A method for additive manufacturing of a microbially corrosion resistant TiN / TC4 composite coating

Abstract

The application discloses a kind of TiN / TC4 composite coating of microorganism corrosion resistance additive preparation method, comprising: one, Al-Cu-Mg alloy coating is prepared by spraying on the surface of pipeline steel;Two, TiN particles are prepared;Three, TC4 titanium alloy powder is mixed with TiN particles uniformly, and mixed powder is obtained;Four, laser stereolithography is used to prepare TiN / TC4 ceramic metal composite coating on Al-Cu-Mg alloy coating, and TiN / TC4 composite coating of microorganism corrosion resistance is obtained.The ceramic metal composite coating prepared by the application has excellent microorganism corrosion resistance, and is used in the microorganism corrosion working environment of long-distance pipeline steel.The coating material shows excellent microorganism corrosion resistance, can meet the requirements of long-distance pipeline steel working environment, effectively solves the problem of long-distance pipeline steel microorganism corrosion, and has good application prospect in long-distance pipeline protection field.

Description

Technical Field

[0001] This invention belongs to the field of laser stereolithography technology, and particularly relates to an additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion. Background Technology

[0002] In recent years, my country's petroleum and energy industry has developed rapidly, and the construction of buried pipelines has seen steady growth. Since most long-distance pipelines are laid in soil environments, microbial corrosion has a significant impact on the safety and service life of pipeline steel. Microbial corrosion refers to the failure of pipeline steel caused by the direct or indirect promotion of corrosion by biological life activities. It has been found in equipment in various working environments, including soil, machinery, oil fields, and seawater. Microbial corrosion always occurs simultaneously with electrochemical corrosion. The microorganisms that cause corrosion of metallic materials are generally bacteria and fungi, but protozoa and algae also exist. The corrosion process of metallic materials by microorganisms mainly involves changes in electrode potential and concentration potential. Especially for the steel of long-distance oil and gas pipelines, microbial corrosion exists beneath the peeled coating on the outer surface of most pipelines. Microbial metabolic activities greatly alter the environmental characteristics of the pipeline's outer surface under service conditions, leading to severe pitting corrosion of the pipeline steel. Microbial corrosion is also one of the important factors leading to stress corrosion cracking of pipeline steel; most stress corrosion cracking initiation cracks originate at the bottom of the pitting pits. Therefore, microbial corrosion failure has become an unavoidable and important issue in the research, development, and application of pipeline steel.

[0003] Laser stereolithography is an important surface modification technology that has developed rapidly and matured in recent years. Developed based on rapid prototyping, it is an advanced manufacturing technology capable of achieving near-net-shape forming of dense metal parts. Initially applied in the aerospace field, it is now widely used in various other fields. As a new technology for rapidly prototyping high-performance dense metal parts, it solves the technical challenge of simultaneously meeting multiple high-performance requirements, showing great promise. The powder feeding processes used in laser stereolithography are mainly divided into two categories: powder pre-placement and synchronous powder feeding. Compared to powder pre-placement, synchronous powder feeding laser stereolithography requires the interaction of the laser beam, the substrate, and the powder alloy particles to achieve layer-by-layer stacking, thereby preparing the desired material. The materials prepared by this powder feeding process have high coating quality, low deformation under high temperatures, and dense microstructure in the cladding zone.

[0004] Titanium and titanium alloys are widely used as biomedical materials primarily due to their excellent biocompatibility and resistance to microbial corrosion. Titanium and titanium alloys spontaneously form an oxide film on their surface, typically a few nanometers in size, which exhibits high stability, contributing to their high chemical stability and resistance to microbial corrosion. Titanium alloys, with their strong resistance to microbial corrosion, non-toxicity, light weight, high strength, and excellent biocompatibility, are ideal medical metal materials and are commonly used hard tissue substitutes for artificial joints, artificial bones, and dental implants. Titanium nitride ceramics are characterized by high melting point, high hardness, and corrosion resistance. With its excellent mechanical properties and chemical stability, titanium nitride is widely used in industry and has become an effective method for solving corrosion problems. Titanium nitride coatings are golden-yellow films with high hardness, good corrosion resistance, and strong adhesion to metals, making them commonly used wear-resistant ceramic coating materials in industry. Because of its strong resistance to microbial corrosion, titanium nitride coatings are frequently used to improve the surface properties of medical devices, thereby enhancing the alloy's resistance to microbial corrosion.

[0005] This invention utilizes carbothermal reduction reaction, plasma spraying technology, and laser stereolithography technology to prepare a TiN / TC4 ceramic-metal composite coating on the surface of pipeline steel. This coating has excellent resistance to microbial corrosion and wear resistance, thus possessing good industrial feasibility. It can meet the requirements of the working environment for microbial corrosion of pipeline steel in long-distance pipelines. The process is simple, low-cost, and suitable for widespread application. Summary of the Invention

[0006] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing an additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion. This method utilizes TC4 titanium alloy instead of traditional pure titanium as the coating powder, combined with titanium nitride powder. The passivation film of TC4 titanium alloy is thin, stable, intact, and prone to self-healing, thus preventing corrosion progression. The composite coating prepared by this method exhibits excellent resistance to microbial corrosion. When used in the microbial corrosion-prone working environment of long-distance pipeline steel, the coating material demonstrates superior resistance to microbial corrosion, meeting the requirements of the working environment of long-distance pipeline steel and effectively solving the problem of microbial corrosion in long-distance pipeline steel. It has promising application prospects in the field of long-distance pipeline protection.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion, characterized by comprising the following steps:

[0008] Step 1: Using Al-Cu-Mg alloy powder as the coating powder, the coating powder is dried, and the dried coating powder is sprayed onto the surface of the pipeline steel using a plasma spraying process to obtain an Al-Cu-Mg alloy coating.

[0009] Step 2: Prepare TiN particles using the carbothermal reduction method; the TiN particles contain a TiN mass percentage of not less than 98%, and the average particle size of the TiN particles is not greater than 10 μm;

[0010] Step 3: Mix the TC4 titanium alloy powder with the TiN particles prepared in Step 2 to obtain a mixed powder; the mass percentage of TC4 titanium alloy powder in the mixed powder is 90% to 95%, and the remainder is TiN particles; the average particle size of the TC4 titanium alloy powder is not greater than 50 μm.

[0011] Step 4: Start the laser stereolithography equipment. Using argon as a protective gas, feed the mixed powder obtained in Step 3 coaxially and clad it with laser to prepare a TiN / TC4 ceramic-metal composite coating on the Al-Cu-Mg alloy coating prepared in Step 1, thus obtaining a TiN / TC4 composite coating resistant to microbial corrosion. The laser stereolithography process is as follows: substrate preheating temperature 1800℃, preheating time 2h, powder feeding pressure 0.4MPa~0.6MPa, powder feeding voltage 18V~22V, scanning speed 600mm / h~800mm / h, protective atmosphere argon pressure 0.04MPa~0.06MPa, laser power 1300W~1500W, powder feeding amount 4g~6g, and spot diameter 2mm.

[0012] The above-mentioned additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion is characterized in that the average particle size of the sprayed powder in step one is <30μm, and the alloy powder of the Al-Cu-Mg alloy is composed of the following elemental composition by weight percentage: Cu 3.86%, Mg 1.47%, Fe <0.3%, Si <0.3%, and Al balance.

[0013] The above-mentioned additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion is characterized in that the process conditions of the plasma spraying process in step one are as follows: arc voltage of 100V to 120V, arc current of 600A to 800A, nitrogen flow rate of 20L / min to 40L / min, nitrogen pressure of 1.0MPa to 1.2MPa, hydrogen flow rate of 10L / min to 12L / min, spray gun moving speed of 10mm / s to 12mm / s, and spraying distance of 120mm to 150mm.

[0014] The above-mentioned additive manufacturing method for a microbial corrosion-resistant TiN / TC4 composite coating is characterized in that the carbothermic reduction method for preparing TiN particles in step two includes: placing titanium dioxide and graphene in a wet ball mill for wet ball milling, then drying the wet-milled material and placing it in an atmosphere furnace, heating it to 1600℃~1700℃ at a heating rate of 20℃ / min~30℃ / min under a flowing nitrogen atmosphere, and holding it at that temperature for 4h~6h to obtain TiN particles; the mass ratio of titanium dioxide to graphene is 69:21.

[0015] The above-mentioned additive manufacturing method for a microbial corrosion-resistant TiN / TC4 composite coating is characterized in that the titanium dioxide has a mass purity of not less than 98% and an average particle size of not more than 5 μm; the graphene powder is commercially available reinforced graphene with a specific surface area of ​​180 m². 2 / g~280m 2 / g, C content is 70% to 80%, and average particle size is <10μm.

[0016] The additive manufacturing method for the above-mentioned microbial corrosion-resistant TiN / TC4 composite coating is characterized in that the flow rate of the flowing nitrogen gas is 4L / min to 6L / min.

[0017] The above-mentioned additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion is characterized in that, in step four, the mixed powder is heated in an oven at 100℃~120℃ and dried for 2h~4h before coating preparation, so as to improve the flowability of the mixed powder when coaxially fed.

[0018] The above-mentioned additive manufacturing method for a TiN / TC4 composite coating resistant to microbial corrosion is characterized in that, in step one, before spraying to prepare the Al-Cu-Mg alloy coating, the pipeline steel is subjected to surface cleaning treatment for rust removal, oxide scale removal, and oil removal.

[0019] The above-mentioned additive manufacturing method for a microbial corrosion-resistant TiN / TC4 composite coating is characterized in that the thickness of the microbial corrosion-resistant TC4 / TiN composite coating in step four is 0.8 mm to 1.2 mm.

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

[0021] 1. Thermodynamically, pure titanium is a reactive metal. In oxidizing environments (such as aqueous solutions and atmospheric environments), its surface readily oxidizes to form a passivation film (TiO2), improving its corrosion resistance. The method of this invention utilizes TC4 titanium alloy instead of traditional pure titanium as the coating powder. The passivation film of TC4 titanium alloy is thinner and possesses characteristics such as stability, integrity, and easy self-healing, which can prevent corrosion development. Therefore, the ceramic-metal composite coating prepared using TC4 titanium alloy as the spray powder has stronger resistance to localized corrosion and is less sensitive to atmospheric corrosion, pitting corrosion, and microbial corrosion, exhibiting superior resistance to microbial corrosion.

[0022] 2. This invention preferably utilizes titanium dioxide powder and graphene as the main raw materials to prepare titanium nitride powder via a carbothermic reduction reaction (TiO2 + 2C + 1 / 2N2 → TiN + 2CO). This method has the advantages of simple production process and low preparation cost. The titanium nitride powder prepared by this process has uniform and fine particles without impurity generation. In the usual carbothermic reduction reaction to prepare boron carbide, the actual contact area between reactants is small, and the carbon source is unevenly distributed on the TiO2 surface. These obstacles result in the final titanium nitride having large grains, particle agglomeration, and uneven morphology, and may even contain some unreacted titanium oxide and free carbon. This invention uses graphene as the carbon source, leveraging the high specific surface area and abundant edges of graphene to provide a large number of active sites for titanium nitride nucleation, which is conducive to sufficient contact between the carbon source and the titanium source, and complete reaction. Using graphene as the carbon source, the prepared titanium nitride powder has fine grains, uniform powder dispersion, no particle agglomeration, no need for secondary crushing, complete reaction, and extremely high purity.

[0023] 3. If a TiN / TC4 ceramic-metal composite coating is directly prepared on the pipeline steel surface using laser stereolithography, the poor wettability of the TC4 alloy on the pipeline steel surface can easily lead to cracking between the coating and the substrate. This invention first prepares an Al-Cu-Mg alloy coating on the pipeline steel surface, and then uses laser stereolithography to prepare a TiN / TC4 ceramic-metal composite coating on the Al-Cu-Mg alloy coating. Using the Al-Cu-Mg alloy coating as a transition layer between the pipeline steel surface and the TiN / TC4 ceramic-metal composite coating can effectively improve the wettability between the two, which is beneficial for improving the bonding between the substrate and the TiN / TC4 ceramic metal. The TiN / TC4 ceramic-metal composite coating has a uniform microstructure, a dense structure, and no obvious aggregated pores or macroscopic cracks, indicating good bonding between the substrate and the coating material. Furthermore, this coating exhibits extremely excellent resistance to microbial corrosion, effectively protecting the outer surface of the pipeline steel in environments with microbial corrosion and extending the service life of the pipeline steel.

[0024] 4. The TiN / TC4 ceramic-metal composite coating prepared by this invention exhibits high hardness and wear resistance. When the oxide film on the surface of the titanium alloy coating is damaged due to wear or shear force, the exposed titanium alloy surface reduces the microbial corrosion resistance of the ceramic-metal composite coating. Titanium nitride ceramics possess extremely high hardness and excellent wear resistance. The titanium nitride particles in the ceramic-metal composite coating can effectively improve the wear resistance and strength of the coating, providing effective mechanical protection.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 Metallographic photograph of the TiN / TC4 ceramic-metal composite coating prepared for this invention. Detailed Implementation

[0027] Example 1

[0028] The method for preparing the TiN / TC4 ceramic-metal composite coating in this embodiment includes the following steps:

[0029] Step 1: Perform surface cleaning treatment on pipeline steel (X80) to remove rust, scale, and oil. Use Al-Cu-Mg alloy powder as the spraying powder, dry the powder, and apply it to the treated pipeline steel (X80) surface using plasma spraying technology to obtain an Al-Cu-Mg alloy coating. The average particle size of the spraying powder is <30μm, and the Al-Cu-Mg alloy powder is composed of the following elemental composition by weight percentage: Cu 3.86%, Mg 1.47%, Fe <0.3%, Si <0.3%, and Al balance. The process conditions for plasma spraying are: arc voltage 100V, arc current 600A, nitrogen flow rate 20L / min, nitrogen pressure 1.0MPa, hydrogen flow rate 10L / min, spray gun moving speed 10mm / s, and spraying distance 120mm.

[0030] Step 2: TiN particles are prepared using the carbothermic reduction method. Specifically, titanium dioxide and graphene are weighed at a mass ratio of 69:21. The weighed titanium dioxide and graphene are placed in a wet ball mill for wet ball milling. The wet-milled material is then dried and placed in an atmosphere furnace. Under a flowing nitrogen atmosphere, the temperature is increased to 1600℃ at a heating rate of 20℃ / min, with a nitrogen flow rate of 4L / min, and held at this temperature for 4 hours to obtain TiN particles. The titanium dioxide has a purity of not less than 98% and an average particle size of not more than 5μm; the graphene powder (commercially available reinforced graphene with a specific surface area of ​​180–280m²) is used. 2 / g, C content 70-80%, average particle size <10μm), the mass percentage of TiN in the TiN particles is not less than 98%, and the average particle size of the TiN particles is not greater than 10μm;

[0031] Step 3: Mix the TC4 titanium alloy powder and the TiN particles prepared in Step 2 evenly to obtain a mixed powder; the mass percentage of TC4 titanium alloy powder in the mixed powder is 90%, and the remainder is TiN particles; the average particle size of the TC4 titanium alloy powder is not greater than 50 μm.

[0032] Step 4: Start the laser stereolithography equipment. Using argon as the protective gas, feed the mixed powder obtained in Step 3 onto the Al-Cu-Mg alloy coating prepared in Step 1 using coaxial powder feeding and laser cladding to prepare a TiN / TC4 ceramic-metal composite coating. Before coating preparation, heat the mixed powder in an oven to 100℃ and dry for 2 hours to improve the flowability of the mixed powder during coaxial feeding. Then, perform laser cladding as required. The laser stereolithography process is as follows: substrate preheating temperature 1800℃, preheating time 2 hours, powder feeding pressure 0.4MPa, powder feeding voltage 18V, scanning speed 800mm / h, protective atmosphere argon pressure 0.04MPa, laser power 1300W, powder feeding amount 6g, and spot diameter 2mm. The thickness of the TiN / TC4 ceramic-metal composite coating is 0.8mm.

[0033] Figure 1 The image shows a metallographic photograph of the TiN / TC4 ceramic-metal composite coating prepared in Example 1. It reveals that the TiN / TC4 powder in the coating powder exhibits good melting and surface spreading. The melting state of the powder particles determines the characteristics of the coating structure; good melting and spreading can fill pores as much as possible, reducing the presence of defects. The pipeline steel substrate and the ceramic-metal composite coating show good bonding, uniform microstructure, and a dense coating structure without obvious aggregated pores or macroscopic cracks.

[0034] The TiN / TC4 ceramic-metal composite coating prepared in this embodiment has excellent resistance to microbial corrosion. When used in the microbial corrosion working environment of long-distance pipeline steel, the coating material exhibits excellent resistance to microbial corrosion, which can meet the requirements of the working environment of long-distance pipeline steel and effectively solve the problem of microbial corrosion of long-distance pipeline steel. It has good application prospects in the field of long-distance pipeline protection.

[0035] Example 2

[0036] The method for preparing the TiN / TC4 ceramic-metal composite coating in this embodiment includes the following steps:

[0037] Step 1: The pipeline steel (X80) is cleaned by removing rust, scale, and oil. Al-Cu-Mg alloy powder is used as the coating powder. The coating powder is dried, and plasma spraying is used to spray the dried powder onto the treated pipeline steel (X80) surface to obtain an Al-Cu-Mg alloy coating. The average particle size of the coating powder is <30μm. The Al-Cu-Mg alloy powder is composed of the following elemental composition by weight percentage: Cu 3.86%, Mg 1.47%, Fe <0.3%, Si <0.3%, and Al balance. The process conditions for plasma spraying are: arc voltage 110V, arc current 700A, nitrogen flow rate 30L / min, nitrogen pressure 1.1MPa, hydrogen flow rate 11L / min, spray gun moving speed 11mm / s, and spraying distance 130mm.

[0038] Step 2: TiN particles are prepared using the carbothermic reduction method. Specifically, titanium dioxide and graphene are weighed at a mass ratio of 69:21. The weighed titanium dioxide and graphene are placed in a wet ball mill for wet ball milling. The milled material is then dried and placed in an atmosphere furnace. Under a flowing nitrogen atmosphere, the temperature is increased to 1650℃ at a heating rate of 25℃ / min, with a nitrogen flow rate of 5L / min, and held at this temperature for 5 hours to obtain TiN particles. The titanium dioxide has a purity of not less than 98% and an average particle size of not more than 5μm. The graphene powder (commercially available reinforced graphene with a specific surface area of ​​180–280 m²) is used. 2 / g, C content 70-80%, average particle size <10μm), the mass percentage of TiN in the TiN particles is not less than 98%, and the average particle size of the TiN particles is not greater than 10μm;

[0039] Step 3: Mix the TC4 titanium alloy powder and the TiN particles prepared in Step 2 evenly to obtain a mixed powder; the mass percentage of TC4 titanium alloy powder in the mixed powder is 93%, and the remainder is TiN particles; the average particle size of the TC4 titanium alloy powder is not greater than 50 μm.

[0040] Step 4: Start the laser stereolithography equipment. Using argon as the protective gas, feed the mixed powder obtained in Step 4 onto the Al-Cu-Mg alloy coating prepared in Step 1 using coaxial powder feeding and laser cladding to prepare a TiN / TC4 ceramic-metal composite coating. Before coating preparation, heat the mixed powder in an oven to 110℃ and dry it for 3 hours to improve the flowability of the mixed powder during coaxial feeding. Then, perform laser cladding according to requirements. The laser stereolithography process is as follows: substrate preheating temperature 1800℃, preheating time 2 hours, powder feeding pressure 0.5MPa, powder feeding voltage 20V, scanning speed 700mm / h, protective atmosphere argon pressure 0.05MPa, laser power 1400W, powder feeding amount 5g, and spot diameter 2mm. The thickness of the TiN / TC4 ceramic-metal composite coating is 1.0mm.

[0041] The TiN / TC4 ceramic-metal composite coating prepared in this embodiment has excellent resistance to microbial corrosion. When used in the microbial corrosion working environment of long-distance pipeline steel, the coating material exhibits excellent resistance to microbial corrosion, which can meet the requirements of the working environment of long-distance pipeline steel and effectively solve the problem of microbial corrosion of long-distance pipeline steel. It has good application prospects in the field of long-distance pipeline protection.

[0042] Example 3

[0043] The method for preparing the TiN / TC4 ceramic-metal composite coating in this embodiment includes the following steps:

[0044] Step 1: The pipeline steel (X80) is cleaned by removing rust, scale, and oil. Al-Cu-Mg alloy powder is used as the coating powder. The coating powder is dried, and plasma spraying is used to spray the dried powder onto the treated pipeline steel (X80) surface to obtain an Al-Cu-Mg alloy coating. The average particle size of the coating powder is <30μm. The Al-Cu-Mg alloy powder is composed of the following elemental composition by weight percentage: Cu 3.86%, Mg 1.47%, Fe <0.3%, Si <0.3%, and Al balance. The process conditions for plasma spraying are: arc voltage 120V, arc current 800A, nitrogen flow rate 40L / min, nitrogen pressure 1.2MPa, hydrogen flow rate 12L / min, spray gun moving speed 12mm / s, and spraying distance 150mm.

[0045] Step 2: TiN particles are prepared using the carbothermic reduction method. Specifically, titanium dioxide and graphene are weighed at a mass ratio of 69:21. The weighed titanium dioxide and graphene are placed in a wet ball mill for wet ball milling. The wet-milled material is then dried and placed in an atmosphere furnace. Under a flowing nitrogen atmosphere, the temperature is increased to 1700℃ at a heating rate of 30℃ / min, with a nitrogen flow rate of 6L / min, and held at this temperature for 6 hours to obtain TiN particles. The titanium dioxide has a purity of not less than 98% and an average particle size of not more than 5μm; the graphene powder (commercially available reinforced graphene with a specific surface area of ​​180–280 m²) is used. 2 / g, C content 70-80%, average particle size <10μm), the mass percentage of TiN in the TiN particles is not less than 98%, and the average particle size of the TiN particles is not greater than 10μm;

[0046] Step 3: Mix the TC4 titanium alloy powder and the TiN particles prepared in Step 2 evenly to obtain a mixed powder; the mass percentage of TC4 titanium alloy powder in the mixed powder is 95%, and the remainder is TiN particles; the average particle size of the TC4 titanium alloy powder is not greater than 50 μm.

[0047] Step 4: Start the laser stereolithography equipment. Using argon as the protective gas, feed the mixed powder obtained in Step 3 onto the Al-Cu-Mg alloy coating prepared in Step 1 using coaxial powder feeding and laser cladding to prepare a TiN / TC4 ceramic-metal composite coating. Before coating preparation, heat the mixed powder in an oven to 100℃ and dry for 2 hours to improve the flowability of the mixed powder during coaxial feeding. Then, perform laser cladding as required. The laser stereolithography process is as follows: substrate preheating temperature 1800℃, preheating time 2 hours, powder feeding pressure 0.6MPa, powder feeding voltage 22V, scanning speed 600mm / h, protective atmosphere argon pressure 0.06MPa, laser power 1500W, powder feeding amount 4g, and spot diameter 2mm. The thickness of the TiN / TC4 ceramic-metal composite coating is 1.2mm.

[0048] The TiN / TC4 ceramic-metal composite coating prepared in this embodiment has excellent resistance to microbial corrosion. When used in the microbial corrosion working environment of long-distance pipeline steel, the coating material exhibits excellent resistance to microbial corrosion, which can meet the requirements of the working environment of long-distance pipeline steel and effectively solve the problem of microbial corrosion of long-distance pipeline steel. It has good application prospects in the field of long-distance pipeline protection.

[0049] The average corrosion rate of pipeline steel in Examples 1, 2, and 3 with and without the TiN / TC4 ceramic-metal composite coating was determined using weight loss analysis. Table 1 shows the average corrosion rate of the pipeline steel in Examples 1, 2, and 3 after immersion in simulated solutions of sulfate-reducing bacteria and iron-oxidizing bacteria for 10, 20, 30, and 40 days, respectively, with and without the TiN / TC4 ceramic-metal composite coating. The experimental data in Table 1 show that, under the same microbial corrosion conditions, the average corrosion rate with the TiN / TC4 ceramic-metal composite coating is significantly lower than that without it. Therefore, the TiN / TC4 ceramic-metal composite coating can significantly reduce the corrosion rate of pipeline steel and effectively improve its resistance to microbial corrosion.

[0050] Table 1. Results of average corrosion rate determination

[0051]

[0052]

[0053] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, and equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for additive manufacturing of a microbially corrosion resistant TiN / TC4 composite coating, characterized in that, The method comprises the following steps: Step one: adopt Al-Cu-Mg alloy powder as spraying powder, dry the spraying powder, adopt plasma spraying process to spray the dried spraying powder on the surface of pipeline steel to obtain Al-Cu-Mg alloy coating; the process conditions of the plasma spraying process are as follows: arc voltage is 100V-120V, arc current is 600A-800A, nitrogen flow is 20L / min-40L / min, nitrogen pressure is 1.0MPa-1.2MPa, hydrogen flow is 10L / min-12L / min, spraying gun moving speed is 10mm / s-12mm / s, and spraying distance is 120mm-150mm; Step two: adopt carbon thermal reduction method to prepare TiN particles; the mass percentage of TiN in the TiN particles is not less than 98%, and the average particle size of the TiN particles is not more than 10μm; the carbon thermal reduction method for preparing TiN particles comprises the following steps: placing titanium dioxide and graphene in a wet ball mill for wet ball milling, then drying the wet ball-milled material and placing it in an atmosphere furnace, heating to 1600℃-1700℃ at a heating rate of 20℃ / min-30℃ / min under a flowing nitrogen atmosphere, and keeping the temperature for 4h-6h to obtain TiN particles; the mass ratio of the titanium dioxide and the graphene is 69:21; Step three: uniformly mix TC4 titanium alloy powder with the TiN particles prepared in step two to obtain a mixed powder; the mass percentage of the TC4 titanium alloy powder in the mixed powder is 90%-95%, and the balance is TiN particles; the average particle size of the TC4 titanium alloy powder is not more than 50μm; Step four: start a laser solid forming device, use argon as protective gas, adopt coaxial powder feeding and laser cladding to prepare TiN / TC4 ceramic metal composite coating on the Al-Cu-Mg alloy coating prepared in step one to obtain a TiN / TC4 composite coating resistant to microbial corrosion; the laser solid forming process is as follows: substrate preheating temperature is 1800℃, preheating time is 2h, powder feeding pressure is 0.4MPa-0.6MPa, powder feeding voltage is 18V-22V, scanning speed is 600mm / h-800mm / h, protective atmosphere argon pressure is 0.04MPa-0.06MPa, laser power is 1300W-1500W, powder feeding amount is 4g-6g, and spot diameter is 2mm.

2. The additive manufacturing method of a micro-biologically resistant TiN / TC4 composite coating according to claim 1, characterized in that, The average particle size of the spraying powder in step one is <30μm, and the Al-Cu-Mg alloy powder is composed of the following weight percentage of elements: Cu 3.86%, Mg 1.47%, Fe <0.3%, Si <0.3%, and Al balance.

3. The additive manufacturing method of a micro-biologically resistant TiN / TC4 composite coating according to claim 1, characterized in that, The mass purity of the titanium dioxide is not less than 98%, and the average particle size is not more than 5μm; the graphene powder is a commercial reinforcing graphene, the specific surface area is 180m2 / g-280m2 / g, the C content is 70%-80%, and the average particle size is <10μm.

4. The additive manufacturing method of a microorganism corrosion resistant TiN / TC4 composite coating according to claim 1 or 3, characterized in that, The flow of the flowing nitrogen is 4L / min-6L / min.

5. The additive manufacturing method of a micro-biologically resistant TiN / TC4 composite coating according to claim 1, characterized in that, The mixed powder is heated in an oven at 100-120 DEG C for 2-4 hours before the coating is prepared in step four to improve the flowability of the mixed powder when it is fed coaxially.

6. The additive manufacturing method of a micro-biologically resistant TiN / TC4 composite coating according to claim 1, characterized in that, The pipeline steel is cleaned by removing rust, scale and oil before the Al-Cu-Mg alloy coating is prepared by spraying in step one.

7. The additive manufacturing method of a micro-biologically resistant TiN / TC4 composite coating according to claim 1, characterized in that, The thickness of the micro-bio-corrosion resistant TC4 / TiN composite coating is 0.8-1.2 mm in step four.

Images