A thin strip continuous casting long-life crystallization roller sleeve and its preparation method

Abstract

The present invention relates to a thin strip continuous casting crystallization roller sleeve and a preparation method thereof. The crystallization roller sleeve is made of a Cu‑Ni‑Be alloy; a composite coating composed of a nickel-chromium alloy layer and a titanium nitride layer is provided on the crystallization roller sleeve, wherein the nickel-chromium alloy layer is coated on the surface of the crystallization roller sleeve; the titanium nitride layer is attached to the nickel-chromium alloy layer; the thickness of the nickel-chromium alloy layer is greater than or equal to 2 mm; the thickness of the titanium nitride layer is 3‑5 microns. The present invention first attempts to use a Cu‑Ni‑Be alloy with a Be content of 1‑5% as a crystallization roller sleeve, combined with a composite coating composed of a nickel-chromium alloy layer and a titanium nitride layer provided on the crystallization roller sleeve, and obtains a wear amount less than or equal to 0.12 g and a peak heat flux greater than or equal to 14.05 MW / m 2 The invention has a reasonable structural design, scientifically selected ingredients, and the obtained product has excellent comprehensive performance. The preparation process is simple and controllable, and is convenient for large-scale production and application.

Description

Technical Field

[0001] The invention relates to a thin strip continuous casting crystallization roller sleeve, and in particular to a long-life design of the thin strip continuous casting crystallization roller sleeve and a preparation method thereof. Background Art

[0002] Strip casting is an advanced continuous casting process that directly casts and rolls liquid metal into thin strip products. In this process, molten steel solidifies directly on rotating crystallization rollers and is cast into finished or semi-finished thin strip steel with a thickness of 1-5 mm. This achieves integrated casting and rolling, and is a current research hotspot and cutting-edge technology in the steel and nonferrous metals industries. The crystallization roller is a key component in twin-roller thin strip casting machinery. The basic principle is that molten steel passes through a distributor into a molten pool consisting of two counter-rotating crystallization rollers and side closure plates. The liquid metal rapidly cools and solidifies on the surfaces of the crystallization rollers into a shell of a certain thickness. This shell is then rolled together to form a thin strip. The basic structure of the crystallization roller consists of a core and a sleeve. The sleeve is typically made of copper alloy, while the core is typically made of carbon steel. The core and sleeve are connected mechanically or by welding. During the production process of crystallization rollers, they are subjected to high-temperature alternating thermal stress, rolling force, impact from cold steel blocks, and friction between the end faces and side seal materials. Therefore, they are easily damaged, resulting in dimensional changes, cracks, pits, and other defects. Roller sleeves or crystallization rollers made of pure copper alloys have a short service life. Therefore, people began to try coating technology.

[0003] Various coating technologies for thin-strip continuous casting crystallization rolls have been developed. For example, Patent Application No. 200910197646.2, "Highly Wear-Resistant Composite Coatings for Crystallizer or Crystallization Roller Surfaces and Their Manufacturing Methods," discloses a method for preparing composite coatings using cold air dynamic spraying, where metal or alloy particles undergo intense plastic deformation and adhere to the mold or crystallization roll surface to form a composite coating. This coating exhibits excellent wear resistance and can effectively extend the service life of the crystallization roll. However, the combination of compound reinforcements and metal particles results in reduced thermal conductivity compared to pure metal, resulting in mediocre heat transfer performance. Furthermore, the reinforcement particles in the coating can react with the target product during equipment use, leading to a sharp decline in performance in the later stages of equipment life. Furthermore, the patent discloses data showing only a 15-35% improvement in wear resistance compared to a metal substrate (see the examples for details). Patent application number: 200610030213.4, a method for electroplating the surface of a thin strip continuous casting crystallization roller and its electroplating solution, discloses a method for nickel plating the surface of a crystallization roller and its special electroplating solution. The resulting metal nickel plating has strong bonding with the substrate, low stress, and good thermal conductivity, but its wear resistance is significantly worse than hard coatings such as ceramics. The previous patent CN107641806A of this research group is a composite coating on the surface of a thin strip continuous casting crystallization roller and its preparation method. This patent designs a composite coating composed of a nickel-copper alloy layer and a titanium nitride layer; wherein the nickel-copper alloy layer is coated on the surface of the thin strip continuous casting crystallization roller; the titanium nitride layer is attached to the nickel-copper alloy layer; the thickness of the nickel-copper alloy layer is greater than or equal to 3mm; the thickness of the titanium nitride layer is 3-5 microns. The product obtained by this patent can achieve a wear amount as low as 0.13g and a peak heat flux maintained at 14.72MW / m 2 This level; however, as the research deepened, it was found that its continuous working time needs to be further improved.

[0004] Furthermore, existing crystallization roller sleeves are primarily made of pure copper or Cu-Be alloys. Furthermore, existing Be-containing crystallization roller sleeves generally use less than 0.5% Be (e.g., US3083328, CN02136307.2). Cu-Be alloys with Be content greater than 1% are generally not used for crystallization roller sleeves. Summary of the Invention

[0005] The present invention goes against this trend and tries for the first time to use a Cu-Ni-Be alloy with a Be content of 1-5% as the crystallization roller sleeve, and a composite coating composed of a nickel-chromium alloy layer and a titanium nitride layer provided on the crystallization roller sleeve, thereby obtaining a wear loss of less than 0.11g and a peak heat flux of greater than or equal to 13.6MW / m 2 The product shall not have cracks greater than or equal to 3mm after 300h of friction when the friction body is medium carbon steel and the load is 400N.

[0006] The present invention provides a long-life crystallization roller sleeve for thin-strip continuous casting and a method for manufacturing the same. The designed and manufactured crystallization roller comprises a crystallization roller sleeve and a surface composite coating. The sleeve is constructed from a Cu-Ni-Be alloy with a Be content of 1-5%, and is coated with a composite coating consisting of a nickel-chromium alloy layer and a titanium nitride layer, achieving excellent service performance and a long life.

[0007] The present invention provides a long-life crystallization roller sleeve for thin-strip continuous casting. The crystallization roller sleeve is made of a Cu-Ni-Be alloy and is provided with a composite coating comprising a nickel-chromium alloy layer and a titanium nitride layer. The nickel-chromium alloy layer covers the surface of the crystallization roller sleeve; the titanium nitride layer is attached to the nickel-chromium alloy layer. The nickel-chromium alloy layer has a thickness of 2 mm or greater, and the titanium nitride layer has a thickness of 3-5 microns. The Cu-Ni-Be alloy comprises ≥90 wt% Cu, ≥5 wt% Ni, and 1-5 wt% Be.

[0008] In the present invention, the roll core and the crystallization roll sleeve constitute a crystallization roll, and the crystallization roll sleeve is covered on the roll core. In the present invention, the roll core adopts the existing roll core material and structure.

[0009] The present invention provides a long-life crystallization roller sleeve for continuous casting of thin strips. The Cu-Ni-Be alloy comprises 90-93wt% Cu, 5-7.5wt% Ni, and 1.5-2.5wt% Be, preferably 2wt%.

[0010] As a further preference, the present invention provides a long-life crystallization roller sleeve for continuous strip casting, wherein the Cu-Ni-Be alloy comprises 91wt% Cu, 7wt% Ni, and 2wt% Be.

[0011] The present invention provides a thin strip continuous casting long-life crystallization roller sleeve, wherein the molar ratio of nickel to chromium in the nickel-chromium alloy layer is 1:0.5-1, preferably 1:0.75-0.85.

[0012] The invention discloses a thin strip continuous casting long-life crystallization roller sleeve, wherein the thickness of the nickel-chromium alloy layer is 2-2.5 mm.

[0013] The present invention provides a method for preparing a long-life crystallization roller sleeve for continuous casting of thin strips, comprising the following steps:

[0014] Step 1

[0015] A Cu-Ni-Be alloy is prepared into a crystallized roller sleeve by casting and machining; in the Cu-Ni-Be alloy, Cu≥90wt%, Ni≥5wt%, and Be1-5wt%.

[0016] Step 2

[0017] The surface of the clean and dry crystallized roller sleeve is roughened to obtain a spare roller sleeve with a roughness Ra of 50-100 microns.

[0018] Step 3

[0019] Ni source powder and Cr source powder are mixed according to the designed composition, and a nickel-chromium alloy layer is prepared on the surface of the spare roller sleeve by adopting the supersonic flame spraying technology to obtain the thin strip continuous casting crystallization roller sleeve to be annealed.

[0020] Step 4

[0021] Annealing the thin strip continuous casting crystallization roller sleeve to be annealed to obtain an annealed thin strip continuous casting crystallization roller sleeve; the annealing atmosphere is selected from one of argon and nitrogen, the annealing temperature is 650-750° C., and the time is 1.5-2.5 hours;

[0022] Step 5

[0023] Titanium nitride with a purity greater than or equal to 99.99% is used as a target material, and a titanium nitride layer is prepared on the surface of the annealed thin strip continuous casting crystallization roller sleeve by magnetron sputtering; the thickness of the titanium nitride layer is 3-5 microns.

[0024] When used in industry, the Cu-Ni-Be alloy is prepared into a crystallized roller sleeve by casting and machining according to the designed size.

[0025] When used in industry, after obtaining the continuous casting crystallization roller sleeve with the titanium nitride layer on the surface, it is assembled with the roller core to obtain a thin strip continuous casting long-life crystallization roller.

[0026] The present invention provides a method for preparing a thin strip continuous casting long-life crystallization roller sleeve. In step 2, the Ni source powder is Ni powder or Ni alloy powder; and the Cr source powder is chromium powder or chromium alloy powder.

[0027] The invention discloses a method for preparing a thin strip continuous casting long-life crystallization roller sleeve. The particle size of the Ni source powder is 15-85 microns; the particle size of the Cr source powder is 30-100 microns.

[0028] The invention discloses a method for preparing a thin strip continuous casting long-life crystallization roller sleeve. During supersonic flame spraying, the flame flow velocity is controlled to be 600-650m / s, the particle velocity is controlled to be 450-500m / s, and the flame temperature is controlled to be 2750-3050°C.

[0029] The present invention discloses a method for preparing a long-life crystallization roller sleeve for continuous casting of thin strips. When preparing a titanium nitride layer by magnetron sputtering, the crystallization roller sleeve serving as a substrate is controlled to be cooled to 250-300° C. after annealing treatment; the magnetron sputtering power is controlled to be 180-220 W, and the spraying time is controlled to be 110-130 min; during the magnetron sputtering, the atmosphere used is high-purity argon or high-purity nitrogen, and the purity of the high-purity argon or high-purity nitrogen is greater than or equal to 99.99%.

[0030] The present invention provides a method for preparing a thin strip continuous casting long-life crystallization roller sleeve, wherein the prepared thin strip continuous casting long-life crystallization roller has a peak heat flux greater than or equal to 14.05MW / m during the production process. 2 The wear amount is less than or equal to 0.12g, preferably less than or equal to 0.11g, and further preferably less than or equal to 0.10g; under the conditions that the friction body is medium carbon steel and the load is 400N, the friction is 300h, and the surface of the obtained thin strip continuous casting long-life crystallization roller sleeve does not have cracks greater than or equal to 3mm.

[0031] The long-life crystallization roller designed and manufactured for thin-strip continuous casting combines the advantages of a crystallization roller sleeve material with a variety of coating materials and methods. The crystallization roller sleeve substrate utilizes a Cu-Ni-Be alloy with a Be content of 1-5wt%, followed by a nickel-chromium alloy coating and a titanium nitride coating. Compared to traditional pure copper or Cu-Be alloys (Be content less than 0.5%), the resulting product maintains thermal conductivity (only a 3-5% decrease) while significantly increasing continuous operating time (greater than or equal to 90%), thereby ensuring the roller sleeve's strength and resistance to cracking.

[0032] The crystallized roller sleeve substrate of the present invention utilizes a Cu-Ni-Be alloy with a Cu content of 90-93wt%, a Ni content of 5-7.5wt%, and a Be content of 1.5-2.5wt%. Prior art believes that the addition of Be rapidly reduces the thermal and electrical conductivity of the product (see Patent 02136307.2), and the amount is generally adjusted to below 0.5%. Furthermore, supplementary elements such as Zr, Ce, Cr, Ta, and Ha are also required. However, the present invention has discovered that using the Cu-Ni-Be substrate designed in the present invention, combined with a 2-2.5mm thick Ni-Cr alloy layer, can minimize the negative effects of excessive Be addition. Furthermore, the addition of a titanium nitride coating of appropriate thickness reduces the thermal conductivity by only 3-5% compared to pure copper. Crucially, this significantly improves the product's continuous operating time (by at least 90% compared to copper with 0.5% Be).

[0033] The composite alloy layer designed and prepared in the present invention utilizes a nickel-chromium alloy layer, with a nickel-to-chromium molar ratio of 1:0.5-1, preferably 1:0.75-0.85. The alloy coating has a thickness of 2-2.5 mm. Nickel-based alloys are the most widely used type of high-temperature alloys. Nickel-based alloys can dissolve a variety of alloying elements. Adding alloying elements to nickel-based alloys can form stable intermetallic compounds. The addition of chromium to nickel-based alloys provides strong bonding between nickel and chromium, and chromium itself has advantages such as a high melting point and high specific strength. The intermetallic compound reinforcement phase formed by nickel and chromium is more stable, significantly enhancing the hardness and wear resistance of the alloy coating. Since nickel primarily dissolves chromium in nickel-based alloys, the molar ratio of nickel to chromium in the alloy is 1:0.5-1. While the addition of chromium improves the hardness and wear resistance of the nickel-based alloy, excessive chromium can also reduce the heat transfer performance of the alloy coating. Therefore, the molar ratio of nickel to chromium is preferably 1:0.75-0.85. The nickel-chromium alloy coating has excellent wear resistance, and based on the consideration of the heat transfer performance of the crystallization roller, the coating thickness should not be too thick, so the coating thickness is designed to be 2-2.5mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a flow chart of the preparation method of the long-life crystallization roller for thin strip continuous casting. DETAILED DESCRIPTION

[0035] Example 1

[0036] In this embodiment, the steps for preparing a long-life crystallization roller for continuous strip casting are as follows:

[0037] Step 1

[0038] Cu-Ni-Be alloy (mass ratio: Cu:Ni:Be=92:6:2) was prepared into crystallized roller sleeves by casting and machining;

[0039] Step 2

[0040] The surface of the clean and dry crystallization roller sleeve is roughened to obtain a spare roller sleeve with a roughness Ra of 70 microns;

[0041] Step 3

[0042] Ni powder and Cr powder are mixed according to the designed composition, and a nickel-chromium alloy layer is prepared on the surface of the spare roller sleeve by using supersonic flame spraying technology; a thin strip continuous casting crystallization roller sleeve to be annealed is obtained; the molar ratio of the mixed Ni powder and Cr powder is 1:0.8; the particle size of the Ni powder is 35-65 microns; the particle size of the Cr powder is 50-80 microns;

[0043] During supersonic flame spraying, the flame velocity is controlled to be 630m / s, the particle velocity is controlled to be 480m / s, the flame temperature is controlled to be around 2950℃, and the temperature of the backup roller is 180℃.

[0044] The thickness of the resulting nickel-chromium alloy layer was approximately 2.32 mm.

[0045] Step 4

[0046] The thin strip continuous casting crystallization roller sleeve to be annealed is subjected to annealing treatment to obtain an annealed thin strip continuous casting crystallization roller sleeve; the annealing atmosphere is argon, the annealing temperature is 720° C., and the time is 2.2 hours;

[0047] Step 5

[0048] Titanium nitride with a purity of greater than or equal to 99.99% was used as a target material. A titanium nitride layer was deposited on the surface of a thin-strip continuous casting crystallization roller sleeve after annealing and cooled to 280°C via magnetron sputtering. The titanium nitride layer had a thickness of approximately 4.18 microns. The magnetron sputtering process was performed at a power of 200W and a spraying time of 120 minutes. High-purity argon was used as the protective atmosphere.

[0049] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0050] Example 2

[0051] In this embodiment, the steps for preparing a long-life crystallization roller for continuous strip casting are as follows:

[0052] Step 1

[0053] Cu-Ni-Be alloy (mass ratio: Cu:Ni:Be=91:7:2) was prepared into crystallized roller sleeves by casting and machining;

[0054] Step 2

[0055] The surface of the clean and dry crystallization roller sleeve is roughened to obtain a spare roller sleeve with a roughness Ra of 70 microns;

[0056] Step 3

[0057] Ni powder and Cr powder are mixed according to the designed composition, and a nickel-chromium alloy layer is prepared on the surface of the spare roller sleeve by using supersonic flame spraying technology; a thin strip continuous casting crystallization roller sleeve to be annealed is obtained; the molar ratio of the mixed Ni powder and Cr powder is 1:0.8; the particle size of the Ni powder is 35-65 microns; the particle size of the Cr powder is 50-80 microns;

[0058] During supersonic flame spraying, the flame velocity is controlled to be 620m / s, the particle velocity is controlled to be 470m / s, the flame temperature is controlled to be around 2900℃, and the temperature of the backup roller is 185℃.

[0059] The thickness of the resulting nickel-chromium alloy layer was approximately 2.34 mm.

[0060] Step 4

[0061] The thin strip continuous casting crystallization roller sleeve to be annealed is subjected to annealing treatment to obtain an annealed thin strip continuous casting crystallization roller sleeve; the annealing atmosphere is argon, the annealing temperature is 715° C., and the time is 2.2 hours;

[0062] Step 5

[0063] Titanium nitride with a purity of greater than or equal to 99.99% was used as a target material. A titanium nitride layer was deposited on the surface of a thin-strip continuous casting crystallization roller sleeve after annealing and cooled to 280°C via magnetron sputtering. The titanium nitride layer had a thickness of approximately 4.17 microns. The magnetron sputtering process was performed at a power of 200W and a spraying time of 120 minutes. High-purity argon was used as the protective atmosphere.

[0064] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0065] Example 3

[0066] In this embodiment, the steps for preparing a long-life crystallization roller for continuous strip casting are as follows:

[0067] Step 1

[0068] Cu-Ni-Be alloy (mass ratio: Cu:Ni:Be=93:5:2) was prepared into crystallized roller sleeves by casting and machining;

[0069] Step 2

[0070] The surface of the clean and dry crystallization roller sleeve is roughened to obtain a spare roller sleeve with a roughness Ra of 75 microns;

[0071] Step 3

[0072] Ni powder and Cr powder are mixed according to the designed composition, and a nickel-chromium alloy layer is prepared on the surface of the spare roller sleeve by using supersonic flame spraying technology; a thin strip continuous casting crystallization roller sleeve to be annealed is obtained; the molar ratio of the mixed Ni powder and Cr powder is 1:0.8; the particle size of the Ni powder is 35-65 microns; the particle size of the Cr powder is 50-80 microns;

[0073] During supersonic flame spraying, the flame velocity is controlled to be 620m / s, the particle velocity is controlled to be 480m / s, the flame temperature is controlled to be around 2900℃, and the temperature of the backup roller is 180℃.

[0074] The thickness of the resulting nickel-chromium alloy layer was approximately 2.31 mm.

[0075] Step 4

[0076] The thin strip continuous casting crystallization roll sleeve to be annealed is subjected to annealing treatment to obtain an annealed thin strip continuous casting crystallization roll sleeve; the annealing atmosphere is argon, the annealing temperature is 725° C., and the time is 2.2 hours;

[0077] Step 5

[0078] Titanium nitride with a purity of greater than or equal to 99.99% was used as a target material. A titanium nitride layer was deposited on the surface of a thin-strip continuous casting crystallization roller sleeve after annealing and cooled to 280°C via magnetron sputtering. The titanium nitride layer had a thickness of approximately 4.13 microns. The magnetron sputtering process was performed at a power of 200W and a spraying time of 120 minutes. High-purity argon was used as the protective atmosphere.

[0079] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0080] Example 4

[0081] Other conditions were the same as those in Example 1, except that: Ni powder and Cr powder were mixed according to the designed composition, and a nickel-chromium alloy layer was prepared on the surface of the spare roller sleeve by using supersonic flame spraying technology; a thin strip continuous casting crystallization roller sleeve to be annealed was obtained; the molar ratio of the mixed Ni powder and Cr powder was 1:0.5; the particle size of the Ni powder was 35-65 μm; and the particle size of the Cr powder was 50-80 μm.

[0082] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0083] Example 5

[0084] Other conditions were the same as those in Example 1, except that: Ni powder and Cr powder were mixed according to the designed composition, and a nickel-chromium alloy layer was prepared on the surface of the spare roller sleeve by supersonic flame spraying technology; a thin strip continuous casting crystallization roller sleeve to be annealed was obtained; the molar ratio of the mixed Ni powder and Cr powder was 1:0.9; the particle size of the Ni powder was 35-65 μm; and the particle size of the Cr powder was 50-80 μm.

[0085] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0086] Example 6

[0087] Other conditions were the same as those in Example 1, except that: Ni powder and Cr powder were mixed according to the designed composition, and a nickel-chromium alloy layer was prepared on the surface of the spare roller sleeve by supersonic flame spraying technology; a thin strip continuous casting crystallization roller sleeve to be annealed was obtained; the molar ratio of the mixed Ni powder and Cr powder was 1:1; the particle size of the Ni powder was 35-65 μm; and the particle size of the Cr powder was 50-80 μm;

[0088] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0089] Comparative Example 1

[0090] Compared with Example 1, step 1

[0091] Cu-Be alloy (mass ratio: Cu: Be=99.5:0.5) was prepared into a crystalline roller sleeve by casting and machining.

[0092] The remaining steps are consistent with Example 1

[0093] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer / titanium nitride layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0094] Comparative Example 2

[0095] Compared with Example 1, this comparative example omitted step 5;

[0096] The rest of the steps are the same

[0097] The structure of the obtained product is a crystallized roller sleeve / nickel-chromium alloy layer. The test values of its continuous working time, wear amount, and peak heat flow are shown in Table 1.

[0098] Comparative Example 3

[0099] Other conditions were the same as in Example 1, except that steps 3 and 4 were omitted. A titanium nitride layer was formed directly on the surface of the spare roller sleeve after annealing. The titanium nitride layer was prepared in the same manner as in Example 1, resulting in a product structure of crystallized roller sleeve / titanium nitride layer. The measured values for continuous operating time, wear, and peak heat flux are shown in Table 1.

[0100] Comparative Example 4

[0101] Cu-Be alloy (mass ratio: Cu: Be=99.5:0.5) was prepared into crystallized roller sleeve by casting and machining.

[0102] Comparative Example 5

[0103] The same process as in Example 1 in CN107641806A is used to convert the crystallization roller into a crystallization roller sleeve; the details are as follows:

[0104] Step 1: preparing a crystallization roller sleeve from pure copper by casting and machining; performing a surface roughening treatment on the clean and dry crystallization roller to obtain a spare roller sleeve with a roughness Ra of 70 microns;

[0105] Step 2: Ni powder and Cu powder are mixed according to the designed composition and a nickel-copper alloy layer is prepared on the surface of the spare roller sleeve using supersonic flame spraying technology. A thin strip continuous casting crystallization roller to be annealed is obtained. The molar ratio of the Ni powder to the Cu powder is 1:0.8. The particle size of the Ni powder is 40-80 microns, and the particle size of the Cu powder is 70-100 microns. During the supersonic flame spraying, the flame velocity is controlled at 420 m / s, the particle velocity is controlled at 400 m / s, the flame temperature is controlled at approximately 2950°C, and the temperature of the spare roller sleeve is 180°C. The resulting nickel-copper alloy layer has a thickness of 4.32 mm.

[0106] Step 3: Annealing the thin strip continuous casting crystallization roller sleeve to be annealed to obtain an annealed thin strip continuous casting crystallization roller; the annealing atmosphere is argon, the annealing temperature is 760° C., and the annealing time is 2.4 hours;

[0107] Step 4: Titanium nitride with a purity of 99.99% or greater was used as a target material to deposit a titanium nitride layer on the surface of the annealed strip casting crystallization roll via magnetron sputtering. The thickness of the titanium nitride layer was 4.13 microns (i.e., coating 1). The magnetron sputtering power was controlled at 200 W, and the spraying time was 180 minutes. High-purity argon was used as the protective atmosphere during magnetron sputtering. The resulting product had a structure of substrate / nickel-copper alloy layer / titanium nitride layer.

[0108] In the examples and comparative examples of this invention, product wear resistance was measured using the wear parameter. The friction element was medium-carbon steel, the load was 400N, and the friction time was from 30 minutes until a 3mm crack appeared. The wear value refers to the 30-minute friction period. Continuous operation time was measured from the start of the friction test until a 3mm crack appeared. Heat transfer performance was tested using a proprietary heat flow tester (Patent No.: 201610049659.5) using a low-carbon steel specimen weighing 3.5g at a temperature of 1520°C. Peak heat flow was used to evaluate performance.

[0109]

[0110] As shown in the table above, the long-life crystallization roller of the present invention significantly increases continuous operating time compared to other crystallization rollers while maintaining thermal conductivity. Therefore, the long-life crystallization roller can significantly improve production efficiency and reduce production costs.

Claims

1. A long-life crystallization roller sleeve for continuous strip casting, characterized by: The crystallization roller sleeve is made of Cu-Ni-Be alloy; a composite coating is provided on the crystallization roller sleeve, and the composite coating is composed of a nickel-chromium alloy layer and a titanium nitride layer; The nickel-chromium alloy layer is coated on the surface of the crystallization roller sleeve; the titanium nitride layer is attached to the nickel-chromium alloy layer; the thickness of the nickel-chromium alloy layer is greater than or equal to 2 mm; the thickness of the titanium nitride layer is 3-5 microns; the Cu-Ni-Be alloy contains 90-93wt% Cu, 5-7.5wt% Ni, and 1.5-2.5wt% Be; In the nickel-chromium alloy layer, the molar ratio of nickel to chromium is 1:0.5-1; The thin strip continuous casting long-life crystallization roller sleeve is prepared by the following steps: Step 1 Cu-Ni-Be alloy was prepared into crystallized roller sleeve by casting and machining; Step 2 The surface of the clean and dry crystallization roller sleeve is roughened to obtain a spare roller sleeve with a roughness Ra of 50-100 microns; Step 3 Ni source powder and Cr source powder are mixed according to the designed composition, and a nickel-chromium alloy layer is prepared on the surface of the spare roller sleeve by supersonic flame spraying technology; thus, a thin strip continuous casting crystallization roller sleeve to be annealed is obtained; during the supersonic flame spraying, the flame velocity is controlled to be 600-650m / s, the particle velocity is controlled to be 450-500m / s, and the flame temperature is controlled to be 2750-3050°C; Step 4 Annealing the thin strip continuous casting crystallization roller sleeve to be annealed to obtain an annealed thin strip continuous casting crystallization roller sleeve; the annealing atmosphere is selected from one of argon and nitrogen, the annealing temperature is 650-750° C., and the time is 1.5-2.5 hours; Step 5 Titanium nitride with a purity greater than or equal to 99.99% is used as a target material, and a titanium nitride layer is prepared on the surface of the annealed thin strip continuous casting crystallization roller sleeve by magnetron sputtering.

2. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: In the Cu-Ni-Be alloy, Cu is 90-93 wt%, Ni is 5-7.5 wt%, and Be is 2 wt%.

3. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: In the nickel-chromium alloy layer, the molar ratio of nickel to chromium is 1:0.75-0.

85.

4. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: The thickness of the nickel-chromium alloy layer is 2-2.5 mm.

5. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: In step 3, the Ni source powder is Ni powder or Ni alloy powder; and the Cr source powder is chromium powder or chromium alloy powder.

6. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: The particle size of the Ni source powder is 15-85 microns; the particle size of the Cr source powder is 30-100 microns.

7. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: When preparing the titanium nitride layer by magnetron sputtering, the temperature of the crystallization roller sleeve after annealing is controlled to cool to 250-300°C; the magnetron sputtering power is controlled to 180-220W, and the spraying time is 110-130min; during magnetron sputtering, the atmosphere used is high-purity argon or high-purity nitrogen, and the purity of the high-purity argon or high-purity nitrogen is greater than or equal to 99.99%.

8. The long-life crystallization roller sleeve for continuous strip casting according to claim 1, characterized in that: The prepared thin-strip continuous casting long-life crystallization roller sleeve has a peak heat flux greater than or equal to 14.05MW / m2 and a wear amount less than or equal to 0.12g during the production process; under the conditions that the friction body is medium carbon steel and the load is 400N, the friction is 300h, and the surface of the obtained thin-strip continuous casting long-life crystallization roller sleeve does not have cracks greater than or equal to 3mm.

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