Polycrystalline diamond compact with good conductivity

Abstract

The invention discloses a polycrystalline diamond compact with good conductivity, a formula of mixed powder is improved, Ti3AlC2 powder and graphene nanosheets are added, particle size composition and sintering molding parameters are limited, and the sintered graphene nanosheets provide a carbon source to facilitate formation of firm carbon-carbon bonding among diamond particles, so that the conductivity of the polycrystalline diamond compact is improved. Parts of graphene nanosheets are filled in triangular grain boundary gaps among diamond grains to play a role of a framework, crack propagation can be effectively prevented, meanwhile, adjacent grains can be firmly fixed, meanwhile, crack propagation can be effectively inhibited through the stick-slip effect of graphene, Ti3AlC2 powder is decomposed in the sintering process, Al is formed to fill the pores, and therefore the service life of the diamond is prolonged, and the service life of the diamond is prolonged. And the formed polycrystalline diamond compact has good electrical conductivity, meanwhile, the toughness is greatly improved, the cutting edge quality is improved, and meanwhile, the machining precision is improved.

Description

Technical Field

[0001] The present invention relates to the field of materials technology, and particularly to a polycrystalline diamond composite sheet with good electrical conductivity. Background Art

[0002] The polycrystalline diamond composite sheet is a superhard composite material sintered and formed under high temperature and high pressure conditions by a specific synthesis process with diamond micropowder as the raw material and cemented carbide as the matrix. It is widely used in the cutting of aluminum alloys and other non-ferrous metals, and also in the cutting of some high-end woodworking fields. However, traditional PCD composite sheets have disadvantages such as poor electrical conductivity, difficult electrical processing, poor edge quality, and difficult control of machining accuracy, which need to be improved. Summary of the Invention

[0003] To solve the above at least one technical defect, the present invention provides the following technical solutions:

[0004] This application document discloses a polycrystalline diamond composite sheet with good electrical conductivity, which uses silicon-coated diamond, carbon fiber, diamond micropowder, Ti3AlC2 powder, graphene nanosheets, and iron-nickel alloy powder as the mixed powder, and is sintered and formed with cemented carbide under a pressure of 5.0 - 6.3 GPa and a temperature of 1580 - 1700 °C. Among them, the particle size of the silicon-coated diamond micropowder is 20 - 30 μm, the particle size of the carbon fiber is 1 nm - 100 μm, the particle size of the diamond micropowder is 8 - 20 μm, the particle size of the iron-nickel alloy powder is 1 - 6 μm, and the particle size of the Ti3AlC2 powder is 40 - 80 μm. And the mass percentages of each component in the mixed powder are: carbon fiber 0.1 - 0.5%, diamond micropowder 2 - 6%, Ti3AlC2 powder 0.3 - 0.8%, graphene nanosheets 0.1 - 0.2%, iron-nickel alloy powder 3 - 7%, and the rest is silicon-coated diamond micropowder.

[0005] Improve the formula of the mixed powder, increase the Ti3AlC2 powder and graphene nanosheets, and limit the particle size composition and sintering and forming parameters. The sintered graphene nanosheets provide a carbon source to help promote the formation of strong carbon-carbon bonds between diamond particles. Some graphene nanosheets fill the triangular grain boundary voids between diamond grains, playing a role as a framework, which can effectively prevent crack propagation. At the same time, it can firmly fix adjacent grains. At the same time, the stick-slip effect of graphene itself can also effectively inhibit crack propagation. During the sintering process, the Ti3AlC2 powder decomposes and forms Al to fill the pores, promoting the densification of the structure, and forming a transition layer on the diamond surface, which helps to improve the bonding force. The formed polycrystalline diamond composite sheet not only has good electrical conductivity, but also greatly improves in toughness, edge quality, and helps to improve machining accuracy.

[0006] Further, a transition layer is deposited on the surface of the cemented carbide part. The transition layer is a molybdenum layer, and the deposition thickness of the molybdenum layer is 10 - 15 μm. Adding the molybdenum layer helps reduce local thermal stress and improve interface stability.

[0007] Further, the cemented carbide is of the tungsten-cobalt alloy type, with excellent wear resistance and toughness.

[0008] Further, the raw material composition of the cemented carbide is as follows by mass percentage: 87 - 92% WC powder, 7 - 11% Co powder, and 1 - 3% Ti powder. Defining the component ratio helps improve wear resistance and extend service life.

[0009] Further, the cemented carbide is formed by the flowing warm compaction process, where the forming pressure is 650 - 760 MPa and the forming temperature is 160 - 180 °C. After forming, the alloy part is sintered, where the sintering temperature is 1300 - 1500 °C and the time is 14 - 19 h. Defining the parameters helps improve performance.

[0010] Further, the cemented carbide is pre-treated by ultrasonic treatment with ethanol, and the mixed powder is pre-treated by drying to better combine with the mixed powder.

[0011] Further, during the sintering process of the cemented carbide and the mixed powder, first raise the temperature to the sintering pressure at a rate of 0.5 - 1 GPa / min, raise the temperature to the sintering temperature at a rate of 35 - 50 °C / s. After sintering, cool down to 650 °C at a rate of 20 - 35 °C / s, keep warm for 20 - 35 min and then cool down to room temperature, and lower the pressure to atmospheric pressure at a rate of 0.3 - 0.7 GPa / min. Defining the parameters helps improve the performance of the polycrystalline diamond compact.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. The present invention improves the formula and forming process parameters, etc. Under the combined action of graphene nanosheets, carbon fibers, Ti3AlC2 powder, etc., the formed polycrystalline diamond compact integrates properties such as electrical conductivity and high toughness, improves the edge quality, extends the service life, and improves the processing accuracy. Specific Embodiments

[0014] The following further illustrates the present invention in conjunction with specific embodiments.

[0015] The raw materials are as follows:

[0016] The particle size of the silicon-coated diamond micropowder is 20 - 30 μm;

[0017] The particle size of the carbon fiber is 20 - 45 μm;

[0018] The particle size of the diamond micropowder is 10 - 20 μm. The diamond micropowder is pre-purified and decontaminated by a high-temperature vacuum furnace, and the vacuum degree is 10-3 Pa, temperature 1200℃;

[0019] The particle size of the iron-nickel alloy powder is 3-6 μm, and the mass ratio of iron to nickel in the iron-nickel alloy powder is 1:1;

[0020] The particle size of Ti3AlC2 powder is 50-70μm;

[0021] The diameter of graphene nanosheets is 5-10 μm and the thickness is 2-10 nm.

[0022] Example 1

[0023] A polycrystalline diamond composite sheet with good electrical conductivity, the preparation process of which is as follows:

[0024] First, prepare the materials. The above-mentioned silicon-coated diamond powder particle size, carbon fiber, diamond powder, iron-nickel alloy powder, and Ti3AlC2 powder are mixed according to the following mass percentages to form a mixed powder: 0.3% carbon fiber, 4% diamond powder, 0.5% Ti3AlC2 powder, 0.1% graphene nanosheets, 5% iron-nickel alloy powder, and the rest is silicon-coated diamond powder. The powders in the above mass percentages are added into a ball mill with anhydrous ethanol as the medium, a ball-to-material ratio of 1:1, a rotation speed of 650 r / min, and the ball milling is stopped after 48 hours. The mixed powder after ball milling is vacuum heat treated at a temperature of 550°C and a vacuum degree of 3×10 -3 Pa, time is 1h.

[0025] The composition of the cemented carbide raw material is as follows in mass percentage: WC powder 90%, Co powder 8%, Ti powder 2%. The WC powder, Co powder, and Ti powder are added to anhydrous ethanol and ultrasonically treated for 30 minutes, and then dried for later use.

[0026] The dried cemented carbide raw material was formed by a flow warm pressing process, wherein the forming pressure was 720 MPa and the forming temperature was 170°C. The formed alloy parts were sintered, wherein the sintering temperature was 1400°C and the time was 17 hours. The sintered alloy parts were plated, and molybdenum was deposited in the grooves and surface of the alloy parts by the CVD method, with a deposition thickness of 11 μm.

[0027] Second, sintering: the mixed powder obtained above and the formed cemented carbide are placed in a container, and are pressed into tablets by a pressing machine to obtain a preformed part.

[0028] The preform obtained after tablet pressing is subjected to high-temperature and high-pressure sintering treatment by a six-sided top large cavity press, where the pressure is 5.8 GPa, the temperature is 1650 °C, and the sintering duration is 15 min. During the sintering process of cemented carbide and mixed powder, the pressure is first increased to the sintering pressure at a rate of 0.7 GPa / min, the temperature is increased to the sintering temperature at a rate of 42 °C / s. After sintering, the temperature is decreased to 650 °C at a rate of 30 °C / s, held at this temperature for 30 min, and then decreased to room temperature, and the pressure is decreased to atmospheric pressure at a rate of 0.5 GPa / min.

[0029] Example 2

[0030] A polycrystalline diamond composite sheet with good electrical conductivity is prepared by the following process:

[0031] First, prepare materials. The above-mentioned silicon-coated diamond micropowder particle size, carbon fiber, diamond micropowder, iron-nickel alloy powder, and Ti3AlC2 powder are mixed to form a mixed powder according to the following mass percentages: carbon fiber 0.3%, diamond micropowder 5%, Ti3AlC2 powder 0.6%, graphene nanosheet 0.2%, iron-nickel alloy powder 6%, and the rest is silicon-coated diamond micropowder. The powders with the above mass percentages are added to a ball mill, using absolute ethanol as the medium, the ball-to-material ratio is 1:1, the rotation speed is 680 r / min, and the ball milling is stopped after 50 h. The ball-milled mixed powder is subjected to vacuum heat treatment at a temperature of 530 °C, a vacuum degree of 3×10 -3 Pa, and the time is 1.3 h.

[0032] The composition of the cemented carbide raw materials is as follows by mass percentage: WC powder 92%, Co powder 7%, Ti powder 1%. First, WC powder, Co powder, and Ti powder are added to absolute ethanol and ultrasonically treated for 30 min, and then dried for standby.

[0033] The above-mentioned dried cemented carbide raw materials are formed by a warm flow compaction process, where the compaction pressure is 690 MPa and the compaction temperature is 165 °C. The formed alloy parts are sintered and formed, where the sintering temperature is 1450 °C and the time is 19 h. The sintered alloy parts are subjected to a coating treatment, and molybdenum is deposited on the grooves and surfaces of the alloy parts by the CVD method, and the deposition thickness is 13 μm.

[0034] Second, sintering. The above-obtained mixed powder and the formed cemented carbide are placed in a container, and a preform is obtained by tablet pressing through a briquetting machine.

[0035] The preform obtained after tablet pressing is subjected to high-temperature and high-pressure sintering treatment by a six-sided top large cavity press, where the pressure is 6.0 GPa, the temperature is 1620 °C, and the sintering duration is 10 min. During the sintering process of cemented carbide and mixed powder, the pressure is first increased to the sintering pressure at a rate of 0.6 GPa / min, the temperature is increased to the sintering temperature at a rate of 45 °C / s. After sintering, the temperature is decreased to 650 °C at a rate of 35 °C / s, held at this temperature for 35 min, and then cooled to room temperature, and the pressure is decreased to atmospheric pressure at a rate of 0.6 GPa / min.

[0036] Example 3

[0037] A polycrystalline diamond composite sheet with good electrical conductivity, and its preparation process is as follows:

[0038] First, prepare materials. The above-mentioned silicon-coated diamond micropowder particle size, carbon fiber, diamond micropowder, iron-nickel alloy powder, and Ti3AlC2 powder are mixed according to the following mass percentages to form a mixed powder: carbon fiber 0.4%, diamond micropowder 6%, Ti3AlC2 powder 0.7%, graphene nanosheet 0.15%, iron-nickel alloy powder 6.5%, and the rest is silicon-coated diamond micropowder. The powders with the above mass percentages are added to a ball mill, using absolute ethanol as the medium, the ball-to-material ratio is 1:1, the rotation speed is 650 r / min, and the ball milling stops after 45 h. The ball-milled mixed powder is subjected to vacuum heat treatment at a temperature of 550 °C, a vacuum degree of 3×10 -3 Pa, and the time is 2 h.

[0039] The composition of the cemented carbide raw materials is as follows in mass percentages: WC powder 89%, Co powder 9%, Ti powder 2%. First, WC powder, Co powder, and Ti powder are added to absolute ethanol and ultrasonically treated for 30 min, and then dried for later use.

[0040] The above-mentioned dried cemented carbide raw materials are formed by a flowing warm compaction process, where the compaction pressure is 720 MPa and the compaction temperature is 170 °C. The formed alloy parts are sintered and formed, where the sintering temperature is 1400 °C and the time is 17 h. The sintered alloy parts are subjected to a plating treatment, and molybdenum is deposited on the grooves and surfaces of the alloy parts by the CVD method, and the deposition thickness is 11 μm.

[0041] Second, sintering. The above-obtained mixed powder and the formed cemented carbide are placed in a container, and a preform is obtained by tablet pressing through a briquetting machine.

[0042] The preform obtained after tabletting treatment is subjected to high-temperature and high-pressure sintering treatment by a six-sided top large cavity press, where the pressure is 6.2 GPa, the temperature is 1620 °C, and the sintering duration is 12 min. During the sintering process of cemented carbide and mixed powder, the pressure is first increased to the sintering pressure at a rate of 0.8 GPa / min, the temperature is increased to the sintering temperature at a rate of 40 °C / s. After sintering, the temperature is decreased to 650 °C at a rate of 32 °C / s, held at this temperature for 30 min, and then decreased to room temperature, and the pressure is decreased to atmospheric pressure at a rate of 0.5 GPa / min.

[0043] Comparative Example 1

[0044] Compared with Example 1, there are no graphene nanosheets in the mixed powder.

[0045] The properties of the polycrystalline composite sheets prepared above are detected. Compared with Comparative Example 1, the toughness of the polycrystalline diamond composite sheets prepared in Examples 1-3 is increased by about 32.5% on average, and the wear ratio is increased by about 20.6% on average. The conductivity of the polycrystalline diamond composite sheets prepared in Examples 1-3 is about 3×10 -2 s / cm, having the advantages of both electrical conductivity and high toughness.

[0046] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A polycrystalline diamond compact with good electrical conductivity, characterized in that, Using silicon-coated diamond, carbon fiber, diamond micropowder, Ti3AlC2 powder, graphene nanosheets, and iron-nickel alloy powder as the mixed powder, sintering and forming with cemented carbide under a pressure of 5.0 - 6.3 GPa and a temperature of 1580 - 1700 °C. Among them, the particle size of the silicon-coated diamond micropowder is 20 - 30 μm, the particle size of the carbon fiber is 1 nm - 100 μm, the particle size of the diamond micropowder is 8 - 20 μm, the particle size of the iron-nickel alloy powder is 1 - 6 μm, and the particle size of the Ti3AlC2 powder is 40 - 80 μm. And the mass percentage of each component in the mixed powder is: carbon fiber 0.1 - 0.5%, diamond micropowder 2 - 6%, Ti3AlC2 powder 0.3 - 0.8%, graphene nanosheets 0.1 - 0.2%, iron-nickel alloy powder 3 - 7%, and the rest is silicon-coated diamond micropowder.

2. The polycrystalline diamond composite sheet with good electrical conductivity according to claim 1, wherein: A transition layer is deposited on the surface of the cemented carbide part, and the transition layer is a molybdenum layer, where the deposition thickness of the molybdenum layer is 10 - 15 μm.

3. A polycrystalline diamond composite sheet with good electrical conductivity according to claim 1, characterized in that: The cemented carbide is of the tungsten-cobalt alloy type.

4. The polycrystalline diamond composite sheet with good electrical conductivity according to claim 3, characterized in that: The raw material composition of the cemented carbide is as follows by mass percentage: WC powder 87 - 92%, Co powder 7 - 11%, Ti powder 1 - 3%.

5. The polycrystalline diamond compact with good electrical conductivity according to claim 4, characterized in that: The cemented carbide is formed by a flowing warm compaction process, where the compaction pressure is 650 - 760 MPa and the compaction temperature is 160 - 180 °C. After forming, the alloy part is sintered and formed, where the sintering temperature is 1300 - 1500 °C and the time is 14 - 19 h.

6. The polycrystalline diamond composite sheet with good electrical conductivity according to claim 1, characterized in that: The cemented carbide is pre-treated by ultrasonic treatment with ethanol, and the mixed powder is pre-treated by drying.

7. A polycrystalline diamond composite sheet with good electrical conductivity as described in claim 1, characterized in that: During the sintering process of the cemented carbide and the mixed powder, first raise the temperature to the sintering pressure at a rate of 0.5 - 1 GPa / min, raise the temperature to the sintering temperature at a rate of 35 - 50 °C / s. After sintering, cool down to 650 °C at a rate of 20 - 35 °C / s, keep warm for 20 - 35 min and then cool down to room temperature, and reduce the pressure to atmospheric pressure at a rate of 0.3 - 0.7 GPa / min.