Mold wear-resistant thermal spray coating

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.

Supersonic Arc Spraying Process: In supersonic arc spraying, two continuously and uniformly fed wire electrodes are connected to the positive and negative terminals of a power supply. At the instant when the ends of the wires briefly touch and an arc is struck, the arc sustains stable combustion under the influence of the electric current. Behind the arc’s point of origin, the airflow—accelerated through a Laval nozzle to reach supersonic speeds—carries away the wire material melted by the arc, atomizing it into fine particles. Under the action of this supersonic airflow, the particles are sprayed onto a pre-treated substrate surface, forming a coating. Supersonic arc spraying is a continuously repeated process of melting, atomization, and deposition. Because the atomized particles are small, uniform, and travel at high velocities, this process enables the production of high-quality coatings. Supersonic arc spraying employs a Laval nozzle to increase the airflow velocity from subsonic to supersonic levels, thereby enhancing the acceleration effect on the particles and boosting their flight speed. The velocity of the particles significantly influences the performance of the coating: higher particle velocities result in stronger impact forces upon deposition onto the substrate, leading to more thorough particle deformation. This promotes robust bonding between particles and the substrate as well as among particles themselves, greatly improving both the adhesion strength and cohesive strength of the coating and reducing its porosity. Coatings produced via supersonic arc spraying include large-area zinc coatings, aluminum coatings, copper coatings, stainless steel coatings, various wear-resistant boiler coatings, and flue gas duct wear-resistant coatings. The bond strength between the supersonic arc-sprayed coating and the substrate is ≥80 MPa. The high-temperature resistance of supersonic arc-sprayed coatings can be precisely controlled within the range of 600–1200°C. Key features of supersonic arc spraying include: a spraying temperature below 120°C, which prevents thermal distortion. We have accumulated extensive experience in coating applications across materials, equipment, processes, and solutions—and we’re now replicating these successful cases. We’ll guide you through the entire coating manufacturing transformation process, ensuring: rapid production start-up; a reliable, turnkey supply solution covering materials, equipment, and processes; coating trials conducted either on-site at your facility or at our technical center; and consistently high coating quality and efficiency. Start collaborating with us today and reap success tomorrow!

Application of Thermal Spray Equipment in the Petrochemical Industry

Guangzhou Sanxin Thermal Spraying specializes in the manufacturing of thermal spraying equipment. Our facilities are fully equipped, and our technology is cutting-edge. Below is an introduction to the application of thermal spraying equipment in the petrochemical industry—the application of thermal spraying technology in the chemical and petroleum sectors.

Applications of Plasma Spraying Equipment in the Aerospace Field

The application of plasma spraying equipment in the aerospace industry has rapidly advanced alongside the evolution of aeroengines toward higher performance, longer overhaul intervals, greater reliability, lower fuel consumption, and reduced costs. A new-generation engine features over 3,000 surfaces across more than a thousand components that require thermal spray coatings. Thus, thermal spray technology has become an integral part of the aerospace manufacturing industry. Among these technologies, plasma spraying stands out for its numerous advantages—low cost, high efficiency, simple operation, excellent coating quality, and suitability for large-scale, mass production—accounting for over 80% of all sprayed parts in aeroengines. Thermal spray coatings used in aeroengines primarily include wear-resistant coatings, thermal barrier coatings, sealing coatings, and high-temperature protective coatings. In the aerospace sector, engines face significant potential wear issues. Many moving parts within engines come into contact with each other, while some stationary parts may experience sudden changes in position. As a result, aeroengines are among the first industries to fully adopt thermal spray technology, using it to optimize engine performance, safety, and reliability. Most engine systems consist of the fan, compressor, combustion chamber, high-pressure turbine, low-pressure turbine, and exhaust nozzle. The engine design includes a non-rotating (stator) system and two coaxial rotating systems. The non-rotating (stator) system comprises a structural frame and an outer casing. The low-pressure rotating system consists of a blade disk, blades, a low-pressure turbine disk, turbine blades, and a connecting shaft. The high-pressure rotating system comprises a high-pressure turbine disk/bucket, compressor blades, turbine blades, and a connecting shaft. Different engine components operate under varying environmental conditions, largely determined by the specific tasks the engine is designed to perform. Temperatures can range from below zero degrees Celsius to as high as 1,095°C (2,000°F), with rotational speeds reaching up to 15,000 revolutions per minute. Rolling bearings bear loads ranging from several megapascals to over 1,720 MPa. Due to the sliding motion between the rotor and stator—where sliding distances can vary from a few thousandths of an inch to several tenths of an inch—or vibrations causing relative movement between components, mechanical parts can collide with each other. Moreover, different components are affected by the materials used for spraying. Depending on the operating environment, various spraying materials and processes are selected to meet the specific design requirements of the engine. Guangzhou Sanxin Thermal Spray specializes in the manufacture of a wide range of thermal spray equipment, including plasma spray equipment, supersonic spray equipment, arc spray equipment, zinc-spraying machines, aluminum-spraying machines; flame powder spray equipment, flame wire spray equipment, flame plastic-coating equipment, and various thermal spray coating services, ceramic coating services, and tungsten carbide coating services.

Understand the Applications of Thermal Spray Processing Technology at a Glance

Thermal spraying technology has a history of nearly a century, dating back to 1910 when Dr. M.U. Schoop from Switzerland developed the first metal-melt spraying apparatus. Initially, thermal spraying was primarily used for applying decorative coatings, with aluminum and zinc wires typically sprayed using oxy-acetylene flames or electric arcs. In the 1930s and 1940s, as flame and arc wire-spraying equipment became more sophisticated and flame powder guns were introduced, thermal spraying evolved from merely applying decorative coatings to repairing mechanical parts with steel wires and to coating steel structures with aluminum or zinc as corrosion-resistant protective layers. In the 1950s, the successful development of detonation spraying and subsequently plasma spraying technologies led to the widespread application of thermal spraying in fields such as aerospace and aviation. Around the same time, self-fluxing alloy powders were developed, enabling the elimination of porosity in coatings through remelting processes and facilitating metallurgical bonding between the coating and the substrate, thereby greatly expanding the application scope of thermal spraying technology. In the early 1980s, supersonic flame spraying technology was successfully developed and gained widespread adoption by the early 1990s, dramatically extending the use of WC-Co hardmetal coatings from aerospace and aviation to various industrial sectors. The emergence of high-energy plasma spraying technologies—such as those with power ratings up to 200 kW, supersonic plasma spraying, and axial-feed plasma spraying, especially the highly efficient supersonic plasma spraying technology—has provided powerful tools for further effective utilization of thermal spraying in diverse industrial applications. As a modern manufacturing technology with broad applicability, relatively simple and flexible processing techniques, wide-ranging applications, and significant economic benefits, thermal spraying can endow surfaces with a variety of functional properties, including wear resistance, corrosion resistance, thermal insulation, heat resistance, electrical conductivity, electrical insulation, erosion resistance, oxidation resistance, friction reduction, lubrication, and radiation protection. Thermal spraying is not only suitable for repairing and strengthening mechanical components but can also be used for manufacturing new parts. Thanks to the wide selection of spray materials, which are not constrained by the need for overall material alloying, it is relatively easy to produce ultra-hard alloys, various ceramic or metal-ceramic coatings, and specialized functional coatings. Moreover, compared to using solid advanced materials throughout, thermal spraying requires significantly less material, making it far more cost-effective than upgrading materials entirely. Consequently, valuable materials can be used boldly without substantially increasing costs, while the surface performance of these materials can be greatly enhanced. Parts repaired by thermal spraying generally have service lives that equal or even exceed several times those of new parts. Thermal spraying technology has a history of nearly a century, dating back to 1910 when Dr. M.U. Schoop from Switzerland developed the first metal-melt spraying apparatus. Initially, thermal spraying was primarily used for applying decorative coatings, with aluminum and zinc wires typically sprayed using oxy-acetylene flames or electric arcs. In the 1930s and 1940s, as flame and arc wire-spraying equipment became more sophisticated and flame powder guns were introduced, thermal spraying evolved from merely applying decorative coatings to repairing mechanical parts with steel wires and to coating steel structures with aluminum or zinc as corrosion-resistant protective layers. In the 1950s, the successful development of detonation spraying and subsequently plasma spraying technologies led to the widespread application of thermal spraying in fields such as aerospace and aviation. Around the same time, self-fluxing alloy powders were developed, enabling the elimination of porosity in coatings through remelting processes and facilitating metallurgical bonding between the coating and the substrate, thereby greatly expanding the application scope of thermal spraying technology. In the early 1980s, supersonic flame spraying technology was successfully developed and gained widespread adoption by the early 1990s, dramatically extending the use of WC-Co hardmetal coatings from aerospace and aviation to various industrial sectors. The emergence of high-energy plasma spraying technologies—such as those with power ratings up to 200 kW, supersonic plasma spraying, and axial-feed plasma spraying, especially the highly efficient supersonic plasma spraying technology—has provided powerful tools for further effective utilization of thermal spraying in diverse industrial applications. As a modern manufacturing technology with broad applicability, relatively simple and flexible processing techniques, wide-ranging applications, and significant economic benefits, thermal spraying can endow surfaces with a variety of functional properties, including wear resistance, corrosion resistance, thermal insulation, heat resistance, electrical conductivity, electrical insulation, erosion resistance, oxidation resistance, friction reduction, lubrication, and radiation protection. Thermal spraying is not only suitable for repairing and strengthening mechanical components but can also be used for manufacturing new parts. Thanks to the wide selection of spray materials, which are not constrained by the need for overall material alloying, it is relatively easy to produce ultra-hard alloys, various ceramic or metal-ceramic coatings, and specialized functional coatings. Moreover, compared to using solid advanced materials throughout, thermal spraying requires significantly less material, making it far more cost-effective than upgrading materials entirely. Consequently, valuable materials can be used boldly without substantially increasing costs, while the surface performance of these materials can be greatly enhanced. Parts repaired by thermal spraying generally have service lives that equal or even exceed several times those of new parts.

Application and Development of Thermal Spray Technology in Aeroengine Manufacturing

The application of thermal spray equipment technology in aeroengines is driven by the wide availability of thermal spray materials, stable preparation processes, highly tunable coating composition and microstructure, controllable coating quality, the ability to produce a variety of functional and protective coatings, and the possibility of automated production. As a result, thermal spray technology has become an important component of aerospace manufacturing technology.

Wear and corrosion-resistant thermal spray coating repair for workpieces such as submerged rolls, guide rolls, furnace bottom rolls, and conveyor rolls in the steel industry.

In the steel industry, numerous equipment components—such as submerged rolls, guide rolls, furnace bottom rolls, and conveyor rolls—are subject to wear, corrosion, and other forms of degradation. These components operate continuously at full capacity under harsh conditions characterized by high temperatures, oxidation, high-temperature corrosion, mechanical wear, and molten-metal erosion, making them highly susceptible to damage. Examples include the severe high-temperature corrosion of converter shell skirts and flues; thermal and cold fatigue in support rolls, guide rolls, and pinch rolls on continuous casting lines; mechanical wear on billet continuous casting line molds, conveyor rolls, and various process rolls; fatigue and wear in tension rolls and straightening rolls on cold-rolling mill lines; high-temperature corrosion and buildup on furnace bottom rolls in continuous annealing furnaces; as well as erosion and wear caused by molten metal on submerged rolls, tension rolls, and guide rolls in continuous hot-dip galvanizing lines. All these issues can be effectively addressed through thermal spraying using high-strength, high-performance materials. The working condition for supersonic (HVOF) flame spraying on roll surfaces: intermetallic wear. Solution: Supersonic spraying with WC/C0. Technical specifications: Coating thickness 70–120 μm; coating surface roughness R3.5–6.5; coating adhesion strength ≥55 MPa. Working condition: Intermetallic friction and wear. Solution: Two-step flame-spraying (welding) induction-coating melting treatment. Spraying material: NiCrBSi (HRc 55–62). Technical specifications: Coating thickness 0.7–1.0 mm; coating surface machinable after grinding. Working condition: High-temperature environment corrosion and metal oxide adhesion. Solution: Explosive spraying of composite ceramic materials or plasma spraying of oxide ceramic materials. Technical specifications: Coating thickness 0.7–1.0 mm; coating surface machinable. Materials, equipment, processes—our solutions: We have accumulated extensive experience in coating applications and are now successfully replicating these proven cases. We will guide you through the entire coating manufacturing transformation process, ensuring: rapid production start-up; a reliable supply solution covering all aspects—from materials and equipment to processes; coating trials conducted either on-site at your facility or at our technical center; and consistently high coating quality and efficiency.