A polycrystalline diamond composite material synthesis process

Abstract

The present invention provides a polycrystalline diamond composite material synthesis process method, belonging to the technical field of superhard materials. The present invention significantly improves the D-D bond of polycrystalline diamond materials, enhances material strength, and increases wear resistance. The material synthesized by the present invention has small internal stress, good impact resistance, high yield rate, and stable quality. In particular, after the metal catalyst of the product is removed, the wear resistance is improved by more than 50%.

Description

Technical Field

[0001] The invention relates to the technical field of superhard materials, and in particular to a polycrystalline diamond composite material synthesis process method. Background Art

[0002] There are few patents and literature research materials related to the synthesis process of polycrystalline diamond composite materials. The commonly used pressure curve is the pressure above the diamond graphite equilibrium line, a single pressure curve, which is divided into a pressure increase section, a pressure holding section, and a pressure reduction section; the synthesis temperature curve is generally a power or voltage curve, which is divided into a temperature increase section, a temperature holding section, and a temperature reduction section.

[0003] The existing synthesis process is simple, stable and reliable. However, the synthesized composite superhard material fails to fully increase the bonding between diamonds. Most single crystals are bonded together by adhesives, resulting in low strength and insufficient wear resistance of the synthesized polycrystalline diamond material. In particular, after the metal catalyst extraction treatment, the wear resistance is greatly reduced due to the removal of the metal catalyst material and other adhesives.

[0004] Therefore, it is necessary to provide a polycrystalline diamond composite material synthesis process method to solve the above-mentioned existing problems. Summary of the invention

[0005] In view of this, the present invention provides a polycrystalline diamond composite material synthesis process method, which can significantly improve the D-D bond of the polycrystalline diamond material, enhance the material strength, and increase the wear resistance.

[0006] In order to achieve the above technical effects, the present invention provides a polycrystalline diamond composite material synthesis process method, which adopts the following technical scheme:

[0007] A polycrystalline diamond composite material synthesis process comprises the following steps:

[0008] Step 1, preliminarily compressing the initial material, placing the initial material diamond into a six-sided top press, setting the pressure in the six-sided top press to P1 and the temperature to T1, and maintaining the temperature T1 and the pressure P1 for a time t1, so as to soften the surface of the diamond particles and promote graphitization of the surface of the diamond particles;

[0009] Step 2, dissolving carbon atoms in graphite, raising the pressure in the six-sided top press in step 1 from P1 to P2, raising the temperature from T1 to T2, maintaining the temperature T2 and the pressure P2 for a time t2, the metal catalyst begins to melt, dissolving the carbon atoms in the graphite; when the carbon atoms reach a supersaturated state in the metal catalyst, diamonds begin to crystallize between the diamond particles, forming d-d bonds;

[0010] Step 3, diamond continues to crystallize, the pressure in the six-sided top press in step 2 is increased from P2 to P3, the temperature is maintained at T2, the temperature T2 and the pressure P3 are maintained for a time t3, the pressure P3 and the temperature T2 are located in the middle and upper part of the thermodynamic stability zone of diamond, the speed and amount of diamond crystallization are increased, the pressure P3 and the temperature T2 are maintained for a certain time, and the carbon atoms dissolved in the graphite in step 2 are completely crystallized into diamond materials;

[0011] Step 4, reducing the internal stress of the diamond material in step 3, first reducing the temperature in the six-sided top press in step 3 from T2 to T3, and then reducing the pressure in the six-sided top press in step 3 from P3 to P4, so that the temperature T3 and the pressure P4 are maintained for a time t4, and the pressure P4 and the temperature T3 are located to the right of the metal catalyst melting point line and to the left of the diamond graphite equilibrium line. This pressure and temperature section significantly reduces the internal stress of the polycrystalline diamond material and improves the performance.

[0012] Step 5: lowering the temperature T3 in step 4 to room temperature, lowering the pressure P4 in step 4 to normal pressure, and taking out the diamond material from the six-sided press. The diamond material at this time is a polycrystalline diamond composite material.

[0013] Furthermore, in step 1, the temperature T1 is 1400-1600° C., the pressure P1 is 2.5-4 GPa, and the time t4 is 1-5 Min.

[0014] Furthermore, in step 2, the temperature T2 is 1600-2000° C., the pressure P2 is 6.5-8 GPa, and the time t2 is 2-8 Min.

[0015] Furthermore, in step 3, the temperature T2 is 1600-2000° C., the pressure P3 is 7.5-10 GPa, and the time t3 is 3-10 Min.

[0016] Furthermore, in step 4, the temperature T3 is 900-1100° C., the pressure P4 is 2.8-3.5 GPa, and the time t4 is 1-5 Min.

[0017] Furthermore, the metal catalyst in step 2 is iron, cobalt, nickel or an alloy thereof.

[0018] Furthermore, the temperature T3 in step 4 is lower than the melting point of the metal catalyst.

[0019] The above technical solution of the present invention includes at least the following beneficial effects:

[0020] 1. The present invention significantly improves the D-D bonding of polycrystalline diamond materials, increases material strength, and increases wear resistance;

[0021] 2. The material synthesized by the present invention has small internal stress, good impact resistance, high yield rate and stable quality. Especially after the metal catalyst of the product is removed, the wear resistance is improved by more than 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the equilibrium phase diagram of diamond graphite in an embodiment of the present invention;

[0023] Figure 2 Schematic diagram of the synthesis process under different pressures, temperatures and times in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1 -2, clearly and completely describe the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0025] like Figure 1 -2: A polycrystalline diamond composite material synthesis process method, comprising the following steps:

[0026] Step 1: Preliminarily compress the initial material, put the initial material diamond into a six-sided top press, set the pressure in the six-sided top press to P1, the temperature to T1, and keep the temperature T1 and pressure P1 for a time of t1, so that the surface of the diamond particles is softened and the surface of the diamond particles is graphitized; in the step 1, the temperature T1 is 1400-1600°C, the pressure P1 is 2.5-4Gpa, and the time t4 is 1-5Min

[0027] Step 2, dissolving carbon atoms in graphite, raising the pressure in the six-sided top press in step 1 from P1 to P2, raising the temperature from T1 to T2, keeping the temperature T2 and the pressure P2 for a time of t2, the metal catalyst begins to melt, dissolving the carbon atoms in the graphite; when the carbon atoms reach an oversaturated state in the metal catalyst, diamonds begin to crystallize between the diamond particles, forming d-d bonds; the metal catalyst is iron, cobalt, nickel or an alloy thereof, in step 2, the temperature T2 is 1600-2000°C, the pressure P2 is 6.5-8Gpa, and the time t2 is 2-8min.

[0028] Step 3, diamond continues to crystallize, the pressure in the six-sided top press in step 2 is increased from P2 to P3, the temperature is maintained at T2, the temperature T2 and the pressure P3 are maintained for a time t3, the pressure P3 and the temperature T2 are located in the middle and upper part of the diamond thermodynamic stability zone, the speed and amount of diamond crystallization are increased, the pressure P3 and the temperature T2 are maintained for a certain time, and the carbon atoms dissolved in the graphite in step 2 are completely crystallized into diamond materials; in the step 3, the temperature T2 is 1600-2000°C, the pressure P3 is 7.5-10Gpa, and the time t3 is 3-10Min.

[0029] Step 4, reducing the internal stress of the diamond material in step 3, first reducing the temperature in the six-sided top press in step 3 from T2 to T3, and then reducing the pressure in the six-sided top press in step 3 from P3 to P4, so that the temperature T3 and the pressure P4 are maintained for a time t4, and the pressure P4 and the temperature T3 are located on the right side of the metal catalyst melting point line and on the left side of the diamond graphite equilibrium line. This section of pressure and temperature significantly reduces the internal stress of the polycrystalline diamond material and improves the performance. The temperature T3 is lower than the melting point of the metal catalyst catalyst. In step 4, the temperature T3 is 900-1100°C, the pressure P4 is 2.8-3.5Gpa, and the time t4 is 1-1.5Min.

[0030] Step 5: lowering the temperature T3 in step 4 to room temperature, lowering the pressure P4 in step 4 to normal pressure, and taking out the diamond material from the six-sided press. The diamond material at this time is a polycrystalline diamond composite material.

[0031] Example 1

[0032] According to the above steps, T1 is set to 1500°C, P1 is set to 2.5 Gpa, t1 is set to 2 Min, T2 is set to 1600°C, P2 is set to 6.5 Gpa, t2 is set to 3 Min, P3 is set to 7.5 Gpa, t3 is set to 4 Min, T3 is set to 900°C, P4 is set to 2.8 Gpa, t4 is set to 3 Min, and Sample 1 of Example 1 is obtained.

[0033] The conditions are the same as above to obtain sample 2 of Example 1.

[0034] Example 2

[0035] According to the above steps, set T1 to 1550℃, P1 to 2.5Gpa, t1 to 2Min; T2 to 1650℃, P2 to 7.0Gpa, t2 to 3.5Min; P3 to 8Gpa, t3 to 4Min; T3 to 950℃, P4 to 3.0Gpa, t4 to 3Min, and obtain Sample 1 of Example 2.

[0036] The conditions are the same as above to obtain Sample 2 of Example 2.

[0037] Example 3

[0038] According to the above steps, set T1 to 1550℃, P1 to 3.0Gpa, t1 to 3Min; T2 to 1700℃, P2 to 7.5Gpa, t2 to 2Min; P3 to 8.5Gpa, t3 to 5Min; T3 to 1000℃, P4 to 3.0Gpa, t4 to 2Min, and obtain Sample 1 of Example 3.

[0039] The conditions are the same as above to obtain sample 2 of Example 3.

[0040] Example 4

[0041] According to the above steps, set T1 to 1600°C, P1 to 3.5 Gpa, t1 to 3 Min; T2 to 1800°C, P2 to 8.0 Gpa, t2 to 5 Min; P3 to 10.0 Gpa, t3 to 9 Min; T3 to 1100°C, P4 to 3.5 Gpa, t4 to 3 Min, and obtain Sample 1 of Example 4.

[0042] The conditions are the same as above to obtain sample 2 of Example 4.

[0043] The comparison of conventional process samples is as follows:

[0044] In the conventional process, T1=1400-1800℃, P1=6.5-8Gpa, time t1=2-8min, the process is as follows: increase the pressure to the P1 set pressure, start heating, increase the temperature to T1 temperature, maintain the temperature for t1 time, cool to room temperature, reduce the pressure to 0Gpa, the synthesis is completed, and the material is taken out.

[0045] Comparative Example 1

[0046] Using temperature T1=1550°C, pressure P1=7Gpa, and time t1=5Min, sample 1 of comparative example 1 was obtained.

[0047] The conditions are the same as above to obtain sample 2 of comparative example 1.

[0048] Comparative Example 2

[0049] Using temperature T1 = 1800°C, pressure P1 = 8 Gpa, and time t1 = 5 Min, sample 1 of comparative example 2 was obtained.

[0050] The conditions are the same as above to obtain Comparative Example 2 Sample 2.

[0051] The products synthesized by the above two processes were subjected to wear resistance test:

[0052] Wear resistance test parameters

[0053] Turning material: granite Φ1000mm;

[0054] Cutting depth: 1.5mm;

[0055] Horizontal feed speed: 2.5mm / r;

[0056] Constant speed turning: 100r / min;

[0057] The wear volume of the composite piece was measured after turning the same volume of granite;

[0058] The results are shown in Tables 1 and 2 below.

[0059]

[0060]

[0061] Table 1

[0062]

[0063]

[0064] Table 2

[0065] The product synthesized by the process method of the present invention has wear resistance improved by more than 50% and a yield improved by more than 10%.

[0066] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A polycrystalline diamond composite material synthesis process, It is characterized in that The following steps are involved: Step 1, preliminarily compressing the initial material, placing the initial material diamond mixed metal catalyst into a six-sided top press, setting the pressure in the six-sided top press to P1, the temperature to T1, and maintaining the temperature T1 and pressure P1 for a time of t1, so that the surface of the diamond particles is softened and the surface of the diamond particles is graphitized; in the step 1, the temperature T1 is 1400-1600°C, the pressure P1 is 2.5-4Gpa, and the time t1 is 1-5Min; Step 2, dissolving carbon atoms in graphite, raising the pressure in the six-sided top press in step 1 from P1 to P2, raising the temperature from T1 to T2, maintaining the temperature T2 and the pressure P2 for a time of t2, the metal catalyst begins to melt, dissolving the carbon atoms in the graphite; when the carbon atoms reach a supersaturated state in the metal catalyst, diamonds begin to crystallize between the diamond particles, forming d-d bonds; in step 2, the temperature T2 is 1600-2000°C, the pressure P2 is 6.5-8Gpa, and the time t2 is 2-8Min; Step 3, diamond continues to crystallize, the pressure in the six-sided top press in step 2 is increased from P2 to P3, the temperature is maintained at T2, the temperature T2 and the pressure P3 are maintained for a time of t3, the pressure P3 and the temperature T2 are located in the middle and upper part of the thermodynamic stability zone of diamond, the speed and amount of diamond crystallization are increased, the pressure P3 and the temperature T2 are maintained for a certain time, and the carbon atoms dissolved in the graphite in step 2 are completely crystallized into diamond materials; In the step 3, the temperature T2 is 1600-2000°C, the pressure P3 is 7.5-10Gpa, and the time t3 is 3-10Min; Step 4, reducing the internal stress of the diamond material in step 3, first reducing the temperature in the six-sided top press in step 3 from T2 to T3, and then reducing the pressure in the six-sided top press in step 3 from P3 to P4, so that the temperature T3 and the pressure P4 are maintained for a time t4, and the pressure P4 and the temperature T3 are located to the right of the metal catalyst melting point line and to the left of the diamond graphite equilibrium line. This section of pressure and temperature significantly reduces the internal stress of the polycrystalline diamond material and improves the performance; in the step 4, the temperature T3 is 900-1100°C, the pressure P4 is 2.8-3.5Gpa, and the time t4 is 1-5Min; Step 5: lowering the temperature T3 in step 4 to room temperature, lowering the pressure P4 in step 4 to normal pressure, and taking out the diamond material from the six-sided press. The diamond material at this time is a polycrystalline diamond composite material.

2. The polycrystalline diamond composite material synthesis process according to claim 1, It is characterized in that The metal catalyst in step 2 is iron, cobalt, nickel or an alloy thereof.

3. The polycrystalline diamond composite material synthesis process according to claim 1, It is characterized in that The temperature T3 in step 4 is lower than the melting point of the metal catalyst.

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