Detailed Process of Metal Surface Treatment Solutions

Metal surface treatment process plays a crucial role in product design. It can not only enhance the appearance and functionality of products, but also realize the innovative ideas of designers and enhance the market competitiveness of products. With the development of technology, future metal surface treatment processes will bring more possibilities and innovative space for product design.

Overview of Surface Treatment Processes

Definition of Surface Treatment
Surface treatment technology refers to a series of techniques that use physical, chemical, or mechanical means to process the surface of metal materials in order to change their surface properties. These technologies include but are not limited to cleaning, polishing, coating, heat treatment, etc., with the aim of improving the corrosion resistance, wear resistance, aesthetics, or other specific physical and chemical properties of materials without changing their basic structure.

The purpose and importance of surface treatment
The surface treatment process is crucial for metal materials, with the main objectives including the following:
Improving corrosion resistance: Through surface treatments such as plating and anodizing, the contact between metals and corrosive media can be effectively isolated, extending the service life of materials.

• Enhanced wear resistance: Surface hardening treatments such as carburizing, nitriding, etc. can form a protective layer with high hardness on the metal surface, reducing wear.
• Enhancing Aesthetics: By using processes such as polishing, drawing, and spraying, the appearance, texture, and color of metals can be improved to meet aesthetic needs.
• Implementing special functions: for example, electromagnetic shielding or improved conductivity can be achieved through surface coating, and metal surfaces can be endowed with antibacterial properties through specific chemical treatments.

The application range of surface treatment technology is very wide, from daily necessities to high-end fields such as aerospace and medical equipment, all of which rely on the application of these technologies. With the development of technology and the increasing demand for environmental protection, surface treatment technology is constantly innovating to meet new market demands.

Surface modification process

Surface Quenching
Surface quenching is a heat treatment process that improves the hardness and wear resistance of metal surfaces through rapid heating and rapid cooling. This technology is mainly applied to steel materials by heating the metal surface to austenitization temperature and then rapidly cooling it to form martensite or other hardened structures.

• Process characteristics: Surface quenching does not change the chemical composition of the material. By adjusting the heating and cooling rates, different surface hardness and depth can be obtained.
  Application areas: commonly used to improve the service life and performance of tools, molds, bearings, and other parts.
• Technical data: For example, for carbon steel materials, the hardness after surface quenching can reach HRC58-62, and the depth of the hardened layer is generally in the range of 0.5-2.5mm.

Laser surface hardening
Laser surface hardening is a process that uses a focused laser beam to rapidly heat and then rapidly cool the metal surface, achieving material surface hardening. This technology has the advantages of small heat affected area, small deformation, and strong controllability.

• Process principle: The laser beam is focused onto the surface of the material through an optical system. After absorbing the laser energy, the material rapidly heats up to the phase transition temperature or melting point, and then rapidly cools down through thermal conduction and convection to form a hardened layer.
• Technical advantages: Laser surface strengthening can achieve local strengthening, with high flexibility and controllability, suitable for surfaces of parts with complex shapes or difficult to contact.
• Application example: In industries such as automotive and aerospace, laser surface strengthening is used to improve the wear resistance and fatigue life of engine components, transmission system parts, etc. For example, the hardness of gears after laser surface hardening can be increased to HRC60 or higher, significantly improving their load-bearing capacity and durability.

Surface alloying process

Chemical surface heat treatment
Chemical surface heat treatment is a process that changes the chemical composition and microstructure of a metal surface by heating it in a specific medium, allowing active atoms in the medium to penetrate the metal surface. This treatment method can significantly improve the hardness, wear resistance, and corrosion resistance of the metal surface.

• Process type: Chemical heat treatment mainly includes carburizing, nitriding, carbon nitrogen co infiltration, multi-element co infiltration, etc. Each process has different performance improvement effects according to the different infiltrating elements.
• Carburizing treatment: During the carburizing process, carbon atoms infiltrate the metal surface, forming a hardened layer rich in carbon. This treatment is suitable for low alloy steel and medium carbon steel, and is commonly used to improve the wear resistance and load-bearing capacity of mechanical parts.
• Nitriding treatment: Nitriding is the process of infiltrating nitrogen atoms into the metal surface to form a nitride layer with excellent wear resistance, corrosion resistance, and fatigue strength. This treatment is suitable for materials such as stainless steel and alloy steel.

Carburizing and nitriding treatment
Carbonization and nitriding are two common processes in chemical heat treatment, which improve material properties by changing the chemical composition of the metal surface.

• Process characteristics: It is carried out in a closed carburizing furnace, and by controlling the atmosphere composition and temperature, carbon atoms form a diffusion layer on the metal surface.
• Technical parameters: For example, the carbon content of the carburized layer is usually between 0.8% and 1.2%, and the depth of the hardened layer can reach 1-2mm.
• Performance improvement: The surface hardness of the metal after carburizing is significantly increased, while maintaining a certain level of toughness and plasticity, making it suitable for parts that can withstand heavy loads and wear.

Nitriding:

• Process characteristics: Nitriding is usually carried out at lower temperatures, by decomposing ammonia gas or directly using nitrogen gas as a medium, nitrogen atoms form a diffusion layer on the metal surface.
• Performance advantages: The nitriding layer has extremely high hardness and wear resistance, while also improving the fatigue strength and corrosion resistance of the metal, making it suitable for manufacturing precision instruments and high-strength parts. Both processes can significantly improve the performance of metal surfaces, but the choice of process depends on the type of material, the required properties, and the application scenario. By precisely controlling the parameters of chemical heat treatment, ideal performance improvement effects can be achieved.

Surface Conversion Coating Process

Blackening and phosphating
The surface conversion coating technology forms a protective film on the metal surface through chemical or electrochemical methods to improve its corrosion resistance and wear resistance, while enhancing its aesthetics.

• Blackening: This is a process of heating a metal (usually steel) to a certain temperature and forming an oxide film in the air. The oxide film is usually blue or black and can provide a certain degree of corrosion resistance.
• Technical features: The blackening process is simple, cost-effective, and suitable for large-scale production. The thickness of the oxide film is relatively thin, usually ranging from a few micrometers to several tens of micrometers.
• Application example: Blackening is widely used in tools, mechanical parts, weapons, etc., providing basic anti-corrosion protection and improving appearance.

Phosphating
Phosphating is a process of forming a phosphate film on the surface of metals, mainly used for steel materials. Phosphating film can improve the adhesion of coatings, enhance corrosion resistance, and provide a good substrate for subsequent coatings.

• Process flow: Phosphating usually includes steps such as degreasing, water washing, phosphating, and water washing. The thickness of the phosphating film is generally in the range of a few micrometers to several tens of micrometers.
• Technical advantages: Phosphating film has good adhesion and uniformity, which can significantly improve coating performance and is widely used in industries such as automotive and aerospace.

Anodization
Anodizing is an electrochemical process primarily used for surface treatment of aluminum and aluminum alloys. In this process, the metal acts as the anode and forms an oxide film in the electrolyte through the action of current.

• Process principle: During anodizing, the aluminum surface reacts with oxygen in the electrolyte to form a dense layer of aluminum oxide film. This layer of film has excellent corrosion resistance, wear resistance, and good decorative properties.
• Technical parameters: The thickness of the oxide film can be adjusted as needed, usually ranging from a few micrometers to several hundred micrometers. The color of the film layer can be achieved by adding dyes or performing special treatments.
• Application areas: Anodizing is widely used in aerospace, automotive, construction, and consumer goods industries. It not only improves the performance of materials, but also endows them with diverse colors and textures, enhancing their decorative value.
• Environmental benefits: The electrolyte used in the anodizing process is usually environmentally friendly, and the formation of the film layer does not produce harmful by-products, which meets the requirements of modern industry for environmental protection. Through surface conversion coating technology, the surface properties of metal materials have been significantly improved, meeting the high requirements for material performance in different industrial fields, and also contributing to the sustainable development and environmental protection of materials.

Surface coating process

Thermal spraying
Thermal spraying is a surface coating technology that heats metal or non-metal materials to a molten or semi molten state, and then sprays them onto the surface of the substrate using high-speed airflow to form a coating with a certain bonding strength.

• Process characteristics: Thermal spraying technology has the advantages of a wide range of coating materials, high bonding strength, and strong adaptability, and can be applied to surface treatment of various metal materials.
• Technology types: mainly including flame spraying, arc spraying, plasma spraying, etc., each technology has its specific application scenarios and advantages.
• Application areas: Thermal spraying technology is widely used in aerospace, mechanical manufacturing, chemical equipment and other fields to improve the wear resistance, corrosion resistance, high temperature resistance and other properties of parts.
• Technical data: For example, ceramic coatings prepared using plasma spraying technology have a bonding strength of over 70 MPa, effectively improving the wear and corrosion resistance of the substrate.

Vacuum plating
Vacuum plating is a technique of depositing thin films on metal surfaces through physical or chemical methods in a vacuum environment to improve the surface properties of materials.

• Process principle: Vacuum plating mainly includes methods such as vacuum evaporation, vacuum sputtering, and chemical vapor deposition. These methods deposit atoms or molecules on the surface of the substrate to form a thin film by evaporating or sputtering the material in a high vacuum environment.
• Technical advantages: Vacuum coating has the characteristics of high film purity, strong adhesion, and good film uniformity, which can achieve precise control of material surface properties.
  Application example: In the electronics industry, vacuum coating technology is used to prepare conductive films, decorative films, etc; In the packaging industry, it is used to prepare films with good barrier properties.
• Technical data: For example, the titanium nitride film on the surface of stainless steel prepared by magnetron sputtering technology has a hardness of over 2000HV, significantly improving the wear resistance and corrosion resistance of stainless steel. Through surface coating technology, significant performance improvements have been achieved on the surface of metal materials, and the application of these technologies in the industrial field continues to expand, providing more possibilities for the functionality and aesthetics of materials.

Other surface treatment processes

Powder coating
Powder coating is a common metal surface treatment process, which involves spraying powder coating onto the metal surface and then melting, leveling, and solidifying it at high temperatures to form a protective and decorative coating.

• Process principle: Use an electrostatic generator to charge the powder coating, and then evenly spray the charged powder onto the grounded metal surface through a spray gun. Due to static electricity, the powder will be uniformly adsorbed on the metal surface. Finally, the sprayed workpiece is sent to a curing furnace, where the powder coating is melted, leveled, and solidified at high temperatures to form a uniform and smooth coating.
• Technical features: Environmentally friendly and pollution-free, with high utilization rate of powder coating. Powder that has not adhered to the workpiece can be recycled and reused. In addition, the powder sprayed coating has excellent quality, good wear resistance, corrosion resistance and aging resistance. High operational safety with no risk of fire or explosion.
• Application example: In the field of household appliances, powder coating is often used for products such as refrigerators, washing machines, and air conditioner casings. In the automotive industry, this process is also widely used for car wheels, body accessories, etc.
• Technical data: The curing temperature of powder spraying is generally between 180 and 200 degrees Celsius, and the time is 10 to 20 minutes; The particle size of powder coating is usually between 10 and 100 microns; The coating thickness is generally 50 to 150 microns; The electrostatic voltage is between 50 and 100 kilovolts; The spraying efficiency is usually 60% to 70%, and can be increased to over 95% after recycling. Powder spraying is an efficient, environmentally friendly, and safe surface treatment technology with broad application prospects and excellent coating performance.

Electroplate
Electroplating is a surface treatment technique that deposits one or more layers of metal or alloy thin films on a metal surface through electrolytic action. This technology can significantly improve the corrosion resistance, wear resistance, conductivity, and decorative properties of metals.

• Process principle: In the electroplating process, the metal to be plated serves as the cathode, and the plated metal serves as the anode, achieving metal deposition through ion migration in the electrolyte.
• Technical advantages: The electroplating layer has the advantages of uniformity, strong adhesion, and the ability to achieve various metal coatings, making it one of the most widely used technologies in surface treatment.
• Application areas: Electroplating is widely used in multiple industries such as automotive, electronics, construction, and jewelry to enhance the appearance, texture, and functionality of products.
• Technical data: For example, nickel plating not only provides good corrosion resistance, but also enhances the adhesion of subsequent chrome plating, with a coating thickness typically ranging from a few micrometers to tens of micrometers.

Vapor deposition
Vapor deposition is a technique of depositing materials from a gaseous state onto the surface of a substrate through physical or chemical methods in a vacuum or specific atmosphere to form a thin film.

• Process classification: Vapor deposition mainly includes two types: physical vapor deposition (PVD) and chemical vapor deposition (CVD). PVD achieves deposition through physical methods such as evaporation or sputtering, while CVD forms a thin film on the substrate surface through chemical reactions.
• Technical features: Vapor deposition technology can achieve the deposition of high-purity, high-density, and ultra-thin films, suitable for preparing high-performance coatings.
  Application example: In the semiconductor industry, PVD technology is used to prepare conductive and barrier films; CVD technology is used to grow various semiconductor materials and ceramic materials.
• Technical data: For example, TiN (titanium nitride) films prepared by PVD technology have extremely high hardness (up to 3000HV) and excellent wear resistance, and are commonly used to improve the durability of cutting tools. Vapor deposition technology plays an important role in modern industry due to its ability to prepare thin films with specific properties, continuously promoting the development and innovation of material surface treatment technology.

Application Area

Aerospace field
The aerospace industry has extremely high requirements for the lightweight, high-strength, and extreme environmental resistance of materials. The metal surface treatment process plays an important role in this field.

• Application example: Anodizing treatment of aluminum and aluminum alloys can provide wear-resistant and corrosion-resistant surfaces, while reducing structural weight. It is widely used in aircraft structural components and engine parts.
• Technical advantages: Surface treated components have longer service life and higher reliability, which helps improve the performance and safety of aircraft.

Automotive manufacturing field
In the field of automobile manufacturing, metal surface treatment processes are used to improve the corrosion resistance, wear resistance, and aesthetics of components.

• Application example: The coating and plating treatment of car wheels not only improves their corrosion resistance, but also enhances their appearance appeal.
• Technical advantages: Electroplating and PVD technology are used to improve the wear resistance and aesthetics of automotive decorative parts, while thermal spraying technology is used to improve the wear resistance and high temperature resistance of engine components.

Electronic and electrical field
In the field of electronics and electrical engineering, metal surface treatment processes are used to improve conductivity, corrosion resistance, and decorative properties.

• Application example: Chemical gold and tin plating treatment of circuit boards to improve their conductivity and soldering performance.
• Technical advantages: PVD technology is used to prepare thin films with good conductivity and corrosion resistance, which are widely used in electronic devices and connectors.

Medical device field
The medical device field has strict requirements for the biocompatibility and corrosion resistance of materials, and metal surface treatment processes help meet these requirements.

• Application example: Anodizing treatment of implants to form an aluminum oxide film with good biocompatibility, reducing adverse reactions between implants and human tissues.
• Technical advantages: Micro arc oxidation technology is used to prepare ceramic coating layers with excellent wear resistance and biocompatibility, suitable for medical devices such as artificial joints.

Architectural decoration
In the field of architectural decoration, metal surface treatment technology is used to improve the durability, aesthetics, and maintainability of materials.

• Application example: Anodized aluminum sheet for building curtain walls, providing diverse color options and good weather resistance.
• Technical advantages: Thermal spraying and PVD technology are used to prepare decorative coatings with high hardness and wear resistance, extending the service life of building decoration materials.

Industrial machinery field
In the field of industrial machinery, metal surface treatment processes are used to improve the wear resistance, corrosion resistance, and high temperature resistance of mechanical components.

• Application example: Surface hardening treatment of gears and bearings, such as carburizing and nitriding, to improve their wear resistance and load-bearing capacity.
• Technical advantages: Laser surface strengthening technology is used to improve the surface hardness and fatigue life of key mechanical components, reduce maintenance costs and downtime.