Polycrystalline cubic boron nitride material

Abstract

To develop a viable alternative material for tool operation.SOLUTION: The present disclosure relates to a polycrystalline cubic boron nitride (PCBN) material which comprises a binder matrix material containing a nitride compound. The nitride compound is selected from HfN, VN, and / or NbN.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to the field of sintered polycrystalline cubic boron nitride materials and methods for making same, and in particular to the machining of Inconel™-based superalloys using sintered polycrystalline cubic boron nitride materials. [Background technology]

[0002] Polycrystalline ultrahard materials, such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN), can be used in a variety of tools to cut, machine, drill, or fracture hard or abrasive materials, such as rock, metals, ceramics, composites, and wood-containing materials. Abrasive compacts are widely used in cutting, turning, milling, grinding, drilling, and other abrasive operations, and typically contain ultrahard abrasive particulates dispersed in a second-phase matrix. The matrix can be metal, ceramic, or cermet. The ultrahard abrasive particulates can be diamond, cubic boron nitride (cBN), silicon carbide, silicon nitride, or the like. These particulates may bond together during commonly used high-pressure, high-temperature compact manufacturing processes to form a polycrystalline mass, or may be bonded by a matrix of second-phase material to form a sintered polycrystalline body. Such bodies are commonly known as polycrystalline diamond or polycrystalline cubic boron nitride, and contain diamond or cBN, respectively, as the ultrahard abrasive. U.S. Patent No. 4,334,928 teaches sintered compacts for use in tools consisting essentially of 20-80% by volume cubic boron nitride; the remainder being a matrix of at least one matrix compound material selected from the group consisting of carbides, nitrides, carbonitrides, borides, and silicides of transition metals from Group IVa or Va of the periodic table, mixtures thereof, and solid solution compounds thereof. All of the methods outlined in this invention involve combining the desired materials using mechanical comminution / mixing techniques, such as ball milling, pulverizers, etc.

[0003] The sintered polycrystalline body may be "backed" by forming it on a substrate. Ultra-hard tungsten carbide may be used to form a suitable substrate, for example, by mixing tungsten carbide particulates / particles with cobalt, followed by heating and solidification to form particulate carbide dispersed in a cobalt matrix. To form a cutting element having an ultra-hard material layer, such as PCD or PCBN, diamond particulates or particles, or CBN particles, are placed adjacent to the ultra-hard tungsten carbide body in a refractory metal housing, such as a niobium housing, and subjected to high pressure and temperature to form intergranular bonds between the diamond or CBN particles, forming a polycrystalline ultra-hard diamond or polycrystalline CBN layer. The substrate may be fully sintered before bonding to the ultra-hard material layer, or the substrate may be green (not fully sintered). In the latter case, the substrate may be fully sintered during the HPHT sintering process. The substrate may be in powder form and may be solidified during the sintering process used to sinter the ultra-hard material layer. Alternatively, the solid sintered polycrystalline body may be unbacked and formed to be free-standing without a substrate.

[0004] Figure 1 shows an exemplary method for making sintered PCBN material. The following numbers correspond to those in Figure 1: S1. Premix the matrix precursor powder. Examples of the matrix precursor powder include titanium and aluminum carbides and / or nitrides. The matrix precursor powder typically has an average particle size of 1 μm to 10 μm. S2. Heat treat the matrix precursor powder above 1000°C for at least 1 hour to initiate pre-reaction between the matrix precursor particles and form a "cake." S3. Crush and sieve the cake to obtain the desired particle size fraction. S4. Cubic boron nitride (cBN) fine particles with an average particle size of 0.5 μm to 15 μm are added to the sieved matrix precursor powder. S5. The resulting mixed powder is ball milled to reduce the matrix precursor powder to the desired diameter (typically 50 nm to 700 nm) and intimately mix the matrix precursor powder with the cBN particulates. This process can take several hours and involves the use of milling media such as tungsten carbide balls. S6. The resulting milled powder is dried under vacuum or low pressure at above 60° C. to remove the solvent, and then conditioned by slowly admitting oxygen to the system to passivate the metal surface, such as aluminum. S7. Sift the dried powder and prepare a pre-composite assembly. S8. Heat treat the pre-composite assembly above 700°C to remove any adsorbed water or gases. S9. Assemble the outgassed pre-composite assembly into a capsule suitable for sintering. S10. Sintering the capsule 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 (CRM). CRMs are raw materials that are deemed to be of economic and strategic importance to the European economy. As a rule, they have a high supply risk, are of significant importance to key sectors in the European economy, such as household appliances, environmental technology, automotive, aerospace, defense, health and steel, and lack (viable) alternatives. Both tungsten and cobalt are key components of two important hard materials: cemented carbide / WC-Co and PCD / diamond-Co. Summary of the Invention

[0006] The objective of this invention is to develop a viable alternative material for tool operation that performs 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, there is provided a polycrystalline cubic boron nitride (PCBN) material comprising: -40 to 95 volume % of cubic boron nitride (cBN) particles; - a binder matrix material in which cBN particles are dispersed and the content of the binder matrix material is 5% to 60% by volume of the PCBN material; Including, the binder matrix material comprises aluminum or a compound thereof and / or titanium or a compound thereof, a polycrystalline cubic boron nitride (PCBN) material, wherein the binder matrix material further comprises an oxide compound, a nitride compound and / or an oxynitride compound, the nitride compound being selected from any one or more of the following: HfN, VN and / or NbN. 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 comprises AlON. Optionally, the oxide compound comprises Al2O3, which may be present in an amount of 10% or 25% by volume of the PCBN material. Optionally, the HfN is present in an amount of 10% or 25% by volume of the PCBN material. The binder matrix material may further comprise HfB2 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 comprise AlN and / or BN. Optionally, the NbN is present in an amount of 10% or 25% by volume of the PCBN material. Optionally, aluminum (Al) or a compound thereof is present in an amount of 2 to 15% by volume of the PCBN material, preferably 5 to 15% by volume, more preferably 5% by volume. The PCBN material may comprise 50-70% by volume cubic boron nitride (cBN). Optionally, the PCBN material comprises 60% by volume 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 and grinding the precursor powder of - compacting the milled precursor powder to form a green body; sintering the green body at a temperature between -1250°C and 2200°C and a pressure between 4.0 GPa and 8.5 GPa to form a sintered PCBN material according to the first aspect of the present invention; A method for making polycrystalline cubic boron nitride (PCBN) material is provided, comprising: Optionally, the oxide-containing powder comprises Al2O3. Optionally, the temperature is between 1250°C and 1450°C. Optionally, the temperature is 1350°C. Optionally, the pressure is about 6.5 GPa. Optionally, the temperature is between 1800°C and 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, which may comprise Inconel™, an austenitic nickel-chromium based superalloy. Non-limiting embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a flow chart illustrating an exemplary known method for producing sintered PCBN material. [Figure 2] FIG. 2 is a flow chart illustrating one embodiment of a process for making PcBN material in accordance with the present invention. [Figure 3] FIG. 3 is an X-ray powder diffraction (XRD) pattern of Example 1 prepared using Powder 1 containing HfN and Al2O3 and sintered at 6.5 GPa. [Figure 4] FIG. 4 shows a scanning electron microscope (SEM) photograph of Example 1 at a magnification of X2000. [Figure 5] FIG. 5 is an energy dispersive X-ray analysis (EDS) image of Example 1. [Figure 6] FIG. 6 shows the XRD pattern of Example 2, which was prepared using Powder 2 containing VN and Al2O3 and sintered under 6.5 GPa conditions. [Figure 7] FIG. 7 is an SEM photograph of Example 2 at a magnification of ×2000. [Figure 8] Figure 8 is an EDS image of Example 2; [Figure 9] FIG. 9 shows the XRD pattern of Example 3, which was produced using Powder 2 containing VN and sintered under the condition of 8.4 GPa. [Figure 10] Figure 10 shows an image of an example indentation in PCBN material, showing the dimensions used to calculate hardness. [Figure 11] FIG. 11 is a line graph showing the performance of HPHT sintered samples with different binder chemistries in profile operations on Inconel™ 718 (HRC 44-46) after aging. [Figure 12] FIG. 12 is a bar graph showing the performance of HPHT and LPLT sintered samples with VN and Al2O3 binder chemistries in longitudinal machining of Inconel™ 718 (HRC 44-46) after aging. [Figure 13] FIG. 13 is an optical image showing the wear scar of the reference PCBN material with TiC binder of FIG. [Figure 14] FIG. 14 is an optical image showing the wear scar of the PCBN material with Al2O3-VN binder sintered under the HPHT conditions of FIG. [Figure 15] FIG. 15 is an optical image showing the wear scar of PCBN material with Al2O3-VN binder sintered under the LPLT conditions of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 2 is a flow chart showing exemplary steps, and the following numbers correspond to those in FIG. S1. Mill the precursor powders to form an intimate mixture and obtain the desired particle size. The precursor powders include oxide-containing powders, nitride-containing powders, aluminum powder, and cBN powder. The precursor powders were mixed in an organic solvent using a ball milling technique and dried in a rotary evaporator. S2. The crushed precursor powder is dry pressed to form a green body with a metal seal before being placed in an HPHT capsule. In the case of HPHT sintering, the powder is dried and then filled into a soft mold, and then compressed using a cold isostatic press to form a green body with high green density, in order to minimize dimensional change after sintering. The green bodies are then cut to different heights and placed in HPHT capsules. S3. The dry-pressed green body is then subjected to high-temperature vacuum heat treatment and then sintered in a capsule. The materials generated so far were tested under two conditions: - pressure of about 6.5 GPa, temperature of 1250 °C to 1450 °C, typically 1350 °C; -Pressure of approximately 8 GPa, temperature of 1800℃ to 2100℃ It was sintered at . 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. [Example]

[0012] All of the PcBN compositions included in this study, along with reference samples of TiC and TiCN, are listed in Table 1. In this section, LPLT stands for low pressure, low temperature, and HPHT stands for high pressure, high temperature. [Table 1] Table 1 Examples 1, 2 and 3 are described in more detail below. Other samples listed in Table 1 of the present invention and references were prepared, characterized and then tested in a similar manner to Examples 1, 2 and 3.

[0013] Example 1 S1. As described above, a precursor powder containing Al2O3 and HfN was mixed with cBN powder and Al powder in the proportions shown in Table 1. S2. The precursor powder was then compacted to form a green body within a metal seal. S3. The green body was placed in a capsule and then sintered. S4. The sintered PCBN material was cooled to room temperature and prepared for further characterization and application testing. The XRD trace in Figure 3 shows the presence of HfN, HfB2, Al2O3 and BN in the sintered article. Figure 4 shows the resulting microstructure, and the EDS image in Figure 5 shows the compositional analysis of the microstructure in a selected area of ​​the sample.

[0014] Example 2 S1. As described above, a precursor powder containing Al2O3 and VN was mixed with cBN powder in the proportions shown in Table 1. S2. The precursor powder was then compacted to form a green body within a metal seal. S3. The green body was placed in a capsule and then LPLT sintered. S4. The sintered PCBN material was cooled to room temperature and prepared for further characterization and application testing. The XRD trace in Figure 6 shows the presence of VN, AlN, Al2O3 and BN in the sintered product. Figure 7 shows the resulting microstructure, and the EDS image in Figure 8 shows the compositional analysis of the microstructure in a selected area of ​​the sample.

[0015] Example 3 S1. As described above, a precursor powder containing Al2O3 and VN was mixed with cBN powder in the proportions shown in Table 1. S2. The precursor powder was then compacted to form a green body. S3. The green bodies were cut and placed in capsules, followed by HPHT sintering. S4. The sintered PCBN material was cooled to room temperature and prepared for further characterization and application testing. The XRD trace in Figure 9 shows the presence of VN, AlN, Al2O3 and BN in the sintered article. SEM and EDS images of the sample were taken but are not included here.

[0016] Hardness The samples were further characterized using Vickers hardness testing, where Vickers hardness (HV) is calculated by introducing a diamond pyramidal indenter at a given load and measuring the diagonal length of the indentation left in the sample material (see, e.g., Figure 10). Table 2 shows the hardness of samples sintered from powders 1 and 2 under different conditions. [Table 2] Table 2 The results show that all samples have relatively high hardness, but that sintering at higher pressures and temperatures increases the hardness slightly.

[0017] Applicable Test PCBN variants with different binder chemistries were then used to perform copy cutting tests on aged Inconel 718 with Rockwell hardnesses of HRC 44-46. The results are shown in Figure 11. Figure 11 shows the surface cutting speed V C Figure 1 shows the surface wear rate (μm / min) versus the surface wear rate (μm / min). For most samples, the surface wear rate was measured at three different cutting speeds: 280 m / min, 350 m / min, and 420 m / min. The general reference TiC binder is shown at 10 and the TiCN binder at 12. Al2O3-VN(HPHT) is reference number 14. Al2O3-VN(LPLT) is reference number 16. Al2O3-NbN(HPHT) is reference number 18. Al2O3-HfN(HPHT) is reference number 20 and is a single data point. From Figure 11 it is clear that all the samples in Table 1 perform better than the reference sample. Also, referring to samples referenced 14 and 16 on the graph (i.e., having the Al2O3-VN binder chemistry), there is a slight difference in wear rate when sintered under LPLT conditions compared to sintering under HPHT conditions. Al2O3-VN (HPHT or LPLT) performs better than any of the samples, Al2O3-NbN performs second best, followed by Al2O3-HfN. See Figure 12. A second test similar to the first application test was conducted. The second test focused on the performance of the Al2O3-VN binder chemistry in longitudinal machining of aged Inconel™ 718 with a Rockwell hardness of 44-46 HRC. Both LPLT and HPHT were investigated. Figure 12 shows the surface cutting speed V C Figure 1 is a bar graph showing the wear rate (µm / min) versus the 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, the performance difference in wear rate between the LPLT and HPHT variants was minimal. 13-15 show the resulting wear scars. The wear scars for the Al2O3-VN binder chemistry in LPLT and HPHT are significantly smaller than the TiC reference sample. In summary, the inventors have been successful in identifying several materials that are suitable for use in extreme tooling applications and that are viable alternatives to CRM. In particular, PCBN materials are particularly well suited for machining Inconel™ 718 and offer numerous advantages over cemented carbide products.

[0018] definition As used herein, "PCBN" material refers to a type of ultrahard material in which cBN particles are dispersed within a matrix that includes a metal or ceramic. PCBN is an example of an ultrahard material. As used herein, "binder matrix material" is understood to mean a matrix material that wholly or partially fills the pores, interstices, or interstitial regions within the polycrystalline structure. The term "binder matrix precursor powder" is used to refer to a powder that becomes a matrix material when subjected to a HPHT or LPLT sintering process. Although the present invention has been particularly shown and described with reference to exemplary embodiments, workers skilled in the art will understand that various changes in form and details can be made therein without departing from the scope of the invention as defined in the appended claims.

Claims

1. A polycrystalline cubic boron nitride (PCBN) material, comprising: 40 to 95 volume % of cubic boron nitride (cBN) fine particles; a binder matrix material in which the cBN particles are dispersed and in which the binder matrix material contains 5% to 60% by volume of the PCBN material; Including, the binder matrix material contains aluminum or a compound thereof, and / or titanium or a compound thereof; the binder matrix material further comprises an oxide compound, a nitride compound and / or an oxynitride compound, the nitride compound being selected from HfN, VN, and NbN; Polycrystalline cubic boron nitride (PCBN) material.

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

4. 4. The PCBN material of claim 1, 2 or 3, wherein the oxynitride compound comprises AlON.

5. The oxide compound is Al 2 O 3 The PCBN material of any one of claims 1 to 4, comprising:

6. The Al 2 O 3 6. The PCBN material of claim 5, wherein is present in an amount of 10% or 25% by volume of the PCBN material.

7. The PCBN material of any one of claims 1 to 6, wherein the HfN is present in an amount of 10% or 25% by volume of the PCBN material.

8. The binder matrix material is HfB 2 and / or BN.

9. The PCBN material of any one of claims 1 to 8, wherein the VN is present in an amount of 10% or 25% by volume of the PCBN material.

10. The PCBN material of claim 9 , wherein the binder matrix material further comprises AlN and / or BN.

11. A PCBN material according to any preceding claim, wherein the NbN is present in an amount of 10% or 25% by volume of the PCBN material.

12. 12. A PCBN material according to any preceding claim, wherein the aluminium Al or compounds thereof are present in an amount of 2 to 15%, preferably 5 to 15%, more preferably 5% by volume of the PCBN material.

13. 13. The PCBN material of any one of claims 1 to 12, comprising 50 to 70 volume percent cubic boron nitride (cBN).

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

15. 1. A method of making a polycrystalline cubic boron nitride (PCBN) material, comprising: grinding together precursor powders of: ・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 milled 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 any one of claims 1 to 14; A method comprising:

16. The oxide-containing powder is Al 2 O 3 16. The method of claim 15, comprising:

17. 17. The method of claim 15 or 16, wherein the temperature is between 1250°C and 1450°C.

18. 18. The method of claim 17, wherein the temperature is 1350°C.

19. 19. The method of claim 17 or 18, wherein the pressure is about 6.5 GPa.

20. 17. The method of claim 15 or 16, wherein the temperature is between 1800°C and 2100°C.

21. 21. The method of claim 20, wherein the pressure is about 8 GPa.

22. Use of the PCBN material according to any one of claims 1 to 14 for machining heat resistant super alloys (HRSA).