Specifically, the raw material of the polycrystalline diamond working layer and the hard alloy substrate layer are placed in a high-temperature resistant metal cup.

Specifically, the high-temperature resistant metal cup is made of one or a combination of more of tantalum, molybdenum, niobium and zirconium.

Example 1

A polycrystalline diamond compact comprises a polycrystalline diamond working layer and a hard alloy substrate layer, wherein the raw materials of the polycrystalline diamond working layer comprise diamond particles and a degassing agent, the diamond particles comprise 70 wt% of diamond primary particle size particles and 30 wt% of diamond auxiliary particle size particles, the particle size section of the diamond primary particle size particles is 50/60 meshes, and the diamond auxiliary particle size particles comprise 6 wt% of diamond particles with the particle size section of 40-50 micrometers and 24 wt% of diamond particles with the particle size section of 22-36 micrometers. The degassing agent adopts a mixture of 0.25 percent of Ni30Zr70, 0.12 percent of Cu30Zr70, 0.55 percent of ZrC and 0.10 percent of Ti; arrange the raw materials of polycrystalline diamond working layer in on the carbide stratum basale, by high temperature resistant metal cup parcel, carry out high temperature high pressure synthesis, first section high temperature high pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1173.15-1373.15K, and the synthesis heating time is 3.5 minutes;

second-stage high-temperature high-pressure: the synthesis high pressure is 7000MPa, the synthesis temperature is 1723.15-1823.15K, and the synthesis heating time is 8 minutes.

Example 2

A polycrystalline diamond compact comprises a polycrystalline diamond working layer and a hard alloy substrate layer, wherein the raw materials of the polycrystalline diamond working layer comprise diamond particles and a degassing agent, the diamond particles comprise 85 wt% of diamond primary particle size particles and 15 wt% of diamond auxiliary particle size particles, the particle size section of the diamond primary particle size particles is 80/100 meshes, and the diamond auxiliary particle size particles comprise 3 wt% of diamond particles with the particle size section of 8-16 micrometers and 12 wt% of diamond particles with the particle size section of 3-6 micrometers. The degassing agent adopts a mixture of 0.18 wt% of Ni30Zr70, 0.25 wt% of Cu30Zr70, 0.25 wt% of ZrC and 0.1 wt% of Ti; arrange the raw materials of polycrystalline diamond working layer in on the carbide stratum basale, by high temperature resistant metal cup parcel, carry out high temperature high pressure synthesis, first section high temperature high pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1173.15-1373.15K, and the synthesis heating time is 4.5 minutes;

second-stage high-temperature high-pressure: the synthesis high pressure is 7000MPa, the synthesis temperature is 1723.15-1823.15K, and the synthesis heating time is 12.5 minutes.

Example 3

A polycrystalline diamond compact comprises a polycrystalline diamond working layer and a hard alloy substrate layer, wherein the raw materials of the polycrystalline diamond working layer comprise diamond particles and a degassing agent, the diamond particles comprise 85 wt% of diamond primary particle size particles and 15 wt% of diamond auxiliary particle size particles, the particle size section of the diamond primary particle size particles is 170/200 meshes, and the diamond auxiliary particle size particles comprise 3 wt% of diamond particles with the particle size section of 8-16 micrometers and 12 wt% of diamond particles with the particle size section of 3-6 micrometers. The degassing agent adopts a mixture of 0.17 wt% of Cu30Zr70, 0.13 wt% of Al30Zr70 and 0.3 wt% of TiC; arrange the raw materials of polycrystalline diamond working layer in on the carbide stratum basale, by high temperature resistant metal cup parcel, carry out high temperature high pressure synthesis, first section high temperature high pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1173.15-1373.15K, and the synthesis heating time is 5 minutes;

second-stage high-temperature high-pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1723.15-1823.15K, and the synthesis heating time is 13.5 minutes.

Example 4

A polycrystalline diamond compact comprises a polycrystalline diamond working layer and a hard alloy substrate layer, wherein the raw materials of the polycrystalline diamond working layer comprise diamond particles and a degassing agent, the diamond particles comprise 96 wt% of diamond main particle size particles and 4 wt% of diamond auxiliary particle size particles, the particle size section of the diamond main particle size particles is 40-60 micrometers, and the diamond auxiliary particle size particles are diamond particles with the particle size section of 3-6 micrometers. The degassing agent adopts a mixture of 0.12 wt% of Cu30Zr70, 0.26 wt% of Al30Zr70 and 0.8 wt% of TiC; arrange the raw materials of polycrystalline diamond working layer in on the carbide stratum basale, by high temperature resistant metal cup parcel, carry out high temperature high pressure synthesis, first section high temperature high pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1173.15-1373.15K, and the synthesis heating time is 6 minutes;

second-stage high-temperature high-pressure: the synthesis high pressure is 7000MPa, the synthesis temperature is 1723.15-1823.15K, and the synthesis heating time is 16 minutes.

Example 5

A polycrystalline diamond compact comprises a polycrystalline diamond working layer and a hard alloy substrate layer, wherein raw materials of the polycrystalline diamond working layer comprise diamond particles and a degassing agent, the diamond particles comprise 100 wt% of diamond primary-grain-size particles, the grain size section of the diamond primary-grain-size particles is 80/100 meshes, and the degassing agent adopts a mixture of 0.12 wt% of Cu30Zr70, 0.26 wt% of Al30Zr70 and 0.8 wt% of TiC; arrange the raw materials of polycrystalline diamond working layer in on the carbide stratum basale, by high temperature resistant metal cup parcel, carry out high temperature high pressure synthesis, first section high temperature high pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1173.15-1373.15K, and the synthesis heating time is 5.5 minutes;

second-stage high-temperature high-pressure: the synthesis high pressure is 7000MPa, the synthesis temperature is 1723.15-1823.15K, and the synthesis heating time is 15 minutes.

Example 6

A polycrystalline diamond compact comprises a polycrystalline diamond working layer and a hard alloy substrate layer, wherein raw materials of the polycrystalline diamond working layer comprise diamond particles and a degassing agent, the diamond particles comprise 100 wt% of diamond primary-grain-size particles, the diamond primary-grain-size particles comprise 60 wt% of diamond particles with the grain size section of 80/100 meshes and 40 wt% of diamond particles with the grain size section of 100/120 meshes, and the degassing agent adopts a mixture of 0.12 wt% of Cu30Zr70, 0.26 wt% of Al30Zr70 and 0.8 wt% of TiC; arrange the raw materials of polycrystalline diamond working layer in on the carbide stratum basale, by high temperature resistant metal cup parcel, carry out high temperature high pressure synthesis, first section high temperature high pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1173.15-1373.15K, and the synthesis heating time is 5 minutes;

second-stage high-temperature high-pressure: the synthesis pressure is 7000MPa, the synthesis temperature is 1723.15-1823.15K, and the synthesis heating time is 15.5 minutes.

The working principle of this application does: in production and research, the applicant finds that the breakage resistance and the cutting finish of raw diamond particles adopting coarse particles gradually decrease with the increase of the particle size when the polycrystalline diamond compact is sintered and synthesized. The larger the particle size of the raw diamond particles is, the more wear-resistant the diamond is, and the impact strength of the polycrystalline diamond working layer is improved. However, the polycrystalline diamond compact has short service life and low cutting smoothness due to large particles falling off after processing abrasion and poor chipping resistance. The main reasons are as follows: the bonding between diamond particles is less, the bonding force is weak, and the diamond particles are easy to fall off. In order to increase the bonding strength between diamond particles, it is necessary to use highly clean diamond raw materials and synthesis environments. The impurities of silicon and metal on the surface of the diamond particles are removed, and air in the synthesis environment is removed. The impurities exist on the surfaces of the diamond particles and air exists among the diamond particles, under the conditions of high temperature and high pressure, the impurities and the oxygen and nitrogen elements in the air interfere with the graphitization of the surfaces of the diamond particles under the conditions of high temperature and high pressure, the graphite structure of the graphitized surfaces of the diamond particles is damaged, and stable and continuous diamond recrystallization cannot be formed in the diamond particles during recrystallization.

In the application, high cleanliness is firstly limited for the polycrystalline diamond working layer raw material, the hard alloy substrate layer and the high-temperature resistant metal cup, and the diamond particle micro powder abrasive material needs to reach the cleanliness requirement through acid treatment, high-temperature alkali treatment, purified water cleaning, ultrasonic cleaning and other treatment modes.

Specifically, the requirements for the surface cleanliness of the diamond particle micro powder abrasive are as follows. The diamond grain size is less than 3 microns, and the surface silicon and metal impurity content of the diamond grain size is less than 55 ppm. The diamond particle size is 3-40 microns, and the surface silicon and metal impurity content is less than 40 ppm. The diamond particle size is 40-60 microns, and the surface silicon and metal impurity content is less than 27 ppm. The diamond grain size is larger than 60 microns, and the surface silicon and metal impurity content of the diamond grain size is less than 15 ppm.

The high-temperature resistant metal cup, the polycrystalline diamond working layer raw material mixture in the high-temperature resistant metal cup and the hard alloy substrate layer are treated with high cleanliness. However, as mentioned above, there are still residual impurities on the surface of the diamond particles, and air, including oxygen and nitrogen, is in the gaps in the raw material mixture of the polycrystalline diamond working layer. These impurities still affect the performance of polycrystalline diamond compacts synthesized from coarse-grained diamond particles.

Prior to synthesis, a schematic cross-sectional structure of a polycrystalline diamond compact is shown in fig. 1. The polycrystallinediamond working layer 10 raw material mixture and the cemented carbidebase layer alloy 20 are in ametal cup 60. The diamond primaryparticle size particles 30 are naturally stacked and uniformly distributed after being pressed under a pressure of less than 10 MP. The diamond secondaryparticle size particles 40 are uniformly distributed on the surface of the diamondprimary particle size 30. Thevoids 50 in the polycrystalline diamond working layer feedstock mixture are air, and the volume of the voids is the volume of air. At room temperature before the polycrystalline diamond compact is synthesized, the porosity of the polycrystalline diamond working layer raw material mixture is about 40%. In the raw material mixture of the polycrystallinediamond working layer 10, the diamond mainparticle size particles 30, the diamond auxiliaryparticle size particles 40, the getter on the close contact surface of the diamond auxiliary particle size particles, silicon and metal oxide impurities and air are uniformly distributed and coexist.

And preparing the polycrystalline diamond compact, namely synthesizing the polycrystalline diamond compact at high temperature and high pressure. The synthesis pressure is 6500-7500MPa, the first-stage synthesis temperature is 1173.15-1373.15K, and the synthesis time is 3.5-6 minutes; the second stage synthesis temperature is 1723.15-1823.15K. The synthesis heating time is 8-16 minutes.

In the first stage of synthesis pressing, the cross-sectional structure of the polycrystallinediamond working layer 10 is schematically shown in fig. 2. The pressure of a synthesis cavity in the synthesis process is 6500-7500MPa, and the sintering temperature reaches 1173.15-1373.15K. The polycrystalline diamond workinglayer feedstock mixture 10 is highly compressed by about 70% and is almost uncompressed in the radial direction. Crystals of the irregularly shaped diamond primaryparticle size particles 30 start to deform, and diamond primaryparticle size particles 30 of the hexaoctahedral intact crystals are deformed little. The diamond secondaryparticle size particles 40 are compressively deformed or crushed at the close contact surface of the diamond primaryparticle size particles 30. Thevoids 50 in the polycrystalline diamond working layer feedstock mixture are compressed by a factor of about 10 and the air in thevoids 50 is compressed by a factor of 10. The pressure of the void air at this time was about 4 MPa. The low pressure surface of the interstitial diamond crystals begins to graphitize.

The impurities silicon and metal on the surface of the diamond particles exist in the form of oxides. The non-metal oxide silicon oxide, the metal oxide calcium oxide, the metal oxide chromium oxide, the metal oxide iron oxide, the metal oxide magnesium oxide, the metal oxide manganese oxide, the metal oxide sodium oxide, the metal oxide nickel oxide, the metal oxide aluminum oxide and the like can be melted into the graphitized layer and are not easy to be taken away when cobalt is scanned and permeated.

In addition, oxygen in theinterstices 50 between the diamond crystals reacts with the graphitized carbon to form oxycarbides which disrupt the graphite structure. The nitrogen in the voids slows down the growth of graphite, and the gas pressure is not conducive to graphitization.

To eliminate the adverse effects of oxides and oxygen and nitrogen, one or more degassing agents are added to theraw material mixture 10 of the polycrystalline diamond working layer of the present invention. These degassing agents are metallic zirconium powder, zirconium copper alloy, zirconium aluminum alloy, zirconium nickel alloy, zirconium carbide or compounds of metallic titanium powder, titanium alloy, titanium carbide and the like. The proportions are 0.1% to 3.0% respectively.

The melting point of the degassing agent is low and the molten degassing agent compound will dissolve the oxide of the uncompressed surface of the diamondprimary particles 30 and diamondsecondary particles 40 crystals at the temperature of the first stage. The melted degasifier compounds penetrate into crystal gaps of the primary diamondgrain size particles 30 and the secondary diamondgrain size particles 40 to dissolve the oxides. And cleaning the diamond surface. The molten degasser compound may also absorb oxygen and nitrogen in the voids, reducing or eliminating the gas pressure within voids 50. As mentioned above, a high cleanliness environment is created, and a high purity graphite layer is produced on the surface of the diamond crystal in the graphitization process.

In the second stage, the pressure of the synthesis cavity is 6500-7500MPa in the synthesis process, and the sintering temperature is raised to 1723.15-1823.15K in the second stage. Cobalt in the cemented carbide substrate layer sweeps across the polycrystalline diamond working layer raw material mixture voids 50 for cobalt infiltration. Theinterstices 50 of the polycrystalline diamond working layer feedstock mixture continue to be compressed by a factor of more than 17. When the primarydiamond grain size 30 is between 35 microns and 275 microns, theinterstices 50 of the polycrystalline diamond working layer feedstock mixture are compressed 17-27 times. The polycrystalline diamond working layer is highly compressed to 70% and below.

In the second stage, when the temperature exceeds 1573.15K, the cobalt in the cemented carbide substrate layer rapidly sweeps into the cobalt penetration line of the polycrystallinediamond working layer 10. After getters and silicon and metal oxide impurities in crystal planes of tight contact surfaces among the diamond mainparticle size particles 30, the diamond auxiliaryparticle size particles 40 and the diamond mainparticle size particles 30 and the diamond auxiliaryparticle size particles 40 are melted in cobalt liquid, the silicon and metal oxide impurities are dissolved in the adjacent getters, and the surface of the diamond is cleaned.

The front cobalt liquid brings the getters, which are melted into the oxides and absorb oxygen and nitrogen, to the upper surface of the polycrystallinediamond working layer 10, forming adiamond surface layer 70 containing impurities. Subsequent processing will remove the contaminateddiamond surface layer 70 and the portion of the polycrystalline diamond working layer adjacent thereto.

After the cobalt liquid fills the gap, the diamond crystals in the whole polycrystalline diamond working layer have the same pressure as the cobalt liquid, and the cobalt liquid can permeate into the diamond crystal face which is originally in close contact with the cobalt liquid. The whole crystal face of the diamond particle is accelerated to graphitize under the action of cobalt. The cobalt solution will then dissolve the graphite on the diamond surface. When the graphite in the cobalt solution is supersaturated, the graphite starts to generate the recrystallizeddiamond 80 between the crystal faces of thediamond 30 and thediamond 40 under the action of the catalyst of the cobalt. After the synthesis is completed, most of the crystal faces of the primary diamondgrain size particles 30 and the secondary diamondgrain size particles 40 in the polycrystallinediamond working layer 10 form diamond bonding bonds as shown in fig. 3.

This application adopts 35 microns to 275 microns's diamond major diameter, in the synthetic sintering, can form wide cobalt seepage line, and the resistance that wide cobalt seepage line oozed cobalt is little, oozes cobalt fast, and the ability of taking away getter in the space and impurity is big to make diamond recrystallization's graphite purity high, the environmental cleaning, the good quality of recrystallization diamond, the quantity of recrystallization diamond is many, and the bonding ability of formation is strong. Thereby making the diamond compact of the present application have high chipping resistance, high impact strength, high wear resistance, and a finished surface finish.

The invention is described above with reference to the accompanying drawings as an example, in so far as it is a insubstantial improvement in the method concept and technical solutions of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.

Claims

1. The utility model provides a polycrystalline diamond compact, polycrystalline diamond compact comprises polycrystalline diamond working layer and carbide base layer, its characterized in that: the polycrystalline diamond working layer is prepared from a mixture of a degassing agent and diamond particles with certain surface cleanliness, and the porosity of the polycrystalline diamond working layer is 30% -45% at room temperature; the diamond particles consist of diamond primary particle size particles and diamond secondary particle size particles, and the particle size of the diamond primary particle size particles is 35-275 microns; the grain diameter of the diamond auxiliary grain size particles is less than or equal to 1/4 grain diameter of the diamond main grain size particles, and the weight percentage of the diamond main grain size particles in the diamond grains is 70-100%; the degassing agent accounts for 0.1-3.0% of the weight of the diamond particles; the hard alloy base layer is made of tungsten carbide containing cobalt.

2. The polycrystalline diamond compact of claim 1, wherein: the degassing agent is one or more of metal zirconium powder, zirconium copper alloy, zirconium aluminum alloy, zirconium nickel alloy, zirconium carbide, metal titanium powder, titanium alloy and titanium carbide.

3. A polycrystalline diamond compact according to claim 1 or claim 2, wherein: the cobalt content of the cemented carbide substrate layer is 12-16 wt%.

4. A polycrystalline diamond compact according to claim 3, wherein: the surface cleanliness of the diamond particles was: the grain diameter of the diamond particles is less than 3 microns, and the surface impurity content of the diamond particles is less than 55 ppm; the grain diameter of the diamond particles is 3-40 microns, and the surface impurity content of the diamond particles is less than 40 ppm; the grain diameter of the diamond particles is 40-60 microns, and the surface impurity content of the diamond particles is less than 27 ppm; the diamond particles have a particle size of greater than 60 microns and a surface impurity level of less than 15 ppm.

5. A method of making a polycrystalline diamond compact according to any one of claims 1 to 4, wherein: placing the raw materials of the polycrystalline diamond working layer on a hard alloy substrate layer, and sintering and synthesizing the polycrystalline diamond working layer through two sections of high temperature and high pressure;

6. The method of making a polycrystalline diamond compact of claim 5, wherein: the diamond particles are divided into a plurality of granularity sections according to the average particle size, the main granularity of the diamond particles is selected from one granularity section or the mixture of two to three adjacent granularity sections, and the auxiliary granularity of the diamond particles is selected from one granularity section or the mixture of a plurality of finer granularity sections.

7. The method of making a polycrystalline diamond compact of claim 6, wherein: the raw material of the polycrystalline diamond working layer and the hard alloy basal layer are placed in a high-temperature resistant metal cup during sintering synthesis.

8. The method of making a polycrystalline diamond compact of claim 7, wherein: the high-temperature resistant metal cup is made of one or a combination of more of tantalum, molybdenum, niobium and zirconium.