Metal surface modification technology
Metal surface modification technology refers to a process that changes the chemical composition, organizational structure or physical properties of the metal material surface through physical, chemical or mechanical means, thereby giving the metal surface new functional properties to meet the requirements of specific use environments. In industrial production, the failure of metal materials often begins on the surface, such as wear, corrosion, fatigue, etc., while the internal performance may still remain good. Through surface modification technology, there is no need to change the overall chemical composition and properties of the metal. By only treating the surface, its wear resistance, corrosion resistance, high temperature resistance, etc. can be significantly improved, while reducing material costs and extending service life. For example, forming a high-hardness modified layer on the surface of mechanical parts can reduce friction and wear; performing corrosion-resistant modification on the surface of chemical equipment can resist the erosion of acid and alkali media. Therefore, metal surface modification technology plays an important role in aerospace, automobile manufacturing, petrochemical and other fields.
There are many types of metal surface modification technologies, which can be divided into three categories according to the modification principle: chemical modification, physical modification, and mechanical modification. Chemical modification mainly achieves performance improvement by changing the chemical composition of the surface. Common plating technologies include carburizing, nitriding, and boronizing, as well as coating technologies such as chemical vapor deposition (CVD) and physical vapor deposition (PVD). Carburizing treatment improves the wear resistance of parts by infiltrating carbon atoms into the steel surface to form a high-hardness carburized layer; nitriding treatment causes nitrogen atoms to react with the metal surface to form nitrides, enhancing surface hardness and corrosion resistance. Physical modification focuses on changing the surface structure through physical methods, such as laser surface melting and ion implantation. Laser surface melting uses a laser to heat the surface to a molten state and then rapidly cool it, refining the grains and improving surface hardness and wear resistance; ion implantation implants high-energy ions into the metal surface to form a solid solution or compound, improving the mechanical and chemical properties of the surface.
Mechanical modification primarily changes the stress state and microstructure of metal surfaces through mechanical processing methods, such as shot peening and rolling. Shot peening uses high-speed projectiles to impact the metal surface, causing plastic deformation and residual compressive stress. This increases the material’s fatigue strength and stress corrosion resistance, and is widely used in parts such as springs and gears that bear alternating loads. Rolling, on the other hand, uses hard rollers to apply pressure to the metal surface, flattening raised areas and reducing surface roughness. This process also produces cold work hardening, increasing surface hardness and wear resistance. Mechanical modification technology is simple to operate and relatively low-cost, making it suitable for applications where surface performance requirements are low but fatigue strength needs to be improved.
Different metal surface modification technologies have their own scope of application and advantages and disadvantages. In practical applications, they must be reasonably selected based on the material type, operating environment, and performance requirements. For example, for gears that require high hardness and wear resistance, carburizing or quenching and tempering are commonly used modification methods; for stainless steel parts that require corrosion resistance, ion implantation or plating technology can be used; for springs that bear fatigue loads, shot peening is an ideal choice. At the same time, the combined application of multiple modification technologies is also becoming a trend. For example, nitriding treatment is first performed to increase surface hardness, and then a wear-resistant coating is deposited through PVD technology to further enhance surface performance. In addition, surface quality testing after modification is also crucial. Common testing methods include hardness testing, wear resistance testing, corrosion resistance testing, etc. to ensure that the modification effect meets the design requirements.
With the development of materials science and advanced manufacturing technology, metal surface modification technology is moving towards high efficiency, environmental protection, and intelligentization. The application of new coating materials such as nano-coatings and ceramic coatings has further improved the effect of surface modification; the maturity of advanced technologies such as plasma spraying and laser surface alloying has expanded the application scope of modification technology. Environmentally friendly modification technologies are also gaining attention, such as low-temperature nitriding and cyanide-free electroplating, which reduce pollution to the environment. The integration of intelligent technologies, such as computer simulation to optimize modification process parameters and online monitoring of the modification process, has improved the stability and reliability of the modification technology. In the future, metal surface modification technology will focus more on multifunctional integration, such as achieving multiple properties such as wear resistance, corrosion resistance, and self-lubrication at the same time, providing more powerful technical support for high-end equipment manufacturing.