Method for filling cobalt-removed PDC (Polycrystalline Diamond Compact) ceramic self-lubricating layer under driving of extreme pressure

Abstract

The invention discloses a method for filling a cobalt-removed PDC (Polycrystalline Diamond Compact) ceramic self-lubricating layer under driving of extreme pressure, and belongs to the technical field of preparation of inorganic non-metallic materials. The method comprises the following steps: wrapping a layer of self-lubricating powder outside the processed and formed cobalt-removed PDC, and then wrapping the cobalt-removed PDC with a metal wrapping body; treating the metal inclusion at high temperature and high pressure or treating the metal inclusion at high pressure; and the treated sample is taken out, the metal inclusion and the residual self-lubricating block outside the sample are removed, and the cobalt-removed PDC self-lubricating ceramic containing the lubricating layer is obtained. The PDC self-lubricating ceramic prepared by the method disclosed by the invention has the same mechanical property as cobalt-removed PDC ceramic, and the wear resistance is obviously improved compared with that of a non-lubricating layer.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic non-metallic material preparation, and more particularly to a method for filling a decobaltized PDC ceramic self-lubricating layer driven by extreme pressure. Background Art

[0002] At present, PDC (polycrystalline diamond composite) drill bits have been widely used in oil and gas drilling projects, and the footage accounts for more than 90% of the total footage of oil and gas drilling in the world. The market share is more than 80% and is still growing. The two most important characteristics of PDC drill bits are drilling efficiency and service life. The wear of the cutting teeth is too fast, and the cutting depth is reduced, which is not conducive to breaking rocks and reducing rock breaking efficiency. In terms of drill bit life, the cost of the drill bit accounts for one-third of the drilling cost. How to improve the wear resistance of PDC drill bits and extend their service life is an urgent problem to be solved. There are currently two ways to improve the wear resistance of PDC drill bits. One is to increase the hardness of PDC materials, and the other is to improve the lubrication environment of the drill bit. However, the optimization of PDC microstructure has almost reached its limit, and the cost of preparing polycrystalline diamond without binder will increase sharply. In addition, the lubrication efficiency provided by the drilling fluid is insufficient. As the drilling depth increases, the rheology, leaching and chemical stability of the drilling fluid change, resulting in blockage and significantly affecting the drilling efficiency.

[0003] Self-lubricating ceramics are hard materials that meet the extreme working conditions of high-speed drilling. They can release self-lubricating particles to the friction interface during friction, increasing the lubrication efficiency to 100%, effectively improving the wear resistance of ceramics. However, the current preparation of self-lubricating ceramics is to sinter the ceramic matrix and lubricating phase powder together. The lubricating phase is a soft phase, which will cause the mechanical properties of PDC to be significantly reduced. How to give PDC self-lubricating properties while ensuring mechanical properties is an urgent problem to be solved.

[0004] Studies have shown that the preparation of self-lubricating PDC materials with excellent wear resistance requires the material to have high hardness, high toughness, high density, and good high-temperature stability, which poses great engineering challenges.

[0005] Therefore, how to develop a method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure is an urgent problem that technicians in this field need to solve. Summary of the invention

[0006] In view of this, the present invention provides a method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure comprises the following steps:

[0009] (1) Wrapping the processed cobalt-free PDC with a layer of self-lubricating powder, and then wrapping it with a metal inclusion;

[0010] The self-lubricating powder is a metal powder, and the metal inclusion is treated at high temperature and high pressure. The specific steps are: first increase the pressure to a set pressure, then increase the temperature to the melting point of the metal powder under the set pressure, keep the temperature, stop heating, continue to keep the pressure for a period of time, and then slowly reduce the pressure;

[0011] Alternatively, the self-lubricating powder is a non-metallic powder, and the metal inclusion is treated under high pressure, specifically, the steps are: firstly increasing the pressure to a set pressure, maintaining the pressure for a period of time, and then slowly reducing the pressure;

[0012] (2) Taking out the sample after being treated in step (1), removing the metal inclusions and residual self-lubricating blocks outside the sample, and obtaining a decobaltized PDC self-lubricating ceramic including a lubricating layer.

[0013] Furthermore, in step (1), the pressure is set to 5.5 GPa.

[0014] Furthermore, in step (1), the self-lubricating powder is MoS2, WS2, Cu or Al powder, and the particle size of the self-lubricating powder is 10nm-10μm.

[0015] Furthermore, the metal inclusion in step (1) is Mo, Zr or Ta.

[0016] Furthermore, in step (1), the layer thickness of the self-lubricating powder is 0.5 mm or more.

[0017] Furthermore, in step (1), the self-lubricating powder is a metal powder, and is sintered at high temperature and high pressure, with a pressure increase rate and a pressure reduction rate of 5 GPa / min, and the temperature is increased to the melting point of the metal powder at 5.5 GPa, the temperature increase rate is 100°C / min, the holding time is 5 minutes, the heating is stopped, the pressure is maintained for 5 minutes, and then the pressure is slowly reduced to 0 GPa;

[0018] Alternatively, the self-lubricating powder is a non-metallic powder, and is subjected to high pressure treatment, with a pressure increase rate and a pressure reduction rate of 5 GPa / min, and the pressure is maintained for 5 minutes and then slowly reduced to 0 GPa.

[0019] Beneficial effects of the present invention: The present invention uses extreme temperature and pressure loads to fill solid / liquid self-lubricating particles into the micropores in the PDC along the pores of the decobaltized PDC, and the particle size of the self-lubricating particles is much larger than the pore size of the micropores in the PDC.

[0020] The PDC self-lubricating ceramics prepared by the method of the present invention have the same mechanical properties as the decobaltized PDC;

[0021] The wear resistance of the cobalt-free PDC self-lubricating ceramic prepared by the method of the present invention is significantly improved compared with the non-lubricating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope analysis image of the cobalt-free PDC-MoS2 self-lubricating ceramic of Example 1;

[0023] Figure 2 This is a scanning electron microscope analysis image of the decobaltized PDC-Cu self-lubricating ceramic of Example 2;

[0024] Figure 3 This is a scanning electron microscope analysis image of the decobaltized PDC-Al self-lubricating ceramic in Example 3. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] The method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure comprises the following steps:

[0028] (1) Preparation of decobaltized PDC ceramics: 10 g of ferric chloride and 100 mL of 6 mol / L hydrochloric acid were mixed to prepare a decobaltizing reagent, and the Co-containing PDC ceramics were immersed in the decobaltizing reagent at a temperature of 200° C. for 20 h to obtain a decobaltized PDC ceramic material;

[0029] (2) Wrapping the processed cobalt-free PDC ceramic with a layer of self-lubricating powder MoS2 powder, the particle size of the self-lubricating powder is 1 μm, the layer thickness of the self-lubricating powder is 1 mm, and then wrapping it with a metal inclusion, the material of the metal inclusion is Mo, and the sample with the metal inclusion is placed in a high-pressure unit, and then high-pressure treatment is performed. The specific steps are: first increase the pressure to a set pressure of 5.5 GPa, the pressure increase rate is 5 GPa / min, and then slowly reduce the pressure to 0 GPa after maintaining the pressure for 5 minutes, and the pressure reduction rate is 5 GPa / min;

[0030] (3) Taking out the sample after high pressure treatment in step (2), removing the metal inclusions and residual self-lubricating blocks wrapped around the outside of the sample, and obtaining a PDC-MoS2 ceramic containing a lubricating layer.

[0031] The thickness of the ceramic lubrication layer obtained was 1 μm; the Vickers hardness of the PDC-MoS2 ceramic was measured to be 98.5±1.1 GPa; the nanoindentation hardness of part of the PDC-MoS2 lubrication layer was measured to be 105 GPa, and the hardness of the decobaltized PDC remained unchanged before and after the lubrication layer was filled.

[0032] The wear resistance of decobaltized PDC and PDC-MoS2 ceramics was measured by rubbing against a cemented carbide ball (YG6) (pressure 10N, friction time 15min, rotation speed 400rpm). The PDC wear rate was 150×10 -8 mm 3 / Nm, the wear rate of PDC-MoS2 is 20×10 - 8 mm 3 / Nm, the wear resistance of the decobaltized PDC after high-pressure filling of the lubricating layer is significantly improved compared with that before filling.

[0033] Example 2

[0034] The method for filling the cobalt-free PDC self-lubricating layer under extreme pressure driving comprises the following steps:

[0035] (1) Preparation of decobaltized PDC ceramics: 10 g of ferric chloride and 100 mL of 6 mol / L hydrochloric acid were mixed to prepare a decobaltizing reagent, and the Co-containing PDC ceramics were immersed in the decobaltizing reagent at a temperature of 200° C. for 20 h to obtain a decobaltized PDC ceramic material;

[0036] (2) Wrapping the processed cobalt-free PDC interstitial ceramic with a layer of self-lubricating powder Cu powder, the particle size of the self-lubricating powder is 1 μm, the layer thickness of the self-lubricating powder is 1 mm, and then wrapping it with a metal inclusion, the metal inclusion is Ta, and loading the raw material with the metal inclusion into a high-pressure sintering unit, and then treating it at high temperature and high pressure. The specific steps are: first increase the pressure to a set pressure of 5.5 GPa, the pressure increase rate is 5 GPa / min, then increase the temperature to 1400°C, the melting point of Cu at 5.5 GPa, the heating rate is 100°C / min, and the temperature is kept at a temperature of 30 minutes. Stop heating, continue to hold the pressure for 5 minutes, and then slowly reduce the pressure to 0 GPa, and the pressure reduction rate is 5 GPa / min;

[0037] (3) Taking out the sample after the high temperature and high pressure treatment in step (2), removing the metal inclusions and residual self-lubricating blocks wrapped around the outside of the sample, and obtaining a PDC-Cu ceramic containing a lubricating layer.

[0038] The thickness of the PDC lubrication layer was obtained to be 1 μm. The Vickers hardness of the PDC-Cu ceramic was measured to be 97.3±1.1 GPa. The nanoindentation hardness of part of the PDC-Cu lubrication layer was measured to be 103 GPa. The hardness of the decobaltized PDC remained unchanged before and after the lubrication layer was filled.

[0039] The wear resistance of decobaltized PDC and PDC-MoS2 ceramics was measured by rubbing against a cemented carbide ball (YG6) (pressure 10N, friction time 15min, rotation speed 400rpm). The wear rate of PDC was 143×10 -8 mm 3 / Nm, the wear rate of PDC-Cu is 40×10 -8 mm 3 / Nm, the wear resistance of the decobaltized PDC after high-pressure filling of the lubricating layer is significantly improved compared with that before filling.

[0040] Example 3

[0041] The method for filling the cobalt-free PDC self-lubricating layer under extreme pressure driving comprises the following steps:

[0042] (1) Preparation of decobaltized PDC ceramics: 10 g of ferric chloride and 100 mL of 6 mol / L hydrochloric acid were mixed to prepare a decobaltizing reagent, and the Co-containing PDC ceramics were immersed in the decobaltizing reagent at a temperature of 200° C. for 20 h to obtain a decobaltized PDC ceramic material;

[0043] (2) Wrapping the processed WC-based porous ceramic with a layer of self-lubricating powder Al powder, the particle size of the self-lubricating powder is 1 μm, the layer thickness of the self-lubricating powder is 1 mm, and then wrapping it with a metal inclusion, the material of the metal inclusion is Zr, and loading the raw material with the metal inclusion into a high-pressure sintering unit, and then treating it at high temperature and high pressure. The specific steps are: first increase the pressure to a set pressure of 5.5 GPa, the pressure increase rate is 5 GPa / min, then increase the temperature to 800°C, the melting point of Al at 5.5 GPa, the heating rate is 100°C / min, and keep warm for 30 minutes, stop heating, continue to keep the pressure for 5 minutes, and then slowly reduce the pressure to 0 GPa, the pressure reduction rate is 5 GPa / min;

[0044] (3) Taking out the sample after high pressure treatment in step (2), removing the metal inclusions and residual self-lubricating blocks wrapped around the outside of the sample, and obtaining a PDC-Al ceramic containing a lubricating layer.

[0045] The thickness of the PDC lubrication layer was obtained to be 1 μm. The Vickers hardness of the PDC-Al ceramic was measured to be 92.3±1.1 GPa. The nanoindentation hardness of part of the PDC-Al lubrication layer was measured to be 99 GPa. The hardness of the decobaltized PDC remained unchanged before and after the lubrication layer was filled.

[0046] The wear resistance of decobaltized PDC and PDC-MoS2 ceramics was measured by rubbing against a cemented carbide ball (YG6) (pressure 10N, friction time 15min, rotation speed 400rpm). The wear rate of PDC was 162×10 -8 mm 3 / Nm, the wear rate of PDC-Al is 13×10 -8 mm 3 / Nm, the wear resistance of the decobaltized PDC after high-pressure filling of the lubricating layer is significantly improved compared with that before filling.

[0047] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure, characterized in that: The steps include: (1) wrapping a layer of self-lubricating powder on the outside of the processed cobalt-free PDC ceramic, and then wrapping it with a metal inclusion; The self-lubricating powder is a metal powder, and the metal inclusion is treated at high temperature and high pressure. The specific steps are: first increase the pressure to a set pressure, then increase the temperature to the melting point of the metal powder under the set pressure, keep the temperature, stop heating, continue to keep the pressure for a period of time, and then slowly reduce the pressure; Alternatively, the self-lubricating powder is a non-metallic powder, and the metal inclusion is treated under high pressure, specifically, the steps are: firstly increasing the pressure to a set pressure, maintaining the pressure for a period of time, and then slowly reducing the pressure; (2) Taking out the sample after being treated in step (1), removing the metal inclusions and residual self-lubricating blocks outside the sample, and obtaining a decobaltized PDC self-lubricating ceramic including a lubricating layer.

2. According to the method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure in claim 1, it is characterized in that: In step (1), the pressure was set to 5.5 GPa.

3. According to the method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure in claim 1, it is characterized in that: In step (1), the self-lubricating powder is MoS2, WS2, Cu or Al powder, and the particle size of the self-lubricating powder is 10nm-10μm.

4. According to the method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure in claim 1, it is characterized in that: The metal inclusion in step (1) is Mo, Zr or Ta.

5. According to the method for filling a cobalt-free PDC ceramic self-lubricating layer driven by extreme pressure in claim 1, it is characterized in that: In step (1), the layer thickness of the self-lubricating powder is 0.5 mm or more.

6. The method for filling a cobalt-free PDC ceramic self-lubricating layer under extreme pressure drive according to claim 1, characterized in that: In step (1), the self-lubricating powder is a metal powder, which is sintered at high temperature and high pressure, with a pressure increase rate and a pressure reduction rate of 5 GPa / min, and the temperature is increased to the melting point of the metal powder at 5.5 GPa, the temperature increase rate is 100°C / min, the holding time is 5 minutes, the heating is stopped, the pressure is maintained for 5 minutes, and then the pressure is slowly reduced to 0 GPa; Alternatively, the self-lubricating powder is a non-metallic powder, and is subjected to high pressure treatment, with a pressure increase rate and a pressure reduction rate of 5 GPa / min, and the pressure is maintained for 5 minutes and then slowly reduced to 0 GPa.

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