Method for coating steel rolling roll collar with nano-composite coating

Abstract

The invention belongs to the technical field of steel rolling roll collars, and particularly relates to a method for coating a steel rolling roll collar with a nano-composite coating, which comprises the following steps: S1, pretreatment; s2, vacuum heating treatment; s3, primary etching treatment is carried out, wherein ion source bombardment etching treatment is carried out on the base body for 30-120 min; s4, carrying out primary coating treatment; s5, carrying out secondary etching treatment; and S6, carrying out secondary coating treatment. According to the invention, the unique double-layer composite coating is matched with a specific parameter range of coating treatment and etching treatment, so that the prepared coating has the characteristics of high-temperature oxidation resistance, high-temperature friction resistance, moderate surface roughness, large coating thickness and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of rolling mill roll rings, and particularly relates to a method for coating a nano-composite coating on a rolling mill roll ring. Background Art

[0002] Rolling mill roll rings are one of the key components of production equipment, and their working environment is extremely harsh, often operating under high temperature, high pressure, and high friction conditions. Therefore, improving the service life and performance of roll rings is crucial for improving production efficiency and reducing costs. Traditional roll ring surface treatment technologies such as thermal spraying and electroless plating often struggle to meet the requirements of high strength and high precision, especially in terms of wear resistance and oxidation resistance during long-term continuous operation.

[0003] In recent years, with the development of nanotechnology, nano-composite coatings have been widely used to improve the surface characteristics of metal components due to their excellent physical and chemical properties. Nano-composite coatings formed by technologies such as physical vapor deposition (PVD) can significantly enhance the hardness, wear resistance, corrosion resistance, etc. of the substrate material.

[0004] In rolling steel production, due to high temperature, high speed, and high pressure, the surface of the roll ring grooves wears, the roll rings are consumed quickly, the specifications of the rolled finished products exceed the standard, and the surface is rough. Therefore, it is necessary to stop the machine to change the rolls.

[0005] To solve the above problems, the current conventional method is to coat the surface of the substrate by ion plating, thereby improving the wear resistance of the roll, extending the service life of the rolling mill roll ring, and then achieving the purpose of increasing production.

[0006] Therefore, developing a new preparation method that improves the coating performance while simplifying the preparation process and reducing costs has become an important research direction at present. Summary of the Invention

[0007] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for coating a nano-composite coating on a rolling mill roll ring. In the present invention, a double-layer composite coating is formed through a specific parameter range of coating treatment and etching treatment, so that the prepared coating has characteristics such as high temperature oxidation resistance, high temperature friction resistance, moderate surface roughness, and large coating thickness.

[0008] The specific technical solution adopted by the present invention is: The red part is modified with reference to the previous text A method for coating a nano-composite coating on a rolling mill roll ring, comprising the following steps: S1. Pretreatment: Pretreat the surface of the roll ring substrate; S2. Vacuum heating treatment: Put the pretreated roll ring into a coating machine for heating and pressure holding treatment to remove the water vapor and miscellaneous gases volatilized from the surface of the workpiece and the wall of the vacuum chamber; S3. Primary etching treatment: Perform ion source bombardment etching treatment on the substrate after vacuum heating treatment for 30 - 120 minutes; S4. Primary coating treatment: Sequentially deposit an underlayer for 8 - 12 minutes, a transition layer for 40 - 80 minutes, an upgraded layer for 8 - 12 minutes, and a functional layer for 90 - 150 minutes on the surface of the substrate after primary etching treatment to form a composite lining coating; S5. Secondary etching treatment: Perform ion source bombardment etching treatment on the surface of the composite lining coating for 15 - 60 minutes; S6. Secondary coating treatment: Sequentially deposit an underlayer for 4 - 6 minutes, a transition layer for 20 - 40 minutes, an upgraded layer for 4 - 6 minutes, and a functional layer for 45 - 75 minutes on the surface of the composite lining coating to form a nano - composite coating.

[0009] The pretreatment includes sandblasting, spraying, ultrasonic cleaning, deionized water rinsing, and drying.

[0010] The heating temperature of the vacuum heating treatment is 450 - 550 °C, the vacuum degree is 1 - 8×10⁻³ Pa, and the pressure - holding time is 60 - 120 minutes.

[0011] The etching treatment method in the primary etching treatment is the same as that in the secondary etching treatment, including the following steps: S311. Place the substrate in a vacuum chamber, introduce argon into the vacuum chamber, and control the air pressure at 0.2 - 1 Pa; S312. Turn on the etching arc, perform ion cleaning on the substrate surface, set the arc current at 120 - 150 A, the bias power supply at - 50 - - 800 V, and the duty cycle at 60 - 90%; S313. Turn off the etching arc, adjust the argon flow rate to make the vacuum degree 0.1 - 0.5 Pa, turn on the arc again, and bombard the substrate surface, set the arc current at 120 - 150 A, the bias power supply at - 300 - - 800 V, and the duty cycle at 35 - 70%.

[0012] The coating method in the primary coating treatment is the same as that in the secondary coating treatment, including the following steps: S411. Deposit the underlayer: Place the substrate in a vacuum chamber, adjust the argon flow rate in the vacuum chamber to make the vacuum degree 1 - 1.5 Pa, use a chromium target to coat the substrate surface, with an arc current of 120 - 150 A, a bias power supply of - 80 - - 150 V, and a duty cycle of 35 - 70%; S412. Deposit the transition layer: Adjust the argon flow rate to make the vacuum degree 2 - 3.5 Pa, use a chromium - aluminum target, with an arc current of 120 - 150 A, a bias power supply of - 30 - - 50 V, and a duty cycle of 35 - 70%; S413. Coating the upgraded layer: Adjust the argon flow rate to make the vacuum degree 3 - 4 Pa. Use a composite target, with an arc current of 120 - 150 A, a bias power supply of -30 - -150 V, and a duty cycle of 60 - 80%; S414. Coating the functional layer: Adjust the argon flow rate to make the vacuum degree 3.5 - 4.5 Pa. Use a chromium-aluminum target, with an arc current of 120 - 150 A, a bias power supply of -100 - -180 V, and a duty cycle of 40 - 80%.

[0013] The preparation method of the composite target described in step S414 includes the following steps: A. Prepare 80 - 85 parts by mass of aluminum inorganic salt, 1 - 2 parts of titanium powder, 1 - 3 parts of chromium powder, and 15 - 20 parts of aluminum powder; B. React the aluminum inorganic salt with urea under hydrothermal conditions to form an aluminum precursor. After drying the aluminum precursor, calcine it at 600 - 800 °C to form porous alumina; C. Mix the porous alumina, titanium powder, and chromium powder evenly, then melt the aluminum powder and add it to the mixture and stir evenly to obtain a composite target blank; D. Ball-mill and crush the composite target blank, then put it into a mold and press it into shape to form a green body of the composite target; E. Perform heat treatment on the green body of the composite target, and then machine it to obtain the composite target.

[0014] The heat treatment described in step E is to put the green body of the composite target into a heating furnace, heat it at a rate of 5 - 10 °C / min to 600 - 800 °C, hold for 2 - 3 h, and then heat it at a rate of 1 - 5 °C / min to 850 - 1000 °C, hold for 1 - 2 h.

[0015] The particle size of the porous alumina is 40 - 50 μm, the particle size of the titanium powder is 0.5 - 2 μm, and the particle size of the chromium powder is 0.5 - 2 μm.

[0016] The beneficial effects of the present invention are as follows: 1. In the prior art, in order to increase the film layer thickness, usually the film layer thickness is adjusted by changing the magnetic field of the target and prolonging the coating time. In the present invention, through controlling the parameters of the etching treatment and coating treatment, a double-layer nano-composite coating is formed on the surface of the substrate. The coating process adopts process parameters within a specific range, and during the secondary etching and secondary coating, both the etching time and the coating time are shortened by half. Therefore, on the premise of increasing the film layer thickness, it still has high-temperature oxidation resistance and high-temperature friction resistance.

[0017] 2. In the present invention, etching treatment is adopted between the coating and the substrate and between the coatings. On the one hand, the etching treatment can play a cleaning role, and on the other hand, after the etching treatment, it is beneficial to the diffusion of ions, thereby improving the bonding ability between the coating and the substrate and between the coatings.

[0018] 3. A composite target is also adopted in the present invention. In the traditional technology, in order to improve the wear resistance of the film layer, efforts are usually made to increase the density of the target. However, in the present invention, better wear resistance is obtained through the target with a core-shell structure.

[0019] 4. In the traditional process for preparing the composite target, different metal powders are usually mixed and then directly put into a mold for pressing and forming. However, in the present invention, alumina with a large particle size and a porous structure is first prepared, and then the alumina is mixed with titanium powder and chromium powder with small particle sizes. The titanium powder and chromium powder will enter the pores of the alumina to form a core. Finally, the pores of the alumina are blocked by molten aluminum and together with the alumina form a shell layer. Compared with ordinary aluminum alloys, the core-shell aluminum alloy in the present invention effectively reduces its wear rate and friction coefficient, and at the same time has better toughness, and the probability of brittle spalling of the composite coating is smaller. Specific embodiments

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Embodiment 1

[0021] S1. Pretreatment: Sandblasting: Use the SY-ZPT-A double-station automatic sandblasting machine manufactured by Dongguan Sanyi Machinery Technology Co., Ltd. and perform sandblasting treatment on all surfaces of the substrate with white corundum of 320 mesh. The pressure of the sandblasting treatment is 0.6 MPa, the distance between the nozzle and the substrate is 50 mm, the body rotates with the platform, the nozzle moves up and down at the same time, and the sandblasting time is 12 minutes; Spraying: Use the XL-A-060652 type automatic ultrasonic cleaning machine manufactured by Suzhou Xuelu Ultrasonic Equipment Co., Ltd. and use the cleaning liquid of type 440 of Swiss Enjing (NGL) cleaning agent, with a concentration of 4% and a temperature of 65 °C, and spray for 6 minutes; Ultrasonic cleaning twice: Use the XL-A-060652 type automatic ultrasonic cleaning machine manufactured by Suzhou Xuelu Ultrasonic Equipment Co., Ltd. In the first tank, use the cleaning liquid of type spura of Swiss Enjing (NGL) cleaning agent, with a concentration of 4% and a temperature of 65 °C, and perform ultrasonic cleaning for 6 minutes; in the second tank, use the AC type cleaning liquid of Swiss Enjing, with a concentration of 2%, and perform ultrasonic cleaning for 4 minutes; Rinsing with deionized water twice: The temperature of the first tank is 40 °C, and bubble rinsing is performed for 3 minutes; the temperature of the second tank is 80 °C, and up and down shaking rinsing is performed for 3 minutes; Hot air drying: Set the temperature at 90 °C and perform closed-loop circulating hot air drying for 5 minutes; S2. Vacuum heating treatment: Put the pretreated substrate into the coating machine for heating and pressure maintaining treatment to remove the water vapor and miscellaneous gases volatilized from the surface of the workpiece and the wall of the vacuum chamber. The heating temperature is 520 °C, and the vacuum degree is 3*10 -3Pa, the holding pressure time is 120 minutes; S3. First etching treatment: S311. Place the substrate into the vacuum chamber, introduce argon gas into the vacuum chamber, and control the air pressure at 0.25 Pa; S312. Turn on the etching arc ion source, perform ion cleaning on the substrate surface, set the ion source current at 140 A, the bias power supply at -200 V, and the duty cycle at 85%; S313. Turn off the etching ion source, adjust the argon gas flow rate to make the vacuum degree 0.5 Pa, perform metal bombardment on the substrate surface, turn on the 1-4 chromium target arcs, set the arc current at 1400140 A, the bias power supply at -500 V, the duty cycle at 50%, and the bombardment etching treatment time at 10 min; S4. First coating treatment: S411. Coat the bottom layer: Place the substrate that has undergone the first etching treatment into the vacuum chamber, adjust the argon gas flow rate in the vacuum chamber to make the vacuum degree 1.2 Pa, coat the substrate surface, use a chromium target, the arc current is 130 A, the bias power supply is -100 V, the duty cycle is 60%, and the time is 10 min; S412. Coat the transition layer: Adjust the argon gas flow rate to make the vacuum degree 3 Pa, use a chromium-aluminum target, the arc current is 130 A, the bias power supply is -40 V, the duty cycle is 60%, and the time is 60 min; S413. Coat the upgraded layer: Adjust the argon gas flow rate to make the vacuum degree 3.5 Pa, use a chromium-aluminum target, the arc current is 140 A, the bias power supply is -100 V, the duty cycle is 70%, and the time is 10 min; S414. Coat the functional layer: Adjust the argon gas flow rate to make the vacuum degree 4.13 Pa, use a chromium-aluminum target, the arc current is 150 A, the bias power supply is -150 V, the duty cycle is 78%, and the time is 120 min to form a composite lining coating. S5. Second etching treatment: Perform ion source bombardment etching treatment on the coordination coating surface for 30 min. The parameters of the second etching treatment except for the time are the same as those of the first etching treatment in step S3; S6. Second coating treatment: Coat the bottom layer for 5 min, the transition layer for 30 min, the upgraded layer for 5 min, and the functional layer for 60 min on the coordination coating surface in sequence and form a nano-composite coating. The parameters of the second coating treatment except for the time are the same as those of the first coating treatment in step S4. Example 2

[0022] The difference between Example 2 and Example 1 is only that in Example 2, both upgraded layers of the composite coating use composite targets. The preparation method of the composite target includes the following steps: A. Prepare 82 parts by mass of aluminum inorganic salt, 2 parts of titanium powder, 3 parts of chromium powder, and 18 parts of aluminum powder; B. React the aluminum inorganic salt with urea under hydrothermal conditions to form an aluminum precursor. The molar ratio of the aluminum inorganic salt to urea is [specific ratio]. After drying, the aluminum precursor is calcined at 650 °C to form porous alumina; C. Mix the porous alumina, titanium powder, and chromium powder evenly, and then melt and add the aluminum powder to it and stir evenly to obtain a composite target blank; D. Ball-mill and crush the composite target blank and then put it into a mold for pressing to form a green composite target; E. Put the green composite target into a heating furnace, heat it at a rate of 8 °C / min to 750 °C, hold for 2 h, then heat it at a rate of 3 °C / min to 950 °C, hold for 1 h, and then perform machining to obtain the composite target.

[0023] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is only that in Comparative Example 1, the time of the secondary etching treatment is the same as that of the primary etching treatment.

[0024] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is only that in Comparative Example 2, during the secondary coating treatment, the coating times of the bottom layer, transition layer, upgrade layer, and functional layer are the same as those in the primary treatment respectively.

[0025] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is only that in Comparative Example 3, the preparation method of the composite target is different, and the specific steps are as follows: A. Prepare 82 parts by mass of aluminum inorganic salt, 2 parts of titanium powder, 3 parts of chromium powder, and 18 parts of aluminum powder; B. React the aluminum inorganic salt with urea under hydrothermal conditions to form an aluminum precursor. The molar ratio of the aluminum inorganic salt to urea is [specific ratio]. After drying, the aluminum precursor is calcined at 650 °C to form porous alumina; C. Mix the porous alumina, titanium powder, chromium powder, and aluminum powder evenly to obtain a composite target blank; D. Ball-mill and crush the composite target blank and then put it into a mold for pressing to form a green composite target; E. Put the green composite target into a heating furnace, heat it at a rate of 8 °C / min to 750 °C, hold for 2 h, then heat it at a rate of 3 °C / min to 950 °C, hold for 1 h, and then perform machining to obtain the composite target.

[0026] Performance Test The roll ring prepared in Example 1 was used for 24 h and rolled 4000 tons of steel. The surface of the roll ring was basically not worn before and after use. The coating in the present invention can effectively reduce the loss of the roll ring.

[0027] The roller ring coatings prepared in Examples 1-2 and Comparative Examples 1-3 were respectively tested, and the test results are shown in Table 1.

[0028] Table 1

[0029] As can be seen from Table 1, the composite coatings prepared in Example 1 and Example 2 of the present invention have a moderate thickness, good hardness, high temperature fatigue resistance and wear resistance, and the bonding firmness between the double-layer coatings is good.

Claims

1. A method for applying a nanocomposite coating on a steel rolling roll ring, characterized in that: The following steps are involved: S1. Pretreatment: pretreatment of the surface of the roller ring substrate; S2. Vacuum heating treatment: put the pre-treated roller ring into the coating machine for heating and pressure-maintaining treatment to remove the water vapor and impurities volatilized from the workpiece surface and the vacuum chamber wall; S3, primary etching treatment: performing ion source bombardment etching treatment on the substrate after vacuum heating treatment for 30-120 minutes; S4, primary coating treatment: on the surface of the substrate that has been etched once, a base layer is plated for 8-12 minutes, a transition layer is plated for 40-80 minutes, an upgrade layer is plated for 8-12 minutes, and a functional layer is plated for 80-160 minutes to form a composite lining coating; S5. Secondary etching treatment: ion source bombardment etching treatment is performed on the surface of the composite lining coating for 30-60 minutes; S6. Secondary coating treatment: on the surface of the composite lining coating, a base layer is plated for 4-6 minutes, a transition layer is plated for 20-40 minutes, an upgrading layer is plated for 4-6 minutes, and a functional layer is plated for 40-80 minutes to form a nano-composite coating.

2. The method for applying a nanocomposite coating on a steel rolling roll ring according to claim 1, characterized in that: The pretreatment includes sandblasting, spraying, ultrasonic cleaning, deionized water rinsing and drying.

3. The method for applying a nanocomposite coating on a steel rolling roll ring according to claim 1, characterized in that: The heating temperature of the vacuum heating treatment is 450-550°C, and the vacuum degree is 1-8*10 -3 Pa, the pressure holding time is 60 to 120 minutes.

4. The method for applying a nanocomposite coating on a steel rolling roll ring according to claim 1, characterized in that: The etching method in the primary etching process is the same as the etching method in the secondary etching process, and comprises the following steps: S311, placing the substrate in a vacuum chamber, introducing argon gas into the vacuum chamber, and controlling the gas pressure at 0.2-1 Pa; S312, turn on the etching arc ion source to perform ion cleaning on the substrate surface, set the ion source current to 120-150A, the bias power supply to -50-800V, and the duty cycle to 60-90%; S313. Turn off the etching ion source, adjust the argon gas flow rate to make the vacuum degree 0.1-0.5Pa, turn on the No. 1-4 chromium target arc, and perform metal bombardment on the substrate surface. The arc current is set to 120-150A, the bias power supply is -300-800V, and the duty cycle is 35-70%.

5. The method for applying a nanocomposite coating on a steel rolling roll ring according to claim 1, characterized in that: The coating method in the primary coating process is the same as the coating method in the secondary coating process, and includes the following steps: S411, base coating: put the substrate into a vacuum chamber, adjust the argon gas flow rate in the vacuum chamber to make the vacuum degree 1-1.5Pa, start the arc of chromium targets No. 1-4 to deposit chromium base coating, the arc current is 120-150A, the bias power supply is -80--150V, and the duty cycle is 35-70%; S412, transition layer plating: turn off the argon flow, adjust the argon and nitrogen flow to make the vacuum degree 2-3.5Pa, start the 5-8 chromium aluminum target arc deposition chromium aluminum nitride base layer, arc current 120-150A, bias power supply -30-50V, duty cycle 35-70%; S413, upgrade layer plating: adjust the argon nitrogen flow rate to make the vacuum degree 3-4Pa, use the composite target to start the 5-8 chromium aluminum target arc deposition chromium aluminum nitride upgrade layer, the arc current is 120-150A, the bias power supply is -30--150V, and the duty cycle is 60-80%; S414, functional layer plating: adjust the argon gas flow rate to make the vacuum degree 3.5 ~ 4.5Pa, use chromium aluminum target to start 5-8 chromium aluminum target arc deposition chromium aluminum nitride functional layer, arc current 120 ~ 150A, bias power supply -100 ~ -180V, duty cycle 40 ~ 80%.

6. A method for applying a nanocomposite coating on a steel rolling roll ring according to claim 5, characterized in that: The method for preparing the composite target in step S414 includes the following steps: A. Prepare 80-85 parts of aluminum inorganic salt, 1-2 parts of titanium powder, 1-3 parts of chromium powder, and 15-20 parts of aluminum powder by mass; B. Aluminum inorganic salt and urea are reacted under hydrothermal conditions to generate an aluminum precursor, and the aluminum precursor is dried and then calcined at 600-800° C. to form porous alumina; C. Mix porous alumina, titanium powder and chromium powder evenly, then melt aluminum powder and add them into the mixture and stir evenly to obtain a composite target material blank; D. After the composite target material is ball-milled and crushed, it is placed in a mold for compression molding to form a composite target material green body; E. Heat-treating the composite target green body, and then machining to obtain the composite target.

7. A method for applying a nanocomposite coating on a steel rolling roll ring according to claim 6, characterized in that: The heat treatment in step E is to place the composite target green body into a heating furnace, heat it to 600-800°C at a rate of 5-10°C / min, keep it warm for 2-3h, then heat it to 850-1000°C at a rate of 1-5°C / min, keep it warm for 1-2h.

8. A method for applying a nanocomposite coating on a steel rolling roll ring according to claim 6, characterized in that: The particle size of the porous alumina is 40-50 μm, the particle size of the titanium powder is 0.5-2 μm, and the particle size of the chromium powder is 0.5-2 μm.

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