A nitriding treatment process for the surface of a PDC drill bit

Abstract

The present invention relates to the technical field of PDC drill bit processing, specifically to a PDC drill bit surface nitriding treatment process: comprising the following steps: pretreatment, selecting a PDC drill bit, cleaning the oil stains and rust on the surface of the PDC drill bit, grinding and polishing after cleaning, and completing the pretreatment of the PDC drill bit. In the present invention, the surface of the PDC drill bit treated with sandblasting can be effectively combined with the nitriding layer, so that a thicker and more tightly combined nitriding layer can be formed on the surface of the PDC drill bit, effectively improving the treatment effect of the PDC drill bit, through the pretreatment of sand and gravel, using the carbon water coated on the surface of the sand and gravel and the heat generated by the sand and gravel impacting the surface of the PDC drill bit, the heat generated will make the carbon water evenly cover the surface of the PDC drill bit to form a gelatinized layer with rich pore structure, further improving the combination effect of the PDC drill bit surface and the nitriding layer, thereby improving the use performance of the PDC drill bit.

Description

Technical Field

[0001] The invention relates to the technical field of PDC drill bit processing, in particular to a PDC drill bit surface nitriding processing process. Background Art

[0002] PDC drill bit is a kind of efficient cutting tool, mainly used for rock drilling operations in oil, natural gas and other drilling projects, as well as geological exploration and other fields.

[0003] In the prior art, when a PDC drill bit is subjected to nitriding treatment, in order to improve the treatment effect, the PDC drill bit needs to be thoroughly cleaned. However, the surface of the PDC drill bit after cleaning is relatively smooth. During the nitriding process, the binding performance of nitrogen atoms with the surface of the PDC drill bit is poor, which affects the nitriding treatment effect of the PDC drill bit. Based on this, the present invention provides a surface nitriding treatment process for a PDC drill bit. Summary of the invention

[0004] The purpose of the present invention is to provide a surface nitriding treatment process for a PDC drill bit. The PDC drill bit prepared by the present invention not only has good wear resistance, but also has excellent hardness performance, thereby effectively improving the performance of the PDC drill bit.

[0005] To achieve the above object, the present invention provides the following technical solution: a PDC drill bit surface nitriding treatment process, comprising the following steps:

[0006] S1: Pretreatment, select a PDC drill bit, clean the oil and rust on the surface of the PDC drill bit, grind and polish it after cleaning, and complete the pretreatment of the PDC drill bit;

[0007] S2: Activation treatment, immersing the PDC drill bit pretreated in step S1 in a treatment liquid to complete the activation treatment of the PDC drill bit;

[0008] S3: sandblasting, using a sandblasting machine to fully cover the surface of the PDC drill bit that has completed the activation treatment in step S2 with sandblasting to complete the sandblasting;

[0009] S4: coating treatment, using a coating material to coat the surface of the PDC drill bit that has been sandblasted in step S3 to complete the coating treatment;

[0010] S5: nitriding treatment, placing the PDC drill bit that has completed the coating treatment in step S4 into a nitriding furnace, introducing the treatment gas, and completing the nitriding treatment of the PDC drill bit.

[0011] Furthermore, the activation treatment method is: putting the PDC drill bit into an ultrasonic cleaning machine, then pouring the treatment liquid until the PDC drill bit is immersed, preheating the treatment liquid to 80-90°C before pouring, letting it stand for reaction for 4-8 minutes after pouring, then starting the ultrasonic cleaning machine, treating it at 60-80kHz for 6-10 minutes, taking it out, cleaning it with clean water, and then using an air gun to blow dry the PDC drill bit, thereby completing the activation treatment of the PDC drill bit.

[0012] Furthermore, the treatment liquid is prepared by the following method: mixing a hydrochloric acid solution and a hydrofluoric acid solution, wherein the mass ratio of the hydrochloric acid solution to the hydrofluoric acid solution is 1:(0.4-0.8), the concentration of the hydrochloric acid solution is 1-3%, and the concentration of the hydrofluoric acid solution is 4-6%. After mixing, deionized water is added and stirred evenly, wherein the mass of the deionized water is 1.2-1.6 times the mass of the hydrochloric acid solution. After mixing evenly, the treatment liquid is prepared.

[0013] Furthermore, the sandblasting method is: fix the PDC drill bit in a fixture, then pour sand and gravel into a sandblasting machine, set the pressure of the sandblasting machine to 0.6-0.8 MPa, the distance between the sandblasting gun and the drill bit is 150-200 mm, the sandblasting gun maintains a displacement speed of 0.6-0.8 mm, and sandblasts the surface of the PDC drill bit. After the sandblasting is completed, use a brush to clean the surface of the PDC drill bit, and the sandblasting of the PDC drill bit is completed.

[0014] Furthermore, the sand and gravel are brown corundum sand, and the sand and gravel are sieved with a 200-mesh sieve before being added.

[0015] Furthermore, the sand and gravel are pretreated after screening, and the sand and gravel are poured into a mixer, and then starch water is poured in, the mass of the starch water is 20-30% of the mass of the sand and gravel, the starch water is composed of potato starch and clean water, and the mass ratio of potato starch to clean water is 1:3, the mixer is set at 400-600r / min, and the mixing and stirring is performed for 6-10min to complete the pretreatment of the sand and gravel.

[0016] Furthermore, the coating treatment method is: weigh a coating material with a mass of 12 to 16% of the mass of the PDC drill bit, evenly apply the coating material on the surface of the PDC drill bit, then let it stand for 8 to 12 minutes, and then put it into an oven after standing, set it to 80 to 100°C for drying for 45 to 55 minutes, and the coating treatment of the PDC drill bit is completed.

[0017] Furthermore, the coating is prepared by the following method: titanium powder, chromium powder and iron powder are mixed, the mass ratio of the titanium powder, chromium powder and iron powder is 1:1.5:0.8, and water-based phenolic resin is added after mixing, the mass of the water-based phenolic resin is 6 to 8 times that of the titanium powder, and the coating is prepared after stirring and mixing.

[0018] Furthermore, the nitriding treatment method is: placing the PDC drill bit in a nitriding furnace, setting the nitriding temperature to 850-950° C., introducing nitrogen and hydrogen, wherein the amount of hydrogen introduced is 4-8% of the total gas amount.

[0019] Furthermore, the gas flow rate into the nitriding furnace is 0.2-0.4 m³ / h, the gas pressure is 500-600 Pa, and the nitriding treatment time is 6-10 h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, in the surface nitriding treatment of the PDC drill bit, the PDC drill bit is pre-sandblasted, and the sand and gravel ejected at a high speed acts on the surface of the PDC drill bit, so that the roughness of the surface of the PDC drill bit can be improved. In the process of nitriding, the surface of the PDC drill bit treated with sandblasting can be effectively combined with the nitriding layer, so that a thicker and more tightly combined nitriding layer can be formed on the surface of the PDC drill bit, which effectively improves the treatment effect of the PDC drill bit. By pre-treating the sand and gravel, the carbon water coated on the surface of the sand and gravel and the heat generated by the sand and gravel impacting the surface of the PDC drill bit are used. The heat generated can make the carbon water uniformly cover the surface of the PDC drill bit to form a gelatinized layer with rich pore structure, further improving the combination effect between the surface of the PDC drill bit and the nitriding layer, thereby improving the use performance of the PDC drill bit.

[0022] 2. In the present invention, the PDC drill bit is coated by mixing titanium powder, chromium powder, iron powder and water-based phenolic resin, and the water-based phenolic resin is used as a binder, so that carbon powder, chromium powder and iron powder are evenly coated on the surface of the PDC drill bit, wherein the iron powder can fill the pores, so that the coating layer structure is dense, and the coating layer can react during the nitriding treatment process. The titanium powder reacts with nitrogen atoms to form titanium nitride with higher hardness on the surface of the PDC drill bit. The titanium nitride compound is evenly covered on the surface of the PDC drill bit, which can improve the wear resistance and hardness of the PDC drill bit. The good corrosion resistance of the chromium powder can be used to improve the stability of the titanium nitride, thereby further improving the performance of the PDC drill bit.

[0023] 3. In the present invention, by activating the PDC drill bit, the treatment liquid and the PDC drill bit can be evenly covered by the treatment liquid on the surface of the PDC drill bit under the action of an ultrasonic cleaning machine. By adding hydrochloric acid solution and hydrofluoric acid solution, the oxides and impurities on the surface of the PDC drill bit can be corroded, so that the metal atoms on the surface of the PDC drill bit are fully exposed. When performing nitriding treatment, the activity of the nitriding reaction can be increased, thereby improving the nitriding treatment effect of the PDC drill bit. DETAILED DESCRIPTION

[0024] The following will be combined with 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 making creative work are within the scope of protection of the present invention.

[0025] This embodiment provides a PDC drill bit surface nitriding treatment process, comprising the following steps:

[0026] S1: Pretreatment, select a PDC drill bit, clean the oil and rust on the surface of the PDC drill bit, grind and polish it after cleaning, and complete the pretreatment of the PDC drill bit;

[0027] S2: Activation treatment, immersing the PDC drill bit pretreated in step S1 in a treatment liquid to complete the activation treatment of the PDC drill bit;

[0028] S3: sandblasting, using a sandblasting machine to fully cover the surface of the PDC drill bit that has completed the activation treatment in step S2 with sandblasting to complete the sandblasting;

[0029] S4: coating treatment, using a coating material to coat the surface of the PDC drill bit that has been sandblasted in step S3 to complete the coating treatment;

[0030] S5: nitriding treatment, placing the PDC drill bit that has completed the coating treatment in step S4 into a nitriding furnace, introducing the treatment gas, and completing the nitriding treatment of the PDC drill bit.

[0031] In some embodiments, the activation treatment method is: put the PDC drill bit into an ultrasonic cleaning machine, then pour the treatment liquid until the PDC drill bit is immersed, preheat the treatment liquid to 80-90°C before pouring, let it stand for reaction for 4-8 minutes after pouring, then start the ultrasonic cleaning machine, treat it at 60-80kHz for 6-10 minutes, take it out, wash it with clean water, and then use an air gun to blow dry the PDC drill bit, thus completing the activation treatment of the PDC drill bit.

[0032] In this embodiment, by activating the PDC drill bit, the treatment liquid and the PDC drill bit can be evenly covered by the treatment liquid on the surface of the PDC drill bit under the action of an ultrasonic cleaning machine.

[0033] In some embodiments, the treatment liquid is prepared by the following method: mixing hydrochloric acid solution and hydrofluoric acid solution, the mass ratio of hydrochloric acid solution to hydrofluoric acid solution is 1: (0.4-0.8), the concentration of hydrochloric acid solution is 1-3%, and the concentration of hydrofluoric acid solution is 4-6%, after mixing, deionized water is added and stirred evenly, the mass of deionized water is 1.2-1.6 times the mass of hydrochloric acid solution, and after mixing evenly, the treatment liquid is prepared.

[0034] In this embodiment, by adding hydrochloric acid solution and hydrofluoric acid solution, the oxides and impurities on the surface of the PDC drill bit can be corroded, so that the metal atoms on the surface of the PDC drill bit are fully exposed. When the nitriding treatment is performed, the activity of the nitriding reaction can be increased, thereby improving the nitriding treatment effect of the PDC drill bit.

[0035] In some embodiments, the sandblasting method is: fix the PDC drill bit in a fixture, then pour sand and gravel into a sandblasting machine, set the pressure of the sandblasting machine to 0.6-0.8 MPa, set the distance between the sandblasting gun and the drill bit to 150-200 mm, maintain a displacement speed of 0.6-0.8 mm, and sandblast the surface of the PDC drill bit. After the sandblasting is completed, use a brush to clean the surface of the PDC drill bit, thereby completing the sandblasting of the PDC drill bit.

[0036] In this embodiment, the PDC drill bit is pre-sandblasted, and the sand and gravel ejected at high speed acts on the surface of the PDC drill bit, so that the roughness of the surface of the PDC drill bit can be improved. During the nitriding process, the surface of the PDC drill bit that has been sandblasted can be effectively combined with the nitrided layer, so that a thicker and more tightly combined nitrided layer can be formed on the surface of the PDC drill bit, effectively improving the treatment effect on the PDC drill bit.

[0037] In some embodiments, the sand and gravel are brown corundum sand, and are sieved with a 200-mesh screen before being added.

[0038] In this embodiment, by using relatively fine sand and gravel, a relatively dense rough surface structure can be formed without destroying the surface state of the PDC drill bit.

[0039] In some embodiments, the sand and gravel are pretreated after screening, and the sand and gravel are poured into a mixer, and then starch water is poured in. The mass of the starch water is 20-30% of the mass of the sand and gravel. The starch water is composed of potato starch and clean water, and the mass ratio of potato starch to clean water is 1:3. The mixer is set at 400-600r / min, and the mixing and stirring is performed for 6-10 minutes to complete the pretreatment of the sand and gravel.

[0040] In this embodiment, by pre-treating the sand and gravel, utilizing the carbon water coated on the surface of the sand and gravel and the heat generated by the sand and gravel impacting the surface of the PDC drill bit, the heat generated will cause the carbon water to evenly cover the surface of the PDC drill bit to form a gelatinized layer with rich pore structure, further improving the bonding effect between the surface of the PDC drill bit and the nitriding layer, thereby improving the performance of the PDC drill bit.

[0041] In some embodiments, the coating method is: weigh a coating material with a mass of 12 to 16% of the mass of the PDC drill bit, evenly apply the coating material on the surface of the PDC drill bit, let it stand for 8 to 12 minutes, and then put it into an oven after standing, set it to 80 to 100°C for drying for 45 to 55 minutes, and the coating treatment of the PDC drill bit is completed.

[0042] In this embodiment, the coating layer can react during the nitriding treatment process. The titanium powder reacts with nitrogen atoms to form titanium nitride with higher hardness on the surface of the PDC drill bit. The titanium nitride compound is evenly covered on the surface of the PDC drill bit, which can improve the wear resistance and hardness of the PDC drill bit. The better corrosion resistance of chromium powder can be used to improve the stability of titanium nitride, thereby further improving the performance of the PDC drill bit.

[0043] In some embodiments, the coating is prepared by the following method: titanium powder, chromium powder and iron powder are mixed, and the mass ratio of titanium powder, chromium powder and iron powder is 1:1.5:0.8; after mixing, water-based phenolic resin is added, and the mass of the water-based phenolic resin is 6 to 8 times that of the titanium powder; after stirring and mixing, the coating is prepared.

[0044] In this embodiment, water-based phenolic resin is used as an adhesive to uniformly coat the surface of the PDC drill bit with carbon powder, chromium powder and iron powder, wherein the iron powder can fill the pores to make the coating layer structure dense.

[0045] In some embodiments, the nitriding treatment method is: placing the PDC drill bit in a nitriding furnace, setting the nitriding temperature to 850-950° C., introducing nitrogen and hydrogen, and the amount of hydrogen introduced is 4-8% of the total gas amount.

[0046] In some embodiments, the gas flow rate into the nitriding furnace is 0.2-0.4 m³ / h, the gas pressure is 500-600 Pa, and the nitriding treatment time is 6-10 h.

[0047] Based on the above embodiments, the inventors also conducted the following experiments:

[0048] It should be noted that the raw materials used in the following experiments are all commercially available raw materials.

[0049] Experiment 1:

[0050] S1: Pretreatment, select a PDC drill bit, clean the oil and rust on the surface of the PDC drill bit, grind and polish it after cleaning, and complete the pretreatment of the PDC drill bit;

[0051] S2: Activation treatment: put the PDC drill bit into an ultrasonic cleaning machine, then pour the treatment liquid into it until the PDC drill bit is immersed. The treatment liquid is preheated to 80°C before pouring, and then allowed to stand for 4 minutes. Then, the ultrasonic cleaning machine is started and treated at 60kHz for 6 minutes. The PDC drill bit is taken out and cleaned with clean water and then blown dry with an air gun to complete the activation treatment of the PDC drill bit.

[0052] The hydrochloric acid solution and the hydrofluoric acid solution are mixed, the mass ratio of the hydrochloric acid solution to the hydrofluoric acid solution is 1:0.4, the concentration of the hydrochloric acid solution is 1%, and the concentration of the hydrofluoric acid solution is 4%. After mixing, deionized water is added and stirred evenly, the mass of the deionized water is 1.2 times the mass of the hydrochloric acid solution, and after mixing evenly, a treatment solution is obtained;

[0053] S3: sandblasting, fix the PDC drill bit in the fixture, then pour sand and gravel into the sandblasting machine, set the pressure of the sandblasting machine to 0.6MPa, set the distance between the sandblasting gun and the drill bit to 150mm, maintain the displacement speed of 0.6mm, sandblast the surface of the PDC drill bit, and after the sandblasting is completed, use a brush to clean the surface of the PDC drill bit to complete the sandblasting of the PDC drill bit;

[0054] The sand and gravel are made of brown corundum sand. Before adding the sand and gravel, they are sieved with a 200-mesh screen. After sieving, the sand and gravel are pre-treated. The sand and gravel are poured into a mixer, and then starch water is poured in. The mass of starch water is 20% of the mass of the sand and gravel. The starch water is composed of potato starch and clean water. The mass ratio of potato starch to clean water is 1:3. The mixer is set at 400r / min, and the mixing is stirred for 6 minutes to complete the pretreatment of the sand and gravel.

[0055] S4: coating treatment, weighing a coating material with a mass of 12% of the mass of the PDC drill bit, evenly applying the coating material on the surface of the PDC drill bit, and then letting it stand for 8 minutes, and then putting it into an oven after standing, setting it to 80°C for drying for 45 minutes, and completing the coating treatment of the PDC drill bit;

[0056] Titanium powder, chromium powder and iron powder are mixed, and the mass ratio of titanium powder, chromium powder and iron powder is 1:1.5:0.8. After mixing, water-based phenolic resin is added, and the mass of the water-based phenolic resin is 6 times that of the titanium powder. After stirring and mixing, a coating material is obtained;

[0057] S5: Nitriding treatment, place the PDC drill bit in the nitriding furnace, set the nitriding temperature to 850℃, introduce nitrogen and hydrogen, the hydrogen introduction amount is 4% of the total gas amount, the gas flow rate in the nitriding furnace is 0.2m³ / h, the gas pressure is 500Pa, and the nitriding treatment time is 6h.

[0058] Experiment 2:

[0059] S1: Pretreatment, select a PDC drill bit, clean the oil and rust on the surface of the PDC drill bit, grind and polish it after cleaning, and complete the pretreatment of the PDC drill bit;

[0060] S2: Activation treatment: put the PDC drill bit into an ultrasonic cleaning machine, then pour the treatment liquid into it until the PDC drill bit is immersed. The treatment liquid is preheated to 85°C before pouring, and then allowed to stand for 6 minutes. Then, the ultrasonic cleaning machine is started and treated at 70kHz for 8 minutes. The PDC drill bit is taken out and cleaned with clean water and then blown dry with an air gun to complete the activation treatment of the PDC drill bit.

[0061] The hydrochloric acid solution and the hydrofluoric acid solution are mixed, the mass ratio of the hydrochloric acid solution to the hydrofluoric acid solution is 1:0.6, the concentration of the hydrochloric acid solution is 2%, and the concentration of the hydrofluoric acid solution is 5%, and after mixing, deionized water is added and stirred evenly, the mass of the deionized water is 1.4 times the mass of the hydrochloric acid solution, and after mixing evenly, a treatment solution is obtained;

[0062] S3: Sandblasting, fix the PDC drill bit in the fixture, then pour sand and gravel into the sandblasting machine, set the pressure of the sandblasting machine to 0.7MPa, set the distance between the sandblasting gun and the drill bit to 170mm, maintain the displacement speed of 0.7mm, sandblast the surface of the PDC drill bit, and after the sandblasting is completed, use a brush to clean the surface of the PDC drill bit to complete the sandblasting of the PDC drill bit;

[0063] The sand and gravel are made of brown corundum sand. Before adding the sand and gravel, they are sieved with a 200-mesh screen. After sieving, the sand and gravel are pre-treated. The sand and gravel are poured into a mixer, and then starch water is poured in. The mass of starch water is 25% of the mass of the sand and gravel. The starch water is composed of potato starch and clean water. The mass ratio of potato starch to clean water is 1:3. The mixer is set at 500r / min, and the mixing and stirring are performed for 8 minutes to complete the pretreatment of the sand and gravel.

[0064] S4: coating treatment, weighing a coating material with a mass of 14% of the mass of the PDC drill bit, evenly applying the coating material on the surface of the PDC drill bit, and then letting it stand for 10 minutes, and then putting it into an oven after standing, setting it to 90°C for drying treatment for 50 minutes, and completing the coating treatment of the PDC drill bit;

[0065] Titanium powder, chromium powder and iron powder are mixed, and the mass ratio of titanium powder, chromium powder and iron powder is 1:1.5:0.8. After mixing, water-based phenolic resin is added, and the mass of the water-based phenolic resin is 7 times that of the titanium powder. After stirring and mixing, a coating material is obtained;

[0066] S5: Nitriding treatment: place the PDC drill bit in a nitriding furnace, set the nitriding temperature to 900°C, introduce nitrogen and hydrogen, the amount of hydrogen introduced is 6% of the total gas amount, the gas flow rate introduced into the nitriding furnace is 0.3m³ / h, the gas pressure is 550Pa, and the nitriding treatment time is 8h.

[0067] Experiment 3:

[0068] S1: Pretreatment, select a PDC drill bit, clean the oil and rust on the surface of the PDC drill bit, grind and polish it after cleaning, and complete the pretreatment of the PDC drill bit;

[0069] S2: Activation treatment, put the PDC drill bit into an ultrasonic cleaning machine, then pour the treatment liquid until the PDC drill bit is immersed, preheat the treatment liquid to 90°C before pouring, let it stand for 8 minutes after pouring, then start the ultrasonic cleaning machine, treat it at 80kHz for 10 minutes, take it out, wash it with clean water, and then use an air gun to blow dry the PDC drill bit to complete the activation treatment of the PDC drill bit; mix the hydrochloric acid solution and the hydrofluoric acid solution, the mass ratio of the hydrochloric acid solution to the hydrofluoric acid solution is 1:0.4, the concentration of the hydrochloric acid solution is 3%, and the concentration of the hydrofluoric acid solution is 6%, add deionized water after mixing and stir evenly, the mass of the deionized water is 1.6 times the mass of the hydrochloric acid solution, and after mixing evenly, obtain the treatment liquid;

[0070] S3: Sandblasting, fix the PDC drill bit in the fixture, then pour sand and gravel into the sandblasting machine, set the pressure of the sandblasting machine to 0.8MPa, set the distance between the sandblasting gun and the drill bit to 200mm, maintain the displacement speed of 0.8mm, sandblast the surface of the PDC drill bit, and after the sandblasting is completed, use a brush to clean the surface of the PDC drill bit to complete the sandblasting of the PDC drill bit;

[0071] The sand and gravel are made of brown corundum sand. Before adding the sand and gravel, they are sieved with a 200-mesh screen. After sieving, the sand and gravel are pre-treated. The sand and gravel are poured into a mixer, and then starch water is poured in. The mass of starch water is 30% of the mass of the sand and gravel. The starch water is composed of potato starch and clean water. The mass ratio of potato starch to clean water is 1:3. The mixer is set at 600r / min, and the mixing is stirred for 10 minutes to complete the pretreatment of the sand and gravel.

[0072] S4: coating treatment, weighing a coating material with a mass of 16% of the mass of the PDC drill bit, evenly applying the coating material on the surface of the PDC drill bit, and then letting it stand for 12 minutes, and then putting it into an oven after standing, setting it to 100°C for drying for 55 minutes, and completing the coating treatment of the PDC drill bit;

[0073] Titanium powder, chromium powder and iron powder are mixed, and the mass ratio of titanium powder, chromium powder and iron powder is 1:1.5:0.8. After mixing, water-based phenolic resin is added, and the mass of the water-based phenolic resin is 8 times that of the titanium powder. After stirring and mixing, a coating material is obtained;

[0074] S5: Nitriding treatment: place the PDC drill bit in a nitriding furnace, set the nitriding temperature to 950°C, introduce nitrogen and hydrogen, the amount of hydrogen introduced is 8% of the total gas amount, the gas flow rate introduced into the nitriding furnace is 0.4m³ / h, the gas pressure is 600Pa, and the nitriding treatment time is 10h.

[0075] Comparative Example 1: The difference between this comparative example and Experiment 1 is that:

[0076] In this comparative example, no sandblasting was performed.

[0077] Comparative Example 2: The difference between this comparative example and Experiment 1 is that:

[0078] This comparative example was not subjected to activation treatment.

[0079] Comparative Example 3: The difference between this comparative example and Experiment 1 is that:

[0080] In this comparative example, no pretreatment of the sand and gravel was performed during the sandblasting process.

[0081] Comparative Example 4: The difference between this comparative example and Experiment 1 is that:

[0082] This comparative example was not subjected to coating treatment.

[0083] Performance test: The pdc drill bits treated in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were subjected to performance tests, and the test data obtained are recorded in the following table:

[0084] Table 1:

[0085]

[0086] Table 2:

[0087]

[0088] In the wear test, the PDC drill bits treated in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were installed on the testing machine, and the hard rock formation at the same position was drilled with a drilling pressure of 25kN, a rotation speed of 100r / min, and a time of 45min. The weight of the PDC drill bits before and after drilling was weighed and recorded, and the weight difference before and after was calculated to obtain the wear amount of each PDC drill bit.

[0089] In the hardness test, the PDC drill bits treated in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were installed on the fixture of the hardness testing equipment, and the PDC drill bits were subjected to Rockwell hardness tests. Three test points at the same position were selected for each PDC drill bit for hardness tests, and the average value of the three tests was taken as the hardness test result of the PDC drill bit.

[0090] Among them, the wear volume of the PDC drill bit wear test after treatment in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were 5.8g, 5.6g, 6.1g, 18.4g, 16.4g, 22.5g and 21.9g respectively; the average values ​​of the PDC drill bit hardness test after treatment in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were 103HRA, 110HRA, 104.6HRA, 85HRA, 81.6HRA, 87HRA and 88.3HRA respectively.

[0091] It can be seen that the wear resistance and hardness performance data of the PDC drill bit after treatment in Comparative Examples 1, 2, 3 and 4 are lower than those in Experiments 1, 2 and 3; this shows that the surface of the PDC drill bit treated with sandblasting can effectively combine with the nitriding layer, so that a thicker and more tightly combined nitriding layer can be formed on the surface of the PDC drill bit, which effectively improves the treatment effect of the PDC drill bit. By pre-treating the sand and gravel, the heat generated by the carbon water coated on the surface of the sand and gravel and the impact of the sand and gravel on the surface of the PDC drill bit is used. The heat generated will make the carbon water evenly cover the gelatinized layer with rich pore structure on the surface of the PDC drill bit, further improving the combination effect between the surface of the PDC drill bit and the nitriding layer, thereby improving the performance of the PDC drill bit. The coating layer can react during the nitriding treatment process, and the titanium powder reacts with nitrogen atoms to form titanium nitride with higher hardness on the surface of the PDC drill bit. The titanium nitride compound is evenly covered on the surface of the PDC drill bit, which can improve the wear resistance and hardness of the PDC drill bit.

[0092] By comparing and analyzing the relevant data in the table, it can be seen that the PDC drill bit treated by the PDC drill bit surface nitriding treatment process of the present invention not only has good wear resistance, but also has excellent hardness performance.

[0093] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0094] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A PDC drill bit surface nitriding treatment process, characterized in that: The following steps are involved: S1: Pretreatment, select a PDC drill bit, clean the oil and rust on the surface of the PDC drill bit, grind and polish it after cleaning, and complete the pretreatment of the PDC drill bit; S2: Activation treatment, immersing the PDC drill bit pretreated in step S1 in a treatment liquid to complete the activation treatment of the PDC drill bit; S3: sandblasting, using a sandblasting machine to fully cover the surface of the PDC drill bit that has completed the activation treatment in step S2 with sandblasting to complete the sandblasting; The sand and gravel are made of brown corundum sand, and they are sieved with a 200-mesh screen before being added; After the sand and gravel are sieved, they are pre-treated and poured into a mixer, followed by starch water, the mass of which is 20-30% of the mass of the sand and gravel. The starch water is composed of potato starch and clean water, and the mass ratio of potato starch to clean water is 1:

3. The mixer is set at 400-600 r / min, and the mixing is performed for 6-10 minutes to complete the pre-treatment of the sand and gravel; S4: coating treatment, using a coating material to coat the surface of the PDC drill bit that has been sandblasted in step S3 to complete the coating treatment; The coating material is prepared by the following method: titanium powder, chromium powder and iron powder are mixed, the mass ratio of the titanium powder, chromium powder and iron powder is 1:1.5:0.8, water-based phenolic resin is added after mixing, the mass of the water-based phenolic resin is 6 to 8 times that of the titanium powder, and the coating material is prepared after stirring and mixing; S5: nitriding treatment, placing the PDC drill bit that has completed the coating treatment in step S4 into a nitriding furnace, introducing the treatment gas, and completing the nitriding treatment of the PDC drill bit.

2. The surface nitriding treatment process of the PDC drill bit according to claim 1 is characterized in that: The activation treatment method is as follows: putting the PDC drill bit into an ultrasonic cleaning machine, then pouring a treatment liquid until the PDC drill bit is immersed, preheating the treatment liquid to 80-90°C before pouring it, letting it stand for reaction for 4-8 minutes after pouring it, then starting the ultrasonic cleaning machine, treating it at 60-80kHz for 6-10 minutes, taking it out, cleaning it with clean water, and then using an air gun to blow dry the PDC drill bit, thus completing the activation treatment of the PDC drill bit.

3. The surface nitriding treatment process of the PDC drill bit according to claim 1 is characterized in that: The treatment liquid is prepared by the following method: mixing a hydrochloric acid solution and a hydrofluoric acid solution, wherein the mass ratio of the hydrochloric acid solution to the hydrofluoric acid solution is 1:(0.4-0.8), the concentration of the hydrochloric acid solution is 1-3%, and the concentration of the hydrofluoric acid solution is 4-6%, and after mixing, deionized water is added and stirred evenly, wherein the mass of the deionized water is 1.2-1.6 times the mass of the hydrochloric acid solution, and after mixing evenly, the treatment liquid is prepared.

4. The surface nitriding treatment process of the PDC drill bit according to claim 1 is characterized in that: The sandblasting method is as follows: fix the PDC drill bit in a fixture, then pour sand and gravel into a sandblasting machine, set the pressure of the sandblasting machine to 0.6-0.8MPa, set the distance between the sandblasting gun and the drill bit to 150-200mm, maintain the displacement speed of the sandblasting gun at 0.6-0.8mm, perform sandblasting on the surface of the PDC drill bit, and after the sandblasting is completed, use a brush to clean the surface of the PDC drill bit, thereby completing the sandblasting of the PDC drill bit.

5. The surface nitriding treatment process of the PDC drill bit according to claim 1 is characterized in that: The coating treatment method is: weighing a coating material with a mass of 12 to 16% of the mass of the PDC drill bit, evenly applying the coating material on the surface of the PDC drill bit, then letting it stand for 8 to 12 minutes, and then sending it into an oven after standing, setting it to 80 to 100° C. for drying for 45 to 55 minutes, thereby completing the coating treatment of the PDC drill bit.

6. The process for nitriding the surface of a PDC drill bit according to claim 1, characterized in that: The nitriding treatment method is: placing the PDC drill bit in a nitriding furnace, setting the nitriding temperature to 850-950° C., introducing nitrogen and hydrogen, wherein the amount of hydrogen introduced is 4-8% of the total gas amount.

7. The process for nitriding the surface of a PDC drill bit according to claim 6, characterized in that: The gas flow rate into the nitriding furnace is 0.2-0.4 m³ / h, the gas pressure is 500-600 Pa, and the nitriding treatment time is 6-10 hours.

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