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Spray coating processing SPRAY PROCESSING
The Application of Thermal Spraying Technology in the Modern Iron and Steel Industry
Application of Thermal Spraying Technology in Modern Steel Industry Steel production—from raw materials to finished products—involves numerous processes, including raw material handling, ironmaking, steelmaking, pressure processing, and surface treatment. The equipment used is extensive and predominantly large-scale and heavy-duty. Due to the harsh operating conditions in steel production, many pieces of equipment suffer from failure and damage caused by high temperatures, wear, and corrosion, seriously affecting improvements in production efficiency and product quality. With advancing technology, the steel industry increasingly needs new technologies that are automated, high-speed, and high-quality, placing ever-higher demands on equipment performance. Therefore, enhancing equipment performance and extending equipment service life have become urgent issues for the steel industry to improve enterprise economic benefits and strengthen competitiveness in the commodity market. Thermal spraying technology boasts advantages such as a wide variety of sprayable materials, the ability to impart multiple functions—including wear resistance, corrosion resistance, and high-temperature resistance—to workpiece surfaces, and its simple, flexible, and easy-to-operate nature. It is particularly well-suited for on-site construction and localized repair of components. Thus, thermal spraying technology is not only an effective method for surface strengthening and pre-protection of new equipment but also a cost-effective and efficient means for on-site equipment maintenance. In the steel industry, it has been widely applied to various general mechanical components, such as shafts, valves, and fans, achieving remarkable protective effects and significant economic benefits. With recent advances in thermal spraying technology—such as the introduction of high-energy, high-speed plasma equipment and high-speed flame spraying techniques—as well as the continuous development of new, high-quality spray materials, previously identified weaknesses of thermal-sprayed coatings, such as low bonding strength and poor impact resistance, have been overcome. The application of these new thermal-spraying methods has brought about a qualitative leap in coating quality; coating porosity can now be reduced to 0.5–1.0%, and the bonding strength between the coating and substrate can reach as high as 70–140 MPa. As a result, the application of thermal-sprayed coatings in the steel industry has not only expanded in scope but has also extended into higher-load applications. According to reports, at Nippon Steel’s Nagoya Works, the use of thermal spraying as a surface-modification method for working rolls has been steadily increasing. In 1990, the coated area of working rolls at this plant was only 90 m², whereas by 1995 it had reached 456 m²—a more than fivefold increase. Coatings have also achieved excellent results when applied to rollers in high-value-added surface-treated steel manufacturing processes—for example, annealing furnace rollers and molten-galvanized immersion rollers. Typical applications of thermal spraying technology in modern steel industry include: 1. Continuous Casting Mold Copper Plates The surface of continuous casting mold copper plates suffers wear due to friction from the solidifying metal layer. Traditionally, chrome plating has been used to enhance the wear resistance of the mold surface. However, the hardness of chrome layers drops rapidly at high temperatures (Figure 1), resulting in less-than-ideal protective effects. By adopting self-fluxing alloy coatings that maintain their hardness at high temperatures and using technical measures to strengthen the bond between the coating and substrate, the service life of coated continuous casting mold copper plates has exceeded 1,000 hours (1 hour = 250 tons)—more than three times that of chrome-plated molds. Figure 1: High-Temperature Hardness Comparison Between Sprayed Coatings and Chrome Plating 2. Continuous Casting Rolls Supporting rolls, guide rolls, and clamping rolls in continuous casting lines often develop large cracks around the circumference of the roll surface due to various stresses and thermal fatigue, leading to roll failure. After strengthening the roll surface with self-fluxing alloys, the coating produces only tiny microcracks along grain boundaries during operation, with extremely slow crack propagation rates. This significantly extends the service life of continuous casting rolls and prevents surface defects in castings, thereby improving casting quality. 3. Cold-Rolling Mill Rolls Cold-rolling mill rolls (such as tension rolls, guide rolls, and straightening rolls) require surfaces that are highly wear-resistant, with minimal changes in surface roughness during use and consistent clamping force. These rolls were traditionally surface-chrome-plated, but their wear resistance was insufficient, shortening their service life. After applying thermal-sprayed coatings followed by special treatments, the surface roughness changes very slowly, and the clamping force remains stable (Figure 2). Tests show that the wear resistance of specially treated coated rolls is 5–10 times greater than that of chrome-plated rolls. Figure 2: Changes in Surface Roughness of Various Coatings 4. Continuous Annealing Furnace Rolls Continuous annealing furnaces typically consist of heating zones, temperature-homogenizing zones, and cooling zones. Steel sheets are heated and processed while being wrapped around furnace rolls arranged inside the furnace at a 180° angle. Oxides on the steel sheet surface are reduced to iron under the furnace atmosphere and adhere to the roll surface, forming scale buildup. When the steel sheet passes over the roll surface, it leaves behind pits that affect the surface quality of the steel. With the rapid development of the automotive industry, higher requirements have been placed on the surface quality of cold-rolled and galvanized steel sheets. To improve steel quality, CAPL and CGL furnace roll coating technology has emerged. This coating technology originated in Japan in the 1980s and was widely adopted for almost all CAPL and CGL furnace rolls by the mid-1980s. It wasn’t until the late 1980s that it gained attention and began to be applied in Europe and the United States. Furnace roll coating technology involves using thermal spraying to apply a coating with low affinity for iron, a thermal expansion coefficient matching that of the furnace roll substrate, and high-temperature wear resistance that maintains surface roughness over time. Such coatings reduce scale buildup on the roll surface, enabling the production of high-quality automotive steel sheets with excellent surface quality. A series of coating materials have been developed to suit different processing temperatures and application needs. Currently, research on new furnace roll coating materials remains active. Reports indicate that countries such as Japan and the U.S. have successively developed coating materials containing borides and nitrides, all exhibiting outstanding anti-scale properties, with furnace roll lifespans reaching up to six years. 5. Molten-Galvanizing Production Line Components Immersion rolls, stabilizing rolls, roller bearings, and bearing supports in molten-galvanizing production lines are immersed in Zn liquid at 450–480°C, enduring severe corrosion and wear from the Zn liquid. Their service lives are generally short. Preventing Zn penetration into the coating material is crucial. Figure 3 shows the corrosion resistance of various materials and coatings against molten Zn. As shown in the figure, stainless steels like SUS304 suffer intense corrosion within a short period; Co-based self-fluxing alloys offer better resistance to molten Zn than the aforementioned stainless steels, though with considerable variation; WC-Co demonstrates the best resistance to molten Zn. According to reports, immersion rolls coated with Co-based self-fluxing alloys can last 150–180 days. Figure 3: Corrosion Resistance of Sprayed Coatings and Stainless Steels Against Molten Zinc 6. Conductive Electroplating Rollers Conductive rollers used for tin plating and galvanizing are made from Fe- and Cu-based conductive materials and Hastelloy corrosion-resistant alloys, with Ni or Cr plating on their surfaces. Due to corrosion, wear, and the adhesion of foreign substances during electroplating, their service lives are very short. Generally, ideal conductive roller coating materials should possess the following characteristics: (1) Conductivity meeting the requirements of the electroplating process; (2) Resistance to corrosion and wear without causing significant changes in surface condition; (3) Surfaces that are difficult to accumulate or electrodeposited foreign substances, and if they do accumulate, they should be easily removable. Several schemes for conductive roller coating materials have been reported, among which an amorphous sprayed coating remained unchanged after 70 days of practical use, while the service life of Cr-plated rollers was only 30 days. 7. Conclusion As the steel industry continues to demand stronger surface protection for equipment components, thermal spraying technology—being both practical and effective—will undoubtedly see even wider application in the steel industry. Guangzhou Sanxin Thermal Spraying specializes in the manufacture of various thermal spraying equipment, including plasma spraying equipment, supersonic spraying equipment, arc spraying equipment, zinc-spraying machines, aluminum-spraying machines, flame powder spraying equipment, flame wire spraying equipment, flame plastic-coating equipment, and various thermal-sprayed coating services, ceramic coating services, and tungsten carbide coating services.
电弧喷涂设备
喷锌机
喷铝机
火焰粉末喷涂设备
Product Description
The Application of Thermal Spraying Technology in the Modern Steel Industry
Steel production—from raw materials to finished products—involves a variety of processes, including raw material processing, ironmaking, steelmaking, pressure processing, and surface treatment. , The equipment used is numerous and mostly large, heavy-duty machinery. This is because the operating conditions in steel production are extremely harsh. , In production, a large number of equipment failures and damages occur due to factors such as high temperatures, wear, and corrosion. , It severely hinders the improvement of production efficiency and product optimization. As times advance, , The iron and steel industry needs to widely adopt new technologies that are essential for automation, high speed, and high quality. , Higher requirements are placed on equipment performance. Therefore, , Improving the operational performance of equipment and extending its service life have become pressing issues that the iron and steel industry must address urgently in order to enhance enterprise economic efficiency and strengthen its competitiveness in the commodity market.
Thermal spraying technology features a wide variety of sprayable materials. , It can impart multiple functions to the workpiece surface, such as wear resistance, corrosion resistance, and high-temperature resistance, while also featuring simple and flexible processes and operations. , Particularly suitable for on-site construction and localized repair of workpieces. Therefore, , Thermal spraying technology is not only an effective method for surface strengthening and pre-protection of new equipment. , Moreover, it is an effective and economical method for on-site equipment maintenance. , It has been widely used in the steel industry for various general-purpose mechanical components. , Reinforcement and repair of various shaft components, valves, fans, and the like. , and has achieved remarkably significant protective effects and economic benefits. With the advancements in thermal spraying technology in recent years, , The successive introduction of high-energy, high-speed plasma equipment and high-speed flame spraying technology, among others. , As well as the continuous development of various new, high-quality spraying materials. , This has enabled overcoming the previous weaknesses of thermal spray coatings, such as low bonding strength and poor impact resistance. The application of new thermal spraying techniques has brought about a qualitative leap in coating quality. , Coating porosity can be reduced to 0.5 – 1.0%, The bonding strength between the coating and the substrate can be as high as 70 – 140 MPa Therefore, the application of thermal spray coatings in the steel industry has not only expanded in scope. , Moreover, it is expanding into higher-load applications. According to reports, the new Nippon Steel Nagoya Steelworks... , The application of thermal spraying as a surface modification method for processing rollers is steadily increasing. , The coated area of the rollers processed by this plant. 1990 Only for the year 90 M2, And 1995 The annual figure reaches 456 M2 Growth reaches 5 Multiple times. Rollers used in the surface treatment steel plate manufacturing process, which involves high-value-added coatings. ( Such as annealing furnace rollers and molten galvanizing immersion rollers, etc. ) Its application has also achieved excellent results.
Typical applications of thermal spraying technology in the modern steel industry include:
1. Continuous casting mold copper plate
The surface of the copper plates in continuous casting molds wears down due to friction from the solidifying metal layer. , Chromium plating has long been used to enhance the wear resistance of mold surfaces. However, the hardness of chromium coatings decreases rapidly at high temperatures. ( Figure 1), Its protective performance is not entirely ideal. After adopting a self-fluxing alloy coating that does not significantly lose hardness at high temperatures and supplementing it with technical measures to enhance the bonding between the coating and the substrate, , The durability of the copper plates used in coated continuous casting molds exceeds... 1000 ch￠s (1 ch = 250 ton ), For the chrome plating layer 3 More than double.
Figure 1 High-Temperature Hardness of Spray-Coated and Chrome-Plated Layers
2. Continuous casting roll
In continuous casting production lines, components such as support rolls, guide rolls, and clamping rolls are often affected by various factors, including different types of stress and thermal fatigue. , Large cracks develop in the circumferential direction of the roll surface, leading to roll failure and malfunction. After reinforcing the roll surface with a self-melting alloy, ... , During use, this coating develops only tiny microcracks with a very low crack propagation rate along its grain boundaries. , It significantly extends the service life of continuous casting rolls and also prevents surface defects from occurring in the cast material. , Improved the quality of the castings.
3. Cold-rolled processing roll
Processing rollers in the cold rolling production line ( Such as tension rollers, guide rollers, and straightening rollers. ) Requires its surface to be wear-resistant. , The change in surface roughness during use should be minimal. , It features a constant clamping force. This roller typically has a chrome-plated surface. , But its wear resistance is insufficient. , affect the service life. However, after applying a thermal spray coating and subjecting it to special treatment, , The change in its surface roughness is very slow. , The surface clamping force is not easy to decrease. ( Figure 2.) The experiment shows that... , The wear resistance of the specially treated coating roller is equivalent to that of a chrome-plated roller. 5 – 10 Twice.
Figure 2 Variations in surface roughness of various coated surfaces
4. Continuous Annealing Furnace Roller
A continuous annealing furnace typically consists of a heating zone, a homogenizing zone, and a cooling zone. , The steel plate is positioned on the furnace rollers inside the furnace. 180° The steel sheet undergoes heat treatment via wrap-around contact. Due to the reduction of oxides on the steel sheet surface into iron under the furnace atmosphere, these oxides adhere to the roll surfaces, forming buildup lumps. , When the steel plate is conveyed through the roller surface, it leaves a pit on the plate, affecting the surface quality of the steel plate.
The automotive industry is experiencing rapid development. , Higher requirements are being placed on the surface quality of cold-rolled and galvanized steel sheets. , To improve the quality of steel plates , CAPL and CGL Furnace roller coating technology has emerged in response to demand. This coating technology... 80 The era began in Japan, 80 It had already been widely adopted and applied to nearly all [things] by the mid-20th century. CAPL and CGL Furnace roller, 80 It only began to receive attention and be applied in Europe and the United States at the end of the century.
Furnace roller coating technology involves using thermal spraying to apply a coating onto the surface of furnace rollers that has low affinity for iron. , Moreover, its coefficient of thermal expansion is matched to that of the furnace roller substrate material. , A coating that also withstands high temperatures and abrasion while maintaining surface roughness over the long term. This coating can reduce the formation of build-up on the surface of furnace rolls. , Therefore, high-quality automotive steel sheets with excellent surface quality can be obtained.
Corresponding to different processing temperatures , A series of coating materials has been developed. , To meet the needs of different applications, research on new furnace roller coating materials remains highly active. According to reports, countries such as Japan and the United States have successively developed coating materials containing borides and nitrides. , All possess excellent anti-scaling performance, and the furnace rollers with the longest service life can reach... 6 Year.
5. Melting Galvanizing Production Line Department
Components such as immersion rolls, stabilizing rolls, roll bearings, and bearing supports in the hot-dip galvanizing production line. , Immerse yourself in Zn at 450–480℃ In liquid , Suffering from very serious Zinc Liquid corrosion and wear , The working life is generally relatively short. Prevent. Zinc The erosion is mainly prevented. Zinc Diffusion into the coating material , Figure 3. Resistant to various materials and coatings Zinc The performance of liquid erosion. As shown in the figure, , SUS 304 Stainless steel materials are subjected to intense corrosion within a short period of time. Co The self-fluxing alloy has better resistance to molten metals than the aforementioned stainless steel. Zinc The erosion effect is good. , But the deviation is significant; WC - Co Demonstrates the finest melt resistance. Zinc the erosion performance. According to reported data, , With Co Submerged Roll with Self-Fusing Alloy Coating , Its lifespan can reach 150–180 Heaven.
Figure 3 Corrosion Resistance of Coatings and Stainless Steel to Molten Zinc
6. Conductive
Conductive rollers for tin plating and zinc plating in electroplating production lines , Made of conductive material Fe system and With you Department of Materials and Hastelloy Corrosion-resistant alloy manufacturing , and coat its surface You or Cr Due to the effects of corrosion, wear, and the adhesion of foreign substances during the electroplating process, , Its lifespan is very short. Generally speaking, , The coating material for electroplated conductive rollers should possess the following properties:
(1) The conductivity meets the requirements of the electroplating process.
(2) Corrosion and wear are unlikely to cause changes in surface characteristics.
(3) The surface should be resistant to the adhesion or electrodeposition of foreign substances. , Even when attached, it’s easy to remove.
There are reports on various options for coating materials used in electroplated conductive rollers. , One of the amorphous spray coatings is performing well in practical applications. 70 The surface of the celestial body remains unchanged. , And plating Cr The roller's lifespan is only 30 Heaven.
7 ．Concluding remarks
As the steel industry’s demands for surface strengthening of equipment components continue to grow, , As a practical and effective surface treatment technology, thermal spraying will undoubtedly see even wider application in the steel industry.
Guangzhou Sanxin Thermal Spraying specializes in the manufacture of various thermal spraying equipment, including plasma spraying equipment, supersonic spraying equipment, arc spraying equipment, zinc-spraying machines, aluminum-spraying machines; flame powder spraying equipment, flame wire spraying equipment, flame plastic-coating equipment, as well as a wide range of thermal spraying coating services, ceramic coating services, and tungsten carbide coating services.
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The Application of Thermal Spraying Technology in the Modern Iron and Steel Industry
Application of Thermal Spraying Technology in Modern Steel Industry Steel production—from raw materials to finished products—involves numerous processes, including raw material handling, ironmaking, steelmaking, pressure processing, and surface treatment. The equipment used is extensive and predominantly large-scale and heavy-duty. Due to the harsh operating conditions in steel production, many pieces of equipment suffer from failure and damage caused by high temperatures, wear, and corrosion, seriously affecting improvements in production efficiency and product quality. With advancing technology, the steel industry increasingly needs new technologies that are automated, high-speed, and high-quality, placing ever-higher demands on equipment performance. Therefore, enhancing equipment performance and extending equipment service life have become urgent issues for the steel industry to improve enterprise economic benefits and strengthen competitiveness in the commodity market. Thermal spraying technology boasts advantages such as a wide variety of sprayable materials, the ability to impart multiple functions—including wear resistance, corrosion resistance, and high-temperature resistance—to workpiece surfaces, and its simple, flexible, and easy-to-operate nature. It is particularly well-suited for on-site construction and localized repair of components. Thus, thermal spraying technology is not only an effective method for surface strengthening and pre-protection of new equipment but also a cost-effective and efficient means for on-site equipment maintenance. In the steel industry, it has been widely applied to various general mechanical components, such as shafts, valves, and fans, achieving remarkable protective effects and significant economic benefits. With recent advances in thermal spraying technology—such as the introduction of high-energy, high-speed plasma equipment and high-speed flame spraying techniques—as well as the continuous development of new, high-quality spray materials, previously identified weaknesses of thermal-sprayed coatings, such as low bonding strength and poor impact resistance, have been overcome. The application of these new thermal-spraying methods has brought about a qualitative leap in coating quality; coating porosity can now be reduced to 0.5–1.0%, and the bonding strength between the coating and substrate can reach as high as 70–140 MPa. As a result, the application of thermal-sprayed coatings in the steel industry has not only expanded in scope but has also extended into higher-load applications. According to reports, at Nippon Steel’s Nagoya Works, the use of thermal spraying as a surface-modification method for working rolls has been steadily increasing. In 1990, the coated area of working rolls at this plant was only 90 m², whereas by 1995 it had reached 456 m²—a more than fivefold increase. Coatings have also achieved excellent results when applied to rollers in high-value-added surface-treated steel manufacturing processes—for example, annealing furnace rollers and molten-galvanized immersion rollers. Typical applications of thermal spraying technology in modern steel industry include: 1. Continuous Casting Mold Copper Plates The surface of continuous casting mold copper plates suffers wear due to friction from the solidifying metal layer. Traditionally, chrome plating has been used to enhance the wear resistance of the mold surface. However, the hardness of chrome layers drops rapidly at high temperatures (Figure 1), resulting in less-than-ideal protective effects. By adopting self-fluxing alloy coatings that maintain their hardness at high temperatures and using technical measures to strengthen the bond between the coating and substrate, the service life of coated continuous casting mold copper plates has exceeded 1,000 hours (1 hour = 250 tons)—more than three times that of chrome-plated molds. Figure 1: High-Temperature Hardness Comparison Between Sprayed Coatings and Chrome Plating 2. Continuous Casting Rolls Supporting rolls, guide rolls, and clamping rolls in continuous casting lines often develop large cracks around the circumference of the roll surface due to various stresses and thermal fatigue, leading to roll failure. After strengthening the roll surface with self-fluxing alloys, the coating produces only tiny microcracks along grain boundaries during operation, with extremely slow crack propagation rates. This significantly extends the service life of continuous casting rolls and prevents surface defects in castings, thereby improving casting quality. 3. Cold-Rolling Mill Rolls Cold-rolling mill rolls (such as tension rolls, guide rolls, and straightening rolls) require surfaces that are highly wear-resistant, with minimal changes in surface roughness during use and consistent clamping force. These rolls were traditionally surface-chrome-plated, but their wear resistance was insufficient, shortening their service life. After applying thermal-sprayed coatings followed by special treatments, the surface roughness changes very slowly, and the clamping force remains stable (Figure 2). Tests show that the wear resistance of specially treated coated rolls is 5–10 times greater than that of chrome-plated rolls. Figure 2: Changes in Surface Roughness of Various Coatings 4. Continuous Annealing Furnace Rolls Continuous annealing furnaces typically consist of heating zones, temperature-homogenizing zones, and cooling zones. Steel sheets are heated and processed while being wrapped around furnace rolls arranged inside the furnace at a 180° angle. Oxides on the steel sheet surface are reduced to iron under the furnace atmosphere and adhere to the roll surface, forming scale buildup. When the steel sheet passes over the roll surface, it leaves behind pits that affect the surface quality of the steel. With the rapid development of the automotive industry, higher requirements have been placed on the surface quality of cold-rolled and galvanized steel sheets. To improve steel quality, CAPL and CGL furnace roll coating technology has emerged. This coating technology originated in Japan in the 1980s and was widely adopted for almost all CAPL and CGL furnace rolls by the mid-1980s. It wasn’t until the late 1980s that it gained attention and began to be applied in Europe and the United States. Furnace roll coating technology involves using thermal spraying to apply a coating with low affinity for iron, a thermal expansion coefficient matching that of the furnace roll substrate, and high-temperature wear resistance that maintains surface roughness over time. Such coatings reduce scale buildup on the roll surface, enabling the production of high-quality automotive steel sheets with excellent surface quality. A series of coating materials have been developed to suit different processing temperatures and application needs. Currently, research on new furnace roll coating materials remains active. Reports indicate that countries such as Japan and the U.S. have successively developed coating materials containing borides and nitrides, all exhibiting outstanding anti-scale properties, with furnace roll lifespans reaching up to six years. 5. Molten-Galvanizing Production Line Components Immersion rolls, stabilizing rolls, roller bearings, and bearing supports in molten-galvanizing production lines are immersed in Zn liquid at 450–480°C, enduring severe corrosion and wear from the Zn liquid. Their service lives are generally short. Preventing Zn penetration into the coating material is crucial. Figure 3 shows the corrosion resistance of various materials and coatings against molten Zn. As shown in the figure, stainless steels like SUS304 suffer intense corrosion within a short period; Co-based self-fluxing alloys offer better resistance to molten Zn than the aforementioned stainless steels, though with considerable variation; WC-Co demonstrates the best resistance to molten Zn. According to reports, immersion rolls coated with Co-based self-fluxing alloys can last 150–180 days. Figure 3: Corrosion Resistance of Sprayed Coatings and Stainless Steels Against Molten Zinc 6. Conductive Electroplating Rollers Conductive rollers used for tin plating and galvanizing are made from Fe- and Cu-based conductive materials and Hastelloy corrosion-resistant alloys, with Ni or Cr plating on their surfaces. Due to corrosion, wear, and the adhesion of foreign substances during electroplating, their service lives are very short. Generally, ideal conductive roller coating materials should possess the following characteristics: (1) Conductivity meeting the requirements of the electroplating process; (2) Resistance to corrosion and wear without causing significant changes in surface condition; (3) Surfaces that are difficult to accumulate or electrodeposited foreign substances, and if they do accumulate, they should be easily removable. Several schemes for conductive roller coating materials have been reported, among which an amorphous sprayed coating remained unchanged after 70 days of practical use, while the service life of Cr-plated rollers was only 30 days. 7. Conclusion As the steel industry continues to demand stronger surface protection for equipment components, thermal spraying technology—being both practical and effective—will undoubtedly see even wider application in the steel industry. Guangzhou Sanxin Thermal Spraying specializes in the manufacture of various thermal spraying equipment, including plasma spraying equipment, supersonic spraying equipment, arc spraying equipment, zinc-spraying machines, aluminum-spraying machines, flame powder spraying equipment, flame wire spraying equipment, flame plastic-coating equipment, and various thermal-sprayed coating services, ceramic coating services, and tungsten carbide coating services.
电弧喷涂设备
喷锌机
喷铝机
火焰粉末喷涂设备
Product Description
The Application of Thermal Spraying Technology in the Modern Steel Industry
Steel production—from raw materials to finished products—involves a variety of processes, including raw material processing, ironmaking, steelmaking, pressure processing, and surface treatment. , The equipment used is numerous and mostly large, heavy-duty machinery. This is because the operating conditions in steel production are extremely harsh. , In production, a large number of equipment failures and damages occur due to factors such as high temperatures, wear, and corrosion. , It severely hinders the improvement of production efficiency and product optimization. As times advance, , The iron and steel industry needs to widely adopt new technologies that are essential for automation, high speed, and high quality. , Higher requirements are placed on equipment performance. Therefore, , Improving the operational performance of equipment and extending its service life have become pressing issues that the iron and steel industry must address urgently in order to enhance enterprise economic efficiency and strengthen its competitiveness in the commodity market.
Thermal spraying technology features a wide variety of sprayable materials. , It can impart multiple functions to the workpiece surface, such as wear resistance, corrosion resistance, and high-temperature resistance, while also featuring simple and flexible processes and operations. , Particularly suitable for on-site construction and localized repair of workpieces. Therefore, , Thermal spraying technology is not only an effective method for surface strengthening and pre-protection of new equipment. , Moreover, it is an effective and economical method for on-site equipment maintenance. , It has been widely used in the steel industry for various general-purpose mechanical components. , Reinforcement and repair of various shaft components, valves, fans, and the like. , and has achieved remarkably significant protective effects and economic benefits. With the advancements in thermal spraying technology in recent years, , The successive introduction of high-energy, high-speed plasma equipment and high-speed flame spraying technology, among others. , As well as the continuous development of various new, high-quality spraying materials. , This has enabled overcoming the previous weaknesses of thermal spray coatings, such as low bonding strength and poor impact resistance. The application of new thermal spraying techniques has brought about a qualitative leap in coating quality. , Coating porosity can be reduced to 0.5 – 1.0%, The bonding strength between the coating and the substrate can be as high as 70 – 140 MPa Therefore, the application of thermal spray coatings in the steel industry has not only expanded in scope. , Moreover, it is expanding into higher-load applications. According to reports, the new Nippon Steel Nagoya Steelworks... , The application of thermal spraying as a surface modification method for processing rollers is steadily increasing. , The coated area of the rollers processed by this plant. 1990 Only for the year 90 M2, And 1995 The annual figure reaches 456 M2 Growth reaches 5 Multiple times. Rollers used in the surface treatment steel plate manufacturing process, which involves high-value-added coatings. ( Such as annealing furnace rollers and molten galvanizing immersion rollers, etc. ) Its application has also achieved excellent results.
Typical applications of thermal spraying technology in the modern steel industry include:
1. Continuous casting mold copper plate
The surface of the copper plates in continuous casting molds wears down due to friction from the solidifying metal layer. , Chromium plating has long been used to enhance the wear resistance of mold surfaces. However, the hardness of chromium coatings decreases rapidly at high temperatures. ( Figure 1), Its protective performance is not entirely ideal. After adopting a self-fluxing alloy coating that does not significantly lose hardness at high temperatures and supplementing it with technical measures to enhance the bonding between the coating and the substrate, , The durability of the copper plates used in coated continuous casting molds exceeds... 1000 ch￠s (1 ch = 250 ton ), For the chrome plating layer 3 More than double.
Figure 1 High-Temperature Hardness of Spray-Coated and Chrome-Plated Layers
2. Continuous casting roll
In continuous casting production lines, components such as support rolls, guide rolls, and clamping rolls are often affected by various factors, including different types of stress and thermal fatigue. , Large cracks develop in the circumferential direction of the roll surface, leading to roll failure and malfunction. After reinforcing the roll surface with a self-melting alloy, ... , During use, this coating develops only tiny microcracks with a very low crack propagation rate along its grain boundaries. , It significantly extends the service life of continuous casting rolls and also prevents surface defects from occurring in the cast material. , Improved the quality of the castings.
3. Cold-rolled processing roll
Processing rollers in the cold rolling production line ( Such as tension rollers, guide rollers, and straightening rollers. ) Requires its surface to be wear-resistant. , The change in surface roughness during use should be minimal. , It features a constant clamping force. This roller typically has a chrome-plated surface. , But its wear resistance is insufficient. , affect the service life. However, after applying a thermal spray coating and subjecting it to special treatment, , The change in its surface roughness is very slow. , The surface clamping force is not easy to decrease. ( Figure 2.) The experiment shows that... , The wear resistance of the specially treated coating roller is equivalent to that of a chrome-plated roller. 5 – 10 Twice.
Figure 2 Variations in surface roughness of various coated surfaces
4. Continuous Annealing Furnace Roller
A continuous annealing furnace typically consists of a heating zone, a homogenizing zone, and a cooling zone. , The steel plate is positioned on the furnace rollers inside the furnace. 180° The steel sheet undergoes heat treatment via wrap-around contact. Due to the reduction of oxides on the steel sheet surface into iron under the furnace atmosphere, these oxides adhere to the roll surfaces, forming buildup lumps. , When the steel plate is conveyed through the roller surface, it leaves a pit on the plate, affecting the surface quality of the steel plate.
The automotive industry is experiencing rapid development. , Higher requirements are being placed on the surface quality of cold-rolled and galvanized steel sheets. , To improve the quality of steel plates , CAPL and CGL Furnace roller coating technology has emerged in response to demand. This coating technology... 80 The era began in Japan, 80 It had already been widely adopted and applied to nearly all [things] by the mid-20th century. CAPL and CGL Furnace roller, 80 It only began to receive attention and be applied in Europe and the United States at the end of the century.
Furnace roller coating technology involves using thermal spraying to apply a coating onto the surface of furnace rollers that has low affinity for iron. , Moreover, its coefficient of thermal expansion is matched to that of the furnace roller substrate material. , A coating that also withstands high temperatures and abrasion while maintaining surface roughness over the long term. This coating can reduce the formation of build-up on the surface of furnace rolls. , Therefore, high-quality automotive steel sheets with excellent surface quality can be obtained.
Corresponding to different processing temperatures , A series of coating materials has been developed. , To meet the needs of different applications, research on new furnace roller coating materials remains highly active. According to reports, countries such as Japan and the United States have successively developed coating materials containing borides and nitrides. , All possess excellent anti-scaling performance, and the furnace rollers with the longest service life can reach... 6 Year.
5. Melting Galvanizing Production Line Department
Components such as immersion rolls, stabilizing rolls, roll bearings, and bearing supports in the hot-dip galvanizing production line. , Immerse yourself in Zn at 450–480℃ In liquid , Suffering from very serious Zinc Liquid corrosion and wear , The working life is generally relatively short. Prevent. Zinc The erosion is mainly prevented. Zinc Diffusion into the coating material , Figure 3. Resistant to various materials and coatings Zinc The performance of liquid erosion. As shown in the figure, , SUS 304 Stainless steel materials are subjected to intense corrosion within a short period of time. Co The self-fluxing alloy has better resistance to molten metals than the aforementioned stainless steel. Zinc The erosion effect is good. , But the deviation is significant; WC - Co Demonstrates the finest melt resistance. Zinc the erosion performance. According to reported data, , With Co Submerged Roll with Self-Fusing Alloy Coating , Its lifespan can reach 150–180 Heaven.
Figure 3 Corrosion Resistance of Coatings and Stainless Steel to Molten Zinc
6. Conductive
Conductive rollers for tin plating and zinc plating in electroplating production lines , Made of conductive material Fe system and With you Department of Materials and Hastelloy Corrosion-resistant alloy manufacturing , and coat its surface You or Cr Due to the effects of corrosion, wear, and the adhesion of foreign substances during the electroplating process, , Its lifespan is very short. Generally speaking, , The coating material for electroplated conductive rollers should possess the following properties:
(1) The conductivity meets the requirements of the electroplating process.
(2) Corrosion and wear are unlikely to cause changes in surface characteristics.
(3) The surface should be resistant to the adhesion or electrodeposition of foreign substances. , Even when attached, it’s easy to remove.
There are reports on various options for coating materials used in electroplated conductive rollers. , One of the amorphous spray coatings is performing well in practical applications. 70 The surface of the celestial body remains unchanged. , And plating Cr The roller's lifespan is only 30 Heaven.
7 ．Concluding remarks
As the steel industry’s demands for surface strengthening of equipment components continue to grow, , As a practical and effective surface treatment technology, thermal spraying will undoubtedly see even wider application in the steel industry.
Guangzhou Sanxin Thermal Spraying specializes in the manufacture of various thermal spraying equipment, including plasma spraying equipment, supersonic spraying equipment, arc spraying equipment, zinc-spraying machines, aluminum-spraying machines; flame powder spraying equipment, flame wire spraying equipment, flame plastic-coating equipment, as well as a wide range of thermal spraying coating services, ceramic coating services, and tungsten carbide coating services.
Next: Understand the Applications of Thermal Spray Processing Technology at a Glance
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