Drill pipe and method of making same

Abstract

The application provides a drill pipe and a preparation method thereof. The drill pipe comprises a drill pipe body, a female joint and a male joint connected with the drill pipe body, and a carbon-silicon co-permeation layer and an erosion-resistant layer arranged on the surface of the drill pipe body in sequence, wherein the erosion-resistant layer comprises a CrAlSiN layer. The drill pipe with the above structure has the advantages of high hardness, good wear resistance and erosion resistance, long service life and the like.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field drilling tools, and more specifically, to a drill pipe and its manufacturing method. Background Technology

[0002] Drill pipe is a commonly used downhole tool in oil and gas field development. As the actual working conditions in oil and gas field development become increasingly complex, drill pipes face increasingly severe corrosive environments and risks. Titanium alloy drill pipes, due to their light weight, high specific strength, and certain corrosion resistance, are one of the main types of drill pipes currently used in oil and gas fields. However, due to their low surface hardness, poor wear resistance, unsatisfactory corrosion and erosion resistance, and high cost, titanium alloy drill pipes still cannot meet the requirements of practical applications in oil and gas fields.

[0003] Currently, preparing metallic coatings on the surface of titanium alloy drill pipes is the main approach to improving their wear resistance and erosion resistance. Corresponding metal coating preparation technologies include micro-arc oxidation, laser cladding, vacuum evaporation, and hot-dip galvanizing. However, although the prepared metallic coatings possess advantages such as high hardness, high film-substrate bonding strength, corrosion resistance, and wear resistance, they still suffer from defects such as relatively rough surfaces, porous structures, and high coefficients of friction. These defects reduce the erosion resistance and shorten the service life of titanium alloy drill pipes, severely limiting their application in the erosive environments of oil and gas fields. Summary of the Invention

[0004] The main objective of this invention is to provide a drill pipe and its manufacturing method to solve the problems of low erosion resistance and short service life of existing drill pipes.

[0005] To achieve the above objectives, the present invention provides a drill pipe, including a drill pipe body, a female connector and a male connector connected to the drill pipe body, and a carbon-silicon co-diffusion layer and an erosion-resistant layer sequentially disposed on the surface of the drill pipe body, wherein the erosion-resistant layer includes a CrAlSiN layer.

[0006] Furthermore, the thickness of the erosion-resistant layer is 2–5 μm, and the thickness of the carbon-silicon co-diffusion layer is 100–300 μm.

[0007] Furthermore, the erosion-resistant layer includes: a CrAlSiN layer, a silicon-infiltrating layer, and a CrAlSi transition layer stacked together, with the CrAlSi transition layer disposed on the side close to the carbon-silicon co-infiltrating layer.

[0008] Furthermore, the drill pipe also includes a silicon-carbon reinforcing layer, which is disposed on the surface of the erosion-resistant layer away from the carbon-silicon co-diffusion layer.

[0009] Furthermore, the thickness of the silicon-carbon reinforcement layer is 0.5–3 μm.

[0010] The second aspect of this application also provides a method for preparing the above-mentioned drill pipe, the method comprising: performing carbon-silicon co-diffusion treatment on the surface of the drill pipe body to form a carbon-silicon co-diffusion layer; and using plasma vapor deposition to deposit on the surface of the carbon-silicon co-diffusion layer to form an erosion-resistant layer containing a CrAlSiN layer.

[0011] Further, the deposition process includes: S1, a first deposition process is performed on the drill pipe body using a CrAl target under vacuum conditions, argon gas flow, and SiH4 gas flow to form a CrAlSi transition layer; S2, a silicon infiltration treatment is performed on the surface of the CrAlSi transition layer under vacuum conditions, argon gas flow, and SiH4 gas flow to form a silicon infiltrated layer; and S3, a second deposition treatment is performed on the surface of the silicon infiltrated layer using a Cr target, a CrAl target, and an AlSi target under vacuum conditions, argon gas flow, SiH4 gas flow, and N2 flow to form a CrAlSiN layer; and optionally, S1 to S3 are repeated to obtain an erosion-resistant layer.

[0012] Further, during the first deposition process, the temperature of the reaction chamber is 150℃~300℃, the argon flow rate is 900~1200 sccm, the vacuum degree is 2.2Pa~3Pa, the target current is 130A~160A, the substrate bias voltage is -85V~-115V, and the deposition time is 30min~50min; optionally, during the silicon infiltration process, the temperature of the reaction chamber is 310℃~400℃, the argon flow rate is 50sccm~100sccm, the SiH4 gas flow rate is 200sccm~500sccm, the vacuum degree is 1.1~1.5Pa, and the substrate bias voltage is 130A~160A. The bottom bias voltage is -90V to -120V, and the silicon diffusion time is 3min to 10min. Optionally, the reaction chamber temperature is 310℃ to 400℃, the argon flow rate is 800sccm to 1200sccm, the N2 flow rate is 200sccm to 400sccm, the vacuum degree is 2.0Pa to 3Pa, the substrate bias voltage is -85V to -115V, the arc current of the Cr target is 20A to 40A, the arc current of the CrAl target is 70 to 100A, the arc current of the AlSi target is 60 to 90A, and the deposition time of the CrAlSiN layer is 40min to 70min.

[0013] Furthermore, the carbon-silicon co-diffusion treatment process includes: permeating the drill pipe body with a carbon source and a silicon source to obtain a carbon-silicon co-diffusion layer; preferably, the carbon source is selected from one or more of methane, ethane, propylene, and acetylene; the silicon source is selected from one or more of silane, methyltrichlorosilane, silicon tetrachloride, and tetramethylsilane. Preferably, the temperature of the carbon-silicon co-diffusion treatment process is 400–500°C, and the co-diffusion time is 30–90 min.

[0014] Furthermore, the method for preparing the drill pipe also includes: forming a silicon-carbon reinforced layer on the surface of the erosion-resistant layer away from the carbon-silicon co-diffusion layer using plasma-enhanced chemical vapor deposition.

[0015] By applying the technical solution of this invention, forming a carbon-silicon co-diffusion layer on the surface of the drill pipe body can improve and enhance the hardness and strength of the drill pipe body. Simultaneously, the carbon-silicon co-diffusion layer, acting as a transition layer, can alleviate the mismatch in thermal expansion coefficients between the drill pipe body and the erosion-resistant layer, while reducing interfacial stress and improving the bonding strength between the erosion-resistant layer and the drill pipe body, thus enhancing the erosion resistance of the drill pipe. Placing a CrAlSiN layer on the surface of the carbon-silicon co-diffusion layer significantly improves the hardness, wear resistance, and erosion resistance of the titanium alloy drill pipe. In summary, drill pipes with the above structure possess advantages such as high hardness, good wear resistance and erosion resistance, and long service life. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0017] Figure 1 This is a schematic diagram of the drill pipe structure provided for a typical embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure of the protective coating in the drill pipe according to a preferred embodiment of this application.

[0019] Figure 3 The surface morphology test image of the CrAlSiN erosion-resistant layer on the surface of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application.

[0020] Figure 4 This is a test image of the surface morphology of the SiC reinforcement layer on the surface of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application.

[0021] Figure 5 This is a graph showing the test results of the hardness value of the erosion-resistant layer on the surface of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application.

[0022] Figure 6 This is a test diagram of the friction performance of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application.

[0023] Figure 7 This is a test diagram of the erosion resistance performance of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application.

[0024] The above figures include the following reference numerals:

[0025] 10. Drill pipe body; 20. Female connector; 30. Male connector; 40. Carbon-silicon co-diffusion layer; 50. Erosion-resistant layer; 51. CrAlSiN layer; 52. Silicon-diffused layer; 53. CrAlSi transition layer; 60. Silicon-carbon reinforced layer. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0027] As described in the background section, existing drill pipes suffer from low erosion resistance and short service life. To address these technical problems, this application provides a drill pipe, such as... Figure 1 As shown, the drill pipe includes a drill pipe body 10, a female connector 20 and a male connector 30 connected to the drill pipe body 10, and a carbon-silicon co-diffusion layer 40 and an erosion-resistant layer 50 sequentially stacked on the surface of the drill pipe body 10, wherein the erosion-resistant layer 50 includes a CrAlSiN layer 51.

[0028] Forming a carbon-silicon co-diffusion layer 40 on the surface of the drill pipe body 10 can improve and enhance its hardness and strength. Simultaneously, the carbon-silicon co-diffusion layer 40, acting as a transition layer, can alleviate the mismatch in thermal expansion coefficients between the drill pipe body 10 and the erosion-resistant layer 50, while reducing interfacial stress and improving the bonding strength between the erosion-resistant layer 50 and the drill pipe body 10, thus enhancing the drill pipe's erosion resistance. Placing a CrAlSiN layer 51 on the surface of the carbon-silicon co-diffusion layer 40 significantly improves the hardness, wear resistance, and erosion resistance of the titanium alloy drill pipe. In summary, drill pipes with the above structure possess advantages such as high hardness, good wear resistance and erosion resistance, and long service life.

[0029] In a preferred embodiment, the thickness of the erosion-resistant layer 50 is 2–5 μm, and the thickness of the carbon-silicon co-diffusion layer 40 is 100–300 μm. The thicknesses of the erosion-resistant layer 50 and the carbon-silicon co-diffusion layer 40 include, but are not limited to, the above-mentioned ranges. Limiting them to these ranges is beneficial for further improving the hardness, strength, and erosion resistance of the drill pipe, and also for reducing manufacturing costs.

[0030] To further improve the corrosion resistance and hardness of the drill pipe, in a preferred embodiment, the erosion-resistant layer 50 includes: a CrAlSiN layer 51, a silicon-infiltrating layer 52, and a CrAlSi transition layer 53 stacked together, with the CrAlSi transition layer 53 disposed on the side close to the carbon-silicon co-infiltrating layer 40.

[0031] In a preferred embodiment, such as Figure 1As shown, the drill pipe also includes a silicon-carbon reinforcing layer 60, which is disposed on the surface of the erosion-resistant layer 50 away from the carbon-silicon co-diffusion layer 40. The silicon-carbon reinforcing layer 60, prepared on the surface of the erosion-resistant layer 50, not only further seals the micropores on the surface of the CrAlSiN layer 51, but also further improves the overall hardness and density of the erosion-resistant layer 50, thereby enhancing the overall performance of the drill pipe. More preferably, the thickness of the silicon-carbon reinforcing layer 60 is 0.5–3 μm.

[0032] Figure 1 In this process, the carbon-silicon co-diffusion layer 40, the erosion-resistant layer 50, and the silicon-carbon reinforcing layer 60 are collectively referred to as the protective coating. Preferably, the hardness of the protective coating on the drill pipe surface is 40–53 GPa, the coefficient of friction is 0.10–0.35, and the average erosion rate is 1.5–4.8 × 10⁻⁶. -9 Kg / m 2 ·s.

[0033] The second aspect of this application also provides a method for preparing the aforementioned drill pipe. The method includes: performing a carbon-silicon co-diffusion treatment on the surface of the drill pipe body 10 to form a carbon-silicon co-diffusion layer 40; and depositing a erosion-resistant layer 50 containing a CrAlSiN layer 51 on the surface of the carbon-silicon co-diffusion layer 40 using plasma vapor deposition. This preparation method is simple, easy to operate, and has low cost. The resulting drill pipe exhibits advantages such as high hardness, good wear resistance and erosion resistance, and long service life.

[0034] The carbon-silicon co-diffusion layer 40 can be formed using conventional methods in the art. For example, the drill pipe body 10 can be permeated with a carbon source and a silicon source to obtain the carbon-silicon co-diffusion layer 40; wherein the carbon source includes, but is not limited to, one or more of methane, ethane, propylene, and acetylene; and the silicon source includes, but is not limited to, one or more of silane, methyltrichlorosilane, silicon tetrachloride, and tetramethylsilane.

[0035] The carbon-silicon co-diffusion layer 40 enhances the surface hardness of the drill pipe body and matches its coefficient of thermal expansion with that of the erosion-resistant layer 50, thereby reducing interfacial stress and strengthening the bond between the drill pipe body 10 and the erosion-resistant layer 50. To further increase the silicon infiltration depth, preferably, the temperature of the carbon-silicon co-diffusion process is 400–500°C, and the co-diffusion time is 30–90 minutes.

[0036] In a preferred embodiment, the above deposition process includes:

[0037] S1, Under vacuum conditions, argon flow and SiH4 flow, CrAl target material is used to perform the first deposition process on drill pipe body 10 to form CrAlSi transition layer 53.

[0038] S2, under vacuum conditions, in an argon gas flow and a SiH4 gas flow, silicon infiltration treatment is performed on the surface of the CrAlSi transition layer 53 to form a silicon infiltrated layer 52; and

[0039] S3, under vacuum conditions, argon flow, SiH4 flow and N2 flow, a second deposition treatment is performed on the surface of silicon-diffused layer 52 using Cr target, CrAl target and AlSi target to form CrAlSiN layer 51; and optionally repeats S1 to S3 to obtain erosion-resistant layer 50.

[0040] To further improve the corrosion resistance and strength of the erosion-resistant layer 50, the process in each step can be optimized. In a preferred embodiment, during the first deposition process, the temperature of the reaction chamber is 150℃~300℃, the argon flow rate is 900~1200sccm, the vacuum degree is 2.2Pa~3Pa, the target current is 130A~160A, the substrate bias voltage is -85V~-115V, and the deposition time is 30min~50min;

[0041] Optionally, during the silicon infiltration process, the temperature of the reaction chamber is 310℃~400℃, the argon flow rate is 50sccm~100sccm, the SiH4 gas flow rate is 200sccm~500sccm, the vacuum degree is 1.1~1.5Pa, the substrate bias voltage is -90V~-120V, and the silicon infiltration time is 3min~10min;

[0042] Optionally, during the second deposition process, the temperature of the reaction chamber is 310℃~400℃, the argon flow rate is 800sccm~1200sccm, the N2 flow rate is 200sccm~400sccm, the vacuum degree is 2.0Pa~3Pa, the substrate bias voltage is -85V~-115V, the arc current of the Cr target is 20A~40A, the arc current of the CrAl target is 70~100A, the arc current of the AlSi target is 60~90A, and the CrAlSiN layer is deposited for 40min~70min.

[0043] To avoid impurities affecting the carbon-silicon co-diffusion treatment, preferably, the drill pipe preparation method before the carbon-silicon co-diffusion treatment includes: cleaning the drill pipe body 10 under vacuum conditions using plasma. Preferably, the plasma is argon plasma. The cleaning solution includes, but is not limited to, one or more components of alcohol, acetone, and deionized water.

[0044] In a preferred embodiment, the process of depositing a CrAlSiN layer 51 on the carbon-silicon co-diffusion layer 40 further includes: a step of activating the target material. Specifically, the cleaned drill rod substrate, Cr target, CrAl target, and AlSi alloy target are loaded into the reaction chamber of the plasma vapor deposition equipment, and then the reaction chamber is evacuated to 10 °C using a vacuum pump group.-4 -10 - 8 Pa; the mass purity of the Cr target, CrAl target, and AlSi alloy is not less than 99.9%; then the reaction chamber containing the target and substrate in S2 is heated to a temperature of 150℃~300℃, and held at 150℃~300℃ for 1min~5min; while holding at 150℃~300℃, Ar gas is introduced until the vacuum degree of the reaction chamber is 1Pa~2Pa, the Ar flow rate is 500sccm~800sccm, and the argon purity is not less than 99.999%; then the Cr target, CrAl target, and AlSi alloy target are activated in sequence, the activation target current is 70A~90A, and the activation time is 3~8min.

[0045] To further improve the cleanliness of the drill pipe surface, preferably, the surface of the cleaned drill pipe tube 10 is subjected to bombardment cleaning treatment. Specifically, the reaction chamber temperature is maintained at 150℃~300℃, the Ar gas flow rate is increased to 900sccm~1200sccm, and the vacuum degree of the reaction chamber is increased to 1.6Pa~2.2Pa; then, a bias voltage of -900V~-1100V is applied to the substrate (drill pipe tube 10) to form Ar plasma, and the substrate is bombarded for 6min~12min to remove impurities on the substrate surface.

[0046] In a preferred embodiment, the above-mentioned drill pipe preparation method further includes: forming a silicon-carbon reinforcing layer 60 on the surface of the erosion-resistant layer 50 away from the carbon-silicon co-diffusion layer 40 using plasma-enhanced chemical vapor deposition.

[0047] Specifically, the following steps are included:

[0048] (1) The drill rod with the carbon-silicon co-diffusion layer 40 and the erosion-resistant layer 50 prepared is placed into the reaction chamber of the plasma vapor deposition equipment, and then the reaction chamber is evacuated to 10°C using a vacuum pump group. -5 ~10 -7 Pa.

[0049] (2) The Cr target, CrAl target, and AlSi alloy target are loaded into the reaction chamber of the plasma vapor deposition equipment, and then the reaction chamber is evacuated to 10°C using a vacuum pump group. -4 ~10 -8 Pa.

[0050] (3) Maintain the reaction chamber temperature at 100℃~200℃, the flow rate of CH4 gas is 900~1200sccm, the flow rate of SiH4 gas is 50~200sccm, increase the vacuum degree of the reaction chamber to 2.5Pa~3.5Pa, and at the same time adjust the substrate bias voltage to -95V~-125V to prepare silicon-carbon reinforced layer 60 for 0.5h~3h.

[0051] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0052] Example 1

[0053] A corrosion-resistant titanium alloy drill pipe includes: a drill pipe body 10, a female connector 20 and a male connector 30 connected to the drill pipe body 10, and a carbon-silicon co-diffusion layer 40, a corrosion-resistant layer 50, and a silicon-carbon reinforcing layer 60 sequentially stacked on the surface of the drill pipe body 10, wherein the corrosion-resistant layer 50 includes a CrAlSiN layer 51, a silicon-diffusion layer 52, and a CrAlSi transition layer 53.

[0054] The specific preparation method is as follows:

[0055] (1) Place the drill pipe body 10 into the vacuum chamber and use the vacuum pump set to evacuate the chamber to a vacuum level of 10. - 4 Pa; then a certain amount of argon gas is introduced, and a high-frequency pulse voltage is applied to form a high-energy argon plasma to clean the surface of the drill pipe 10 for 30 minutes.

[0056] (2) Formation of carbon-silicon co-diffusion layer 40: After cleaning, a certain amount of SiH4 and C2H2 are introduced, and C-Si co-diffusion is performed on the surface of the drill pipe body 10 using low-temperature plasma technology. The co-diffusion temperature is 430℃, and the C-Si co-diffusion time is 45min.

[0057] (3) Formation of erosion-resistant layer 50:

[0058] S1. The substrate (drill pipe body 10 containing carbon-silicon co-diffusion layer 40) is cleaned. The cleaning solution is acetone and deionized water in a volume ratio of 1:5.

[0059] S2. The cleaned substrate, Cr target, CrAl target, and AlSi alloy target obtained in S1 are loaded into the reaction chamber of the plasma vapor deposition equipment, and then the reaction chamber is evacuated to 10°C using a vacuum pump. -8 Pa; The mass purity of the Cr target, CrAl target, and AlSi alloy is 99.99%;

[0060] S3. The reaction chamber containing the target and substrate in S2 is heated to 230℃ and held at 200℃ for 5 minutes. While holding at 200℃, argon gas is introduced until the vacuum degree of the reaction chamber is 1.5 Pa, the argon gas flow rate is 600 sccm, and the argon gas purity is 99.999%. Then, the Cr target, CrAl target, and AlSi alloy target are activated in sequence. The activation target current is 85A and the activation time is 6 minutes.

[0061] S4. Perform plasma bombardment cleaning on the substrate surface in S3. The specific process is as follows: maintain the reaction chamber temperature at 230℃, increase the argon flow rate to 1100 sccm, and increase the vacuum degree of the reaction chamber to 2 Pa; then apply a bias voltage of -1020V to the substrate to form argon plasma, and bombard the substrate for 10 min to remove impurities from the substrate surface.

[0062] S5. Prepare the CrAlSi transition layer 53 on the substrate surface after cleaning in S4. The specific process is as follows: keep the reaction chamber temperature at 230℃, change the argon flow rate to 1050 sccm, and simultaneously introduce SiH4 gas with a flow rate of 150 sccm to increase the vacuum degree of the reaction chamber to 2.6 Pa. Turn on the CrAl target and adjust the target current to 145 A. At the same time, adjust the substrate bias voltage to -105 V and deposit CrAlSi for 40 min to form the required CrAlSi transition layer 53.

[0063] S6. The CrAlSi transition layer prepared in S5 is subjected to Si infiltration treatment to prepare the silicon-infiltrated layer 52. The specific process is as follows: the reaction chamber is further heated to raise the temperature to 340℃; the argon flow rate is adjusted to 75 sccm and the SiH4 gas flow rate is adjusted to 300 sccm; the vacuum degree of the reaction chamber is adjusted to 1.2 Pa; the substrate bias is adjusted to -100V; the Si infiltration treatment time is 8 min to form the required silicon-infiltrated layer 52.

[0064] S7. A CrAlSiN layer 51 is prepared on the surface of the CrAlSi transition layer after Si infiltration treatment in S6. The specific process is as follows:

[0065] Raise the temperature of the reaction chamber to 380℃, adjust the argon flow rate to 1000 sccm, and adjust the SiH4 gas flow rate to 500 sccm;

[0066] The N2 gas flow rate was adjusted to 300 sccm, the vacuum level was adjusted to 2.5 Pa, and the substrate bias voltage was adjusted to -105 V. The Cr target, CrAl target, and AlSi target were turned on, with the arc current of the Cr target being 35 A, the arc current of the CrAl target being 85 A, and the arc current of the AlSi target being 80 A. CrAlSiN was deposited for 60 min to form the required CrAlSiN layer 51.

[0067] S8. Repeat S5, S6 and S7 for a total of 6 times to obtain 50 erosion-resistant layers.

[0068] (4) Forming the silicon-carbon reinforced layer 60, the specific process is as follows:

[0069] S1, the drill rod obtained in step (3) is placed into the reaction chamber of the plasma vapor deposition equipment, and then pumped through a vacuum pump.

[0070] The reaction chamber was evacuated to 10°C. -5 ~10 -7 Pa;

[0071] S2, the titanium alloy drill pipe, Cr target, CrAl target, and AlSi alloy target obtained in N1 are loaded into the plasma vapor deposition system.

[0072] In the reaction chamber of the equipment, a vacuum pump unit is used to evacuate the reaction chamber to 10. -4 ~10 -8 Pa;

[0073] S3. Under N2 atmosphere, a SiC reinforcement layer is prepared on the surface of a titanium alloy drill rod. The SiC reinforcement layer preparation process is as follows: the reaction chamber temperature is maintained at 100℃~200℃, the flow rate of CH4 gas is 900~1200sccm, the flow rate of SiH4 gas is 50~200sccm, the vacuum degree of the reaction chamber is increased to 2.5Pa~3.5Pa, and the substrate bias voltage is adjusted to -95V~-125V. The SiC reinforcement layer is prepared for 0.5h~3h.

[0074] After step (4) is completed, the drill pipe body is connected to the titanium alloy female connector 20 by thread, and the right end is connected to the titanium alloy male connector 30 by thread, finally obtaining the erosion-resistant titanium alloy drill pipe.

[0075] Performance testing:

[0076] Figure 3 This is a surface morphology test image of the CrAlSiN layer 51 in the erosion-resistant layer 50 on the surface of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application. Figure 3 It can be seen that the CrAlSiN layer 51 in the erosion-resistant layer 50 on the surface of the erosion-resistant titanium alloy drill pipe obtained in Example 1 has a tight grain bond and a high coating density.

[0077] Figure 4 This is a surface morphology test image of the silicon-carbon reinforcing layer 60 on the surface of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application. Figure 4 It can be seen that the silicon-carbon reinforced layer 60 on the surface of the erosion-resistant titanium alloy drill pipe obtained in Example 1 has a tight grain bond and a high coating density.

[0078] Figure 5 This image shows the hardness test results of the erosion-resistant layer 50 on the surface of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application. Figure 5 It can be seen that the hardness value of the erosion-resistant layer 50 on the surface of the erosion-resistant titanium alloy drill pipe obtained in Example 1 is 53 GPa.

[0079] Figure 6 This is a test diagram showing the frictional performance of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application. (Source: [Insert Source Here]) Figure 6 It can be seen that the average friction coefficient of the erosion-resistant titanium alloy drill pipe body obtained in Example 1 is 0.10.

[0080] Figure 7 This is a test diagram showing the erosion resistance performance of the erosion-resistant titanium alloy drill pipe body prepared in Example 1 of this application. Figure 7 It can be seen that,

[0081] The average erosion rate of the erosion-resistant layer 50 on the surface of the erosion-resistant titanium alloy drill pipe body obtained in Example 1 was 1.5 × 10⁻⁶. -9 Kg / m 2

[0082] ·s.

[0083] Example 2

[0084] The preparation method is the same as in Example 1, except that in step (1), the high-energy plasma cleaning time is 10 min.

[0085] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 50 GPa, a friction coefficient of 0.14, and an average erosion rate of 2.2 × 10⁻⁶. -9 Kg / m 2 ·s.

[0086] Example 3

[0087] The preparation method is the same as in Example 1, except that in step (2), the preparation temperature of the carbon-silicon co-diffusion layer 40 is 400℃.

[0088] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 48 GPa, a friction coefficient of 0.15, and an average erosion rate of 2.5 × 10⁻⁶. -9 Kg / m 2 ·s.

[0089] Example 4

[0090] The preparation method is the same as in Example 1, except that in step (2), the preparation temperature of the carbon-silicon co-diffusion layer 40 is 500℃.

[0091] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 46 GPa, a friction coefficient of 0.17, and an average erosion rate of 2.9 × 10⁻⁶. -9 Kg / m 2 ·s.

[0092] Example 5

[0093] The preparation method is the same as in Example 1, except that in step (2), the preparation time of the carbon-silicon co-permeation layer 40 is 30 min.

[0094] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 47 GPa, a friction coefficient of 0.14, and an average erosion rate of 2.8 × 10⁻⁶. -9 Kg / m 2 ·s.

[0095] Example 6

[0096] The preparation method is the same as in Example 1, except that in step (2), the preparation time of the carbon-silicon co-permeation layer 40 is 90 min.

[0097] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 42 GPa, a friction coefficient of 0.15, and an average erosion rate of 3.5 × 10⁻⁶. -9 Kg / m 2 ·s.

[0098] Example 7

[0099] The preparation method is the same as in Example 1, except that in step (2), the carbon source for carburizing is methane.

[0100] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 50 GPa, a friction coefficient of 0.15, and an average erosion rate of 2.4 × 10⁻⁶. -9 Kg / m 2 ·s.

[0101] Example 8

[0102] The preparation method is the same as in Example 1, except that in step (2), the silicon source used for silicon infiltration is tetramethylsilane.

[0103] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 42 GPa, a friction coefficient of 0.28, and an average erosion rate of 3.2 × 10⁻⁶. -9 Kg / m 2 ·s.

[0104] Example 9

[0105] The preparation method is the same as in Example 1, except that the deposition temperature is 300℃ during the preparation of the CrAlSiN layer 51.

[0106] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 40 GPa, a friction coefficient of 0.35, and an average erosion rate of 4.8 × 10⁻⁶. -9 Kg / m 2 ·s.

[0107] Example 10

[0108] The preparation method is the same as in Example 1, except that the deposition temperature is 450°C during the preparation of the CrAlSiN layer 51.

[0109] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 48 GPa, a friction coefficient of 0.25, and an average erosion rate of 2.1 × 10⁻⁶. -9 Kg / m 2 ·s.

[0110] Example 11

[0111] The preparation method is the same as in Example 1, except that the deposition time for the CrAlSiN layer 51 is 30 min.

[0112] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 51 GPa, a friction coefficient of 0.14, and an average erosion rate of 1.8 × 10⁻⁶. -9 Kg / m 2 ·s.

[0113] Example 12

[0114] The preparation method is the same as in Example 1, except that the deposition time for the CrAlSiN layer 51 is 90 min.

[0115] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 46 GPa, a friction coefficient of 0.15, and an average erosion rate of 2.0 × 10⁻⁶. -9 Kg / m 2 ·s.

[0116] Example 13

[0117] The preparation method is the same as in Example 1, except that the deposition temperature is 100°C during the preparation of the silicon-carbon reinforced layer 60.

[0118] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 51 GPa, a friction coefficient of 0.13, and an average erosion rate of 2.2 × 10⁻⁶. -9 Kg / m 2 ·s.

[0119] Example 14

[0120] The preparation method is the same as in Example 1, except that the deposition temperature is 200°C during the preparation of the silicon-carbon reinforced layer 60.

[0121] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 45 GPa, a friction coefficient of 0.21, and an average erosion rate of 2.5 × 10⁻⁶. -9 Kg / m 2 ·s.

[0122] Example 15

[0123] The preparation method is the same as in Example 1, except that the deposition time for the silicon-carbon reinforced layer 60 is 30 min.

[0124] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 47 GPa, a friction coefficient of 0.18, and an average erosion rate of 2.1 × 10⁻⁶. -9 Kg / m 2 ·s.

[0125] Example 16

[0126] The preparation method is the same as in Example 1, except that the deposition time for the CrAlSiN layer 51 is 3 hours.

[0127] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 48 GPa, a friction coefficient of 0.16, and an average erosion rate of 2.0 × 10⁻⁶. -9 Kg / m 2 ·s.

[0128] Example 17

[0129] The preparation method is the same as in Example 1, except that the erosion-resistant layer 50 does not contain the CrAlSi transition layer 53.

[0130] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 41 GPa, a friction coefficient of 0.23, and an average erosion rate of 3.3 kg / m. 2 ·s.

[0131] Example 18

[0132] The preparation method is the same as in Example 1, except that the erosion-resistant layer 50 does not contain the CrAlSi transition layer 53 and the silicon-infiltrating layer 52.

[0133] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 40 GPa, a friction coefficient of 0.26, and an average erosion rate of 3.9 kg / m. 2 ·s.

[0134] Comparative Example 1

[0135] The preparation method is the same as in Example 1, except that the erosion-resistant layer 50 is not provided.

[0136] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 21 GPa, a friction coefficient of 0.52, and an average erosion rate of 8.3 kg / m. 2 ·s.

[0137] Comparative Example 2

[0138] The preparation method is the same as in Example 1, except that the silicon-carbon reinforcing layer 60 is not provided.

[0139] The results show that the prepared erosion-resistant titanium alloy drill pipe has a hardness of 38 GPa, a friction coefficient of 0.42, and an average erosion rate of 6.1 kg / m. 2 ·s.

[0140] From the above description, it can be seen that the embodiments of the present invention achieve the following technical effects: forming a carbon-silicon co-diffusion layer on the surface of the drill pipe body can improve and enhance the hardness and strength of the drill pipe body. Simultaneously, the carbon-silicon co-diffusion layer, as a transition layer, can alleviate the mismatch in thermal expansion coefficients between the drill pipe body and the erosion-resistant layer, while reducing interfacial stress and improving the bonding strength between the erosion-resistant layer and the drill pipe body, thus enhancing the erosion resistance of the drill pipe. Setting a CrAlSiN layer on the surface of the carbon-silicon co-diffusion layer is beneficial for significantly improving the hardness, wear resistance, and erosion resistance of the titanium alloy drill pipe. In summary, the drill pipe with the above structure has advantages such as high hardness, good wear resistance and erosion resistance, and long service life.

[0141] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0142] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drill pipe, characterized in that, The drill pipe includes a drill pipe body (10), a female connector (20) and a male connector (30) connected to the drill pipe body (10), and a carbon-silicon co-permeation layer (40) and an erosion-resistant layer (50) sequentially disposed on the surface of the drill pipe body (10). The erosion-resistant layer (50) includes: a CrAlSiN layer (51), a silicon-infiltrating layer (52), and a CrAlSi transition layer (53) stacked together, and the CrAlSi transition layer (53) is disposed on the side close to the carbon-silicon co-infiltrating layer (40). The drill pipe also includes a silicon-carbon reinforcing layer (60), which is disposed on the surface of the erosion-resistant layer (50) away from the carbon-silicon co-diffusion layer (40).

2. The drill pipe according to claim 1, characterized in that, The thickness of the erosion-resistant layer (50) is 2 to 5 μm, and the thickness of the carbon-silicon co-permeation layer (40) is 100 to 300 μm.

3. The drill pipe according to claim 1, characterized in that, The thickness of the silicon-carbon reinforced layer (60) is 0.5 to 3 mm.

4. A method for preparing a drill pipe according to any one of claims 1 to 3, characterized in that, The method for preparing the drill pipe includes: The surface of the drill pipe body (10) is subjected to carbon-silicon co-diffusion treatment to form a carbon-silicon co-diffusion layer (40). Plasma vapor deposition is used to deposit a rust-resistant layer (50) containing a CrAlSiN layer (51) on the surface of the carbon-silicon co-diffusion layer (40).

5. The method for preparing drill pipe according to claim 4, characterized in that, The deposition process includes: S1, under vacuum conditions, argon gas flow and SiH4 gas flow, the drill pipe body (10) is subjected to a first deposition process using CrAl target material to form a CrAlSi transition layer (53). S2, under vacuum conditions and in an argon and SiH4 gas flow, silicon infiltration is performed on the surface of the CrAlSi transition layer (53) to form a silicon-infiltrated layer (52); and S3, under vacuum conditions, argon flow, SiH4 flow and N2 flow, a second deposition treatment is performed on the surface of the silicon-diffused layer (52) using Cr target, CrAl target and AlSi target to form CrAlSiN layer (51); and optionally repeats S1 to S3 to obtain the erosion-resistant layer (50).

6. The method for preparing drill pipe according to claim 5, characterized in that, During the first deposition process, the temperature of the reaction chamber is 150℃~300℃, the argon flow rate is 900~1200sccm, the vacuum degree is 2.2Pa~3Pa, the target current is 130A~160A, the substrate bias voltage is -85V~-115V, and the deposition time is 30min~50min.

7. The method for preparing drill pipe according to claim 5, characterized in that, During the silicon infiltration process, the temperature of the reaction chamber is 310℃~400℃, the argon flow rate is 50sccm~100sccm, the SiH4 gas flow rate is 200sccm~500sccm, the vacuum degree is 1.1-1.5Pa, the substrate bias voltage is -90V~-120V, and the silicon infiltration time is 3min~10min.

8. The method for preparing drill pipe according to claim 5, characterized in that, The reaction chamber temperature was 310℃~400℃, the argon flow rate was 800sccm~1200sccm, the N2 flow rate was 200sccm~400sccm, the vacuum degree was 2.0Pa~3Pa, the substrate bias voltage was -85V~-115V, the arc current of the Cr target was 20A~40A, the arc current of the CrAl target was 70~100A, the arc current of the AlSi target was 60~90A, and the deposition time of the CrAlSiN layer was 40min~70min.

9. The method for preparing drill pipe according to claim 4, characterized in that, The carbon-silicon co-infiltration process includes: using a carbon source and a silicon source to infiltrate the drill pipe body (10) to obtain the carbon-silicon co-infiltration layer (40).

10. The method for preparing a drill pipe according to claim 9, characterized in that, The carbon source is selected from one or more of methane, ethane, propylene, and acetylene; the silicon source is selected from one or more of silane, methyltrichlorosilane, silicon tetrachloride, and tetramethylsilane.

11. The method for preparing drill pipe according to claim 9, characterized in that, The carbon-silicon co-diffusion process is carried out at a temperature of 400–500°C for a duration of 30–90 minutes.

12. The method for preparing drill pipe according to claim 9, characterized in that, The method for preparing the drill pipe further includes: forming a silicon-carbon reinforced layer (60) on the surface of the erosion-resistant layer (50) away from the carbon-silicon co-diffusion layer (40) using plasma-enhanced chemical vapor deposition.

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