Laser cladding elbow pipe and preparation method thereof

Abstract

The invention discloses a laser cladding elbow and a preparation method thereof, according to the laser cladding elbow and the preparation method thereof, through a protective coating formed by a laser cladding technology, the wear resistance of the elbow is remarkably improved, the wear of the inner wall is reduced, and the service life of the elbow is prolonged; according to the laser cladding elbow pipe and the preparation method thereof, selected wear-resistant materials such as tungsten carbide, silicon nitride and aluminum oxide have good chemical corrosion resistance, so that the elbow pipe can stably work in an environment containing corrosive chemical substances; according to the laser cladding elbow pipe and the preparation method thereof, the adhesive force between the coating and the base material is enhanced by using the coating, such as the micro groove and bulge structures, and the adhesion promoter, and the laser cladding elbow pipe and the preparation method thereof adopt the preparation method of the laser cladding technology, so that the production efficiency is improved, the maintenance and replacement frequency caused by elbow pipe abrasion or corrosion is reduced, and the total cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of laser cladding, in particular to a laser cladding bent pipe and a preparation method thereof. Background Art

[0002] In industrial applications, especially in the petroleum, chemical and automotive industries, pipe elbows are an indispensable component of fluid transmission systems. Traditional pipe elbows often face the problem of insufficient wear resistance and corrosion resistance, especially under extreme working conditions, such as high temperature, high pressure or environments containing corrosive chemicals. These conditions will cause rapid wear and corrosion of the inner wall of the pipe elbow, thus shortening its service life and increasing the frequency and cost of maintenance and replacement.

[0003] In the prior art, the main protective measure for bent pipes is to coat them with one or more layers of protective materials. However, these protective layers are often difficult to coat evenly, have poor adhesion, and are prone to fall off under high loads. In addition, the existing coating materials have insufficient performance stability at high temperatures and cannot effectively resist the effects of long-term thermal cycles.

[0004] In view of this, a laser cladding bent pipe and a preparation method thereof are designed. Summary of the invention

[0005] The purpose of the present invention is to provide a laser cladding elbow and a preparation method thereof, which can form one or more layers of high-performance protective coatings on the inner wall of the elbow. Such coatings need to have excellent wear resistance and corrosion resistance, and can maintain stable performance under extreme working conditions. At the same time, the uniformity and adhesion of the coating, as well as good metallurgical bonding between the coating and the substrate, should be ensured during the preparation process, so as to solve the problems existing in the prior art mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a laser cladding pipe bending device, comprising:

[0007] a) forming at least one protective coating on the inner wall of the bent pipe by laser cladding technology;

[0008] b) The protective coating is composed of the following components in parts by weight:

[0009] 50-70 parts of tungsten carbide;

[0010] 20-30 parts of silicon nitride;

[0011] 5 to 15 parts of aluminum oxide;

[0012] 1 to 5 parts of adhesion promoter.

[0013] Preferably, the inner wall of the curved pipe has a microstructure design, including:

[0014] a) Micro grooves with a width of 0.1-0.5 mm and a depth of 0.1-0.3 mm to improve the adhesion of the coating;

[0015] b) Raised structure with a height of 0.1 to 0.5 mm and a spacing of 1 to 2 mm to enhance the wear resistance of the coating.

[0016] A laser cladding bent pipe, the preparation method of which comprises the following steps:

[0017] S1) providing a prefabricated elbow, wherein the prefabricated elbow is made of a high temperature resistant alloy material;

[0018] S2) cleaning the inner wall of the prefabricated elbow by using ultrasonic cleaning equipment to remove oil, rust or other impurities;

[0019] S3) uniformly coating a layer of adhesive on the inner wall of the prefabricated elbow, wherein the adhesive is epoxy resin-based to enhance the adhesion of subsequent coatings;

[0020] S4) using laser cladding equipment to coat the inner wall of the prefabricated elbow with a wear-resistant material, wherein the wear-resistant material is a mixed powder of tungsten carbide and silicon nitride in a ratio of 70:30;

[0021] S5) adjusting the parameters of the laser cladding equipment, including a laser power of 1.5 kW, a scanning speed of 500 mm / min, and a powder flow rate of 25 g / min, to control the thickness and quality of the coating to be 0.5 mm;

[0022] S6) During the coating process, an infrared thermal imager is used to monitor the temperature distribution of the coating in real time to ensure that the coating is uniform and defect-free and the temperature is controlled at 200-250°C;

[0023] S7) After the coating is completed, the bent pipe is placed in a temperature-controlled environment and slowly cooled to room temperature, and the cooling rate is controlled at 5°C / min to avoid cracking of the coating;

[0024] S8) performing non-destructive testing on the bent pipe, including ultrasonic testing and X-ray testing, to confirm the integrity and uniformity of the coating;

[0025] S9) If the test results meet the standards, a subsequent heat treatment process is performed at a temperature of 400°C and a holding time of 2 hours to improve the wear resistance and corrosion resistance of the coating;

[0026] S10) Finally, the bent pipe is subjected to a performance test to verify its applicability.

[0027] Preferably, the powder nozzle in step S4 is configured to move along the inner wall of the prefabricated elbow, and the distance between the nozzle and the inner wall of the elbow can be adjusted to 10 to 15 mm.

[0028] Preferably, the heat treatment process in step S9 further includes rapid cooling after the heat treatment to form a denser coating structure.

[0029] Preferably, the performance test in step S10 includes testing the tensile strength of the bent pipe, and the specific steps are as follows:

[0030] S11) Fixing the bent pipe sample in the fixture of a standard tensile testing machine;

[0031] S12) gradually increasing the tensile force until the bent pipe sample breaks;

[0032] S13) recording the maximum tensile force and elongation of the bent pipe sample before fracture;

[0033] S14) Calculate the tensile strength and elongation of the bent pipe based on the recorded data.

[0034] Preferably, the performance test in step S10 includes testing the compressive strength of the bent pipe, and the specific steps are as follows:

[0035] S21) placing the bent pipe sample on a compression platform of a standard compression testing machine;

[0036] S22) gradually applying a compressive force until the bent pipe sample yields or is damaged;

[0037] S23) recording the maximum compression force of the bent pipe sample before yielding or failure;

[0038] S24) Calculate the compressive strength of the bent pipe based on the recorded data.

[0039] Preferably, the performance test in step S10 includes testing the impact toughness of the bent pipe, and the specific steps are as follows:

[0040] S31) fixing the bent pipe sample on the supporting device of the standard impact testing machine;

[0041] S32) releasing the impact hammer to impact the bent pipe sample with a certain energy;

[0042] S33) recording the impact energy absorbed by the bent pipe sample and the deformation after the impact;

[0043] S34) Calculate the impact toughness of the bent pipe based on the recorded data.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The protective coating formed by the laser cladding technology of the laser cladding bent pipe and its preparation method significantly improves the wear resistance of the bent pipe, reduces the wear of the inner wall, and prolongs the service life of the bent pipe;

[0046] 2. The wear-resistant materials selected for the laser cladding bent pipe and its preparation method, such as tungsten carbide, silicon nitride and aluminum oxide, have good chemical corrosion resistance, so that the bent pipe can work stably in an environment containing corrosive chemicals;

[0047] 3. The microstructure design of the inner wall of the laser cladding bent pipe and its preparation method, such as micro grooves and protrusions, and the use of adhesion promoters, enhance the adhesion between the coating and the substrate;

[0048] 4. The laser cladding bent pipe and its preparation method use the laser cladding technology to improve production efficiency, reduce the maintenance and replacement frequency caused by wear or corrosion of the bent pipe, and reduce the overall cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a preparation flow chart of the preparation method of the present invention;

[0050] Figure 2 The test results of Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the present invention are summarized in the following table;

[0051] Figure 3 It is a schematic diagram of the microstructure design of the inner wall of the curved pipe of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In the description of the invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0054] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] See also Figure 1-3 The present invention provides a technical solution: a laser cladding bent pipe and a preparation method thereof, comprising:

[0056] a) forming at least one protective coating on the inner wall of the bent pipe by laser cladding technology;

[0057] b) The protective coating is composed of the following components in parts by weight:

[0058] 50-70 parts of tungsten carbide;

[0059] 20-30 parts of silicon nitride;

[0060] 5 to 15 parts of aluminum oxide;

[0061] 1 to 5 parts of adhesion promoter.

[0062] Specifically, the protective coating formed by laser cladding technology significantly improves the wear resistance and corrosion resistance of the bent pipe, and is suitable for various extreme working conditions.

[0063] The inner wall of the curved pipe has a microstructure design, including:

[0064] a) Micro grooves with a width of 0.1-0.5 mm and a depth of 0.1-0.3 mm to improve the adhesion of the coating;

[0065] b) Raised structure with a height of 0.1 to 0.5 mm and a spacing of 1 to 2 mm to enhance the wear resistance of the coating.

[0066] For details, please refer to the attached manual. Figure 3 The adhesion and wear resistance of the coating are improved through microstructure design, and the micro-groove and protrusion structure enhances the mechanical interlocking between the coating and the substrate, thereby improving the durability of the coating.

[0067] A laser cladding bent pipe, the preparation method of which comprises the following steps:

[0068] S1) providing a prefabricated elbow, wherein the prefabricated elbow is made of a high temperature resistant alloy material;

[0069] S2) cleaning the inner wall of the prefabricated elbow by using ultrasonic cleaning equipment to remove oil, rust or other impurities;

[0070] S3) uniformly coating a layer of adhesive on the inner wall of the prefabricated elbow, wherein the adhesive is epoxy resin-based to enhance the adhesion of subsequent coatings;

[0071] S4) using laser cladding equipment to coat the inner wall of the prefabricated elbow with a wear-resistant material, wherein the wear-resistant material is a mixed powder of tungsten carbide and silicon nitride in a ratio of 70:30;

[0072] S5) adjusting the parameters of the laser cladding equipment, including a laser power of 1.5 kW, a scanning speed of 500 mm / min, and a powder flow rate of 25 g / min, to control the thickness and quality of the coating to be 0.5 mm;

[0073] S6) During the coating process, an infrared thermal imager is used to monitor the temperature distribution of the coating in real time to ensure that the coating is uniform and defect-free and the temperature is controlled at 200-250°C;

[0074] S7) After the coating is completed, the bent pipe is placed in a temperature-controlled environment and slowly cooled to room temperature, and the cooling rate is controlled at 5°C / min to avoid cracking of the coating;

[0075] S8) performing non-destructive testing on the bent pipe, including ultrasonic testing and X-ray testing, to confirm the integrity and uniformity of the coating;

[0076] S9) If the test results meet the standards, a subsequent heat treatment process is performed at a temperature of 400°C and a holding time of 2 hours to improve the wear resistance and corrosion resistance of the coating;

[0077] S10) Finally, the bent pipe is subjected to a performance test to verify its applicability.

[0078] Specifically, a detailed preparation method is provided to ensure uniformity and adhesion of the coating, as well as good metallurgical bonding between the coating and the substrate, thereby improving the overall performance of the bent pipe.

[0079] The powder nozzle in step S4 is configured to move along the inner wall of the prefabricated elbow, and the distance between the nozzle and the inner wall of the elbow can be adjusted to 10-15 mm. Specifically, by precisely controlling the position of the powder nozzle, the uniformity and thickness of the coating are ensured, thereby improving the manufacturing quality of the elbow.

[0080] The heat treatment process in step S9 further includes rapid cooling after the heat treatment to form a denser coating structure. Specifically, through the rapid cooling step after the heat treatment process, a denser coating structure is formed, and the wear resistance and corrosion resistance of the coating are improved.

[0081] The performance test in step S10 includes testing the tensile strength of the bent pipe, and the specific steps are as follows:

[0082] S11) Fixing the bent pipe sample in the fixture of a standard tensile testing machine;

[0083] S12) gradually increasing the tensile force until the bent pipe sample breaks;

[0084] S13) recording the maximum tensile force and elongation of the bent pipe sample before fracture;

[0085] S14) Calculate the tensile strength and elongation of the bent pipe based on the recorded data.

[0086] Specifically, a detailed procedure for a tensile strength test is provided to ensure that the bent pipe can withstand the expected tensile load.

[0087] The performance test in step S10 includes testing the compressive strength of the bent pipe, and the specific steps are as follows:

[0088] S21) placing the bent pipe sample on a compression platform of a standard compression testing machine;

[0089] S22) gradually applying a compressive force until the bent pipe sample yields or is damaged;

[0090] S23) recording the maximum compression force of the bent pipe sample before yielding or failure;

[0091] S24) Calculate the compressive strength of the bent pipe based on the recorded data.

[0092] Specifically, a detailed procedure for a compression strength test is provided to ensure that the bent pipe can withstand the expected compression load.

[0093] The performance test in step S10 includes testing the impact toughness of the bent pipe, and the specific steps are as follows:

[0094] S31) fixing the bent pipe sample on the supporting device of the standard impact testing machine;

[0095] S32) releasing the impact hammer to impact the bent pipe sample with a certain energy;

[0096] S33) recording the impact energy absorbed by the bent pipe sample and the deformation after the impact;

[0097] S34) Calculate the impact toughness of the bent pipe based on the recorded data.

[0098] Specifically, a detailed procedure for an impact toughness test is provided to ensure that the bent pipe can withstand the expected impact load.

[0099] Embodiment 1:

[0100] S1. Select a prefabricated alloy bent pipe with a diameter of 100 mm.

[0101] S2. Use ultrasonic cleaning equipment to thoroughly clean the inner wall of the elbow.

[0102] S3. Evenly apply a layer of epoxy resin-based adhesive to the inner wall of the elbow.

[0103] S4. Set up laser cladding equipment and apply mixed powder of tungsten carbide and silicon nitride on the inner wall in a ratio of 70:30.

[0104] S5. Adjust the laser power to 1.5 kW, the scanning speed to 500 mm / min, and the powder flow rate to 25 g / min.

[0105] S6. Use an infrared thermal imager to monitor the coating temperature and ensure that the temperature is within the range of 200-250℃.

[0106] S7. After coating, the bent pipe is cooled to room temperature at a rate of 5°C / min in a temperature-controlled environment.

[0107] S8. Perform ultrasonic and X-ray testing to confirm coating integrity and uniformity.

[0108] S9. If the test is qualified, heat treatment is carried out at 400℃ and kept warm for 2 hours.

[0109] S10. Perform performance test to verify the bending performance.

[0110] The following performance tests were performed on Example 1:

[0111] Tensile strength test steps:

[0112] 1. Secure the bent pipe sample in the grips of a standard tensile testing machine.

[0113] 2. Gradually increase the tensile force until the bent pipe sample breaks.

[0114] 3. Record the maximum tensile force and elongation of the bent pipe sample before it breaks.

[0115] 4. Calculate the tensile strength and elongation of the bent pipe based on the recorded data.

[0116] Compression strength test steps:

[0117] 1. Place the bent pipe sample on the compression platform of a standard compression testing machine.

[0118] 2. Gradually apply compression force until the bent pipe sample yields or fails.

[0119] 3. Record the maximum compressive force of the bent pipe sample before yielding or failure.

[0120] 4. Calculate the compressive strength of the elbow based on the recorded data.

[0121] Impact toughness test steps:

[0122] 1. Fix the bent pipe sample on the support device of the standard impact testing machine.

[0123] 2. Release the impact hammer to impact the bent pipe sample with a certain energy.

[0124] 3. Record the impact energy absorbed by the bent pipe sample and the deformation after impact.

[0125] 4. Calculate the impact toughness of the bent pipe based on the recorded data.

[0126] Test results:

[0127] Tensile strength test: in compliance with standards.

[0128] Compression strength test: in compliance with the standard.

[0129] Impact toughness test: in compliance with the standard.

[0130] Embodiment 2:

[0131] S1. Select a prefabricated alloy bent pipe with a diameter of 200 mm.

[0132] S2. Use ultrasonic cleaning equipment to thoroughly clean the inner wall of the elbow.

[0133] S3. Evenly apply a layer of epoxy resin-based adhesive to the inner wall of the elbow.

[0134] S4. Set up laser cladding equipment and apply mixed powder of tungsten carbide and silicon nitride on the inner wall in a ratio of 70:30.

[0135] S5. Adjust the laser power to 1.5 kW, the scanning speed to 500 mm / min, and the powder flow rate to 25 g / min.

[0136] S6. Use an infrared thermal imager to monitor the coating temperature and ensure that the temperature is within the range of 200-250℃.

[0137] S7. After coating, the bent pipe is cooled to room temperature at a rate of 5°C / min in a temperature-controlled environment.

[0138] S8. Perform ultrasonic and X-ray testing to confirm coating integrity and uniformity.

[0139] S9. If the test is qualified, heat treatment is carried out at 400℃ and kept warm for 2 hours.

[0140] S10. Perform performance test to verify the bending performance.

[0141] The same performance test as that of Example 1 was performed on Example 2.

[0142] Test results:

[0143] Tensile strength test: in compliance with standards.

[0144] Compression strength test: in compliance with the standard.

[0145] Impact toughness test: in compliance with the standard.

[0146] Comparative Example 1:

[0147] S1. Select a prefabricated alloy bent pipe with a diameter of 100 mm.

[0148] S2. Use simple water washing instead of ultrasonic cleaning equipment to clean the inner wall of the elbow, resulting in some oil and rust not being completely removed.

[0149] S3. Evenly apply a layer of epoxy resin-based adhesive to the inner wall of the elbow.

[0150] S4. Set up laser cladding equipment and apply mixed powder of tungsten carbide and silicon nitride on the inner wall in a ratio of 70:30.

[0151] S5. Adjust the laser power to 1.5 kW, the scanning speed to 500 mm / min, and the powder flow rate to 25 g / min.

[0152] S6. Use an infrared thermal imager to monitor the coating temperature and ensure that the temperature is within the range of 200-250℃.

[0153] S7. After coating, the bent pipe is cooled to room temperature at a rate of 5°C / min in a temperature-controlled environment.

[0154] S8. Perform ultrasonic and X-ray testing to confirm coating integrity and uniformity.

[0155] S9. If the test is qualified, heat treatment is carried out at 400℃ and kept warm for 2 hours.

[0156] S10. Conduct wear resistance and corrosion resistance tests to verify the bending performance.

[0157] The same performance test as that of Example 1 was performed on Comparative Example 1.

[0158] Test results:

[0159] Tensile strength test: Does not meet the standard due to insufficient coating adhesion due to incomplete cleaning.

[0160] Compression strength test: does not meet the standard, the coating easily falls off under compression.

[0161] Impact toughness test: does not meet the standard, the coating cracks under impact.

[0162] Comparative Example 2:

[0163] S1. Select a prefabricated alloy bent pipe with a diameter of 100 mm.

[0164] S2. Use ultrasonic cleaning equipment to thoroughly clean the inner wall of the elbow.

[0165] S3. Evenly apply a layer of epoxy resin-based adhesive to the inner wall of the elbow.

[0166] S4. The wear-resistant material is coated on the inner wall of the pipe by conventional spraying method without laser cladding.

[0167] S5. The coating is cured by baking, but the coating quality is not the same as that of laser cladding.

[0168] S6. Failure to use an infrared thermal imaging camera to monitor coating temperature.

[0169] S7. After coating, cool naturally without controlling the cooling rate.

[0170] S8. Perform ultrasonic and X-ray testing to confirm coating integrity and uniformity.

[0171] S9. Heat treatment was performed, but due to coating quality issues, the heat treatment effect was poor.

[0172] S10. Conduct wear resistance and corrosion resistance tests to verify the bending performance.

[0173] The same performance test as that of Example 1 was performed on Comparative Example 2.

[0174] Test results:

[0175] Tensile Strength Test: Does not meet the standard, performance is reduced due to poor coating quality.

[0176] Compression strength test: Does not meet the standard, coating performance is unstable under compression.

[0177] Impact toughness test: does not meet the standard, the coating cannot effectively absorb impact energy.

[0178] Comparative Example 3:

[0179] S1. Select a prefabricated alloy bent pipe with a diameter of 100 mm.

[0180] S2. Use a combination of mechanical grinding and chemical cleaning to thoroughly clean the inner wall of the elbow.

[0181] S3. Apply a new type of ceramic-based composite coating to form a protective layer through a dipping and thermal curing method.

[0182] S4. The ceramic-based composite coating is cured at high temperature to improve the wear resistance and corrosion resistance of the coating.

[0183] S5. Grind the cured coating to ensure the smoothness of the coating surface.

[0184] S6. Perform thermal cycling tests on the coating to evaluate its stability under high temperature conditions.

[0185] S7. Perform chemical resistance testing to ensure that the coating can resist corrosion by specific chemicals.

[0186] S8. Perform wear resistance test on the coating to evaluate its wear resistance under actual working conditions.

[0187] S9. If the coating performance does not meet the requirements, explore ways to improve the coating formulation or coating process.

[0188] S10. After completing all tests, the bent pipe is put into use in the actual working environment.

[0189] The same performance test as that of Example 1 was performed on Comparative Example 3.

[0190] Test results:

[0191] Tensile strength test: does not meet the standard, the coating is not firmly bonded to the substrate.

[0192] Compression strength test: Does not meet the standard, the coating cracks under compression.

[0193] Impact toughness test: Failure to meet the standard means the coating cannot withstand the expected impact load.

[0194] The test data of the elbows obtained in Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are as follows:

[0195]

[0196]

[0197] From the above examples, comparative examples and physical and chemical index tables, we can draw the following conclusions:

[0198] Example 1 and Example 2:

[0199] Conclusion: The elbows in Example 1 and Example 2 meet the standards in all performance tests and show excellent wear resistance, corrosion resistance, tensile strength, compressive strength and impact toughness.

[0200] reason:

[0201] 1. Laser cladding technology is used to ensure uniform coating and good adhesion of wear-resistant materials.

[0202] 2. The temperature and cooling rate of the coating are precisely controlled to avoid cracking and peeling of the coating.

[0203] 3. The heat treatment process further improves the bonding strength between the coating and the substrate, and enhances the wear resistance and corrosion resistance of the coating.

[0204] 4. Detailed performance testing procedures ensure that the pipe bends can meet the expected workload.

[0205] Comparative Example 1:

[0206] Conclusion: The elbow in Comparative Example 1 did not meet the predetermined standards in the performance test and showed insufficient wear resistance and corrosion resistance.

[0207] reason:

[0208] 1. Inadequate cleaning methods lead to insufficient coating adhesion, affecting the overall performance of the coating.

[0209] 2. The unevenness of the coating results in unstable performance under stress and failure to pass the tensile strength and compressive strength tests.

[0210] 3. Cracks appear in the coating during the impact toughness test, indicating that the coating cannot effectively absorb the impact energy.

[0211] Comparative Example 2:

[0212] Conclusion: The elbow in Comparative Example 2 did not meet the predetermined standards in the performance test and the coating quality was poor.

[0213] reason:

[0214] 1. Instead of using laser cladding, traditional spraying method was adopted, resulting in uneven coating quality and poor wear resistance.

[0215] 2. The coating exhibits unstable performance in compression and impact tests and cannot withstand the expected loads.

[0216] Comparative Example 3:

[0217] Conclusion: The elbow in Comparative Example 3 did not meet the predetermined standard in the performance test, and the coating was not firmly bonded to the substrate.

[0218] reason:

[0219] 1. Different coating methods were used, and the bonding strength between the coating and the substrate was insufficient.

[0220] 2. The coating failed to meet the standard requirements in the tensile strength, compressive strength and impact toughness tests, indicating that the coating cannot provide adequate protection under actual working conditions.

[0221] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser cladding pipe bend, characterized in that: include: a) forming at least one protective coating on the inner wall of the bent pipe by laser cladding technology; b) The protective coating is composed of the following components in parts by weight: 50-70 parts of tungsten carbide; 20-30 parts of silicon nitride; 5 to 15 parts of aluminum oxide; 1 to 5 parts of adhesion promoter.

2. The laser cladding bent pipe according to claim 1, characterized in that: The inner wall of the curved pipe has a microstructure design, including: a) Micro grooves with a width of 0.1-0.5 mm and a depth of 0.1-0.3 mm to improve the adhesion of the coating; b) Raised structure with a height of 0.1 to 0.5 mm and a spacing of 1 to 2 mm to enhance the wear resistance of the coating.

3. A laser cladding bent pipe, the preparation method of which comprises the following steps: S1) providing a prefabricated elbow, wherein the prefabricated elbow is made of a high temperature resistant alloy material; S2) cleaning the inner wall of the prefabricated elbow by using ultrasonic cleaning equipment to remove oil, rust or other impurities; S3) uniformly coating a layer of adhesive on the inner wall of the prefabricated elbow, wherein the adhesive is epoxy resin-based to enhance the adhesion of subsequent coatings; S4) using laser cladding equipment to coat the inner wall of the prefabricated elbow with a wear-resistant material, wherein the wear-resistant material is a mixed powder of tungsten carbide and silicon nitride in a ratio of 70:30; S5) adjusting the parameters of the laser cladding equipment, including a laser power of 1.5 kW, a scanning speed of 500 mm / min, and a powder flow rate of 25 g / min, to control the thickness and quality of the coating to be 0.5 mm; S6) During the coating process, an infrared thermal imager is used to monitor the temperature distribution of the coating in real time to ensure that the coating is uniform and defect-free and the temperature is controlled at 200-250°C; S7) After coating, the bent pipe is placed in a temperature-controlled environment and slowly cooled to room temperature, with the cooling rate controlled at 5°C / min to avoid cracking of the coating; S8) performing non-destructive testing on the bent pipe, including ultrasonic testing and X-ray testing, to confirm the integrity and uniformity of the coating; S9) If the test results meet the standards, a subsequent heat treatment process is performed at a temperature of 400°C and a holding time of 2 hours to improve the wear resistance and corrosion resistance of the coating; S10) Finally, the bent pipe is subjected to a performance test to verify its applicability.

4. The method for preparing a laser cladding bent pipe according to claim 3, characterized in that: The powder nozzle in step S4 is configured to move along the inner wall of the prefabricated elbow, and the distance between the nozzle and the inner wall of the elbow can be adjusted to 10 to 15 mm.

5. The method for preparing a laser cladding bent pipe according to claim 3, characterized in that: The heat treatment process in step S9 further includes rapid cooling after the heat treatment to form a denser coating structure.

6. The method for preparing a laser cladding bent pipe according to claim 3, characterized in that: The performance test in step S10 includes testing the tensile strength of the bent pipe, and the specific steps are as follows: S11) Fixing the bent pipe sample in the fixture of a standard tensile testing machine; S12) gradually increasing the tensile force until the bent pipe sample breaks; S13) recording the maximum tensile force and elongation of the bent pipe sample before fracture; S14) Calculate the tensile strength and elongation of the bent pipe based on the recorded data.

7. The method for preparing a laser cladding bent pipe according to claim 3, characterized in that: The performance test in step S10 includes testing the compressive strength of the bent pipe, and the specific steps are as follows: S21) placing the bent pipe sample on a compression platform of a standard compression testing machine; S22) gradually applying a compressive force until the bent pipe sample yields or is damaged; S23) recording the maximum compression force of the bent pipe sample before yielding or failure; S24) Calculate the compressive strength of the bent pipe based on the recorded data.

8. The method for preparing a laser cladding bent pipe according to claim 3, characterized in that: The performance test in step S10 includes testing the impact toughness of the bent pipe, and the specific steps are as follows: S31) fixing the bent pipe sample on the supporting device of the standard impact testing machine; S32) releasing the impact hammer to impact the bent pipe sample with a certain energy; S33) recording the impact energy absorbed by the bent pipe sample and the deformation after the impact; S34) Calculate the impact toughness of the bent pipe based on the recorded data.

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