Ceramic coating for mine conveying pipes and method for its production

Abstract

The application discloses a kind of ceramic coating for mine conveying pipeline and its preparation method, belong to the technical field of mine conveying pipeline.The application is based on the balance of lining and composite pipe performance, selects a variety of powder combination as additive, by adjusting the effect of various additives and the influence between each other, a kind of ceramic coating with excellent comprehensive performance is prepared on the inner surface of seamless steel pipe, can give enough protection to matrix steel pipe;The application realizes the matching of thermal expansion coefficient and hardness between steel pipe-transition layer-ceramic coating composite system, reduces the interface stress, the ceramic composite steel pipe prepared has the characteristics of high wear resistance, corrosion resistance, good impact resistance, long service life, high temperature resistance and the like, and can be applied to deep well mine and other high temperature and high pressure scenes.

Description

Technical Field

[0001] This invention belongs to the field of mining pipeline technology, specifically relating to a ceramic coating for mining pipelines and its preparation method. Background Technology

[0002] As a core infrastructure of the mining industry, mining pipelines are primarily used for long-distance transport of solid-liquid mixtures such as slurry, tailings, and concentrate. By replacing traditional rail / road transport methods, they reduce transportation costs by 30%-50%, significantly reduce dust pollution, eliminate material spillage, and lower the incidence of traffic accidents. In the field of backfill mining, pipeline systems are also a key carrier for resource recycling, transporting backfill materials such as gangue and fly ash to the goaf to improve mineral recovery rates and control surface subsidence.

[0003] While metal pipes, represented by steel pipes, possess initial strength advantages, they face problems such as susceptibility to corrosion, rapid wear, and high maintenance costs. At the end of the 20th century, ultra-high molecular weight polyethylene (UHMWPE) pipes gradually became mainstream due to their wear resistance (4-7 times that of steel pipes), lightweight design (density only 1 / 8 that of steel), and resistance to acid and alkali corrosion. However, limited by their glass transition temperature and thermal deformation temperature, as well as their limited pressure-bearing capacity, they are unable to meet the requirements of high-temperature and high-pressure scenarios such as deep mines.

[0004] Alumina ceramics have a Mohs hardness of up to 9, and their wear resistance is more than 20 times that of ordinary steel pipes. In applications such as pulverizing systems and mining conveying, their service life can be more than 15 times that of ordinary steel pipes. Al2O3 ceramics have stable chemical properties, excellent resistance to acid, alkali, and salt corrosion, a roughness Ra≤0.2μm, and can withstand high temperatures of 800-1200℃, making them suitable for applications such as conveying high-temperature slag, slurry, or molten metal. However, the inherent brittleness of ceramics results in insufficient impact strength, thus limiting their application range.

[0005] In view of this, ceramic-metal composite pipes with inner ceramic linings have become a current research focus. Summary of the Invention

[0006] To address the problems mentioned in the background art, the present invention aims to provide a ceramic coating for mining pipelines and its preparation method. Based on a balance between the performance of the lining and the composite pipe, the present invention selects a combination of various powders as additives. By adjusting and balancing the effects and interactions of these additives, a ceramic coating with excellent overall performance is provided. This coating can be prepared simply by reacting a combination of aluminothermic agents and additives on the inner surface of a steel pipe, eliminating the need for complex preparation processes. The resulting product exhibits good wear resistance, corrosion resistance, and impact resistance, making it suitable for industrial production.

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0008] This invention provides a ceramic coating for mining pipelines, which is made by applying the following parts by weight of additive powder and aluminothermic agent to the inner surface of a steel pipe:

[0009] Zirconia 15-22 parts, yttrium oxide 2.5-5 parts, silicon dioxide 7.5-12 parts, titanium dioxide 1.4-2.6 parts, cerium dioxide 0.5-2.5 parts, sodium tetraborate 2-4 parts, chromium carbide 2-3.5 parts, silicon carbide whiskers 4-8 parts, nickel oxide 1.5-2.5 parts, ZrO2-carbon nanotubes 3.5-6 parts.

[0010] Preferably, the steel pipe is selected from any one of 42CrMo, 15CrMo, Q345B, 20#, and 45# seamless steel pipes.

[0011] Preferably, the mass ratio of the additive powder to the thermite is (16-20):(80-84), and the thermite is composed of aluminum powder and iron oxide in a mass ratio of 1:(4.2-4.6).

[0012] Preferably, the silicon carbide whiskers have a length of 50-200 nm and an aspect ratio of 20-50.

[0013] Preferably, the ZrO2-carbon nanotubes are prepared by dispersing carbon nanotubes and ZrOCl2 in ethanol, mixing the two, adding glycerol, adjusting the pH and heating to carry out an alcoholic reaction, and then drying and calcining to obtain the final product.

[0014] Preferably, the particle size of zirconium oxide, yttrium oxide, silicon dioxide, titanium dioxide, cerium dioxide, sodium tetraborate, chromium oxide, chromium trioxide, and nickel oxide is 0.1-10 μm; the particle size of the thermite is 20-50 μm.

[0015] The present invention also provides a method for preparing the above-mentioned ceramic coating for mining pipelines, comprising the following steps:

[0016] Step 1: Prepare the seamless steel pipe base and clean its inner surface for later use;

[0017] Step 2: Weigh the additive powder and thermite according to the formula, and add them to the mixer to mix thoroughly;

[0018] Step 3: Load the obtained mixture into a seamless steel pipe, ignite the thermite, and centrifuge at high speed to carry out self-propagating high-temperature synthesis, forming a ceramic coating on the inner surface of the seamless steel pipe.

[0019] Preferably, in step three, the mixture is prepared at a ratio of 0.4-0.6 g / cm² to the inner surface area of ​​the steel pipe. 2 The centrifuge is inserted into a seamless steel pipe; the speed of the high-speed centrifuge is 1050-1450 rpm.

[0020] Preferably, after centrifugal molding in step three, the process also includes annealing at 850-950℃ for 1.5-2 hours.

[0021] Preferably, the thickness of the resulting ceramic lining coating is 2.0-3.0 mm.

[0022] This invention generates an alumina ceramic matrix through an aluminothermic reaction and further strengthens it using a series of additives: zirconia exhibits a phase transformation toughening effect, improving the thermal shock resistance and fracture toughness of the ceramic layer and reducing crack propagation; yttrium oxide prevents volume expansion caused by high-temperature phase transformation, enhancing high-temperature stability while refining grains and improving the uniformity of the ceramic layer; silica reduces porosity and cracks in the ceramic layer, improving corrosion resistance; cerium dioxide, as a rare earth oxide, has redox properties that promote oxygen transport during the reaction, reducing porosity, and during the annealing process after centrifugation, it can also fill cracks through migration, improving the density and flexural strength of the ceramic layer. Sodium tetraborate lowers the melting point of the reaction system, promotes liquid phase formation, and improves mass transfer and interfacial wettability of reactants. Silicon carbide whiskers improve the strength of the ceramic layer through a fiber toughening mechanism, inhibit crack propagation, and improve the bonding between the coating and the transition layer. Nickel oxide promotes the formation of a liquid metallic phase, accelerates the dissolution and redistribution of carbides, and helps to further optimize the gradient structure in the transition layer.

[0023] Based on this, titanium dioxide can form a small amount of titanium-rich carbides distributed at the alumina grain boundaries, improving the physical property matching between the ceramic layer and the metal transition layer and achieving a hardness gradient transition. Chromium carbide can promote interfacial bonding, and its dual-phase reinforcement with titanium-rich carbides further balances the performance adaptation of the transition layer. ZrO2-carbon nanotubes can alleviate thermal stress and reduce cracks. Their coating structure can significantly enhance the interfacial bonding between particles and the matrix, improve overall toughness, and regulate the gradient structure. By controlling the types and proportions of the above additives, this invention forms a carbide gradient distribution in the transition layer, constructs a multi-scale reinforcement system, achieves thermal expansion coefficient and hardness matching between the ceramic layer, transition layer, and metal matrix, reduces interfacial stress, and effectively improves the impact strength, density, and interfacial bonding performance of the ceramic coating.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention places a prepared aluminothermic agent and additive powder inside a steel pipe, and spins it at high speed in a centrifuge to ignite the powder. Utilizing the high temperature generated by the aluminothermic reaction, a self-propagating high-temperature synthesis is performed. The powder is heated to a molten state, and simultaneously, the inner wall of the steel pipe partially melts and fuses with it. Under centrifugal force, the denser material approaches the inner wall of the steel pipe to form a transition layer, while the less dense material forms a uniform ceramic coating on the surface. The final product is a steel pipe-transition layer-ceramic coating composite system. The ceramic coating effectively improves the wear resistance and corrosion resistance of the pipeline, while the transition layer effectively strengthens the bonding force between the steel pipe and the ceramic coating, and balances their coefficients of thermal expansion, thus acting as a gradient buffer.

[0026] This invention overcomes the limitations of traditional ceramics and ultra-high molecular weight polyethylene by combining a special ceramic coating with a corresponding transition layer, thus achieving multiple performance advantages to meet the needs of high-temperature and high-pressure applications such as deep mines. In the ceramic coating preparation process, this invention precisely controls the types and proportions of additives during the aluminothermic reaction to ensure optimal performance enhancement through synergistic effects and appropriate dosage. Ultimately, this significantly improves the impact resistance, high-temperature resistance, and wear resistance of the composite pipe. The resulting ceramic composite steel pipe possesses high wear resistance, corrosion resistance, good impact resistance, long service life, and high-temperature resistance. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Example 1

[0030] A method for preparing a composite mining pipeline with an inner ceramic coating, comprising the following steps:

[0031] 1. Separately, acid-leached and purified carbon nanotubes and ZrOCl2 (mass ratio 1:1) were ultrasonically dispersed in anhydrous ethanol. The two were then mixed, and an appropriate amount of glycerol was added. The pH was adjusted to 12 with sodium hydroxide, and the temperature was raised to 200℃ and maintained at a constant temperature for 12 h. The mixture was then dried and calcined at 500℃ for 2 h to obtain the final product. Weigh out the following components by weight: 20 parts zirconium oxide, 4 parts yttrium oxide, 10 parts silicon dioxide, 2 parts titanium dioxide, 1.8 parts cerium dioxide, 3 parts sodium tetraborate, 2.6 parts chromium carbide, 6 parts silicon carbide whiskers, 2 parts nickel oxide, and 4.8 parts ZrO2-carbon nanotubes. Aluminum powder and iron oxide were mixed at a mass ratio of 1:4.4 to form an aluminothermic agent. This agent was then added to the additive powder at a mass ratio of 18:82 and thoroughly mixed in a mixer to obtain the final mixture.

[0032] 2. Take a 42CrMo seamless steel pipe, clean its inner surface, and then apply the mixture at a ratio of 0.5 g / cm² to the inner surface area of ​​the steel pipe. 2 A seamless steel pipe was loaded, and the thermite was ignited with a magnesium strip. The pipe was then centrifuged at 1300 rpm for high-speed self-propagating high-temperature synthesis. After 40 minutes, the centrifuge was stopped, and the steel pipe was transferred into a furnace and annealed at 900°C for 2 hours to obtain a steel pipe with an inner ceramic coating (average thickness of 2.2 mm).

[0033] Example 2

[0034] A method for preparing a composite mining pipeline with an inner ceramic coating, comprising the following steps:

[0035] 1. Separately, acid-leached and purified carbon nanotubes and ZrOCl2 (mass ratio 1:1) were ultrasonically dispersed in anhydrous ethanol. The two were then mixed, and an appropriate amount of glycerol was added. The pH was adjusted to 12 with sodium hydroxide, and the temperature was raised to 200℃ and maintained at a constant temperature for 12 h. The mixture was then dried and calcined at 500℃ for 2 h to obtain the final product. Weigh out the following components by weight: 15 parts zirconium oxide, 5 parts yttrium oxide, 12 parts silicon dioxide, 1.4 parts titanium dioxide, 0.8 parts cerium dioxide, 4 parts sodium tetraborate, 3.5 parts chromium carbide, 4 parts silicon carbide whiskers, 2.5 parts nickel oxide, and 6 parts ZrO2-carbon nanotubes. Aluminum powder and iron oxide were mixed at a mass ratio of 1:4.4 to form an aluminothermic agent. This agent was then added to the additive powder at a mass ratio of 20:80 and thoroughly mixed in a mixer to obtain the final mixture.

[0036] 2. Take a 42CrMo seamless steel pipe, clean its inner surface, and then apply the mixture at a ratio of 0.5 g / cm² to the inner surface area of ​​the steel pipe. 2 A seamless steel pipe was loaded, and the thermite was ignited with a magnesium strip. The pipe was then centrifuged at 1300 rpm for high-speed self-propagating high-temperature synthesis. After 40 minutes, the centrifuge was stopped, and the steel pipe was transferred into a furnace and annealed at 900°C for 2 hours to obtain a steel pipe with an inner ceramic coating (average thickness of 2.0 mm).

[0037] Example 3

[0038] A method for preparing a composite mining pipeline with an inner ceramic coating, comprising the following steps:

[0039] 1. Separately, acid-leached and purified carbon nanotubes and ZrOCl2 (mass ratio 1:1) were ultrasonically dispersed in anhydrous ethanol. The two were then mixed, and an appropriate amount of glycerol was added. The pH was adjusted to 12 with sodium hydroxide, and the temperature was raised to 200℃ and maintained at a constant temperature for 12 h. The mixture was then dried and calcined at 500℃ for 2 h to obtain the final product. Weigh out the following components by weight: 22 parts zirconium oxide, 2.5 parts yttrium oxide, 7.5 parts silicon dioxide, 2.6 parts titanium dioxide, 2.5 parts cerium dioxide, 2 parts sodium tetraborate, 2 parts chromium carbide, 8 parts silicon carbide whiskers, 1.5 parts nickel oxide, and 3.5 parts ZrO2-carbon nanotubes. Aluminum powder and iron oxide were mixed at a mass ratio of 1:4.4 to form an aluminothermic agent. This agent was then mixed with the additive powder at a mass ratio of 16:84 in a mixer to obtain a final mixture.

[0040] 2. Take a 42CrMo seamless steel pipe, clean its inner surface, and then apply the mixture at a ratio of 0.5 g / cm² to the inner surface area of ​​the steel pipe. 2 A seamless steel pipe was loaded, and the thermite was ignited with a magnesium strip. The pipe was then centrifuged at 1300 rpm for high-speed self-propagating high-temperature synthesis. After 40 minutes, the centrifuge was stopped, and the steel pipe was transferred to a furnace and annealed at 900°C for 2 hours to obtain a steel pipe with an inner ceramic coating (average thickness of 2.3 mm).

[0041] Comparative Example 1

[0042] Refer to the steps and parameters in Example 1, except that titanium dioxide is not added to the additive powder.

[0043] Comparative Example 2

[0044] Refer to the steps and parameters in Example 1, except that cerium dioxide is not added to the additive powder.

[0045] Comparative Example 3

[0046] Refer to the steps and parameters in Example 1, except that silicon carbide whiskers are not added to the additive powder.

[0047] Comparative Example 4

[0048] Refer to the steps and parameters in Example 1, except that chromium carbide is not added to the additive powder.

[0049] Comparative Example 5

[0050] Referring to the steps and parameters of Example 1, the difference is that ordinary carbon nanotubes are used instead of ZrO2-carbon nanotubes in the additive powder.

[0051] The performance of the ceramic-lined steel pipe samples prepared in Examples 1-3 and Comparative Examples 1-5 was tested (YB / T176-2017, SY / T 6662.8-2016), and the results are shown in Table 1.

[0052] Table 1 Performance test results of ceramic-lined steel pipe samples

[0053]

[0054] As shown in Table 1, the ceramic coating prepared by the process of the present invention has high density and hardness, excellent corrosion resistance, and can provide sufficient protection for the base steel pipe. In addition, the present invention achieves matching of thermal expansion coefficient and hardness between the steel pipe-transition layer-ceramic coating composite system, reduces interfacial stress, and the resulting ceramic composite steel pipe has the characteristics of high wear resistance, corrosion resistance, good impact resistance, long service life, and high temperature resistance, and can be applied to high temperature and high pressure scenarios such as deep well mines.

[0055] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A ceramic coating for mining pipelines, characterized in that, It is made from the following parts by weight of additive powder and thermite on the inner surface of the steel pipe: Zirconia 15-22 parts, yttrium oxide 2.5-5 parts, silicon dioxide 7.5-12 parts, titanium dioxide 1.4-2.6 parts, cerium dioxide 0.5-2.5 parts, sodium tetraborate 2-4 parts, chromium carbide 2-3.5 parts, silicon carbide whiskers 4-8 parts, nickel oxide 1.5-2.5 parts, ZrO2-carbon nanotubes 3.5-6 parts; The ZrO2-carbon nanotubes are prepared by dispersing carbon nanotubes and ZrOCl2 in ethanol, mixing them, adding glycerol, adjusting the pH and heating to carry out an alcoholic reaction, and then drying and calcining to obtain the final product.

2. The ceramic coating for mining pipelines according to claim 1, characterized in that, The steel pipe is selected from any one of 42CrMo, 15CrMo, Q345B, 20#, and 45# seamless steel pipes.

3. The ceramic coating for mining pipelines according to claim 1, characterized in that, The mass ratio of the additive powder to the thermite is (16-20):(80-84), and the thermite is composed of aluminum powder and iron oxide in a mass ratio of 1:(4.2-4.6).

4. The ceramic coating for mining pipelines according to claim 1, characterized in that, The length of silicon carbide whiskers is 50-200 nm, and the aspect ratio is 20-50.

5. The ceramic coating for mining pipelines according to claim 1, characterized in that, The particle size of zirconium oxide, yttrium oxide, silicon dioxide, titanium dioxide, cerium dioxide, sodium tetraborate, chromium carbide, and nickel oxide is 0.1-10 μm; the particle size of the thermite is 20-50 μm.

6. The method for preparing the ceramic coating for mining pipelines according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Prepare the seamless steel pipe base and clean its inner surface for later use; Step 2: Weigh the additive powder and thermite according to the formula, and add them to the mixer to mix thoroughly; Step 3: Load the obtained mixture into a seamless steel pipe, ignite the thermite, and centrifuge at high speed to carry out self-propagating high-temperature synthesis, forming a ceramic coating on the inner surface of the seamless steel pipe.

7. The method for preparing the ceramic coating for mining pipelines according to claim 6, characterized in that, In step three, the mixture is prepared at a ratio of 0.4-0.6 g / cm² to the inner surface area of ​​the steel pipe. 2 The seamless steel pipe is inserted; the speed of the high-speed centrifuge is 1050-1450 rpm.

8. The method for preparing the ceramic coating for mining pipelines according to claim 6, characterized in that, After centrifugation in step three, the process also includes annealing at 850-950℃ for 1.5-2 hours.

9. The method for preparing a ceramic coating for a mining pipeline according to claim 6, characterized in that, The thickness of the resulting ceramic coating lining is 2.0-3.0 mm.

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