A foamed diamond compact and a method of making the same

Abstract

The application provides a foamed diamond composite sheet and a preparation method thereof, and belongs to the technical field of diamond polycrystal. The foamed diamond micro powder and a metal catalyst are mixed to obtain mixed powder; the mixed powder is hot-pressed with a hard alloy as a substrate to obtain the foamed diamond composite sheet. The foamed diamond micro powder is used as raw material, and has a larger specific surface area and contact point than single crystal diamond, which is beneficial to the generation of D-D bond; the metal catalyst is doped in the foamed diamond micro powder, and the diamond surface will be graphitized under the hot-pressing environment of high temperature and high pressure; the graphitized carbon will be dissolved in the catalyst, and when the dissolved carbon is precipitated from the catalyst, it is converted into diamond again, at this time, the newly converted diamond grows on the diamond surface which is not graphitized, so that the diamond and diamond are connected by D-D bond, the aggregation between the diamonds is strengthened, and the wear ratio of the diamond composite sheet is improved.

Description

Technical Field

[0001] This invention relates to the field of polycrystalline diamond technology, and particularly to a foamed diamond composite sheet and its preparation method. Background Technology

[0002] Polycrystalline diamond composite sheets are a type of superhard material formed by polymerizing diamond particles on the surface of a cemented carbide substrate. They are characterized by high hardness and good wear resistance and are widely used in industries such as oil drilling, geological exploration, coalfield drilling bits and machining tools. They are especially used in machining for cutting aluminum alloys, copper alloys and titanium alloys.

[0003] To improve the wear resistance of diamond composite sheets, researchers have increased the number of di-dip bonds (DD bonds) by mixing particle sizes or by increasing pressure and temperature to enhance DD bond formation, thereby improving wear resistance. These methods aim to create more inter-diamond bonds in the diamond particles under high temperature and pressure, thus increasing their wear ratio. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a foamed diamond composite sheet and its preparation method. The foamed diamond composite sheet prepared by this invention has a high wear ratio.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing foamed diamond composite sheets, comprising the following steps:

[0007] The foamed diamond micro powder and the metal catalyst were mixed to obtain a mixed powder;

[0008] Using cemented carbide as a substrate, the mixed powder is hot-pressed to obtain a foamed diamond composite sheet;

[0009] The metal catalyst comprises, by mass percentage: 80-98% cobalt and 2-20% nickel.

[0010] Preferably, the mixed powder comprises, by weight percentage: 90-99% foamed diamond micro powder; and 1-10% metal catalyst.

[0011] Preferably, the particle size of the foamed diamond micro powder is 0.5–30 μm;

[0012] The particle size of the metal catalyst is 0.5–5 μm.

[0013] Preferably, the mixing is performed by wet ball milling, and the dispersion medium for wet ball milling is an organic solvent; the wet ball milling rate is 100-300 r / min, and the time is 1-5 h.

[0014] Preferably, the wet ball milling process further includes removing the organic solvent from the resulting mixed powder, drying, and sieving.

[0015] Preferably, the particle size of the mixed powder is below a 100-mesh sieve.

[0016] Preferably, the hot pressing temperature is 1500-1800℃, the pressure is 5-6.5GPa, and the heat and pressure holding time is 10-30min.

[0017] Preferably, the hot pressing method includes the following steps:

[0018] The mixed powder is loaded into a niobium cup, and then covered with a cemented carbide sheet and a zirconium cap in sequence to obtain the assembly component;

[0019] The assembly components are inserted into pyrophyllite blocks, and the pyrophyllite blocks containing the assembly components are hot-pressed using a six-sided top press.

[0020] Preferably, the cemented carbide is a tungsten carbide-cobalt cemented carbide.

[0021] This invention provides foamed diamond composite sheets prepared by the above-described preparation method.

[0022] This invention provides a method for preparing a foamed diamond composite sheet, comprising the following steps: mixing foamed diamond micropowder with a metal catalyst to obtain a mixed powder; hot-pressing the mixed powder with a cemented carbide substrate to obtain a foamed diamond composite sheet; the metal catalyst, by mass percentage, comprises: 80-98% cobalt and 2-20% nickel. This invention uses foamed diamond micropowder as raw material. The foamed diamond surface is already foamed, possessing a larger specific surface area and contact points than single-crystal diamond. The interpenetration of the foamed diamond surfaces facilitates the formation of DD bonds. This invention dops the foamed diamond micropowder with a metal catalyst. Under high temperature and high pressure hot-pressing conditions, the diamond surface undergoes graphitization. The graphitized carbon dissolves in the catalyst. When the dissolved carbon precipitates from the catalyst, it is converted back into diamond. At this point, the newly converted diamond grows on the surface of the ungraphitized diamond, forming DD bond connections between the diamonds, strengthening the polymerization between diamonds, thereby improving the wear ratio of the diamond composite sheet. Simultaneously, the foamed diamond composite sheet provided by this invention also exhibits good self-sharpening properties. The results of the examples show that the wear ratio of the foamed diamond composite sheet provided by the present invention is 37.3 × 10⁻⁶. 3 ~49.6×10 3 The tool made from it can process up to 18,000 aluminum alloy CD-patterned parts with a diameter of 8cm, and has good self-sharpening properties. Attached Figure Description

[0023] Figure 1 The image shows the polycrystalline metallographic microstructure of the foam diamond composite sheet obtained in Example 1 before polishing. Detailed Implementation

[0024] This invention provides a method for preparing foamed diamond composite sheets, comprising the following steps:

[0025] The foamed diamond micro powder and the metal catalyst were mixed to obtain a mixed powder;

[0026] Using cemented carbide as a substrate, the mixed powder is hot-pressed to obtain a foamed diamond composite sheet;

[0027] The metal catalyst comprises, by mass percentage: 80-98% cobalt and 2-20% nickel.

[0028] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0029] This invention involves mixing foamed diamond microparticles and a metal catalyst to obtain a mixed powder. In this invention, the particle size of the foamed diamond microparticles is preferably 0.5–30 μm, more preferably 5–15 μm.

[0030] In this invention, the metal catalyst comprises, by mass percentage: 80-98% cobalt, preferably 85-95%, more preferably 90%; and 2-20% nickel, preferably 5-15%, more preferably 10%.

[0031] In this invention, the particle size of the metal catalyst is preferably 0.5-5 μm, more preferably 1-3 μm; in this invention, the cobalt is added in the form of cobalt powder, the particle size of the cobalt powder is preferably 0.5-5 μm, more preferably 1-3 μm; the nickel is preferably added in the form of nickel powder, the particle size of the nickel powder is preferably 0.5-5 μm, more preferably 1-3 μm.

[0032] In this invention, the mixed powder preferably comprises, by weight percentage: 90-99% foamed diamond micro powder, more preferably 95%; and 1-10% metal catalyst, more preferably 5%.

[0033] In this invention, the mixing is preferably wet ball milling, and the dispersion medium for the wet ball milling is preferably an organic solvent, preferably one or more of ethanol, propanol, butanol, and acetone. In this invention, the wet ball milling rate is preferably 100–300 r / min, more preferably 200 r / min; the time is preferably 1–5 h, more preferably 3 h. In this invention, the ball-to-material ratio for the wet ball milling is preferably 5:1.

[0034] In this invention, the wet ball milling process preferably further includes removing the organic solvent from the resulting mixed powder, drying, and sieving. In this invention, the removal of the organic solvent is preferably achieved by evaporation; the drying temperature is preferably 80°C; and the sieving is preferably performed through a 100-mesh sieve. In this invention, the particle size of the mixed powder is preferably below a 100-mesh sieve.

[0035] After obtaining the mixed powder, the present invention uses a cemented carbide as a substrate and hot-presses the mixed powder to obtain a foamed diamond composite sheet. In the present invention, the cemented carbide is preferably a tungsten carbide-cobalt cemented carbide; as a specific embodiment of the present invention, the type of cemented carbide is preferably YG16.

[0036] In this invention, the hot-pressing temperature is preferably 1500–1800°C, more preferably 1600–1700°C; the pressure is preferably 5–6.5 GPa, more preferably 5.5–6 GPa; the holding time is preferably 10–30 min, more preferably 15–25 min; and the heating rate to the hot-pressing temperature is preferably 15°C / s. In this invention, during the hot-pressing process, it is preferred to first apply pressure to 5–6.5 GPa before heating. During the high-pressure heating process, before the temperature reaches the point of diamond transformation, the diamond surface is graphitized and accumulates. When the temperature reaches a point where the diamond transformation rate exceeds the graphitization rate, DD bonding between diamond particles begins to occur.

[0037] After hot pressing, the present invention also includes depressurization, preferably by a slow depressurization procedure over 5 minutes.

[0038] The present invention preferably uses a six-sided top press for the hot pressing; in the present invention, the hot pressing method preferably includes the following steps:

[0039] The mixed powder is loaded into a niobium cup, and then covered with a cemented carbide sheet and a zirconium cap in sequence to obtain the assembly component;

[0040] The assembly components are inserted into pyrophyllite blocks, and the pyrophyllite blocks containing the assembly components are hot-pressed using a six-sided top press.

[0041] The present invention does not have any special requirements for the specific dimensions of the niobium cup, hard alloy sheet, and zirconium cap; they can be designed according to the dimensions of the foam diamond composite sheet.

[0042] After hot pressing, the resulting foam diamond composite sheet is preferably polished.

[0043] This invention provides a foamed diamond composite sheet prepared by the above-described method. In this invention, the foamed diamond composite sheet contains a polycrystalline layer, and the diamonds within the polycrystalline layer contain abundant DD bonds.

[0044] In this invention, the thickness of the foam diamond composite sheet is preferably 0.4 to 1.2 mm, more preferably 0.6 to 1 mm.

[0045] The following detailed description of the foamed diamond composite sheet and its preparation method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] (1) 95g of foamed diamond particles with a particle size of 5μm, 4.5g of cobalt with a particle size of 1.0μm, 0.5g of nickel with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. After drying at 80℃, the mixture was sieved through a 100-mesh sieve to obtain foamed diamond micro powder mixed with the catalyst.

[0048] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0049] (3) Use a six-sided press to bring the above pyrophyllite blocks to a high temperature and high pressure environment, with a pressure of 5 GPa and a temperature of 1500℃. Keep them at that temperature for 10 minutes and then release the pressure to obtain foamed diamond composite sheets.

[0050] The obtained foam diamond composite sheet was subjected to double-sided planar grinding and wire cutting to expose the polycrystalline layer. The metallographic microstructure of the polycrystalline layer is as follows: Figure 1 As shown in the image, the grayish-white area represents diamonds that have bonded together. The granular texture gradually becomes blurred, and the boundaries between the particles are not obvious. This indicates that under high temperature and high pressure, and with the action of a metal catalyst, DD bonds are formed on the surface of the diamonds, which strengthens the polymerization of the diamond composite sheet.

[0051] The wear performance of the polycrystalline layer of the obtained foam diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 37.3 × 10⁻⁶. 3 .

[0052] The test method adopts the industry standard JB / T 3235-2013, using a standard grinding wheel with an H value of 3.4 to test the wear ratio, and a k value of 1.06;

[0053] Wear ratio E - Wear ratio of polycrystalline diamond; k - Correction factor for a certain hardness value of the grinding wheel; Ms - Mass wear of the standard grinding wheel in grams; M - Mass wear of the test sample in grams.

[0054] The foam diamond composite sheet was used to make cutting tools, and 18,000 aluminum alloy CD-patterned parts with a diameter of 8cm were machined before its use was discontinued.

[0055] Example 2

[0056] (1) 95g of foamed diamond particles with a particle size of 10μm, 4.5g of cobalt with a particle size of 1.0μm, 0.5g of nickel with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. After drying at 80℃, the mixture was sieved through a 100-mesh sieve to obtain foamed diamond micro powder mixed with the catalyst.

[0057] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0058] (3) Use a six-sided press to bring the above pyrophyllite blocks to a high temperature and high pressure environment, with a pressure of 5 GPa and a temperature of 1500℃. Keep them at that temperature for 10 minutes and then release the pressure to obtain foamed diamond composite sheets.

[0059] The obtained foamed diamond composite sheet was subjected to double-sided planar grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 49.6 × 10⁻⁶. 3 .

[0060] Example 3

[0061] (1) 90g of foamed diamond particles with a particle size of 5μm, 9.0g of cobalt with a particle size of 1.0μm, 1g of nickel with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. After drying at 80℃, the mixture was sieved through a 100-mesh sieve to obtain foamed diamond micro powder mixed with the catalyst.

[0062] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0063] (3) Use a six-sided press to bring the above pyrophyllite blocks to a high temperature and high pressure environment, with a pressure of 5 GPa and a temperature of 1500℃. Keep them at that temperature for 10 minutes and then release the pressure to obtain foamed diamond composite sheets.

[0064] The obtained foamed diamond composite sheet was subjected to double-sided planar grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 31.6 × 10⁻⁶. 3 .

[0065] Example 4

[0066] (1) 90g of foamed diamond particles with a particle size of 5μm, 8.0g of cobalt with a particle size of 1.0μm, 2g of nickel with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. After drying at 80℃, the mixture was sieved through a 100-mesh sieve to obtain foamed diamond micro powder mixed with the catalyst.

[0067] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0068] (3) The above-mentioned pyrophyllite blocks were subjected to a high temperature and high pressure environment using a six-sided top press, with a pressure of 5.5 GPa and a temperature of 1500℃. The temperature was maintained for 10 minutes, and the pressure was released to obtain foamed diamond composite sheets.

[0069] The obtained foamed diamond composite sheet was subjected to double-sided planar grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 34.9 × 10⁻⁶. 3 .

[0070] Example 5

[0071] (1) 90g of foamed diamond particles with a particle size of 5μm, 9.0g of cobalt with a particle size of 1.0μm, 1g of nickel with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. After drying at 80℃, the mixture was sieved through a 100-mesh sieve to obtain foamed diamond micro powder mixed with the catalyst.

[0072] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0073] (3) The above-mentioned pyrophyllite blocks were subjected to a high temperature and high pressure environment using a six-sided top press, with a pressure of 6.1 GPa and a temperature of 1500℃. The temperature was maintained for 10 minutes, and the pressure was released to obtain foamed diamond composite sheets.

[0074] The obtained foamed diamond composite sheet was subjected to double-sided planar grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 39.4 × 10⁻⁶. 3 .

[0075] Comparative Example 1

[0076] (1) 100g of foam diamond particles with a particle size of 5μm were dried at 80℃ for 5 hours.

[0077] (2) Spread 5g of foamed diamond micro powder evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup lid with a diameter of 35mm, and then cover it with a suitable zirconium lid. Finally, put the assembled components into the pyrophyllite block.

[0078] (3) The above-mentioned pyrophyllite blocks were subjected to a high temperature and high pressure environment using a six-sided top press, with a pressure of 5.5 GPa and a temperature of 1500℃. The temperature was maintained for 10 minutes, and the pressure was released to obtain foamed diamond composite sheets.

[0079] The obtained foamed diamond composite sheet was subjected to double-sided planar grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 2.9 × 10⁻⁶. 3 .

[0080] Comparative Example 2

[0081] (1) 95g of foamed diamond particles with a particle size of 5μm, 5.0g of cobalt with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. After drying at 80℃, the mixture was sieved through a 100-mesh sieve to obtain foamed diamond micro powder mixed with the catalyst.

[0082] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0083] (3) The pyrophyllite blocks were subjected to a high-temperature and high-pressure environment using a six-sided press (5 GPa, 1500℃) for 10 minutes, followed by depressurization to obtain a foamed diamond composite sheet. The obtained foamed diamond composite sheet was subjected to double-sided grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 36.7 × 10⁻⁶. 3 .

[0084] The foam diamond composite sheet was used to make cutting tools, and 16,500 aluminum alloy CD-patterned parts with a diameter of 8cm were machined before its use was discontinued.

[0085] Comparative Example 3

[0086] 95g of diamond microparticles with a particle size of 5μm, 4.5g of cobalt with a particle size of 1.0μm, 0.5g of nickel with a particle size of 1.0μm, 40g of anhydrous ethanol, and 500g of 5mm stainless steel balls were placed in a 500mL stainless steel container and ball-milled at 120 rpm for 3 hours. The mixture was dried at 80℃ and sieved through a 100-mesh sieve to obtain foamed diamond microparticles mixed with the catalyst.

[0087] (2) Spread 5g of foamed diamond powder mixed with catalyst evenly into a cemented carbide with grade YG16, which is placed in a rare metal niobium cup with a diameter of 35mm, and then cover it with a suitable zirconium cap. Finally, put the assembled component into the pyrophyllite block.

[0088] (3) The pyrophyllite blocks were subjected to a high-temperature and high-pressure environment using a six-sided press (5 GPa, 1500℃) for 10 minutes, followed by depressurization to obtain a foamed diamond composite sheet. The obtained foamed diamond composite sheet was subjected to double-sided grinding and wire cutting to expose the polycrystalline layer. The wear performance of the polycrystalline layer of the obtained foamed diamond composite sheet was tested in an abrasion ratio tester, and the abrasion ratio was 36.1 × 10⁻⁶. 3 .

[0089] The tool made from the foam diamond composite sheet was used to process 14,500 aluminum alloy CD-patterned parts with a diameter of 8cm before its use was terminated.

[0090] Comparing the performance of the diamond composite sheets obtained in the above examples and comparative examples, it can be seen that the diamond composite sheets prepared in Comparative Examples 1 and 2 using cobalt as a single catalyst do not have as good wear resistance and processing service life as those in Example 1.

[0091] The foam diamond composite sheet prepared in Example 1 can be used to process up to 18,000 pieces, while the diamond composite sheet in Comparative Example 3 can only process 14,500 pieces. This indicates that the foam diamond composite sheet of the present invention has good self-sharpening properties during wear, and the cutting edge retains a certain degree of sharpness even after wear.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a foamed diamond composite sheet, comprising the following steps: The foamed diamond micro powder and the metal catalyst were mixed to obtain a mixed powder; Using cemented carbide as a substrate, the mixed powder is hot-pressed to obtain a foamed diamond composite sheet; The metal catalyst comprises, by weight percentage: 80-98% cobalt; 2-20% nickel; The mixed powder comprises, by weight percentage: 90-99% foamed diamond micron powder; and 1-10% metal catalyst. The particle size of the foamed diamond micro powder is 0.5~30μm; the particle size of the metal catalyst is 0.5~5μm; The mixing is performed by wet ball milling, and the dispersion medium for wet ball milling is an organic solvent; the wet ball milling rate is 100~300 r / min, and the time is 1~5 h. The hot pressing method includes the following steps: The mixed powder is loaded into a niobium cup, and then covered with a cemented carbide sheet and a zirconium cap in sequence to obtain the assembly component; The assembly components are inserted into pyrophyllite blocks, and the pyrophyllite blocks containing the assembly components are hot-pressed using a six-sided top press. The cemented carbide is a tungsten carbide-cobalt cemented carbide; The hot pressing temperature is 1500~1800℃, the pressure is 5~6.5GPa, and the holding time is 10~30min; The foamed diamond micro powder is used as a raw material. The surface of the foamed diamond has been foamed, which has a larger specific surface area and contact points than that of single crystal diamond. The interpenetration of the foamed diamond surfaces is conducive to the formation of DD bonds. The foamed diamond micro powder is doped with a metal catalyst. Under the hot pressing environment of high temperature and high pressure, the diamond surface will be graphitized. The graphitized carbon will dissolve in the catalyst. When the dissolved carbon is precipitated from the catalyst, it will be converted back into diamond. At this time, the newly converted diamond grows on the surface of the diamond that has not been graphitized, so that DD bonds are formed between the diamonds. The wear ratio of the foamed diamond compact is 37.3x10 3 49.6x10 3 .

2. The production method according to claim 1, characterized by, The wet ball milling process further includes removing organic solvents from the resulting mixed powder, drying, and sieving.

3. The preparation method according to claim 1, characterized in that, The particle size of the mixed powder is 100 mesh.

4. The foamed diamond composite sheet prepared by the preparation method according to any one of claims 1 to 3.

Images