Preparation method of Ti-plated polycrystalline diamond

Abstract

The invention relates to a preparation method of Ti-plated polycrystalline diamond, which comprises the following steps: step 1, purifying the surface of diamond by using an acid solution, and then drying after treatment; 2, uniformly mixing the treated diamond with Ti powder, Cu powder and a catalyst in a container; step 3, loading the mixture into a sintering boat, and putting the sintering boat into a quartz tube; 4, heating the heat treatment furnace to a certain temperature, pushing the quartz tube into the furnace, and keeping the temperature; 5, cooling to 500 DEG C along with the furnace, pulling out the quartz tube, and air-cooling to room temperature; and 6, taking out the sintering boat from the quartz tube, and screening to obtain the titanium-plated diamond. 7, titanium-plated diamond micro-powder is adopted as a raw material, the purified titanium-plated diamond micro-powder and a sintering aid are packaged in a molybdenum sleeve to be sintered, and after the surface and the cross section of a sintered sample are purified, the sample is analyzed; the adhesive has the advantages that the adhesive strength is improved, high-temperature damage is reduced, the bending strength is good, and the service life is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of polycrystalline diamonds, and in particular relates to a method for preparing Ti-plated polycrystalline diamonds. Background Art

[0002] The high hardness, high wear resistance and good toughness of diamond polycrystals are unmatched by other materials. The application in tools such as cutting tools, wire drawing dies, probes and claws has achieved good results. It is an ideal raw material for making mechanical processing tools. The ideal diamond polycrystal not only has the excellent physical properties of diamond single products, but also exhibits the isotropy advantage that diamond single crystals do not have. At the same time, in order to protect the original inherent strength of the diamond body and prevent its oxidation, a layer of metal is plated on the surface of the diamond crystal. In this way, the service life and efficiency of the polycrystal will be greatly improved. Diamond plated with metal copper and nickel have been used in tools, but diamonds plated with Co, Ni and Fe on the surface will be carbonized when heated to a certain temperature, and the bonding strength between the coating and the diamond will be reduced. Therefore, it is very necessary to provide a preparation method of Ti-plated polycrystalline diamond that improves bonding strength, reduces high-temperature damage, has good bending strength and improves service life. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing Ti-plated polycrystalline diamond which has improved bonding strength, reduced high temperature damage, good bending strength and improved service life.

[0004] The technical solution of the present invention is: a method for preparing Ti-plated polycrystalline diamond, the preparation method comprising the following steps:

[0005] Step 1: Pre-plating treatment: First, use an acid solution of a certain concentration to purify the diamond surface to increase its surface activity, and then dry it after treatment;

[0006] Step 2: Secondly, the treated diamond is uniformly mixed with Ti powder, Cu powder and catalyst in a container in a certain proportion;

[0007] Step 3: Then put the mixed material into a burning boat, and put the burning boat into a quartz tube with inert gas;

[0008] Step 4: Heat the heat treatment furnace to a certain temperature, push the quartz tube into the furnace, and keep it warm for 40min-60min;

[0009] Step 5: Cool to 500°C in the furnace, pull out the quartz tube, and air cool to room temperature;

[0010] Step 6: Take the burning boat out of the quartz tube and sieve to obtain titanium-coated diamond;

[0011] Step 7: Use titanium-coated diamond powder as raw material, encapsulate the purified titanium-coated diamond powder and sintering aid in a molybdenum sleeve for sintering, and perform SEM, XRD and Raman analysis on the surface and cross-section of the sintered sample after purification.

[0012] The diamond in step 1 is SMD grade diamond with a static pressure strength of 136N.

[0013] The diamond in step 1 may also be MBD50 / 60 diamond particles.

[0014] The diamond in step 1 may also be high-grade diamond powder with a double peak distribution of particle size of 10 μm+2 μm.

[0015] The specific processing operation in step 1 is: boil the diamond in hydrochloric acid for 30-40 minutes, boil it in distilled water for 30-40 minutes, clean it with anhydrous ethanol in an ultrasonic cleaning machine for 20-30 minutes, and dry it.

[0016] The particle size of the Ti powder in step 2 is -400 mesh and the purity is 99.9%; the particle size of the copper powder is -300 mesh.

[0017] The inert gas in step 3 is argon gas with a purity of 99.999%.

[0018] The heat treatment furnace in step 4 may be a box-type resistance furnace with a temperature range of 700-950°C.

[0019] The sintering aid in step 7 is a nickel-based alloy catalyst sintering aid.

[0020] The pressure and temperature conditions for the synthesis in step 7 are: 4.9-5.8 GPa, 1200° C.-1500° C.; and the sintering time is 10-30 min.

[0021] The invention has the following advantages: when the invention is used, the diamond plated by the method of the invention is grayish white, the surface coating is uniform, and the coating does not fall off when rubbed on sandpaper; the compressive strength of the Ti-plated polycrystalline diamond prepared by the method of the invention is greatly improved compared with the diamond not plated with titanium; the method of the invention can obtain a uniform and dense Ti coating on the surface of the saw blade-grade diamond, and the diamond strength can be improved after Ti plating; the Ti-plated diamond improves the wettability and improves the service life of the saw blade; under high temperature and high pressure conditions, the nickel-based alloy is used as a sintering aid, and the sintering of the titanium-plated diamond polycrystalline is successfully achieved through the regrowth between diamond micropowder particles, so the method of the invention is a simple, easy and effective method for titanium plating on the diamond surface; the titanium-plated diamond improves the cutting life and cutting efficiency of the diamond saw blade by improving the bonding strength of the matrix to the diamond and reducing the high-temperature damage of the diamond during the hot pressing process; the invention has the advantages of improving the bonding strength, reducing the high-temperature damage, having good bending strength and improving the service life. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments.

[0023] Example 1

[0024] A method for preparing Ti-plated polycrystalline diamond, the preparation method comprising the following steps:

[0025] Step 1: Pre-plating treatment: First, use an acid solution of a certain concentration to purify the diamond surface to increase its surface activity, and then dry it after treatment;

[0026] Step 2: Secondly, the treated diamond is uniformly mixed with Ti powder, Cu powder and catalyst in a container in a certain proportion;

[0027] Step 3: Then put the mixed material into a burning boat, and put the burning boat into a quartz tube with inert gas;

[0028] Step 4: Heat the heat treatment furnace to a certain temperature, push the quartz tube into the furnace, and keep it warm for 40 minutes;

[0029] Step 5: Cool to 500°C in the furnace, pull out the quartz tube, and air cool to room temperature;

[0030] Step 6: Take the burning boat out of the quartz tube and sieve to obtain titanium-coated diamond;

[0031] Step 7: Use titanium-coated diamond powder as raw material, encapsulate the purified titanium-coated diamond powder and sintering aid in a molybdenum sleeve for sintering, and perform SEM, XRD and Raman analysis on the surface and cross-section of the sintered sample after purification.

[0032] In this embodiment, diamond is SMD grade diamond with a static pressure strength of 136N, and a part of it is surface-plated with Ti using the above-mentioned preparation method; the powder used to make the sample is Cu-10Sn, Cr, Fe, Ni, Co and WC with a particle size less than 74μm; the A formula is based on Co, with a small amount of Cu-10Sn and WC added; the B formula is based on Cu-10Sn, with WC, Fe and Ni powders and a small amount of Co and Cr powders added; the bending strength test sample size is 40mm×8mmm×6mm, the cutting test head size is 40mm×3.2mm×6.5mm, and the diamond volume fraction is 8%; the hot pressing sintering process is shown in Table 1.

[0033] Table 1 Experimental formula hot pressing process parameters

[0034]

[0035] In the concrete double-blade cutting test, the cutting object is a concrete slab that has been hardened for 2 months and has a thickness of 7-8 cm. Several steel bars with a diameter of 6 mm are placed along the longitudinal and transverse directions of the concrete. The cutting conditions are shown in Table 2.

[0036] Table 2 Cutting experimental conditions

[0037]

[0038] Experimental results: ① Fracture strength of materials: The stress state during loading in the three-point bending test is basically the same as that during static tension from the tensile side, so it is often used to determine the fracture strength of brittle materials such as cast iron and cemented carbide. Table 3 shows the three-point bending test results of blank matrix, samples with uncoated titanium diamond and samples with coated titanium diamond. It can be found from Table 3 that after adding diamond, the bending strength of the matrix is ​​lower than that of the blank matrix; and the bending strength of the matrix with coated titanium diamond is improved to varying degrees compared with that of the uncoated matrix. For the cobalt-based matrix, σ bb It increased by 3.2%; while for the Cu-Sn based matrix, it increased by 4.1%.

[0039] Table 3 Flexural strength test results

[0040]

[0041] ②Concrete cutting test: In order to ensure the reliability of the experiment, the single cutting area of ​​the material exceeded 0.4m 2Finally, the performance of the cutter head is measured by the area of ​​concrete cut when the average height of the cutter head drops by 1mm. As shown in Table 4, after the diamond is plated with titanium, the performance of the cutter heads of formulas A and B is greatly improved, by 47.0% and 20.1% respectively. After the diamond is plated with titanium, the contact between the diamond and the outside world is isolated (or partially isolated), which effectively reduces the graphitization tendency of the diamond and greatly reduces the chance of forming a solid solution with Fe, Co and Ni elements, so that the strength of the diamond after hot pressing is less reduced. In addition, the coating layer bridges the surface defects of the diamond, so that the strength of the diamond is improved compared with that before titanium plating.

[0042] Table 4 Test results of different carcass cutter head performance

[0043]

[0044] In summary, 1) after titanium plating, the bonding strength between diamond and the matrix is ​​improved, and the bending strength is improved to a certain extent; 2) after titanium plating, diamond is isolated (or partially isolated) from the contact with catalytic elements such as Fe, Co, Ni in the matrix, reducing the graphitization of diamond and the tendency of forming a solid solution with no strong bonding force with them, so that the reduction in strength of diamond after hot pressing is controlled; at the same time, its exposed height is increased, the sharpness is improved, and the wear of the matrix is ​​reduced, thereby increasing its service life.

[0045] The specific processing operation in step 1 is: boil the diamond in hydrochloric acid for 30 minutes, boil it in distilled water for 30 minutes, clean it with anhydrous ethanol in an ultrasonic cleaner for 20 minutes, and dry it.

[0046] The particle size of the Ti powder in step 2 is -400 mesh and the purity is 99.9%; the particle size of the copper powder is -300 mesh.

[0047] The inert gas in step 3 is argon gas with a purity of 99.999%.

[0048] The heat treatment furnace in step 4 can be a box-type resistance furnace with a temperature of 700°C.

[0049] The sintering aid in step 7 is a nickel-based alloy catalyst sintering aid.

[0050] The pressure and temperature conditions for the synthesis in step 7 are: 4.9 GPa, 1200°C; and the sintering time is 10 min.

[0051] The invention discloses a method for preparing Ti-plated polycrystalline diamond. When the invention is used, the diamond plated by the method is grayish white, the surface coating is uniform, and the coating does not fall off when rubbed on sandpaper; the compressive strength of the Ti-plated polycrystalline diamond prepared by the method is greatly improved compared with the diamond not plated with titanium; the method can obtain a uniform and dense Ti coating on the surface of saw blade-grade diamond, and the diamond strength can be improved after Ti plating; the Ti-plated diamond improves wettability and increases the service life of the saw blade; under high temperature and high pressure conditions, nickel-based alloy is used as a sintering aid, and the sintering of the titanium-plated diamond polycrystalline is successfully achieved through the regrowth between diamond micropowder particles, so the method is a simple, easy and effective method for titanium plating on the diamond surface; the titanium-plated diamond improves the cutting life and cutting efficiency of the diamond saw blade by improving the bonding strength of the matrix to the diamond and reducing the high-temperature damage of the diamond during the hot pressing process; the invention has the advantages of improving bonding strength, reducing high-temperature damage, good bending strength and improving service life.

[0052] Example 2

[0053] A method for preparing Ti-plated polycrystalline diamond, the preparation method comprising the following steps:

[0054] Step 1: Pre-plating treatment: First, use an acid solution of a certain concentration to purify the diamond surface to increase its surface activity, and then dry it after treatment;

[0055] Step 2: Secondly, the treated diamond is uniformly mixed with Ti powder, Cu powder and catalyst in a container in a certain proportion;

[0056] Step 3: Then put the mixed material into a burning boat, and put the burning boat into a quartz tube with inert gas;

[0057] Step 4: Heat the heat treatment furnace to a certain temperature, push the quartz tube into the furnace, and keep it warm for 50 minutes;

[0058] Step 5: Cool to 500°C in the furnace, pull out the quartz tube, and air cool to room temperature;

[0059] Step 6: Take the burning boat out of the quartz tube and sieve to obtain titanium-coated diamond;

[0060] Step 7: Use titanium-coated diamond powder as raw material, encapsulate the purified titanium-coated diamond powder and sintering aid in a molybdenum sleeve for sintering, and perform SEM, XRD and Raman analysis on the surface and cross-section of the sintered sample after purification.

[0061] The diamond in step 1 may also be high-grade diamond powder with a double peak distribution of particle size of 10 μm+2 μm.

[0062] The specific processing operation in step 1 is: boil the diamond in hydrochloric acid for 35 minutes, boil it in distilled water for 35 minutes, clean it with anhydrous ethanol in an ultrasonic cleaner for 25 minutes, and dry it.

[0063] In this embodiment, the diamond plated by the method of the present invention is grayish white, the surface coating is uniform, and the coating does not fall off when rubbed on sandpaper; X-ray diffraction analysis of the plated diamond shows diffraction peaks of TiC and Ti on the obtained coated diamond, and the diffraction peak of TiC is stronger, which shows that the chemical bonding between the coating metal and the diamond has been partially achieved in the coating stage by the method of the present invention; the unbonded Ti can bond with the diamond on the one hand and form an alloy with the matrix material on the other hand during the hot pressing process.

[0064] Sample preparation: Two groups of samples, A and B, were prepared in this test. The formula of group A samples was a Cu-Fe based saw blade matrix formula for cutting reinforced concrete (Cu35%, Fe30%, Ni15%, and the balance was Co, Sn, Mn), the diamond concentration was 20%; the diamond grade and ratio were 40 / 50-20kg-100%; the diamond in group B samples was 40 / 50-20kg diamond obtained by the method of the present invention after Ti film coating, and except for the diamond coating, the other parts were exactly the same as those of group A samples. The two groups of samples were made into 30mm×5mm×5mm bending test pieces by the same sintering process; in order to make the results universal, 4 identical samples were made for each sample.

[0065] The three-point bending strength of the two groups of samples was measured using a universal material testing machine, and a comparison of the bonding strength between the diamond and the matrix in the two groups of samples was obtained. The results are shown in Table 5.

[0066] Table 5 Flexural strength results of the samples

[0067]

[0068]

[0069] Titanium-coated diamond is added to the matrix. Since Ti and diamond undergo an interfacial reaction to form TiC during the coating process, a multilayer structure of diamond-TiC-Ti-Ti and an alloy layer of the metal matrix is ​​formed between the diamond and the metal matrix during the subsequent hot pressing process, thereby achieving metallurgical bonding between the diamond and the metal matrix and improving the bonding strength between the matrix and the diamond. Therefore, in the flexural strength results of Table 5, the flexural strength of sample B using titanium-coated diamond is 86.5 MPa, which is 11.3% higher than that of sample A without diamond coating.

[0070] The test of diamond coating to protect the performance of diamond: two groups of samples were electrolyzed in a 1:8 hydrochloric acid aqueous solution, and the electrolyzed diamonds were further dissolved with hydrofluoric acid to remove the surface film. The diamonds after film dissolution were observed under a scanning microscope to observe the surface morphology of the diamonds and examine the degree of erosion. Then, the compressive strength and impact strength of the diamonds and the original diamonds were tested to compare the degree of damage of the plated and unplated diamonds during the hot pressing process.

[0071] Table 6 Compressive strength and impact toughness results of diamond

[0072]

[0073] It can be seen from Table 6 that after electrolytic extraction of diamond from samples A and B and dissolution of the film, the compressive strength and impact toughness of titanium-coated diamond are higher than those of uncoated diamond, with the improvement rates being 14.3% and 25% respectively; this shows that diamond coating has a protective effect on the mechanical properties of diamond during the hot pressing process.

[0074] On-site sawing test: according to the formula and process parameters of the two groups of samples, saw blades A (unplated diamond) and saw blades B (coated diamond) were made for on-site sawing. The specifications of the two saw blades were LW350mm (saw blade outer diameter) × 40mm (saw tooth length) × 3.2mm (saw tooth thickness) × 10mm (saw tooth height). C40 grade concrete containing pebbles was cut on a 13 horsepower hand-propelled gasoline cutting machine with a cutting depth of 50mm. The life and efficiency were compared. Table 7 shows the on-site cutting results of saw blades A and B. It can be seen from Table 7 that due to the addition of titanium-plated diamond, the cutting speed of the saw blade increased from 1.8m / min to 2.3m / min, an increase of 27.8%; the cutting life of the saw blade increased from 612m to 818m, an increase of 33.7%.

[0075] Table 7 On-site sawing results of saw blades A and B

[0076]

[0077] In summary, the method of the present invention is a simple, easy and effective method for titanium coating on the surface of diamond; titanium-coated diamond improves the bonding strength of the matrix to the diamond and reduces the high-temperature damage of the diamond during hot pressing, thereby improving the cutting life and cutting efficiency of the diamond saw blade.

[0078] The particle size of the Ti powder in step 2 is -400 mesh and the purity is 99.9%; the particle size of the copper powder is -300 mesh.

[0079] The inert gas in step 3 is argon gas with a purity of 99.999%.

[0080] The heat treatment furnace in step 4 can be a box-type resistance furnace with a temperature of 820°C.

[0081] The sintering aid in step 7 is a nickel-based alloy catalyst sintering aid.

[0082] The pressure and temperature conditions for the synthesis in step 7 are: 5.3 GPa, 1350° C.; and the sintering time is 20 min.

[0083] The invention discloses a method for preparing Ti-plated polycrystalline diamond. When the invention is used, the diamond plated by the method is grayish white, the surface coating is uniform, and the coating does not fall off when rubbed on sandpaper; the compressive strength of the Ti-plated polycrystalline diamond prepared by the method is greatly improved compared with the diamond not plated with titanium; the method can obtain a uniform and dense Ti coating on the surface of saw blade-grade diamond, and the diamond strength can be improved after Ti plating; the Ti-plated diamond improves wettability and increases the service life of the saw blade; under high temperature and high pressure conditions, nickel-based alloy is used as a sintering aid, and the sintering of the titanium-plated diamond polycrystalline is successfully achieved through the regrowth between diamond micropowder particles, so the method is a simple, easy and effective method for titanium plating on the diamond surface; the titanium-plated diamond improves the cutting life and cutting efficiency of the diamond saw blade by improving the bonding strength of the matrix to the diamond and reducing the high-temperature damage of the diamond during the hot pressing process; the invention has the advantages of improving bonding strength, reducing high-temperature damage, good bending strength and improving service life.

[0084] Example 3

[0085] A method for preparing Ti-plated polycrystalline diamond, the preparation method comprising the following steps:

[0086] Step 1: Pre-plating treatment: First, use an acid solution of a certain concentration to purify the diamond surface to increase its surface activity, and then dry it after treatment;

[0087] Step 2: Secondly, the treated diamond is uniformly mixed with Ti powder, Cu powder and catalyst in a container in a certain proportion;

[0088] Step 3: Then put the mixed material into a burning boat, and put the burning boat into a quartz tube with inert gas;

[0089] Step 4: Heat the heat treatment furnace to a certain temperature, push the quartz tube into the furnace, and keep it warm for 60 minutes;

[0090] Step 5: Cool to 500°C in the furnace, pull out the quartz tube, and air cool to room temperature;

[0091] Step 6: Take the burning boat out of the quartz tube and sieve to obtain titanium-coated diamond;

[0092] Step 7: Use titanium-coated diamond powder as raw material, encapsulate the purified titanium-coated diamond powder and sintering aid in a molybdenum sleeve for sintering, and perform SEM, XRD and Raman analysis on the surface and cross-section of the sintered sample after purification.

[0093] The diamond in step 1 may also be MBD50 / 60 diamond particles.

[0094] The specific processing operation in step 1 is: boil the diamond in hydrochloric acid for 40 minutes, boil it in distilled water for 40 minutes, clean it with anhydrous ethanol in an ultrasonic cleaning machine for 30 minutes, and dry it.

[0095] The particle size of the Ti powder in step 2 is -400 mesh and the purity is 99.9%; the particle size of the copper powder is -300 mesh.

[0096] The inert gas in step 3 is argon gas with a purity of 99.999%.

[0097] The heat treatment furnace in step 4 can be a box-type resistance furnace with a temperature of 950°C.

[0098] In this embodiment, MBD50 / 60 diamond particles are used for Ti plating in this experiment; heating is carried out in an experimental box-type resistance furnace, and the surface condition of the diamond after plating is studied using a SZX12 scientific research system stereo microscope, and the surface morphology and composition distribution of the diamond are studied using a JSM-6380LA scanning electron microscope and a JXA-8800R electron probe; the generated phase is studied using an X-ray diffractometer; and the compressive properties of diamond are studied using a ZMC-I diamond static pressure strength tester.

[0099] Since the heating is carried out in an air furnace, the influence of oxygen must be taken into account when considering the diamond coating process; according to the third law of thermodynamics, find the free energy ΔF 0 T The relationship with temperature T is: Ti+O 2 =TiO 2 , ΔF 0 T1 =-943.84+0.184T (kJ / mol), TiO 2 +3C (d) =TiC+2CO, ΔF 0 T2 =533.41-0.48T(kJ / mol), from ΔF 0 T1 , ΔF 0 T2 It can be seen that when Ti is plated, Ti first combines with oxygen and then with carbon to form TiC; when ΔF 0 T2=0, that is, T=111K (approximately equal to 850°C), the temperature increases by about 100°C during actual heating. Therefore, 950°C is selected as the heating temperature.

[0100] Compressive strength measurement: Titanium-coated diamond particles were tested on a diamond static pressure strength tester. The results showed that the average compressive strength of the uncoated diamond particles was 35N. The average compressive strength of the diamond surface after titanium coating in a salt bath was 129.5N, which increased by 2.7 times.

[0101] In summary, the diamond surface Ti plating method of the present invention obtains a coating layer of a certain thickness on the diamond surface; after the plating treatment, XRD test analysis shows that the alloy element Ti in the coating layer will chemically react with C on the diamond surface to form corresponding carbides (TiC), thereby enhancing the bonding force between the coating layer and the diamond and preventing the coating layer from falling off; after the diamond is plated, its compressive strength is increased by 2.7 times compared with that when it is not plated; after the diamond is plated, a relatively dense coating layer is formed, and its oxidation resistance and heat corrosion resistance are enhanced.

[0102] The sintering aid in step 7 is a nickel-based alloy catalyst sintering aid.

[0103] The pressure and temperature conditions for the synthesis in step 7 are: 5.8 GPa, 1500° C.; and the sintering time is 10-30 min.

[0104] The invention discloses a method for preparing Ti-plated polycrystalline diamond. When the invention is used, the diamond plated by the method is grayish white, the surface coating is uniform, and the coating does not fall off when rubbed on sandpaper; the compressive strength of the Ti-plated polycrystalline diamond prepared by the method is greatly improved compared with the diamond not plated with titanium; the method can obtain a uniform and dense Ti coating on the surface of saw blade-grade diamond, and the diamond strength can be improved after Ti plating; the Ti-plated diamond improves wettability and increases the service life of the saw blade; under high temperature and high pressure conditions, nickel-based alloy is used as a sintering aid, and the sintering of the titanium-plated diamond polycrystalline is successfully achieved through the regrowth between diamond micropowder particles, so the method is a simple, easy and effective method for titanium plating on the diamond surface; the titanium-plated diamond improves the cutting life and cutting efficiency of the diamond saw blade by improving the bonding strength of the matrix to the diamond and reducing the high-temperature damage of the diamond during the hot pressing process; the invention has the advantages of improving bonding strength, reducing high-temperature damage, good bending strength and improving service life.

[0105] Example 4

[0106] A method for preparing Ti-plated polycrystalline diamond, the method comprising the following steps:

[0107] Step 1: Pre-plating treatment: First, use an acid solution of a certain concentration to purify the diamond surface to increase its surface activity, and then dry it after treatment;

[0108] Step 2: Secondly, the treated diamond is uniformly mixed with Ti powder, Cu powder and catalyst in a container in a certain proportion;

[0109] Step 3: Then put the mixed material into a burning boat, and put the burning boat into a quartz tube with inert gas;

[0110] Step 4: Heat the heat treatment furnace to a certain temperature, push the quartz tube into the furnace, and keep it warm for 60 minutes;

[0111] Step 5: Cool to 500°C in the furnace, pull out the quartz tube, and air cool to room temperature;

[0112] Step 6: Take the burning boat out of the quartz tube and sieve to obtain titanium-coated diamond;

[0113] Step 7: Use titanium-coated diamond powder as raw material, encapsulate the purified titanium-coated diamond powder and sintering aid in a molybdenum sleeve for sintering, and perform SEM, XRD and Raman analysis on the surface and cross-section of the sintered sample after purification.

[0114] The specific processing operation in step 1 is: boil the diamond in hydrochloric acid for 40 minutes, boil it in distilled water for 40 minutes, clean it with anhydrous ethanol in an ultrasonic cleaning machine for 30 minutes, and dry it.

[0115] The particle size of the Ti powder in step 2 is -400 mesh and the purity is 99.9%; the particle size of the copper powder is -300 mesh.

[0116] The inert gas in step 3 is argon gas with a purity of 99.999%.

[0117] The heat treatment furnace in step 4 may be a box-type resistance furnace with a temperature range of 950°C.

[0118] The sintering aid in step 7 is a nickel-based alloy catalyst sintering aid.

[0119] The pressure and temperature conditions for the synthesis in step 7 are: 4.9-5.8 GPa, 1200° C.-1500° C.; and the sintering time is 10-30 min.

[0120] In this embodiment, ① SEM analysis: SEM scanning was performed on the treated titanium-coated diamond micropowder, and it can be found that there is a thin metal titanium layer on the surface of the micropowder particles after purification, and its shape is irregular and angular.

[0121] Under the same temperature conditions, SEM analysis of titanium-coated diamond under 5.0-5.6GPa conditions showed that diamond micropowder underwent plastic deformation under high temperature and high pressure, and the gaps between particles decreased as the pressure increased.

[0122] Comparative studies on the properties of synthetic diamonds under different pressures show that the higher the pressure, the greater the density of the aggregate and the correspondingly improved wear resistance; under high pressure, the diamond particles slip and rearrange, and the original point contact becomes surface contact, large diamond particles are broken, and small particles are embedded in the gaps between large particles, which is one of the reasons for the improved density; at the same time, some carbon dissolved in the metal solvent spontaneously nucleates into microcrystals under the driving force of excess pressure, filling the gaps between large particles and growing together with them to form DD bonds, making the bonds between its particles more firmly and improving wear resistance.

[0123] ②XRD analysis: The sintering conditions were set at 5.4GPa and 1400℃. From the XRD patterns of the sintered titanium-coated diamond polycrystals and the sintered ordinary diamond polycrystals, it can be seen that the titanium-coated diamond has a small amount of NiMnCo and Ti in addition to the diffraction peaks of ordinary diamond. x C y The diffraction peaks of the TiMnC compound appear; the NiMnCo component in the sintering aid is the reason for the appearance of its diffraction peak; from the XRD results, it can be concluded that Ti also exists in the synthetic diamond x C y And other carbon titanium manganese metal compounds, Ti x C y The existence of may be that during the process of micro-powder synthesis, a very small part of the titanium layer on the surface has not been delaminated and still maintains its original structure, or that C reacts with Ti again during the dissolution of diamond; and the appearance of TiMnC compounds fully demonstrates that during the sintering process of micro-powder, the bond between the titanium layer and the diamond particles has been broken, and the dissolution of diamond powder in the metal additive is also accompanied by the bond between the titanium layer and the metal additive; and it is precisely the existence of these metal compounds that improves the density and other properties of PCD.

[0124] ③Raman analysis: From the Raman spectrum, it was observed that there were no other non-quality carbon Raman peaks (1500-1600cm -1), the Raman peak of titanium-coated diamond shifts to the high wavenumber direction and blue-shifts; when there is compressive stress in the material, the Raman peak blue-shifts. It may be that during the sintering process, the sintering conditions of titanium-coated micropowder are more stringent than those of ordinary micropowder, and the time requirement is longer, which makes the temperature accumulation process under high pressure longer, resulting in its internal stress being slightly larger than that of ordinary diamond; the presence of defect impurities in titanium-coated PCD is also the cause of its stress.

[0125] In summary, under high temperature and high pressure conditions, the sintering of titanium-coated diamond polycrystals was successfully achieved by using nickel-based alloy as a sintering aid through the regrowth between diamond micropowder particles; SEM results show that under the experimental synthesis pressure conditions, the optimal temperature should be controlled at 1350℃-1450℃; XRD shows that there are NiMnCo, Ti in the diamond sample x C y and TiMnC compound diffraction peaks; Raman spectrum shows that the residual stress of titanium-coated diamond polymer is slightly larger.

[0126] The invention discloses a method for preparing Ti-plated polycrystalline diamond. When the invention is used, the diamond plated by the method is grayish white, the surface coating is uniform, and the coating does not fall off when rubbed on sandpaper; the compressive strength of the Ti-plated polycrystalline diamond prepared by the method is greatly improved compared with the diamond not plated with titanium; the method can obtain a uniform and dense Ti coating on the surface of saw blade-grade diamond, and the diamond strength can be improved after Ti plating; the Ti-plated diamond improves wettability and increases the service life of the saw blade; under high temperature and high pressure conditions, nickel-based alloy is used as a sintering aid, and the sintering of the titanium-plated diamond polycrystalline is successfully achieved through the regrowth between diamond micropowder particles, so the method is a simple, easy and effective method for titanium plating on the diamond surface; the titanium-plated diamond improves the cutting life and cutting efficiency of the diamond saw blade by improving the bonding strength of the matrix to the diamond and reducing the high-temperature damage of the diamond during the hot pressing process; the invention has the advantages of improving bonding strength, reducing high-temperature damage, good bending strength and improving service life.

Claims

1. A method for preparing Ti-plated polycrystalline diamond, characterized in that: The preparation method comprises the following steps: Step 1: Pre-plating treatment: First, use an acid solution of a certain concentration to purify the diamond surface to increase its surface activity, and then dry it after treatment; Step 2: Secondly, the treated diamond is uniformly mixed with Ti powder, Cu powder and catalyst in a container in a certain proportion; Step 3: Then put the mixed material into a burning boat, and put the burning boat into a quartz tube with inert gas; Step 4: Heat the heat treatment furnace to a certain temperature, push the quartz tube into the furnace, and keep it warm for 40min-60min; Step 5: Cool to 500°C in the furnace, pull out the quartz tube, and air cool to room temperature; Step 6: Take the burning boat out of the quartz tube and sieve to obtain titanium-coated diamond; Step 7: Use titanium-coated diamond powder as raw material, encapsulate the purified titanium-coated diamond powder and sintering aid in a molybdenum sleeve for sintering, and perform SEM, XRD and Raman analysis on the surface and cross-section of the sintered sample after purification.

2. The method for preparing Ti-plated polycrystalline diamond according to claim 1, characterized in that: The diamond in step 1 is SMD grade diamond with a static pressure strength of 136N.

3. The method for preparing Ti-plated polycrystalline diamond according to claim 2, characterized in that: The diamond in step 1 may also be MBD50 / 60 diamond particles.

4. The method for preparing Ti-plated polycrystalline diamond according to claim 3, characterized in that: The diamond in step 1 may also be high-grade diamond powder with a double peak distribution of particle size of 10 μm+2 μm.

5. The method for preparing Ti-plated polycrystalline diamond according to claim 1, characterized in that: The specific processing operation in step 1 is: boil the diamond in hydrochloric acid for 30-40 minutes, boil it in distilled water for 30-40 minutes, clean it with anhydrous ethanol in an ultrasonic cleaning machine for 20-30 minutes, and dry it.

6. The method for preparing Ti-plated polycrystalline diamond according to claim 1, characterized in that: The particle size of the Ti powder in step 2 is -400 mesh and the purity is 99.9%; the particle size of the copper powder is -300 mesh.

7. The method for preparing Ti-plated polycrystalline diamond according to claim 1, characterized in that: The inert gas in step 3 is argon gas with a purity of 99.999%.

8. The method for preparing Ti-plated polycrystalline diamond according to claim 1, characterized in that: The heat treatment furnace in step 4 may be a box-type resistance furnace with a temperature range of 700-950°C.

9. The method for preparing Ti-plated polycrystalline diamond according to claim 1, characterized in that: The sintering aid in step 7 is a nickel-based alloy catalyst sintering aid.

10. The method for preparing Ti-plated polycrystalline diamond according to claim 9, characterized in that: The pressure and temperature conditions for the synthesis in step 7 are: 4.9-5.8 GPa, 1200° C.-1500° C.; and the sintering time is 10-30 min.

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