanium-containing powder forming the ground precursor powders into a green body; sintering the green body at a temperature of 1250°C to 2200°C and a pressure of 4.0 GPa to 8.5 GPa to form a sintered PCBN material according to any one of Embodiments 1 to 14. A method comprising the above steps. <Embodiment 16> The method according to Embodiment 15, wherein the oxide-containing powder contains Al. 2 O 3 The method according to Embodiment 15. <Embodiment 17> The method according to Embodiment 15 or 16, wherein the temperature is 1250°C to 1450°C. <Embodiment 18> The method according to Embodiment 17, wherein the temperature is 1350°C. <Embodiment 19> The method according to Embodiment 17 or 18, wherein the pressure is about 6.5 GPa. <Embodiment 20> The method according to Embodiment 15 or 16, wherein the temperature is 1800°C to 2100°C. <Embodiment 21> The method according to Embodiment 20, wherein the pressure is about 8 GPa. <Embodiment 22> Use of the PCBN material according to any one of Embodiments 1 to 14 for machining a heat-resistant superalloy (HRSA).

Claims

1. A polycrystalline cubic boron nitride (PCBN) material, comprising: 40 to 95% by volume of cubic boron nitride (cBN) microparticles; A binder matrix material in which the cBN microparticles are dispersed and the content is 5% to 60% by volume of the PCBN material; wherein the binder matrix material comprises aluminum or a compound thereof, an oxide compound containing Al2O3, and a nitride compound selected from HfN, VN, and NbN; Optionally, the binder matrix material further comprises an oxynitride compound and / or titanium or a compound thereof; A polycrystalline cubic boron nitride (PCBN) material.

2. The PCBN material according to claim 1, wherein the oxynitride compound is present in an amount of 5% to 35% by volume of the PCBN material.

3. The PCBN material according to claim 2, wherein the oxynitride compound is present in an amount of 10% to 25% by volume of the PCBN material.

4. The PCBN material according to claim 1, 2, or 3, wherein the oxynitride compound contains AlON.

5.

6. Said Al 2 O 3 The PCBN material according to any one of claims 1 to 4, wherein said Al 2 O 3 is present in an amount of 10% by volume or 25% by volume of said PCBN material. The PCBN material according to any one of claims 1 to 5, wherein the HfN is present in an amount of 10% or 25% by volume of the PCBN material.

7.

8. The binder matrix material is HfB 2 and / or BN, and the PCBN material according to claim 6 further includes the same. The PCBN material according to any one of claims 1 to 7, wherein the VN is present in an amount of 10% or 25% by volume of the PCBN material.

9. The PCBN material according to claim 8, wherein the binder matrix material further comprises AlN and / or BN.

10. The PCBN material according to any one of claims 1 to 9, wherein the NbN is present in an amount of 10% or 25% by volume of the PCBN material.

11. The PCBN material according to any one of claims 1 to 10, wherein the aluminum Al or a compound thereof is present in an amount of 2 to 15% by volume, preferably 5 to 15% by volume, more preferably 5% by volume of the PCBN material.

12. The PCBN material according to any one of claims 1 to 11, comprising 50 to 70% by volume of cubic boron nitride (cBN).

13. The PCBN material according to any one of claims 1 to 12, comprising 60% by volume of cubic boron nitride (cBN).

14. A method for producing a polycrystalline cubic boron nitride (PCBN) material, comprising: Grinding the following precursor powders together: - Cubic boron nitride (cBN) powder - Oxide-containing powder containing Al2O3 ​ - Nitride-containing powder selected from HfN, VN, and / or NbN - Aluminum-containing powder and optionally titanium-containing powder Forming a green body by shaping the ground precursor powder Sintering the green body at a temperature of 1250°C to 2200°C and a pressure of 4.0 GPa to 8.5 GPa to form the sintered PCBN material according to any one of claims 1 to 13 A method comprising the above steps

15. The method according to claim 14, wherein the temperature is 1250°C to 1450°C

16. The method according to claim 15, wherein the temperature is 1350°C

17. The method according to claim 15 or 16, wherein the pressure is about 6.5 GPa

18. The method according to claim 14, wherein the temperature is 1800°C to 2100°C

19. The method according to claim 18, wherein the pressure is about 8 GPa

20. Use of the PCBN material according to any one of claims 1 to 13 for machining a heat-resistant superalloy (HRSAs)

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