CN108585855B - Polycrystalline diamond sintered body of selenium catalyst and preparation method thereof - Google Patents

Abstract

A selenium-catalyzed polycrystalline diamond sintered body and a preparation method thereof relate to the technical field of superhard materials. A preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising: grinding a mixed powder composed of 31.59-34.047 parts by weight of micron-level diamond powder and 1.473-4.79 parts by weight of micron-level selenium powder until the selenium powder becomes amorphous Selenium powder; the mixed powder is placed in a mold, and formed into a blank under the conditions of room temperature and pressure of 5MPa to 20MPa; the blank is sintered and solidified at a pressure of 6.5GPa to 12.5GPa, wherein the sintering temperature is 1500℃～1900℃ °C. The preparation method has a simple process and can prepare a polycrystalline diamond sintered body with high hardness.

Description

A kind of polycrystalline diamond sintered body of selenium catalyst and preparation method thereof

technical field

The invention relates to the technical field of superhard materials, in particular to a polycrystalline diamond sintered body of a selenium catalyst and a preparation method thereof.

Background technique

Polycrystalline diamond sintered body has become the main material for manufacturing cutting tools, shapers, wire drawing dies and excavation bits due to its excellent mechanical properties such as extremely high hardness, wear resistance and impact resistance.

The traditional polycrystalline diamond sintered body is mostly formed by sintering diamond particles and metal catalysts under high temperature and high pressure, but the process flow of the existing polycrystalline diamond sintered body is complicated, which increases the cost.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a selenium-catalyzed polycrystalline diamond sintered body with high hardness.

Another object of the present invention is to provide a method for preparing a selenium-catalyzed polycrystalline diamond sintered body, which has a simple process and can produce a polycrystalline diamond sintered body with higher hardness.

The present invention solves its technical problems by adopting the following technical solutions.

The invention provides a polycrystalline diamond sintered body of selenium catalyst. The polycrystalline diamond sintered body is made by sintering diamond powder and selenium powder. The gaps of the diamond particles are filled with selenium and selenium carbide, and D-D bonds are formed between the diamond particles.

The present invention also proposes a preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising:

grinding the mixed powder consisting of 31.59-34.047 parts by weight of micron-level diamond powder and 1.473-4.79 parts by weight of micron-level selenium powder until the selenium powder becomes amorphous selenium powder;

The mixed powder is placed in a mold, and is formed into a blank under the conditions of room temperature and pressure of 5 MPa to 20 MPa;

The blank is sintered and solidified under a pressure of 6.5GPa to 12.5GPa, wherein the sintering temperature is 1500°C to 1900°C.

The beneficial effects of the embodiments of the present invention are as follows: the selenium catalyst polycrystalline diamond sintered body and the preparation method thereof disclosed in the present invention utilize selenium powder as a catalyst to mix and sinter the selenium powder and the diamond powder to successfully prepare a polycrystalline diamond sintered body, Selenium has good oxidation resistance at room temperature, so the polycrystalline diamond sintered body using selenium as a catalyst contains less impurities, which improves the hardness of the polycrystalline diamond sintered body, and the hardness can reach 68GPa and above. And in the preparation process, the process of catalyst reduction treatment and vacuum pre-sintering in the production process of the traditional metal catalyst polycrystalline diamond sintered body is omitted. Greatly simplify the production process.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the scanning electron microscope picture of the selenium-polycrystalline diamond of the embodiment of the present invention 2;

2 is a graph showing the results of Vickers hardness of selenium-polycrystalline diamond in Example 2 of the present invention.

Icons: 1-diamond particles; 2-D-D bonds; 3-selenium and selenium carbides.

Detailed ways

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

A selenium-catalyzed polycrystalline diamond sintered body and a preparation method thereof according to an embodiment of the present invention will be specifically described below.

Traditional polycrystalline diamond sintered bodies are mostly made of diamond particles and metal catalysts (such as iron, cobalt, nickel) sintered under high temperature and high pressure conditions. Oxidation is a major problem faced by metal catalysts. In the process of generation, distribution, transportation and mixing with diamond powder, the metal catalyst is easily oxidized to form metal oxide, which brings impurities into the polycrystalline diamond sintered body, thereby reducing the performance of the polycrystalline diamond sintered body. In order to reduce the influence of catalyst oxidation, in the production process of the existing metal catalyst polycrystalline diamond sintered body, the metal catalyst powder needs to be subjected to hydrogen reduction treatment at a temperature above 700 ° C for several hours, and the The assembly is again placed in a vacuum sintering furnace in a hydrogen reducing atmosphere and vacuum treated at a temperature above 900°C for several hours. This complicates the process flow for producing polycrystalline diamond sintered bodies and increases production costs.

Based on this, this embodiment provides a polycrystalline diamond sintered body of a selenium catalyst. The polycrystalline diamond sintered body is made by sintering diamond powder and selenium powder. The gaps between the diamond particles are filled with selenium and selenium carbide, and the diamond particles are filled with selenium and selenium carbide. D-D bonds are formed.

The invention uses selenium powder as a catalyst to mix and sinter selenium powder and diamond powder to successfully prepare a polycrystalline diamond sintered body. Selenium belongs to oxygen group elements and has good oxidation resistance at room temperature. There are fewer impurities in the crystalline diamond sintered body, thereby improving the performance of the polycrystalline diamond sintered body.

A preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising:

The mixed powder consisting of 31.59-34.047 parts by weight of micron-level diamond powder and 1.473-4.79 parts by weight of micron-level selenium powder is ground until the selenium powder becomes amorphous selenium powder.

In this embodiment, the diamond powder and the selenium powder are mainly mixed by ball milling, and the mixed powder after ball milling is subjected to X-ray diffraction analysis to confirm whether the selenium powder has been ball milled into amorphous amorphous selenium.

Further, in some embodiments, the weight percentage of the selenium powder is 4.2% to 13.2%. In some embodiments, the weight percent of selenium powder is 4.2% to 6.7%. It should be noted here that the weight percentage of selenium powder refers to the percentage of the weight of selenium powder in the total amount of selenium powder and diamond powder.

In some embodiments, the grain size of the diamond powder is 0.2-7 μm, and the grain size of the selenium powder is 10-30 μm. In some embodiments, the grain size of the diamond powder is 2-5 μm.

The ball-milled mixed powder is placed in a mold, and formed into a blank under the conditions of room temperature and pressure of 5MPa to 20MPa; the blank is sintered and solidified under a pressure of 6.5GPa to 12.5GPa, wherein the sintering temperature is 1500°C to 1900°C °C.

The selenium element used as a catalyst belongs to the oxygen group and has good oxidation resistance at room temperature. When mixed with diamond powder, selenium will not oxidize during the pre-pressing and assembly process. In this embodiment, the polycrystalline diamond sintered body is successfully prepared by using selenium powder as a catalyst, and the processes of catalyst reduction treatment and vacuum pre-sintering in the production process of the traditional metal catalyst polycrystalline diamond sintered body are omitted. In addition, under relatively high temperature and high pressure conditions, that is, under the sintering temperature and pressure of this embodiment, selenium exists in the gaps of the diamond particles in liquid form, which increases the contact area between the selenium catalyst and the diamond, which is conducive to the formation of More D-D bonds between diamond particles increase the density of D-D bonds in the diamond sintered body and improve the mechanical properties of the polycrystalline diamond sintered body.

It should be noted that the D-D bond refers to the fact that in the sintered body of polycrystalline diamond, the diamond particles grow together under the action of the catalyst, and the carbon atoms between the diamond particles and the particles will be connected by the chemical bonds of diamond. Together, this chemical bond is a D-D bond.

In addition, the room temperature here means normal temperature or normal temperature, and in this embodiment, room temperature is 20-28 degreeC.

In some embodiments, the sintering temperature is 1600-1850°C. The sintering time is 30 to 3600s. In some embodiments, the sintering time is 100-1800 s. In some embodiments, the sintering time is 600-1000 s.

In some embodiments, the pressure at which the blank is sintered and solidified is 9-12.5 GPa.

The features and performances of the present invention will be further described in detail below in conjunction with the embodiments.

Example 1

The present embodiment provides a preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising:

Weigh 3.159 g of diamond powder with a crystal grain of 2 to 5 μm and 0.479 g of selenium powder with a crystal grain of 10 to 30 μm, wherein the weight percentage of diamond powder is 86.8%, and the weight percentage of selenium powder is 13.2%;

Mix above-mentioned diamond powder and selenium powder to obtain mixed powder, put the mixed powder into a tungsten carbide bottle equipped with tungsten carbide balls, then put the tungsten carbide bottle into CERTIPREP SPEX8000-D high-energy ball mill (Metuchen, NJ) to carry out deal with. Among them, the ball mill is located in a sealed glove box purged with argon. The ball milling of the mixed powder takes at least 10 hours until all the selenium powder is ball-milled into amorphous amorphous selenium, and X-ray diffraction analysis is performed on the ball-milled mixed powder to confirm that all the selenium powder is ball-milled into amorphous amorphous selenium.

Put the ball-milled mixed powder into a mold, and then hold it on a double-sided top press for 5 minutes under the conditions of room temperature and pressure of 5 MPa to form a blank;

Put the formed blank into the octahedral cavity press (15MN three-column press), hold the pressure for 10min under the condition of room temperature and pressure of 6.5GPa, then slowly increase the temperature while maintaining the pressure, at The temperature was raised to 1500°C within 5min, and after sintering for 30s at this temperature and pressure, the temperature was lowered to room temperature within 10min, and the pressure was lowered to normal pressure within 15min, and the sample was recovered to obtain selenium-polycrystalline diamond sintering body.

Example 2

The present embodiment provides a preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising:

Weigh 3.404 g of diamond powder with a grain size of 2 to 5 μm and 0.147 g of selenium powder with a grain size of 10 to 30 μm, wherein the weight percentage of diamond powder is 95.8%, and the weight percentage of selenium powder is 4.2%;

Mix above-mentioned diamond powder and selenium powder to obtain mixed powder, put the mixed powder into a tungsten carbide bottle equipped with tungsten carbide balls, then put the tungsten carbide bottle into CERTIPREP SPEX8000-D high-energy ball mill (Metuchen, NJ) to carry out deal with. Among them, the ball mill is located in a sealed glove box purged with argon. The ball milling of the mixed powder takes at least 10 hours until all the selenium powder is ball-milled into amorphous amorphous selenium, and X-ray diffraction analysis is performed on the ball-milled mixed powder to confirm that all the selenium powder is ball-milled into amorphous amorphous selenium.

Put the ball-milled mixed powder into a mold, and then hold it on a double-sided top press for 5 minutes under the conditions of room temperature and pressure of 20 MPa to form a blank;

Put the formed blank into the octahedral cavity press (15MN three-column press), hold the pressure for 10 minutes at room temperature and the pressure is 12.5GPa, then slowly increase the temperature while maintaining the pressure, The temperature was raised to 1900°C within 5min, and after sintering for 3600s at this temperature and pressure, the temperature was lowered to room temperature within 15min, and the pressure was lowered to normal pressure within 6h, and the selenium-polycrystalline diamond was sintered by recovering the sample. body.

Example 3

The present embodiment provides a preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising:

Weigh 3.334 g of diamond powder with a crystal grain of 0.2 to 5 μm and 0.239 g of selenium powder with a crystal grain of 10 to 30 μm, wherein the weight percentage of diamond powder is 93.3%, and the weight percentage of selenium powder is 6.7%;

Mix above-mentioned diamond powder and selenium powder to obtain mixed powder, put the mixed powder into a tungsten carbide bottle equipped with tungsten carbide balls, then put the tungsten carbide bottle into CERTIPREP SPEX8000-D high-energy ball mill (Metuchen, NJ) to carry out deal with. Among them, the ball mill is located in a sealed glove box purged with argon. The ball milling of the mixed powder takes at least 10 hours until all the selenium powder is ball-milled into amorphous amorphous selenium, and X-ray diffraction analysis is performed on the ball-milled mixed powder to confirm that all the selenium powder is ball-milled into amorphous amorphous selenium.

Put the ball-milled mixed powder into a mold, and then hold it on a double-sided top press for 1 min under the conditions of room temperature and pressure of 10 MPa to form a blank;

Put the formed blank into the octahedral cavity press (15MN three-column press), hold the pressure for 10 minutes at room temperature and the pressure is 10GPa, and then slowly increase the temperature while maintaining the pressure, at 5 minutes After sintering for 1800s under the temperature and pressure conditions, the temperature was lowered to room temperature within 10min, and the pressure was lowered to normal pressure within 6h, and the selenium-polycrystalline diamond sintered body was obtained by recovering the sample. .

Example 4

The present embodiment provides a preparation method of a selenium-catalyzed polycrystalline diamond sintered body, comprising:

Weigh 3.231 g of diamond powder with crystal grains of 5 to 10 μm and 0.358 g of selenium powder with crystal grains of 10 to 30 μm, wherein the weight percentage of diamond powder is 90%, and the weight percentage of selenium powder is 10%;

Mix above-mentioned diamond powder and selenium powder to obtain mixed powder, put the mixed powder into a tungsten carbide bottle equipped with tungsten carbide balls, then put the tungsten carbide bottle into CERTIPREP SPEX8000-D high-energy ball mill (Metuchen, NJ) to carry out deal with. Among them, the ball mill is located in a sealed glove box purged with argon. The ball milling of the mixed powder takes at least 10 hours until all the selenium powder is ball-milled into amorphous amorphous selenium, and X-ray diffraction analysis is performed on the ball-milled mixed powder to confirm that all the selenium powder is ball-milled into amorphous amorphous selenium.

Put the ball-milled mixed powder into a mold, and then hold it on a double-sided top press for 4 minutes under the conditions of room temperature and pressure of 15 MPa to form a blank;

Put the formed blank into the octahedral cavity press (15MN three-column press), hold the pressure for 10min under the condition of room temperature and pressure of 9GPa, then slowly increase the temperature while maintaining the pressure, at 5min The temperature was raised to 1600°C within 15 minutes after sintering at this temperature and pressure for 600 s, the pressure was reduced to normal pressure within 4 hours, and the selenium-polycrystalline diamond sintered body was obtained by recovering the sample. .

Test example

(1) Scanning and testing the microstructure of the selenium-polycrystalline diamond sintered body prepared in Example 2 by scanning electron microscopy, and the obtained microstructure diagram is shown in FIG. 1 .

Analysis of the results of Fig. 1: As can be seen from Fig. 1, in this selenium-polycrystalline diamond sintered body, the diamond particles 1 are bonded by D-D bonds 2, and the diamond particles 1 are filled with selenium and selenium carbides 3.

(2) Detect the hardness of the selenium-polycrystalline diamond sintered body prepared in Example 1 with a MICRO4 micro hardness tester (BUEHLER LTD): load the sample with 9.8N and hold the pressure for 15s, each sample is pressed twelve times. The average hardness of the sample was measured, and the obtained average hardness was 21GPa.

(3) Detect the hardness of the selenium-polycrystalline diamond sintered body obtained in Example 2 by using a MICRO4 microhardness tester (BUEHLER LTD): load the samples with 2.45N, 4.9N, 9.8N, and 19.6N respectively, and keep the Press for 15 s, each loading force is loaded multiple times, and the average value of hardness is taken, and the asymptotic hardness of the sample is measured by plotting, as shown in Figure 2.

It can be seen from FIG. 2 that the asymptotic hardness in FIG. 2 is 68GPa, which indicates that the selenium-polycrystalline diamond sintered body prepared by the method of the present embodiment has good hardness.

To sum up, the polycrystalline diamond sintered body of selenium catalyst disclosed in the present invention and the preparation method thereof use selenium powder as a catalyst to mix and sinter selenium powder and diamond powder to successfully prepare a polycrystalline diamond sintered body. Good oxidation resistance, so the polycrystalline diamond sintered body using selenium as a catalyst contains less impurities, which improves the hardness of the polycrystalline diamond sintered body, and the hardness can reach 68GPa and above. And in the preparation process, the process of catalyst reduction treatment and vacuum pre-sintering in the production process of the traditional metal catalyst polycrystalline diamond sintered body is omitted. Greatly simplify the production process.

The above-described embodiments are some, but not all, embodiments of the present invention. The detailed descriptions of the embodiments of the invention are not intended to limit the scope of the invention as claimed, but are merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Claims (10)

1. The polycrystalline diamond sintered body is prepared by sintering diamond powder and selenium powder, wherein gaps among diamond particles are filled with selenium and carbide of the selenium, and D-D bonds are formed among the diamond particles.

2. A method of preparing a polycrystalline diamond sintered compact of a selenium catalyst, comprising:

grinding mixed powder consisting of 31.59-34.047 parts by weight of micron-sized diamond powder and 1.473-4.79 parts by weight of micron-sized selenium powder until the selenium powder becomes amorphous selenium powder;

placing the ground mixed powder into a die, and forming into a blank under the conditions of room temperature and pressure of 5-20 MPa;

sintering and solidifying the blank under the pressure of 6.5-12.5 GPa to obtain a polycrystalline diamond sintered body, wherein selenium and selenium carbide are filled in gaps of diamond particles, and D-D bonds are formed among the diamond particles, wherein the sintering temperature is 1500-1900 ℃.

3. The method for producing a selenium catalyst polycrystalline diamond sintered body according to claim 2, wherein the sintering time is 30 to 3600 s.

4. The method for producing a selenium-catalyzed polycrystalline diamond compact according to claim 2, wherein the sintering temperature is 1600 to 1850 ℃.

5. The method for producing a selenium catalyst polycrystalline diamond sintered body according to claim 2, wherein the pressure at which the blank is sintered and cured is 9 to 12.5 GPa.

6. The method for producing a selenium-catalyzed polycrystalline diamond sintered body according to claim 2, wherein the weight percentage of the selenium powder is 4.2% to 13.2%.

7. The method of producing a selenium-catalyzed polycrystalline diamond compact according to claim 6, wherein the weight percentage of the selenium powder is 4.2 to 6.7%.

8. The method for producing a selenium catalyst polycrystalline diamond sintered body according to claim 2, wherein the diamond powder has a crystal grain size of 0.2 to 10 μm.

9. The method for producing a selenium-catalyzed polycrystalline diamond sintered body according to claim 8, wherein the diamond powder has a crystal grain size of 2 to 5 μm.

10. The method for producing a polycrystalline diamond sintered body with a selenium catalyst according to claim 2, wherein the grain size of the selenium powder is 10 to 30 μm.

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