Aluminum foil roller with WC coating and preparation method of aluminum foil roller

Abstract

The invention discloses an aluminum foil roller with a WC coating and a preparation method of the aluminum foil roller, and belongs to the technical field of metal material surface engineering technologies. A composite coating structure is arranged on the surface of a roller base body and sequentially comprises a transition layer, a gradient layer and a working face layer from inside to outside. According to the structural design, through the pinning effect, micro-metallurgical bonding and gradient transition, the bonding strength of the coating and a base body is greatly improved, stress distribution in the coating is optimized, the roller can effectively resist pressure stress and shear stress of aluminum foil under high rolling force, early-stage stripping and abrasion failure of the coating are fundamentally prevented, and the service life of the roller is prolonged. The service life is obviously prolonged. Meanwhile, the method provides a reliable remanufacturing way for the failed aluminum foil roller, and economic benefits are remarkable.

Description

Technical Field

[0001] This invention belongs to the field of surface engineering technology for metal materials, and specifically relates to an aluminum foil roll with a WC coating and its preparation method. Background Technology

[0002] The aluminum foil production process places extremely high demands on the performance of the rolling mill rolls, which must withstand enormous shearing forces, rolling forces, intense friction, and the adhesion of aluminum. Currently, high-performance aluminum foil rolls often employ high-hardness, high-wear-resistant WC (tungsten carbide)-based cermet coatings for surface strengthening. However, traditional WC coating technology faces the following significant challenges when applied to aluminum foil rolls: 1. Insufficient bonding strength between coating and substrate: Due to the significant differences in physical properties (such as coefficient of thermal expansion and modulus of elasticity) between WC material and the roll substrate (usually high-strength forged steel or cast iron), the coating interface is prone to become the source of crack initiation and propagation under the alternating stress and thermal shock generated by high-speed rolling, leading to coating peeling.

[0003] 2. Internal stress concentration: The internal structure of a single-component WC coating is uniform. When subjected to huge compressive and shear stresses, the stress cannot be effectively dissipated, which can easily lead to transverse cracks in the coating and eventually failure.

[0004] 3. Poor resistance to peeling: In aluminum foil rolling, the roll surface is subjected not only to wear, but more importantly, to enormous shear stress caused by high rolling forces. This places extremely high demands on the coating's resistance to peeling. Traditional coatings are prone to premature peeling failure under these conditions, rather than normal wear failure, which greatly shortens the roll's service life.

[0005] 4. Difficulty in remanufacturing rolls: If the coating peels off after a roll fails, it will damage the substrate, making it difficult to guarantee the performance of the repaired coating. Often, the rolls can only be scrapped, which is very costly.

[0006] Therefore, developing a WC coating technology for aluminum foil rolls that can achieve high-strength bonding between the coating and the substrate, optimized distribution of internal stress, significantly improved anti-stripping ability and wear resistance, and support efficient remanufacturing has significant engineering application value and economic benefits. Summary of the Invention

[0007] In view of the above-mentioned prior art, the present invention provides an aluminum foil roll with WC coating and its preparation method, so as to solve the technical problems of insufficient bonding strength between coating and substrate and poor anti-peeling ability.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is to provide an aluminum foil roll with a WC coating, comprising a roll substrate and a working layer attached to the surface of the roll substrate; the working layer is a composite structure, comprising a transition layer, a gradient layer and a working surface layer from the inside out; the transition layer is a metal alloy layer prepared by high-speed thermal spraying technology, which forms a mechanically interlocked and micro-metallurgically bonded interface with the roughened surface of the roll substrate; the gradient layer comprises a WC ceramic phase and a metal binder phase, and the proportion of the WC ceramic phase in the gradient layer gradually increases from the inside out; the working surface layer comprises WC cemented carbide powder and an additive capable of forming a micro-metallurgical bond and pinning effect with the WC cemented carbide powder.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, high-speed thermal spraying technology includes supersonic flame spraying, high-speed air fuel spraying, explosive spraying, or super-speed explosive spraying.

[0011] Furthermore, the surface texturing treatment of the roll substrate can be electrical discharge texturing, laser texturing, or plasma texturing.

[0012] Furthermore, the transition layer is made of NiAl, NiCr, NiCrAl, NiCrAlY or a metal alloy containing at least one of Ti, Zr and Hf; the thickness of the transition layer is 45~55μm.

[0013] Furthermore, the content of WC ceramic phase in the gradient layer transitions from 50wt% to 95wt% from the inside to the outside; the thickness of the gradient layer is 50~300μm.

[0014] Furthermore, the particle size of the WC ceramic phase is -30 / +5 μm.

[0015] Furthermore, the metal binder phase is NiAl, NiCr, NiCrAl, NiCrAlY, or a metal alloy containing at least one of Ti, Zr, and Hf; the particle size of the metal binder phase is -45 / +15 μm.

[0016] Furthermore, the additive is NiAl, NiCr, NiCrAl, NiCrAlY or a metal alloy containing at least one of Ti, Zr and Hf; the additive accounts for 0 to 20% of the mass of WC cemented carbide powder.

[0017] Furthermore, the thickness of the working surface layer is 190~210μm.

[0018] This invention also discloses a method for preparing the above-mentioned aluminum foil roll with WC coating, comprising the following steps: S1: The surface of the roll substrate is roughened; S2: High-speed thermal spraying technology is used to spray metal alloy powder onto the surface of the roughened roll substrate to form a transition layer; S3: By controlling the powder feeding rate of the WC ceramic phase and the metal binder phase, a gradient layer is formed by spraying on the transition layer; S4: On the gradient layer, a mixed powder containing WC cemented carbide powder and additives is sprayed to form a working surface layer; S5: After spraying, the roller is finely ground and polished to obtain the final product.

[0019] The beneficial effects of this invention are: This invention involves creating a composite coating structure on the surface of the roll substrate. The composite coating structure, from the inside out, comprises a transition layer, a gradient layer, and a working surface layer. This structural design, through pinning effect, micrometallurgical bonding, and gradient transition, significantly improves the bonding strength between the coating and the substrate, and optimizes the stress distribution within the coating. This enables the roll to effectively resist the compressive and shear stresses under the high rolling force of aluminum foil, fundamentally preventing premature peeling and wear failure of the coating, and significantly extending its service life. Simultaneously, the method of this invention provides a reliable remanufacturing pathway for failed aluminum foil rolls, resulting in significant economic benefits. Detailed Implementation

[0020] This invention discloses an aluminum foil roll with a WC coating, comprising a roll substrate and a working layer attached to the surface of the roll substrate; wherein, the working layer is a composite structure, comprising, from the inside out, a transition layer, a gradient layer, and a working surface layer; the transition layer is a metal alloy layer prepared by high-speed thermal spraying technology, which forms a mechanically interlocked and micro-metallurgically bonded interface with the roughened surface of the roll substrate; the gradient layer comprises a WC ceramic phase and a metal binder phase, and the proportion of the WC ceramic phase in the gradient layer gradually increases from the inside out; the working surface layer comprises WC cemented carbide powder and an additive capable of forming a micro-metallurgical bond and pinning effect with the WC cemented carbide powder. The aluminum foil roll with the WC coating is prepared by the following steps: (1) Substrate pretreatment: The surface of the roll substrate is cleaned and then roughened. It is preferred to use a combination of macro-roughening and micro-roughening. For example, sandblasting is performed first: 24-mesh brown corundum sand is used to clean and macro-roughen the roll surface under a pressure of 0.6MPa, so that the surface roughness Ra reaches 8~10μm. Then, the roughening process is carried out by electrical discharge machining, laser roughening or plasma roughening. The laser roughening process is as follows: fiber laser roughening equipment is used, and the parameters are set so that the roughening pit density is 8×10 pits / square millimeter. The laser pulse width and energy control the pit depth. Finally, a regular and uniform array of micro-pits is formed on the macro-ripples formed by sandblasting, so that the overall surface morphology meets the mechanical interlocking requirements. The electrical discharge machining process is as follows: the parameters of energizing time of 800μs, current of 6A, electrode gap of 3.0mm and roll speed of 10rpm are used to roughen the surface in 3 passes to obtain a regular pit surface with Ra of about 0.7μm.

[0021] (2) Employing supersonic flame spraying (HVOF), high-speed air-fuel spraying (HVAF), detonation spraying (D-Gun), or super-velocity detonation spraying (Super D-Gun process for spraying transition layer: Select NiAl, NiCr, NiCrAl, NiCrAlY or metal alloy powder containing at least one of Ti, Zr and Hf (particle size -45 / +15μm) as the spraying material. Under the conditions of spraying distance of 250~400mm, powder feeding rate of 25~50g / min and precise control of fuel (e.g. kerosene 14~26 liters / hour) and oxygen flow, the semi-molten metal alloy powder particles are sprayed onto the surface of the pre-textured roll at a speed of more than 600m / s to form a transition layer with a thickness of 45~55μm. Through the impact of high kinetic energy particles, they are fully filled and plastically deformed in the micro-pits on the surface, thereby achieving mechanical interlocking. With the help of local high temperature, element interdiffusion is induced at the interface to form a crucial micro-metallurgical bond, providing a strong and tough substrate for subsequent gradient functional coating.

[0022] (3) Gradient Layer Spraying: A gradient layer is prepared on the transition layer using a high-velocity oxygen fuel (HVOF) spraying system equipped with dual powder feeders. Powder feeder one is loaded with NiAl, NiCr, NiCrAl, NiCrAlY, or a metal alloy powder containing at least one of Ti, Zr, and Hf (particle size -45 / +15μm), while powder feeder two is loaded with WC-based cermet powder (particle size -30 / +5μm). Through program control, during the spraying of a gradient layer with a total thickness of 50~300μm, the powder feed rate in powder feeder one is linearly reduced from 50% to 5%, while the powder feed rate in powder feeder two is linearly increased from 50% to 95%. The spraying distance is maintained at 300~400mm, and other main process parameters (such as fuel and oxygen flow rates) are kept consistent with those used when spraying the working surface layer to ensure the coating density. Through this method, a functional gradient layer with a continuously increasing WC ceramic phase content from the inside out and a correspondingly decreasing metal binder phase content can be obtained.

[0023] (4) Spraying a wear-resistant working surface layer: Using optimized sonic flame spraying (HVOF), high-speed air fuel spraying (HVAF), explosion spraying (D-Gun), or super-speed explosion spraying (Super D-Gun) processes, a mixed powder composed of WC cemented carbide powder and additives is sprayed to form a high-hardness, high-wear-resistant working surface layer with a thickness of 190~210μm. The additives are NiAl, NiCr, NiCrAl, NiCrAlY, or metal alloys containing at least one of Ti, Zr, and Hf, and the additives account for 0~20% of the mass of WC cemented carbide powder. Preheat the roller surface to approximately 100°C before spraying. During spraying, control the kerosene flow rate to 16-26 L / h, match the oxygen flow rate, maintain a spraying distance of 250-400 mm, and a powder feeding rate of 25-60 g / min. Match the spray gun movement speed with the roller rotation speed to ensure uniform coverage. Continuously use compressed air to cool the roller surface during spraying to ensure the interlayer temperature is below 150°C. Repeat spraying until the coating thickness reaches approximately 190-210 μm. The porosity of this working surface layer is less than 1%, the microhardness is not less than 1200 HV0.3, and the bonding strength with the gradient layer is excellent.

[0024] (5) Post-treatment: After the coating is prepared, fine grinding and polishing are carried out to make the surface of the roll reach the roughness and smoothness required for aluminum foil production.

[0025] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0026] Example 1 An aluminum foil roll with a WC coating is obtained by the following steps: (1) Matrix pretreatment: The surface of the roll matrix (86CrMoV7 forged steel roll) is cleaned. The cleaning method is to use 24-mesh brown corundum sand to clean and macro-roughen the roll surface under a pressure of 0.6MPa, so that the surface roughness Ra reaches about 9μm. Then, laser texturing process is used for texturing. The laser texturing process is to use fiber laser texturing equipment, set the parameters to make the texturing pit density 8×10 pits / square millimeter, and control the pit depth (Ra about 0.7μm) by adjusting the laser pulse width and energy. Finally, a regular and uniform array of micro pits is formed on the macro undulations formed by sandblasting.

[0027] (2) High-speed air fuel spraying (HVAF) process is used to spray the transition layer: NiCrAlY powder (particle size -45 / +15μm) is selected as the spraying material. Under the conditions of spraying distance of 300mm, powder feeding rate of 30g / min and control of kerosene flow rate of 20L / h and corresponding oxygen flow rate, semi-molten NiCrAlY powder particles are sprayed onto the surface of the pre-textured roll at a speed of 800m / s to form a transition layer with a thickness of about 50μm. Through the impact of high kinetic energy particles, they are fully filled and plastically deformed in the micro-pits on the surface, thereby achieving mechanical interlocking. With the help of local high temperature, element interdiffusion is induced at the interface to form a crucial micro-metallurgical bond, providing a strong and tough substrate for subsequent gradient functional coating.

[0028] (3) Gradient Layer Spraying: A gradient layer is prepared on the transition layer using a high-speed air-fuel spraying (HVAF) device equipped with dual powder feeders. Powder feeder one is loaded with NiCrAlY powder (particle size -45 / +15μm), and powder feeder two is loaded with WC-10Co-4Cr powder (particle size -30 / +5μm). Through program control, during the spraying of a gradient layer with a total thickness of 150μm, the powder feeding rate in powder feeder one is linearly reduced from 50% to 5%, while the powder feeding rate in powder feeder two is linearly increased from 50% to 95%. During spraying, the kerosene flow rate is controlled at 20L / h, matched with the oxygen flow rate, the spraying distance is 300mm, the powder feeding rate is 30g / min, and the spray gun movement speed is matched with the roller rotation speed to ensure uniform coverage. Through this method, a functional gradient layer in which the WC ceramic phase content continuously increases from the inside to the outside and the metal binder phase content decreases accordingly can be obtained.

[0029] (4) Spraying a wear-resistant working surface layer: A mixed powder consisting of WC-10Co-4Cr powder and additives is sprayed using a high-speed air fuel spraying (HVAF) process to form a high-hardness, high-wear-resistant working surface layer with a thickness of 200μm. The additive is NiCrAlY, which accounts for 10% of the mass of WC-10Co-4Cr powder. Before spraying, the roller surface is preheated to about 100℃. During spraying, the kerosene flow rate is controlled at 20L / h, matched with the oxygen flow rate, the spraying distance is 300m, the powder feeding rate is 30g / min, and the spray gun moving speed is matched with the roller rotation speed to ensure uniform coverage. Compressed air is continuously used to cool the roller surface during the spraying process to ensure that the interlayer temperature is below 150℃. Spraying is repeated until the coating thickness reaches about 200μm. The porosity of this working surface layer is less than 1%, the microhardness is not less than 1200 HV0.3, and the bonding strength with the gradient layer is excellent.

[0030] (5) Post-treatment: After the coating is prepared, fine grinding and polishing are carried out to make the surface of the roll reach the roughness and smoothness required for aluminum foil production.

[0031] Example 2 An aluminum foil roll with a WC coating is obtained by the following steps: (1) Substrate pretreatment: The surface of the roll substrate (86CrMoV7 forged steel roll) is cleaned. The cleaning method is to use 24-mesh brown corundum sand to clean and macro-roughen the roll surface under a pressure of 0.6MPa, so that the surface roughness Ra reaches about 9μm. Then, the surface roughness Ra is roughened by the electrical discharge machining process. The electrical discharge machining process is to use fiber laser roughening equipment, set the parameters to make the roughening pit density 8×10 pits / square millimeter, and use the parameter combination of energizing time 800μs, current 6A, electrode gap 3.0mm and roll speed 10rpm to roughen 3 times to obtain a regular pit surface with Ra of about 0.7μm.

[0032] (2) High-speed air fuel spraying (HVAF) process is used to spray the transition layer: NiCrAl powder (particle size -45 / +15μm) is selected as the spraying material. Under the conditions of spraying distance of 250mm, powder feeding rate of 25g / min and control of kerosene flow rate of 14L / h and corresponding oxygen flow rate, semi-molten NiCrAl powder particles are sprayed onto the surface of the pre-textured roll at a speed of 800m / s to form a transition layer with a thickness of about 45μm. Through the impact of high kinetic energy particles, they are fully filled and plastically deformed in the micro-pits on the surface, thereby achieving mechanical interlocking. With the help of local high temperature, element interdiffusion is induced at the interface to form a crucial micro-metallurgical bond, providing a strong and tough substrate for subsequent gradient functional coating.

[0033] (3) Gradient Layer Spraying: A gradient layer is prepared on the transition layer using a high-speed air-fuel spraying (HVAF) device equipped with dual powder feeders. Powder feeder one is loaded with NiCrAl powder (particle size -45 / +15μm), and powder feeder two is loaded with WC-17Co powder (particle size -30 / +5μm). Through program control, during the spraying of a gradient layer with a total thickness of 50μm, the powder feeding rate in powder feeder one is linearly reduced from 50% to 5%, while the powder feeding rate in powder feeder two is linearly increased from 50% to 95%. During spraying, the kerosene flow rate is controlled at 14L / h, matched with the oxygen flow rate, the spraying distance is 250mm, the powder feeding rate is 25g / min, and the spray gun movement speed is matched with the roller rotation speed to ensure uniform coverage. Through this method, a functional gradient layer in which the WC ceramic phase content continuously increases from the inside to the outside and the metal binder phase content decreases accordingly can be obtained.

[0034] (4) Spraying a wear-resistant working surface layer: A mixed powder consisting of WC-17Co powder and additives is sprayed using a high-speed air fuel spraying (HVAF) process to form a high-hardness, high-wear-resistant working surface layer with a thickness of 200μm. The additive is NiCrAl, which accounts for 20% of the mass of WC-17Co powder. Before spraying, the roller surface is preheated to about 100℃. During spraying, the kerosene flow rate is controlled at 14L / h, matched with the oxygen flow rate, the spraying distance is 250mm, the powder feeding rate is 25g / min, and the spray gun moving speed is matched with the roller rotation speed to ensure uniform coverage. Compressed air is continuously used to cool the roller surface during the spraying process to ensure that the interlayer temperature is below 150℃. Spraying is repeated until the coating thickness reaches about 200μm. The porosity of this working surface layer is less than 1%, the microhardness is not less than 1200 HV0.3, and the bonding strength with the gradient layer is excellent.

[0035] (5) Post-treatment: After the coating is prepared, fine grinding and polishing are carried out to make the surface of the roll reach the roughness and smoothness required for aluminum foil production.

[0036] Example 3 An aluminum foil roll with a WC coating is obtained by the following steps: (1) Substrate pretreatment: The surface of the roll substrate (86CrMoV7 forged steel roll) is cleaned. The cleaning method is to use 24-mesh brown corundum sand to clean and macro-roughen the roll surface under a pressure of 0.6MPa, so that the surface roughness Ra reaches about 9μm. Then, the surface roughness Ra is roughened by the electrical discharge machining process. The electrical discharge machining process is to use fiber laser roughening equipment, set the parameters to make the roughening pit density 8×10 pits / square millimeter, and use the parameter combination of energizing time 800μs, current 6A, electrode gap 3.0mm and roll speed 10rpm to roughen 3 times to obtain a regular pit surface with Ra of about 0.7μm.

[0037] (2) High-speed air fuel spraying (HVAF) process is used to spray the transition layer: NiCr powder (particle size -45 / +15μm) is selected as the spraying material. Under the conditions of spraying distance of 400mm, powder feeding rate of 50g / min and control of kerosene flow rate of 26L / h and corresponding oxygen flow rate, semi-molten NiCr powder particles are sprayed onto the surface of the pre-textured roll at a speed of 800m / s to form a transition layer with a thickness of about 55μm. Through the impact of high kinetic energy particles, they are fully filled and plastically deformed in the micro-pits on the surface, thereby achieving mechanical interlocking. With the help of local high temperature, element interdiffusion is induced at the interface to form a crucial micro-metallurgical bond, providing a strong and tough substrate for subsequent gradient functional coating.

[0038] (3) Gradient Layer Spraying: A gradient layer is prepared on the transition layer using a high-speed air-fuel spraying (HVAF) device equipped with dual powder feeders. Powder feeder one is loaded with NiCr powder (particle size -45 / +15μm), and powder feeder two is loaded with WC-10Co-4Cr powder (particle size -30 / +5μm). Through program control, during the spraying of a gradient layer with a total thickness of 300μm, the powder feeding rate in powder feeder one is linearly reduced from the initial 50% to 5%, while the powder feeding rate in powder feeder two is linearly increased from 50% to 95%. During spraying, the kerosene flow rate is controlled at 26L / h, matched with the oxygen flow rate, the spraying distance is 400mm, the powder feeding rate is 60g / min, and the spray gun movement speed is matched with the roller rotation speed to ensure uniform coverage. Through this method, a functional gradient layer in which the WC ceramic phase content continuously increases from the inside to the outside and the metal binder phase content decreases accordingly can be obtained.

[0039] (4) Spraying a wear-resistant working surface layer: WC-10Co-4Cr powder is sprayed using high-speed air fuel spraying (HVAF) technology to form a high-hardness, high-wear-resistant working surface layer with a thickness of 200μm. Before spraying, the roller surface is preheated to about 100℃; during spraying, the kerosene flow rate is controlled at 26L / h, matched with the oxygen flow rate, the spraying distance is 400mm, the powder feeding rate is 60g / min, and the spray gun moving speed is matched with the roller rotation speed to ensure uniform coverage; during the spraying process, compressed air is continuously used to cool the roller surface to ensure that the interlayer temperature is below 150℃; spraying is repeated until the coating thickness reaches about 200μm; the porosity of this working surface layer is less than 1%, the microhardness is not less than 1200 HV0.3, and the bonding strength with the gradient layer is excellent.

[0040] (5) Post-treatment: After the coating is prepared, fine grinding and polishing are carried out to make the surface of the roll reach the roughness and smoothness required for aluminum foil production.

[0041] Experimental Example The bonding strength between the WC coating and the roll interface was tested by tensile testing. Specifically, the bonding strength between the WC-coated aluminum foil roll prepared in Example 1 and the substrate reached 82.8 MPa; the bonding strength between the WC-coated aluminum foil roll prepared in Example 2 and the substrate reached 81.4 MPa; and the bonding strength between the WC-coated aluminum foil roll prepared in Example 3 and the substrate reached 84.1 MPa. This indicates that the preparation process of this invention can achieve a strong and tough bond between the coating and the substrate.

[0042] The surface hardness and wear resistance of the aluminum foil rolls with WC coating prepared in the examples were tested. Among them, the aluminum foil roll with WC coating prepared in Example 1 had a coating surface microhardness as high as 1200 HV, and the wear rate was reduced by about 40% compared with the traditional roll coating in the aluminum foil rolling simulated wear test. The aluminum foil roll with WC coating prepared in Example 2 had a coating surface microhardness as high as 1170 HV, and the wear rate was reduced by about 37% compared with the traditional roll coating in the aluminum foil rolling simulated wear test. The aluminum foil roll with WC coating prepared in Example 3 had a coating surface microhardness as high as 1260 HV, and the wear rate was reduced by about 43% compared with the traditional roll coating in the aluminum foil rolling simulated wear test.

[0043] In actual aluminum foil rolling production, the aluminum foil roll with WC coating in Example 1 was used. The continuous service life of the composite coated roll was increased by more than 50% on average compared with the traditional roll, and the failure mode changed from severe local peeling to uniform wear, which greatly improved the reliability.

[0044] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. An aluminum foil roll with a WC coating, characterized in that: The system includes a roll substrate and a working layer attached to the surface of the roll substrate. The working layer is a composite structure, comprising a transition layer, a gradient layer, and a working surface layer from the inside out. The transition layer is a metal alloy layer prepared by high-speed thermal spraying technology, which forms a mechanically interlocked and micro-metallurgically bonded interface with the roughened surface of the roll substrate. The gradient layer consists of a WC ceramic phase and a metal binder phase, and the proportion of the WC ceramic phase in the gradient layer gradually increases from the inside out. The working surface layer consists of WC cemented carbide powder and an additive capable of forming a micro-metallurgical bond and pinning effect with the WC cemented carbide powder.

2. The aluminum foil roll with WC coating according to claim 1, characterized in that: The high-speed thermal spraying technology includes supersonic flame spraying, high-speed air-fuel spraying, explosive spraying, or supersonic explosive spraying.

3. The aluminum foil roll with WC coating according to claim 1, characterized in that: The surface texturing treatment of the roll substrate can be electrical discharge texturing, laser texturing, or plasma texturing.

4. The aluminum foil roll with WC coating according to claim 1, characterized in that: The transition layer is made of NiAl, NiCr, NiCrAl, NiCrAlY or a metal alloy containing at least one of Ti, Zr and Hf; the thickness of the transition layer is 45~55μm.

5. The aluminum foil roll with WC coating according to claim 1, characterized in that: The content of WC ceramic phase in the gradient layer transitions from 50wt% to 95wt% from the inside to the outside; the thickness of the gradient layer is 50~300μm.

6. The aluminum foil roll with WC coating according to claim 1, characterized in that: The particle size of the WC ceramic phase is -30 / +5μm.

7. The aluminum foil roll with WC coating according to claim 6, characterized in that: The metal binder phase is NiAl, NiCr, NiCrAl, NiCrAlY, or a metal alloy containing at least one of Ti, Zr, and Hf; the particle size of the metal binder phase is -45 / +15 μm.

8. The aluminum foil roll with WC coating according to claim 1, characterized in that: The additive is NiAl, NiCr, NiCrAl, NiCrAlY or a metal alloy containing at least one of Ti, Zr and Hf; the additive accounts for 0 to 20% of the mass of WC cemented carbide powder.

9. The aluminum foil roll with WC coating according to claim 1, characterized in that: The thickness of the working surface layer is 190~210μm.

10. The method for preparing the aluminum foil roll with WC coating according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: The surface of the roll substrate is roughened; S2: High-speed thermal spraying technology is used to spray metal alloy powder onto the surface of the roughened roll substrate to form a transition layer; S3: By controlling the powder feeding rate of the WC ceramic phase and the metal binder phase, a gradient layer is formed by spraying on the transition layer; S4: On the gradient layer, a mixed powder containing WC cemented carbide powder and additives is sprayed to form a working surface layer; S5: After spraying, the roller is finely ground and polished to obtain the final product.