A method for preparing nanocomposite coating on surface of crystallizer copper plate

Abstract

The present invention belongs to the technical field of composite coatings, and discloses a method for preparing a nano-composite coating on the surface of a crystallizer copper plate. First, basic hardness aggregate, high-activity binder and nano-additive are premixed according to their respective raw material compositions; then, the basic hardness aggregate is wet-milled, and then the high-activity binder and nano-additive are added in sequence and stirred to obtain a mixed slurry; then, the mixed slurry is dried, sieved and sintered, and the sintered product is crushed to obtain a nano-composite coating powder; finally, the nano-composite coating powder is sprayed onto the surface of the crystallizer copper plate substrate to form a nano-composite coating. In the present invention, the hard phase generated by the basic hardness aggregate and the binding phase generated by the nano-additive make the coating have higher hardness and wear resistance, and the high-activity binder makes the hard phase and the binding phase and the two have better bonding with the crystallizer copper plate substrate, so that the coating has excellent comprehensive performance and stable performance.

Description

Technical Field

[0001] The invention belongs to the technical field of composite coatings, and in particular relates to a method for preparing a nano composite coating on the surface of a crystallizer copper plate. Background Art

[0002] The crystallizer is a core component of continuous casting. The crystallizer copper plate serves as an important heat-conducting component for the process from liquid steel to solidified solid shell. Its quality directly affects the surface quality of the ingot, the casting speed of the continuous casting machine, and other indicators. The molten steel flows through the crystallizer copper plate, and under the action of external cooling water, it crystallizes into an ingot, which is then pulled out of the crystallizer by the ingot guide rod. Frequent casting causes severe wear of the crystallizer copper plate, and frequent replacement not only reduces production efficiency but also consumes a large amount of crystallizer. To increase the service life of the crystallizer copper plate, relevant institutions and experts at home and abroad have made great efforts in the material of the copper plate, which has greatly improved the high-temperature strength and hardness. However, it still cannot effectively solve the problems of Cu ion diffusion and penetration during high-temperature casting, wear of the lower part of the crystallizer, and splashing when casting begins. An effective way to solve these problems is to coat the copper plate surface.

[0003] In the early stages of coating research, Cr coatings were proposed for wear resistance and splash resistance. However, thicker Cr coatings were prone to peeling. To address the coating thickness issue, Ni-Cr composite coatings were proposed. Because Ni's thermal expansion coefficient is close to that of Cu, the peeling problem was alleviated and the thickness could be increased. However, in actual use, it was found that the increased mechanical friction load caused by the increased casting speed and the close contact of the shell under the static pressure of the molten iron increased the wear problem of the lower part of the crystallizer. To further improve the wear resistance of the coating and increase the service life of the crystallizer copper plate, Ni-Fe coatings, Ni-Co coatings, and Co-Ni coatings were subsequently developed. However, the hardness of Ni-Fe coatings is only between HV 250 and 550. At higher hardness, Ni-Co coatings and Co-Ni coatings have high coating stress and poor thermal cycling resistance, which affects their long-term stability and reliability. Overall, to achieve a long crystallizer life, the preparation of wear-resistant coatings on the crystallizer surface has become a trend, but existing coatings still have shortcomings in terms of bonding, wear resistance, hardness, and performance stability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies in the existing technology and provide a method for preparing a nano-composite coating on the surface of a crystallizer copper plate. The raw materials of the nano-composite coating include basic hardness aggregate, nano-additives and a highly active binder. After being sprayed on the surface of the crystallizer copper plate, the hard phase generated by the basic hardness aggregate and the binding phase generated by the nano-additive give the coating high hardness and wear resistance. The highly active binder enables good bonding between the hard phase and the binding phase, as well as between the hard phase and the binding phase and the crystallizer copper plate substrate, so that the coating has excellent comprehensive performance and stable performance.

[0005] In order to solve the technical problem raised by the present invention, the present invention provides a method for preparing a nano-composite coating on the surface of a crystallizer copper plate, comprising the following steps:

[0006] 1) Premix tungsten carbide powder, tungsten powder and titanium carbide powder to obtain basic hardness aggregate;

[0007] 2) premixing cobalt powder, carbonyl iron powder and carbonyl nickel powder to obtain a highly active binder;

[0008] 3) premixing nano zirconium oxide powder and nano titanium carbonitride powder to obtain a nano additive;

[0009] 4) wet ball milling the basic hardness aggregate, then adding a high-activity binder and stirring once, then adding a nano-additive and stirring twice, and finally performing ultrasonic dispersion to obtain a mixed slurry;

[0010] 5) drying the mixed slurry and sieving it, then sintering it by vacuum hot pressing or vacuum hot isostatic pressing, crushing the sintered product to obtain a nanocomposite coating powder;

[0011] 6) The surface of the mold copper plate substrate is treated to ensure that the rust removal and roughness meet the spraying requirements, and the nano-composite coating powder is sprayed onto the surface of the mold copper plate substrate by supersonic flame spraying or plasma spraying to form a nano-composite coating.

[0012] In the above solution, the purity of the tungsten carbide powder is greater than 99% and the particle size is less than 3 μm.

[0013] In the above solution, the purity of the tungsten powder is greater than 99% and the particle size is less than 1 μm.

[0014] In the above solution, the purity of the titanium carbide powder is greater than 99% and the particle size is less than 1 μm.

[0015] In the above solution, the mass ratio of the tungsten carbide powder, tungsten powder and titanium carbide powder is (4-6):(1-2):1.

[0016] Preferably, the mass ratio of the tungsten carbide powder, tungsten powder and titanium carbide powder is (4-5):(1-2):1.

[0017] In the above solution, the purity of the cobalt powder is greater than 99% and the particle size is less than 1 μm.

[0018] In the above solution, the purity of the carbonyl iron powder is greater than 99% and the particle size is less than 2 μm.

[0019] In the above solution, the purity of the carbonyl nickel powder is greater than 99% and the particle size is less than 2 μm.

[0020] In the above solution, the mass ratio of the cobalt powder, carbonyl iron powder and carbonyl nickel powder is 1:(1-3):(1-3).

[0021] Preferably, the mass ratio of the cobalt powder, carbonyl iron powder and carbonyl nickel powder is 1:(1-2.5):(1-2.5).

[0022] In the above solution, the purity of the nano zirconium oxide powder is greater than 99%, and the particle size is 20 to 60 nm.

[0023] In the above solution, the purity of the nano-titanium carbonitride powder is greater than 99%, and the particle size is 50 to 200 nm.

[0024] In the above solution, the mass ratio of the nano zirconium oxide powder to the nano titanium carbonitride powder is 1:(2-4).

[0025] Preferably, the mass ratio of the nano zirconium oxide powder to the nano titanium carbonitride powder is 1:(2-3).

[0026] In the above scheme, the wet ball milling adopts a planetary ball mill, anhydrous ethanol as the ball milling medium, equipped with a stainless steel ball milling jar and high-hardness metal ball mills, the ball milling speed is 50-100 r / min, and the ball milling time is 30-60h.

[0027] In the above scheme, the stirring adopts a V-type mixer; the stirring rate of the first stirring is 50-60 r / min, and the stirring time is 0.5-1 h; the stirring rate of the second stirring is 80-10 r / min, and the stirring time is 4.5-9 h.

[0028] In the above scheme, the ultrasonic dispersion treatment time is 10 to 30 minutes.

[0029] In the above solution, the mass of the high-activity binder is 10-20% of the mass of the basic hardness aggregate.

[0030] Preferably, the mass of the high-activity binder is 10-18% of the mass of the basic hardness aggregate.

[0031] In the above solution, the mass of the nano additive is 1 to 5% of the mass of the basic hardness aggregate.

[0032] Preferably, the mass of the nano-additive is 1 to 3.5% of the mass of the basic hardness aggregate.

[0033] In the above scheme, the mixed slurry is dried and sieved with 250-320 mesh, and the sieve is taken.

[0034] In the above scheme, the vacuum degree of the vacuum hot pressing sintering or vacuum hot isostatic pressing sintering is 3.5×10 -3 ~4.5×10 -3Pa, sintering temperature is 1400-1500℃, pressure is 20-40MPa, and holding time is 1-3h.

[0035] Preferably, the vacuum degree of the vacuum hot isostatic pressing sintering is 3.6×10 -3 ~4.3×10 -3 Pa, the sintering temperature is 1410-1490℃, the pressure is 20-35MPa, and the holding time is 1-2.5h.

[0036] In the above solution, the particle size of the nanocomposite coating powder is less than 10 μm.

[0037] In the above solution, the crystallizer copper plate substrate is Ag-Cu alloy or Cu-Cr-Zr alloy.

[0038] Furthermore, when the mold copper plate substrate is an Ag-Cu alloy, its chemical composition by mass percentage includes: Cu>99.5%, Ag 0.05% to 0.1%, and the rest are unavoidable impurities.

[0039] Furthermore, when the mold copper plate substrate is a Cu-Cr-Zr alloy, its chemical composition by mass percentage includes: Cu>98%, Cr 0.5-1.5%, Zr 0.01-0.3%, and the rest are unavoidable impurities.

[0040] In the above scheme, the rust removal grade of the crystallizer copper plate substrate is Sa3, St2 or St3, and the roughness should reach 2.5-5 μmRa.

[0041] In the above solution, the thickness of the nanocomposite coating is 1.5 to 3 mm.

[0042] In the above scheme, the density of the nano-composite coating is greater than 99.7%, the hardness HV is 500-800, the bonding strength between the nano-composite coating and the crystallizer copper plate substrate is 200-400 MPa, the crystallizer copper plate with the nano-composite coating has a single steel passing capacity of 80,000-150,000 tons / set, and a service life of 2,800-3,500 furnaces.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention uses basic hardness aggregates composed of tungsten carbide, tungsten and titanium carbide as main raw materials, and the generated hard phase can give the coating high basic hardness; then nano additives composed of nano zirconium oxide and nano titanium carbonitride, as well as high-activity binders composed of cobalt, carbonyl iron and carbonyl nickel are added between the aggregates to generate Ni-W / ZrO2, Ni-TiC, WC-Ni, Ni-W-WC, Fe-Ni / ZrO2, Fe-Ni-Ti(C, N)-WC and other intermediate phases between the matrix gaps, thereby improving the density of the coating composite; the amorphous binding phase generated by the nano additive wraps the hard phase, To further improve the hardness and wear resistance, nano ZrO2 and nano TiCN can also form a gradient interwoven arrangement with the matrix at the grain boundary of the matrix, further enhancing the hardness and wear resistance at the grain boundary; Ni, Fe and Co in the high-activity binder can enhance the bonding strength between the hard phase and the bonding phase, as well as between the coating and the crystallizer copper plate matrix; hydroxyl iron powder and hydroxyl nickel powder can also improve the sintering tightness of the hard phase and the bonding phase between the coating, and at the same time help to improve the bonding performance between the coating and the copper plate during the spraying process; the combined effect of the above raw materials makes the coating have excellent comprehensive performance and stable performance, thereby giving the crystallizer copper plate a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is the cross-sectional microstructure of the nanocomposite coating prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0047] In the following examples, the density of the surface coating was tested using the "GB / T 25995-2010 Fine Ceramics - Density and Apparent Porosity Test Method"; the hardness of the surface coating was tested using the "GB / T 16534-2009 Fine Ceramics - Room Temperature Hardness Test Method"; and the bonding strength between the surface coating and the mold copper plate substrate was tested using the "GB / T 6569-2006 Fine Ceramics - Bending Strength Test Method" .

[0048] Example 1

[0049] The raw materials involved in this embodiment are as follows:

[0050] The purity of tungsten carbide powder is 99.7%, and the particle size is 2μm; the purity of tungsten powder is 99.8%, and the particle size is 0.5μm; the purity of titanium carbide powder is 99.8%, and the particle size is 0.5μm; the purity of cobalt powder is 99.5%, and the particle size is 0.8μm; the purity of carbonyl iron powder is 99.5%, and the particle size is 0.8μm; the purity of carbonyl nickel powder is 99.5%, and the particle size is 1μm; the purity of nano zirconium oxide powder is 99.5%, and the particle size is 50nm; the purity of nano titanium carbonitride powder is 99.5%, and the particle size is 80nm.

[0051] The materials involved in this embodiment are as follows:

[0052] The crystallizer copper plate substrate is an Ag-Cu alloy, and its chemical composition includes, by mass percentage, 99.8% Cu, 0.08% Ag, and the rest being unavoidable impurities.

[0053] The method for preparing the nanocomposite coating on the surface of the crystallizer copper plate in this embodiment includes the following steps:

[0054] 1) Mix tungsten carbide powder, tungsten powder and titanium carbide powder in a mass ratio of 4:1:1 to obtain basic hardness aggregate;

[0055] 2) mixing cobalt powder, carbonyl iron powder, and carbonyl nickel powder in a mass ratio of 1:1:1 to obtain a highly active binder;

[0056] 3) mixing nano zirconium oxide powder and nano titanium carbonitride powder in a mass ratio of 1:2 to obtain a nano additive;

[0057] 4) wet-milling the base hardness aggregate using a planetary ball mill with anhydrous ethanol as the milling medium, a stainless steel milling jar, and high-hardness metal balls at a speed of 60 r / min for 48 hours; transferring the milled material to a V-type mixer, adding a high-activity binder at 12% by weight of the base hardness aggregate and stirring at 60 r / min for 0.75 hours, and then adding a nano-additive at 1.5% by weight of the base hardness aggregate and stirring at 85 r / min for 8 hours; introducing the stirred material into a glass container and dispersing it using an ultrasonic device for 15 minutes to obtain a mixed slurry;

[0058] 5) After drying, the mixed slurry was passed through a 250-mesh sieve, and the sieve was taken out, and then vacuum hot pressing was performed. The vacuum degree was 3.9×10 -3 Pa, sintering temperature is 1450℃, hot pressing pressure is 25MPa, holding time is 2h, the sintered product is crushed to obtain nanocomposite coating powder with a particle size of 8μm;

[0059] 6) The surface of the mold copper plate substrate was treated to a rust removal grade of Sa3 and a roughness of 2.5 μm Ra. The nanocomposite coating powder was sprayed onto the surface of the mold copper plate substrate by supersonic flame spraying to form a nanocomposite coating with a thickness of 2 mm.

[0060] Figure 1 This is the cross-sectional microstructure of the nanocomposite coating prepared in this embodiment. As can be seen from the figure, the coating phase composition has good uniformity, in which the hard phase (black area) formed by the basic hardness aggregate is wrapped by the amorphous binding phase (gray area) generated by the nano-additive, thereby improving the hardness and wear resistance of the coating.

[0061] After testing, the density of the nano-composite coating prepared in this embodiment is 99.8%, the hardness HV reaches 550, the bonding strength between the nano-composite coating and the crystallizer copper plate substrate is 295 MPa, and the crystallizer copper plate with the nano-composite coating has an actual single steel throughput of 95,000 tons / set and a service life of 3,100 furnaces.

[0062] Example 2

[0063] The raw materials involved in this embodiment are as follows:

[0064] The purity of tungsten carbide powder is 99.8%, and the particle size is 1μm; the purity of tungsten powder is 99.7%, and the particle size is 0.8μm; the purity of titanium carbide powder is 99.7%, and the particle size is 0.8μm; the purity of cobalt powder is 99.6%, and the particle size is 0.5μm; the purity of carbonyl iron powder is 99.6%, and the particle size is 1μm; the purity of carbonyl nickel powder is 99.6%, and the particle size is 1μm; the purity of nano zirconium oxide powder is 99.6%, and the particle size is 50nm; the purity of nano titanium carbonitride powder is 99.6%, and the particle size is 100nm.

[0065] The materials involved in this embodiment are as follows:

[0066] The crystallizer copper plate substrate is an Ag-Cu alloy, and its chemical composition includes, by mass percentage, 99.7% Cu, 0.06% Ag, and the rest are unavoidable impurities.

[0067] The method for preparing the nanocomposite coating on the surface of the crystallizer copper plate in this embodiment includes the following steps:

[0068] 1) Mix tungsten carbide powder, tungsten powder and titanium carbide powder in a mass ratio of 5:1.5:1 to obtain a basic hardness aggregate;

[0069] 2) mixing cobalt powder, carbonyl iron powder, and carbonyl nickel powder in a mass ratio of 1:1:2 to obtain a highly active binder;

[0070] 3) mixing nano zirconium oxide powder and nano titanium carbonitride powder in a mass ratio of 1:2.5 to obtain a nano additive;

[0071] 4) wet-milling the base hardness aggregate using a planetary ball mill with anhydrous ethanol as the milling medium, a stainless steel milling jar, and high-hardness metal balls at a speed of 80 r / min for 50 hours; transferring the milled material to a V-type mixer, adding a high-activity binder at 18% by weight of the base hardness aggregate and stirring at 50 r / min for 1 hour, and then adding a nano-additive at 3% by weight of the base hardness aggregate and stirring at 90 r / min for 8.5 hours; introducing the stirred material into a glass container and dispersing it using an ultrasonic device for 20 minutes to obtain a mixed slurry;

[0072] 5) After drying, the mixed slurry was passed through a 280 mesh sieve, and the sieve was taken out, and then vacuum hot pressing was performed. The vacuum degree was 4×10 -3 Pa, sintering temperature is 1440℃, hot pressing pressure is 35MPa, holding time is 1.5h, the sintered product is crushed to obtain nanocomposite coating powder with a particle size of 5μm;

[0073] 6) The surface of the mold copper plate substrate was treated to a rust removal grade of St2 and a roughness of 3 μm Ra. The nanocomposite coating powder was sprayed onto the surface of the mold copper plate substrate by supersonic flame spraying to form a nanocomposite coating with a thickness of 1.6 mm.

[0074] Tests have shown that the density of the nanocomposite coating prepared in this embodiment is 99.8%, the hardness HV reaches 620, the bonding strength between the nanocomposite coating and the crystallizer copper plate substrate is 350 MPa, and the crystallizer copper plate with the nanocomposite coating has an actual single steel throughput of 115,000 tons / set and a service life of 3,200 furnaces.

[0075] Example 3

[0076] The raw materials involved in this embodiment are as follows:

[0077] The purity of tungsten carbide powder is 99.5%, and the particle size is 2μm; the purity of tungsten powder is 99.5%, and the particle size is 0.3μm; the purity of titanium carbide powder is 99.5%, and the particle size is 0.3μm; the purity of cobalt powder is 99.5%, and the particle size is 0.5μm; the purity of carbonyl iron powder is 99.5%, and the particle size is 1μm; the purity of carbonyl nickel powder is 99.5%, and the particle size is 1μm; the purity of nano zirconium oxide powder is 99.5%, and the particle size is 30nm; the purity of nano titanium carbonitride powder is 99.5%, and the particle size is 150nm.

[0078] The materials involved in this embodiment are as follows:

[0079] The copper plate substrate of the crystallizer is a Cu-Cr-Zr alloy, and its chemical composition includes, by mass percentage, Cu 98.8%, Cr 1%, Zr 0.02%, and the rest are inevitable impurities.

[0080] The method for preparing the nanocomposite coating on the surface of the crystallizer copper plate in this embodiment includes the following steps:

[0081] 1) Mix tungsten carbide powder, tungsten powder and titanium carbide powder in a mass ratio of 5:1:1 to obtain basic hardness aggregate;

[0082] 2) mixing cobalt powder, carbonyl iron powder, and carbonyl nickel powder in a mass ratio of 1:2:1 to obtain a highly active binder;

[0083] 3) mixing nano zirconium oxide powder and nano titanium carbonitride powder in a mass ratio of 1:3 to obtain a nano additive;

[0084] 4) wet-milling the base hardness aggregate using a planetary ball mill with anhydrous ethanol as the milling medium, a stainless steel milling jar, and high-hardness metal balls at a speed of 100 r / min for 30 hours; transferring the milled material to a V-type mixer, adding a high-activity binder at 18% by weight of the base hardness aggregate and stirring at 55 r / min for 1 hour, and then adding a nano-additive at 1.5% by weight of the base hardness aggregate and stirring at 100 r / min for 7.5 hours; introducing the stirred material into a glass container and dispersing it using an ultrasonic device for 25 minutes to obtain a mixed slurry;

[0085] 5) After drying, the mixed slurry was passed through a 320 mesh sieve, and the sieve was taken out, and then vacuum hot isostatic pressing was performed with a vacuum degree of 4.3×10 -3 Pa, sintering temperature is 1460℃, sintering pressure is 35MPa, holding time is 2h, the sintered product is crushed to obtain nanocomposite coating powder with a particle size of 5μm;

[0086] 6) The surface of the mold copper plate substrate was treated to a rust removal grade of St2 and a roughness of 3.5 μm Ra. The nanocomposite coating powder was sprayed onto the surface of the mold copper plate substrate by supersonic flame spraying to form a nanocomposite coating with a thickness of 2.5 mm.

[0087] After testing, the density of the nanocomposite coating prepared in this embodiment is 99.9%, the hardness HV reaches 710, the bonding strength between the nanocomposite coating and the crystallizer copper plate substrate is 380 MPa, and the crystallizer copper plate with the nanocomposite coating has an actual single steel throughput of 125,000 tons / set and a service life of 3,300 furnaces.

[0088] Example 4

[0089] The raw materials involved in this embodiment are as follows:

[0090] The purity of tungsten carbide powder is 99.8%, and the particle size is 1μm; the purity of tungsten powder is 99.8%, and the particle size is 0.5μm; the purity of titanium carbide powder is 99.8%, and the particle size is 0.5μm; the purity of cobalt powder is 99.6%, and the particle size is 0.2μm; the purity of carbonyl iron powder is 99.6%, and the particle size is 0.2μm; the purity of carbonyl nickel powder is 99.6%, and the particle size is 1μm; the purity of nano zirconium oxide powder is 99.6%, and the particle size is 30nm; the purity of nano titanium carbonitride powder is 99.6%, and the particle size is 60nm.

[0091] The materials involved in this embodiment are as follows:

[0092] The copper plate substrate of the crystallizer is a Cu-Cr-Zr alloy, and its chemical composition includes, by mass percentage, Cu 98.8%, Cr 0.6%, Zr 0.015%, and the rest are inevitable impurities.

[0093] The method for preparing the nanocomposite coating on the surface of the crystallizer copper plate in this embodiment includes the following steps:

[0094] 1) Mix tungsten carbide powder, tungsten powder and titanium carbide powder in a mass ratio of 5:1:1 to obtain basic hardness aggregate;

[0095] 2) mixing cobalt powder, carbonyl iron powder, and carbonyl nickel powder in a mass ratio of 1:2.5:1 to obtain a highly active binder;

[0096] 3) mixing nano zirconium oxide powder and nano titanium carbonitride powder in a mass ratio of 1:2.5 to obtain a nano additive;

[0097] 4) wet-milling the base hardness aggregate using a planetary ball mill with anhydrous ethanol as the milling medium, a stainless steel milling jar, and high-hardness metal balls at a speed of 65 r / min for 50 hours; transferring the milled material to a V-type mixer, adding a high-activity binder at 12% by weight of the base hardness aggregate and stirring at 58 r / min for 1 hour, and then adding a nano-additive at 2.5% by weight of the base hardness aggregate and stirring at 95 r / min for 6 hours; introducing the stirred material into a glass container and dispersing it using an ultrasonic device for 25 minutes to obtain a mixed slurry;

[0098] 5) After drying, the mixed slurry was passed through a 320 mesh sieve, and the sieve was taken out, and then vacuum hot isostatic pressing was performed with a vacuum degree of 4×10 -3 Pa, sintering temperature is 1450℃, sintering pressure is 25MPa, holding time is 3h, the sintered product is crushed to obtain nanocomposite coating powder with a particle size of 6μm;

[0099] 6) The surface of the mold copper plate substrate was treated to a rust removal grade of St3 and a roughness of 3 μm Ra. The nanocomposite coating powder was sprayed onto the surface of the mold copper plate substrate by supersonic flame spraying to form a nanocomposite coating with a thickness of 2.8 mm.

[0100] Tests have shown that the density of the nanocomposite coating prepared in this embodiment is 99.9%, the hardness HV reaches 750, the bonding strength between the nanocomposite coating and the crystallizer copper plate substrate is 385 MPa, and the crystallizer copper plate with the nanocomposite coating has an actual single steel throughput of 145,000 tons / set and a service life of 3,400 furnaces.

[0101] The above embodiments are merely examples for clarification and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications may be made based on the above descriptions. It is not necessary and impossible to enumerate all implementation methods here, and any obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a nanocomposite coating on the surface of a crystallizer copper plate, characterized in that: The following steps are involved: 1) Premix tungsten carbide powder, tungsten powder and titanium carbide powder in a mass ratio of (4-6): (1-2): 1 to obtain basic hardness aggregate; 2) Premixing cobalt powder, carbonyl iron powder, and carbonyl nickel powder in a mass ratio of 1:(1-3):(1-3) to obtain a highly active binder; 3) Premixing nano zirconium oxide powder and nano titanium carbonitride powder in a mass ratio of 1:(2-4) to obtain a nano additive; 4) Wet ball mill the basic hardness aggregate, then add 10-20% of the mass of the basic hardness aggregate in a high-activity binder for primary stirring, then add 1-5% of the mass of the basic hardness aggregate in a nano-additive for secondary stirring, and finally perform ultrasonic dispersion to obtain a mixed slurry; 5) Drying the mixed slurry and sieving it, then vacuum hot pressing or vacuum hot isostatic pressing is used to sinter the sintered product, and crushing the sintered product to obtain a nanocomposite coating powder; 6) The surface of the mold copper plate substrate is treated to ensure that the rust removal and roughness meet the spraying requirements, and the nano-composite coating powder is sprayed onto the surface of the mold copper plate substrate by supersonic flame spraying or plasma spraying to form a nano-composite coating.

2. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: In the basic hardness aggregate, the particle size of tungsten carbide powder is less than 3 μm, the particle size of tungsten powder is less than 1 μm, and the particle size of titanium carbide powder is less than 1 μm.

3. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: In the highly active binder, the particle size of the cobalt powder is less than 1 μm, the particle size of the carbonyl iron powder is less than 2 μm, and the particle size of the carbonyl nickel powder is less than 2 μm.

4. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: In the nano additives, the particle size of the nano zirconium oxide powder is 20-60 nm, and the particle size of the nano titanium carbonitride powder is 50-200 nm.

5. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: The wet ball milling adopts a planetary ball mill, anhydrous ethanol as the ball milling medium, equipped with a stainless steel ball milling jar and high-hardness metal ball mills, the ball milling speed is 50-100 r / min, and the ball milling time is 30-60 hours.

6. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: The stirring is performed using a V-type mixer; the stirring rate of the primary stirring is 50-60 r / min, and the stirring time is 0.5-1 h; the stirring rate of the secondary stirring is 80-10 r / min, and the stirring time is 4.5-9 h.

7. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: The vacuum degree of the vacuum hot pressing sintering or vacuum hot isostatic pressing sintering is 3.5×10 -3 ~4.5×10 -3 Pa, sintering temperature is 1400~1500℃, pressure is 20~40MPa, and holding time is 1~3h.

8. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: The particle size of the nanocomposite coating powder is less than 10 μm; the crystallizer copper plate substrate is Ag-Cu alloy or Cu-Cr-Zr alloy; the rust removal grade of the crystallizer copper plate substrate is Sa3, St2 or St3, and the roughness should reach 2.5~5 μmRa.

9. The method for preparing a nanocomposite coating on a surface of a crystallizer copper plate according to claim 1, wherein: The thickness of the nano-composite coating is 1.5-3 mm, the density is greater than 99.7%, the hardness HV is 500-800, the bonding strength between the nano-composite coating and the crystallizer copper plate substrate is 200-400 MPa, the crystallizer copper plate with the nano-composite coating has a single steel passing capacity of 80,000-150,000 tons / set, and a service life of 2,800-3,500 furnaces.

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