Method for preparing erosion-wear resistant coating on surface of soluble magnesium alloy ball seat

Abstract

The present application relates to a method for preparing an erosion-resistant and wear-resistant coating on the surface of a soluble magnesium alloy ball seat, characterized by comprising the following steps: 1) first, the magnesium alloy surface is subjected to degreasing, cleaning, drying, sandblasting, and ultrasonic cleaning using acetone; 2) iron-based alloy powder and nickel-coated tungsten carbide composite powder are mixed in a powder mixer to form a spray powder; 3) the powder treated in step 2) is placed in a vacuum tube furnace for heat treatment; 4) the powder heat-treated in step 3) is placed in a powder feeding tank and sprayed onto the magnesium alloy surface treated in step 1) using a supersonic velocity flame spraying device controlled by a robotic arm to obtain a coating; 5) the coating sample obtained in step 4) is coated with graphite ribbon, then embedded in graphite powder in a corundum crucible, and finally placed in a microwave oven for subsequent heat treatment. By optimizing the coating powder composition and particle size and combining it with subsequent microwave treatment, the bonding strength and density of the coating are improved, while the erosion resistance and wear resistance of the coating surface are also improved.

Description

Technical Field

[0001] The present application relates to the field of wear-resistant coatings, and in particular to a method for preparing an erosion-resistant wear coating on the surface of a soluble magnesium alloy ball seat. Background Art

[0002] The multi-stage fracturing technology of the packer ball-dropping sleeve is one of the core technologies of unconventional oil and gas production. The application of soluble magnesium alloy ball seats can complete the full diameter of the oil and gas well without the need for secondary downhole fishing or drilling operations, further reducing the production cost, operation time and construction risk of unconventional oil and gas. However, the downhole environment is extremely harsh. The soluble magnesium alloy ball seats are not only exposed to corrosion from groundwater and fracturing fluids under high temperature (50-150°C) and high pressure, but also to erosion and wear from fracturing fluids carrying sand (proppant). Therefore, the soluble magnesium alloy ball seats will suffer from severe corrosion and erosion damage during downhole service, resulting in leakage of high-pressure fracturing fluid during fracturing operations and the inability to open the fracturing sleeve. Solving the two bottleneck problems of surface corrosion protection and erosion wear resistance of soluble magnesium alloy ball seats is the key to large-scale application of soluble magnesium alloy plugging tools and improving the level of unconventional oil and gas production technology in my country.

[0003] Numerous methods exist for preparing protective coatings on magnesium alloy surfaces, including chemical conversion, micro-arc oxidation, anodic oxidation, organic coating, electroplating, and electroless plating. However, these coatings suffer from weaknesses such as low bonding strength, thin thickness, and insufficient corrosion and wear resistance, making them unable to simultaneously meet the requirements for both corrosion protection and erosion and wear resistance in extreme underground environments.

[0004] The above information disclosed in this background technology is only used to increase understanding of the background technology of this application. Therefore, it may contain information that does not constitute the prior art known to ordinary technicians in this field. Summary of the Invention

[0005] The present application provides a method for preparing a coating with uniform internal structure, high bonding strength and erosion and wear resistance, which can solve the problems of low bonding strength, thin thickness and insufficient corrosion and wear resistance of current magnesium alloy surface protective coatings.

[0006] In order to achieve the above objectives, the present application provides a method for preparing an erosion-wear resistant coating on the surface of a soluble magnesium alloy ball seat, comprising the following steps:

[0007] 1) First, the magnesium alloy surface is degreased, cleaned, dried, sandblasted, and ultrasonically cleaned with acetone;

[0008] 2) Mixing the iron-based alloy powder and the nickel-coated tungsten carbide composite powder in a powder mixer to prepare the spraying powder;

[0009] 3) placing the powder treated in step 2) into a vacuum tube furnace for heat treatment;

[0010] 4) placing the powder heat-treated in step 3) into a powder feeding tank, and spraying the powder onto the surface of the magnesium alloy treated in step 1) using a supersonic velocity flame spraying device controlled by a robotic arm to obtain a coating;

[0011] 5) The coating sample obtained in step 4) is coated with a graphite tape, then embedded in graphite powder in a corundum crucible, and finally placed in a microwave oven for subsequent heat treatment.

[0012] In some embodiments of the present application, the iron-based alloy powder and nickel-coated tungsten carbide powder used for spraying in step 2) are spherical in morphology. In terms of mass percentage, the main components of the iron-based alloy powder are 0.5-1% carbon content, 7-12.0% nickel content, and 16-18% chromium content; the nickel content of the nickel-coated tungsten carbide composite powder is 14-18%.

[0013] In some embodiments of the present application, the iron-based alloy powder used for spraying in step 2) has a powder particle size of 15-45 microns, wherein 10-20% of the powder has a particle size of less than 5 μm, 10-30% of the particle size range is 30-45 μm, the fluidity is 50g≤25s, and the bulk density is 2.6-2.9g / cm 3 The powder particle size of nickel-coated tungsten carbide composite powder is 5-30μm, the fluidity is 50g≤20s, and the bulk density is 4.4-4.8g / cm 3 .

[0014] In some embodiments of the present application, in step 2), a mixed powder of iron-based alloy powder and nickel-coated tungsten carbide powder is sprayed, wherein the content of the nickel-coated tungsten carbide powder is 10%-40%.

[0015] In some embodiments of the present application, in step 2), the mixing time of the iron-based alloy powder and the nickel-coated tungsten carbide powder is 60 min-180 min.

[0016] In some embodiments of the present application, in step 3), the powder is vacuum heat-treated for 60-150 min, and the oxygen content of the iron-based alloy powder after heat treatment is ≤800 ppm; the oxygen content of the nickel-coated tungsten carbide powder is ≤500 ppm.

[0017] In some embodiments of the present application, the coating thickness after spraying in step 4) is ≥2 mm, and the coating porosity is ≤4%.

[0018] In some embodiments of the present application, in step 5), the graphite tape is wrapped by completely wrapping the coating portion, with 1-2 layers of graphite tape wrapped; the substrate portion is exposed, and the thickness of the graphite tape is 0.4-0.8 mm.

[0019] In some embodiments of the present application, the power of the microwave treatment in step 5) is 900 W. First, the microwave power is adjusted to 300 W-400 W for preheating, and the preheating time is 3-5 minutes. Then, the sample is placed in the microwave oven, and then the microwave power is adjusted to 800 W-900 W. The insulation time is 7-13 minutes. Then, the sample is taken out and placed at room temperature; the porosity of the coating after heat treatment is ≤2%.

[0020] In some embodiments of the present application, after microwave treatment, WC is transformed into W2C, the carbon content is reduced and the tungsten content is increased. During the heat treatment, carbon seepage occurs and the WC phase is partially transformed into the W2C phase, which is evenly distributed in the alloy layer structure, resulting in a more uniform coating microstructure. After microwave heat treatment, the coating has a porosity of 1.8%, a shear bond strength between the coating and the substrate of 130 MPa, and a coating hardness of 725 HL. The coating was subjected to a friction test, and the wear rate of the coating after the test was 1.7×10 4 mm 3 / (N·m).

[0021] In another aspect of the present application, a coating prepared by the above preparation method is also provided, wherein the porosity of the coating is ≤2%, the shear bonding strength between the coating and the substrate is 130MPa-150MPa, the hardness of the coating is 725HL-800HL, and the wear rate is 1.5-1.7×10 4 mm 3 / (N·m)

[0022] In some embodiments of the present application, during the heat treatment process, the coating undergoes carburization and the WC phase is partially transformed into the W2C phase.

[0023] Compared with the prior art, the advantages of this application are at least:

[0024] 1. The erosion and wear resistant coating prepared by this method has high bonding strength and the coating thickness can be controlled from 10 microns to 5 mm.

[0025] 2. On the one hand, by controlling the oxygen content of the powder, the wettability between the coating and the substrate is increased after the powder particles are sprayed to form a coating, and the bonding strength between the coating and the substrate is higher.

[0026] 3. By post-processing the coating with microwaves, the internal structure of the coating becomes more uniform and dense, and the erosion and wear resistance is better. After microwave treatment, the elements of the coating and the substrate can diffuse with each other, further increasing the bonding strength between the coating and the substrate.

[0027] 4. This application improves the bonding strength and density of the coating by optimizing the coating powder composition and particle size parameters, combined with subsequent microwave treatment, while also improving the erosion resistance and wear resistance of the coating surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is the SEM morphology of the HVOF sprayed coating;

[0030] Figure 2 is the SEM morphology of the coating after microwave treatment;

[0031] Figure 3 It is the three-dimensional morphology of the coating after friction and wear test before microwave treatment;

[0032] Figure 4 It is the three-dimensional morphology of the coating after friction and wear test after microwave treatment;

[0033] Figure 5 Schematic diagram of graphite ribbon wrapping. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] The endpoints of the ranges and any values ​​disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0036] Example 1

[0037] 1) The surface of the magnesium alloy is degreased, dried, sandblasted, and ultrasonically cleaned.

[0038] 2) Iron-based alloy powder and nickel-coated tungsten carbide composite powder were selected as spray powders, with the nickel-coated tungsten carbide powder having a content of 10%. Both spray powders were spherical.

[0039] The main components of the iron-based alloy powder are: carbon content 0.7%, nickel content 7%, chromium content 16%, and the rest is iron.

[0040] The main components of nickel coated tungsten carbide powder are: nickel content 17%, tungsten carbide content 83%.

[0041] The particle size of the iron-based alloy powder is 15-45 microns, of which 10% is powder with a particle size of less than 5μm and 10% is in the range of 30-45μm. The fluidity is 50g / 23s and the apparent density is 2.6g / cm 3 Nickel coated tungsten carbide powder has a particle size of 5-30μm, a fluidity of 50g / 18s, and a bulk density of 4.4g / cm 3 .

[0042] The two powders were mixed and loaded into a powder mixer for 60 minutes.

[0043] 3) The powder was placed in a vacuum tube furnace for heat treatment for 60 minutes. After heat treatment, the oxygen content of the iron-based alloy powder was 600 ppm. The oxygen content of the nickel-coated tungsten carbide powder was 400 ppm.

[0044] 4) The powder treated in step 3) is placed in a powder feeding tank and sprayed on the surface of the magnesium alloy treated in step 1) using a supersonic flame spraying device controlled by a robotic arm to obtain a coating. The micromorphology of the coating is shown in FIG. Figure 1 The coating thickness is 2 mm, the coating porosity is 3.5%, the shear bonding strength between the coating and the substrate is 100 MPa, and the coating hardness is 650 HL. The coating was subjected to a friction test. After the test, the wear rate of the coating was 6×10 4 mm 3 / (N·m). The three-dimensional morphology of the coating after the friction and wear test is shown in Figure 3 .

[0045] 5) The coating sample obtained in step 4) is coated with a graphite tape with a thickness of 0.4 mm and a number of graphite tape wrapping layers of 1. Then it is buried in the graphite powder in the corundum crucible and finally placed in a microwave oven for subsequent heat treatment. First, the microwave power is adjusted to 300 W for preheating for 5 minutes, then the sample is placed in a microwave oven, and then the microwave power is adjusted to 800 W, the holding time is 13 minutes, and then the sample is taken out and placed at room temperature. The microscopic morphology of the coating after heat treatment is shown in FIG. Figure 2 After microwave treatment, WC transforms into W2C, reducing carbon content and increasing tungsten content. Carbon seepage occurs during heat treatment, and the WC phase partially transforms into the W2C phase, which is evenly distributed in the alloy layer, resulting in a more uniform coating microstructure. After microwave heat treatment, the coating has a porosity of 1.8%, a shear bond strength of 130 MPa, and a hardness of 725 HL. A friction test was conducted on the coating, and the wear rate was 1.7 × 10 4 mm 3 / (N·m). The three-dimensional morphology of the coating after the friction and wear test is shown in Figure 4 .

[0046] Example 2

[0047] 1) The surface of the magnesium alloy is degreased, dried, sandblasted, and ultrasonically cleaned.

[0048] 2) Iron-based alloy powder and nickel-coated tungsten carbide composite powder were selected as spray powders, with the nickel-coated tungsten carbide powder content being 15%. Both spray powders were spherical.

[0049] The main components of the iron-based alloy powder are: carbon content: 0.8%, nickel content: 9%, and chromium content: 17%.

[0050] The main components of nickel coated tungsten carbide powder are: nickel content 15%, tungsten carbide content 85%.

[0051] The particle size of the iron-based alloy powder is 15-45 microns, of which 15% is powder with a particle size of less than 5μm, and 20% is in the particle size range of 30-45μm. The fluidity is 50g / 20s and the apparent density is 2.8g / cm 3 Nickel coated tungsten carbide powder has a particle size of 5-30μm, a fluidity of 50g / 16s, and a bulk density of 4.5g / cm 3 .

[0052] The two powders were mixed and loaded into a powder mixer for 90 minutes.

[0053] 3) The powder was placed in a vacuum tube furnace for heat treatment for 60 minutes. After heat treatment, the oxygen content of the iron-based alloy powder was 600 ppm. The oxygen content of the nickel-coated tungsten carbide powder was 400 ppm.

[0054] 4) The powder treated in step 3) is placed in a powder feeding tank and sprayed on the magnesium alloy surface treated in step 1) using a supersonic flame spraying device controlled by a robotic arm to obtain a coating. The coating thickness is 3 mm and the coating porosity is 3.8%.

[0055] 5) The coating sample obtained in step 4) was coated with a graphite tape having a thickness of 0.6 mm and two layers of graphite tape. The sample was then embedded in graphite powder in a corundum crucible and placed in a microwave oven for subsequent heat treatment. The microwave power was first adjusted to 500 W for preheating for 3 minutes. The sample was then placed in a microwave oven and the microwave power was then adjusted to 900 W for a holding time of 10 minutes. The sample was then removed and allowed to cool to room temperature. The porosity of the coating after heat treatment was 1.5%.

[0056] The preparation method of the erosion-resistant coating on the surface of the soluble magnesium alloy ball seat of the present application has a controllable coating thickness. By controlling the oxygen content of the powder, the wettability between the coating and the substrate is increased after the powder particles are sprayed to form the coating, and the bonding strength between the coating and the substrate is higher. In addition, by performing microwave post-treatment on the coating, the internal structure of the coating is made more uniform and dense, and the erosion and wear resistance is better. After microwave treatment, the elements of the coating and the substrate can diffuse with each other, further increasing the bonding strength between the coating and the substrate.

[0057] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing an erosion-wear resistant coating on the surface of a soluble magnesium alloy ball seat, characterized in that: The following steps are involved: 1) First, the magnesium alloy surface is degreased, cleaned, dried, sandblasted, and ultrasonically cleaned with acetone; 2) Mixing the iron-based alloy powder and the nickel-coated tungsten carbide composite powder in a powder mixer as spray powder; 3) placing the powder processed in step 2) into a vacuum tube furnace for heat treatment; 4) placing the powder heat-treated in step 3) into a powder feeding tank and spraying the powder onto the magnesium alloy surface treated in step 1) using a supersonic velocity flame spraying device controlled by a robotic arm to obtain a coating; 5) The coating sample obtained in step 4) is coated with a graphite tape, then embedded in graphite powder in a corundum crucible, and finally placed in a microwave oven for subsequent heat treatment; The iron-based alloy powder and nickel-coated tungsten carbide powder used for spraying in step 2) are spherical in shape. In terms of mass percentage, the main components of the iron-based alloy powder are 0.5-1% carbon, 7-12.0% nickel, and 16-18% chromium; the nickel content of the nickel-coated tungsten carbide composite powder is 14-18%; The iron-based alloy powder used for spraying in step 2) has a particle size of 15-45 μm, wherein 10-20% of the powder has a particle size of less than 5 μm, 10-30% of the powder has a particle size range of 30-45 μm, a fluidity of 50 g ≤ 25 s, and a bulk density of 2.6-2.9 g / cm 3 The powder particle size of nickel-coated tungsten carbide composite powder is 5-30μm, the fluidity is 50g≤20s, and the bulk density is 4.4-4.8g / cm 3 ; In the step 2), a mixed powder of iron-based alloy powder and nickel-coated tungsten carbide powder is sprayed, wherein the content of nickel-coated tungsten carbide powder is 10%-40%, which is a mass percentage; In step 3), the powder is vacuum heat-treated for 60-150 minutes. After heat treatment, the oxygen content of the iron-based alloy powder is ≤800ppm; the oxygen content of the nickel-coated tungsten carbide powder is ≤500ppm. After spraying, the coating thickness is ≥2mm and the coating porosity is ≤4%. Step 5) The microwave treatment power is 900 W. First, the microwave power is adjusted to 300 W-400 W for preheating for 3-5 minutes. Then, the sample is placed in the microwave oven. The microwave power is then adjusted to 800 W-900 W and the holding time is 7-13 minutes. The sample is then removed and allowed to cool to room temperature. After microwave treatment, WC is transformed into W2C, the carbon content decreases and the tungsten content increases. During the heat treatment process, carbon seepage occurs and the WC phase is partially transformed into the W2C phase and evenly distributed in the alloy layer structure, resulting in a more uniform coating microstructure.

2. The preparation method according to claim 1, characterized in that In the step 2), the mixing time of the iron-based alloy powder and the nickel-coated tungsten carbide powder is 60 min to 180 min.

3. The preparation method according to claim 1, characterized in that Step 5) The graphite tape is wrapped in a manner that the coating portion is completely wrapped, with 1-2 layers of the graphite tape being wrapped; the substrate portion is exposed, and the thickness of the graphite tape is 0.4-0.8 mm.

4. The coating prepared by the preparation method according to any one of claims 1 to 3, characterized in that: The porosity of the coating is ≤2%, the shear bonding strength between the coating and the substrate is 130MPa-150MPa, the hardness of the coating is 725HL-800HL, and the wear rate is 1.5-1.7×10 4 mm 3 / (N•m).

5. The coating according to claim 4, characterized in that After microwave treatment, WC transforms into W2C, the carbon content decreases and the tungsten content increases. During the heat treatment, carbon seepage occurs and the WC phase partially transforms into the W2C phase, which is evenly distributed in the alloy layer structure. The coating microstructure is uniform; After microwave heat treatment, the porosity of the coating was 1.8%, the shear bonding strength between the coating and the substrate was 130 MPa, and the hardness of the coating was 725 HL. The coating was subjected to a friction test, and the wear rate of the coating was 1.7×10 4 mm 3 / (N•m).

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