Principles, Features, and Applications of 19 Common Surface TreatmentMethods for Materials

 

I. Electroplating Technology Basics

 

In a specific metal salt solution environment, an electric field is applied, using the object to be plated as the cathode and the plating metal as the anode. When the power is turned on, metal ions in the solution migrate towards the cathode under the influence of the electric field and form the desired plating layer on the cathode surface. Meanwhile, the metal at the anode gradually dissolves into the solution to maintain the ion concentration balance in the solution.

 

Features:

1. Aesthetic Enhancement: Through electroplating, the appearance of the product can be significantly enhanced, with a shiny, uniform, and beautiful metallic color, adding excellent decorative effects to the product.
2. Corrosion Protection: The plating layer effectively isolates the substrate from external corrosive agents, thus extending the product's lifespan and improving its corrosion resistance.
3. Improved Conductivity: Some plating layers, such as silver and gold plating, exhibit excellent conductivity, meeting the high electrical conductivity requirements of electronic components.
4. Thickness Control: Electroplating technology can precisely control the thickness of the plating layer to meet the needs of various applications.

 

Application Scenarios:

Electroplating technology is widely used in automotive parts (e.g., door handles, bumpers), electronics and electrical fields (e.g., printed circuit board traces, connectors), as well as daily hardware products (e.g., faucets, door locks). It not only enhances the product's aesthetic appeal but also provides effective protection.

 

▲ Electroplating Process Illustration

 

 

II. Electrophoretic Coating Process

 

Under the action of a DC electric field, cations in the coating migrate towards the cathode and deposit on the workpiece surface, while anions move towards the anode. The electrophoretic coating process combines electrophoresis, electro-deposition, electrolysis, and electro-osmosis, using water-based coatings for the coating process.

 

Features:

1. Environmentally Friendly and Energy Efficient: Electrophoretic coating uses water as the medium, greatly reducing the use of organic solvents, thus minimizing environmental pollution and the risk of fire.
2. High Efficiency Coating: The coating utilization rate is 90%-95%, ensuring that all parts of the workpiece receive an even and high-quality coating, especially suitable for workpieces with complex shapes.
3. Excellent Coating Performance: The coating formed by electrophoretic coating is full, uniform, smooth, and has excellent hardness, adhesion, and corrosion resistance.

 

Application Scenarios:

Electrophoretic coating is widely used in industries such as automotive manufacturing, military manufacturing, and hardware manufacturing for mass production in assembly lines.

 

▲ Electrophoretic Coating Process Diagram

 

 

III. Anodizing Process

 

The metal material is placed as the anode in an electrolyte solution. When electric current is passed through, cations form a porous oxide film on the anode surface. This process involves two key steps: metal dissolution and oxide film formation.

 

Features:

1. Hardness and Wear Resistance Enhancement: The oxide film has high hardness, which significantly enhances the wear resistance of the substrate.
2. Superior Corrosion Resistance: The oxide film effectively blocks corrosive agents from attacking the substrate, allowing the product to maintain a long service life in harsh environments.
3. Decorative and Functional Integration: By adjusting the process conditions, various colors can be produced, while the oxide film forms a strong bond with the substrate, providing both aesthetic and practical benefits.

 

Application Scenarios:

The anodizing process is widely used in aerospace (e.g., aluminum alloy components), consumer electronics (e.g., tablet computers, laptop shells), and architectural decoration (e.g., aluminum alloy doors and windows, curtain walls).

 

▲ Anodizing Process Diagram

 

 

IV. Chemical Plating Technology

 

Chemical plating is a method of depositing a metal coating on a substrate through a chemical reaction. In the plating solution, metal ions are reduced to atoms and deposit on the substrate surface under the action of a reducing agent, without requiring an external power source.

 

Features:

1. Simple Operation: Chemical plating does not require a power supply, making the process simple and convenient, and it is not limited by the shape or size of the substrate.
2. Excellent Coating Uniformity: Chemical plating can form a uniform coating on complexly structured workpieces, including hard-to-reach areas such as deep holes and grooves.
3. Diverse Properties: Chemical plating can coat various metals and alloys, meeting different performance requirements, and also enhances the hardness, wear resistance, and corrosion resistance of the substrate.

 

Application Scenarios:

Chemical plating is widely used in the petrochemical industry (e.g., pipelines, valves), mold manufacturing (e.g., improving mold release performance and wear resistance), and electronics industry (e.g., small, complex electronic components), providing enhanced performance for parts.

 

▲ Chemical Plating Process Illustration

 

 

V. Spraying Technology Overview

 

Spraying technology uses high-temperature flames or arcs to heat spray materials to a molten or semi-molten state. These materials are then sprayed onto the workpiece surface through high-speed airflow, forming a coating layer.

 

Features:

1. Variety of Spraying Materials: Spraying materials include metals, ceramics, plastics, etc., which can be selected according to actual needs to achieve specific functions (e.g., metals for wear resistance, ceramics for high-temperature insulation).
2. Flexible Coating Thickness: The coating thickness can be adjusted from several micrometers to a few millimeters.
3. Repair Capability: This technology is suitable for a variety of substrate materials and offers excellent repair capabilities. It can effectively repair damaged components, and compared to replacing with new parts, it is more cost-effective.

 

Application Scenarios:

This technology is widely used in the power industry (e.g., boiler pipelines), metallurgy industry (e.g., rolling mills), and mechanical repair (e.g., worn shafts, gears), aiming to improve component performance, extend service life, and reduce costs.

 

▲ Spraying Technology Process

 

 

VI. Vacuum Coating Technology Overview

 

In a vacuum environment, argon gas is injected, and the argon molecules collide with the target material, causing the target material's molecules to be adsorbed onto conductive objects, forming a metallic-like surface layer.

 

Features:

1. Excellent Decorative Effect: It provides a uniform and shiny metallic appearance.
2. Superior Environmental Performance: It has minimal environmental pollution.
3. Wide Applicability: It can be used for metals, soft and hard plastics, composite materials, ceramics, and glass.

 

Application Scenarios:

This technology is widely used in the electronics industry (e.g., product shells), plastic decorations, and automotive interior components to improve the aesthetic quality and class of products.

 

▲ Vacuum Coating Process Diagram

 

 

VII. Electrolytic Polishing Process Analysis

 

The workpiece is immersed in an electrolyte solution, and an electric current is applied. This causes the atoms on the workpiece's surface to be converted into ions and removed, thus removing fine burrs and improving the brightness of the workpiece.

 

Features:

1. High Surface Finish: It effectively removes burrs, scratches, and other defects on the surface, enhancing the surface quality.
2. High Automation: It reduces labor costs.
3. Use of Gentle Chemicals: It helps extend the lifespan of materials like stainless steel and delays the corrosion process.

 

Application Scenarios:

It is mainly used in stainless steel products, precision machinery parts, and medical instruments, where high surface finish and corrosion resistance are required, such as stainless steel tableware, surgical instruments, etc.

 

▲ Electrolytic Polishing Process Flow

 

 

VIII. Detailed Explanation of Metal Passivation Treatment

 

Passivation treatment involves creating a dense and stable oxide or compound layer on the metal surface through chemical or electrochemical methods to prevent further chemical reactions.

 

Features:

1. Simple Process: The process is simple, requiring only the immersion of the workpiece in a passivation solution.
2. Enhanced Corrosion Resistance: It significantly enhances the metal's corrosion resistance, effectively isolating corrosive agents and improving anti-corrosion capability.
3. Minimal Effect on Size or Appearance: The process generally does not alter the size or appearance of the workpiece, making it ideal for parts with strict dimensional requirements.

 

Application Scenarios:

This technology is widely used in stainless steel products (such as tableware, kitchen utensils, medical devices, and architectural decoration components), hardware processing (such as precision small parts), and automobile parts manufacturing, aiming to ensure product durability.

 

▲ Metal Passivation Treatment Process

 

 

IX. Analysis of Metal Surface Phosphating Treatment Technology

 

Phosphating treatment involves immersing metal workpieces into an acidic liquid containing dihydrogen phosphate salts, where specific conditions cause a chemical reaction between the metal surface and the solution to form a phosphate crystal film. This film provides a solid base for subsequent coating treatments.

 

Features:

1. Improved Coating Adhesion: The porous structure of the phosphate film provides good conditions for coating adhesion, ensuring a strong bond between the coating and the metal substrate.
2. Enhanced Corrosion Resistance: The phosphate film itself offers some corrosion resistance, and when combined with a coating, it greatly improves overall anti-corrosion performance.
3. Improved Lubrication Performance: For parts requiring friction pairing, the phosphate film helps reduce friction and increase lubrication.

 

Application Scenarios:

Phosphating treatment is widely used in mechanical manufacturing, automotive industry, and hardware furniture manufacturing, especially in pre-coating treatment of mechanical components, automobile body and chassis parts, as well as in the production of metal filing cabinets and shelves, significantly optimizing the metal surface quality and enhancing product durability.

 

▲ Metal Phosphating Treatment Process

 

 

X. Steel Products Blackening (Bluing) Treatment Technology

 

Blackening (Bluing) treatment involves placing steel products in an alkaline solution containing oxidants and sodium hydroxide, where a chemical reaction generates a black or bluish-black oxide film primarily composed of Fe₃O₄.

 

Features:

1. Cost-Effectiveness: The composition of the treatment solution is simple, with low equipment requirements, resulting in relatively low treatment costs.
2. Moderate Rust Resistance: The oxide film effectively isolates air and moisture, providing short-term rust prevention.
3. Unique Appearance: The treated steel products have an antique and steady visual effect, adding a decorative feature.

 

Application Scenarios:

Blackening (Bluing) treatment technology is widely applied in the manufacture of mechanical components, tools, and weapons, especially in the production of small parts like bolts and nuts, machinist tools, as well as antique weapons and civilian knives, achieving both rust prevention and aesthetic decoration.

 

▲ Blackening (Bluing) Treatment Process

 

 

XI. Introduction to Metal Surface Micro-Arc Oxidation Technology

 

Micro-arc oxidation technology generates plasma micro-arc discharge on the metal surface under high electric field strength. The metal atoms react with ions in the electrolyte, leading to the growth of a ceramic oxide film that is firmly bonded to the metal substrate and possesses a porous structure.

 

Features:

1. High Hardness and Excellent Wear Resistance: The ceramic oxide film is hard, significantly improving the wear resistance of the metal surface, suitable for high wear conditions.
2. Strong Corrosion Resistance: The oxide film is dense and can effectively resist harsh corrosive environments, such as marine environments.
3. Good Electrical Insulation: The micro-arc oxidation film offers excellent electrical insulation, making it suitable for components requiring electrical insulation.
4. Customizable Functions: By adjusting the parameters of the micro-arc oxidation process, the characteristics of the oxide film can be controlled to meet the needs of different applications.

 

Application Scenarios:

Micro-arc oxidation technology has broad application prospects in aerospace, electronics, and biomedical fields. It is particularly useful in the manufacturing of aluminum alloy structural components for aircraft, engine parts, aluminum outer shells for electronic devices, and titanium alloy artificial joints, significantly enhancing the performance of components to meet specific requirements.

 

▲ Micro-Arc Oxidation Process

 

 

XII. Gas Phase Material Deposition Technology

 

This technology can be divided into physical vapor deposition (PVD) and chemical vapor deposition (CVD). PVD uses physical means to transform raw materials into a gaseous state, which is then deposited as a thin film on the substrate. CVD, on the other hand, involves chemical reactions of gaseous precursors in an activated state to form solid films that are deposited on the substrate.

 

Features:

1. High-Quality Films: The films formed are of excellent quality, with high purity, high density, uniform thickness, and strong adhesion to the substrate, while also allowing precise control over various parameters.
2. Variety of Functional Films: This technology can create a variety of functional films, including metals, alloys, ceramics, and semiconductors, meeting diverse performance needs such as wear resistance, corrosion resistance, high temperature resistance, optics, and electrical properties.
3. Minimal Substrate Impact: The impact on the substrate is minimal, making it particularly suitable for processing precise and complex workpieces.

 

Application Scenarios:

Gas phase material deposition technology is widely used in the manufacturing of optical devices (such as optical lenses, filters, and mirrors), electronic information industries (such as semiconductor chips and electronic display screens), and tool surface treatment technologies (such as coatings for metal cutting tools), significantly enhancing the overall performance of products.

 

▲ Gas Phase Material Deposition Process

 

 

XIII. Ion Penetration Technology

 

This technology involves generating specific ions through an ion source, which are accelerated and focused to strike the surface of solid materials and penetrate the crystal lattice, altering the chemical composition, microstructure, and physical properties of the material's surface.

 

Features:

1. Precise Control: The composition and depth of the treatment can be precisely controlled by selecting the ion types, energy, and dosage, allowing for customized adjustments to the surface properties.
2. Enhanced Multiple Properties: Multiple surface properties can be enhanced simultaneously without affecting the overall material properties or shape, making it ideal for precision parts processing.
3. Strong Bonding: The treatment is tightly bonded to the substrate, preventing the risk of coating delamination, ensuring long-term stability and reliability.

 

Application Scenarios:

Ion penetration technology is widely used in aerospace (such as engine blades and bearings), medical devices (such as artificial joints and dental implants), and semiconductor manufacturing (for tuning the electrical performance of semiconductor devices), effectively optimizing component performance and ensuring the desired results.

 

▲ Ion Penetration Process Illustration

 

 

XIV. Shot Peening Hardening Process

 

This process involves using high-speed shot peening to impact the surface of metal workpieces, causing plastic deformation of the surface material, generating residual compressive stress, refining grain structure, and increasing dislocation density.

 

Features:

1. Significant Improvement in Fatigue Strength: Residual compressive stress counteracts tensile stress caused by alternating loads, effectively extending the workpiece's service life.
2. Improved Surface Hardness and Wear Resistance: The process increases surface hardness and wear resistance, thereby extending the service life of easily worn parts.
3. Simple Process and Moderate Cost: The process is straightforward, and the main costs are related to the purchase and maintenance of the shot material and equipment.

 

Application Scenarios:

Shot peening technology is widely used in aerospace (such as aircraft landing gear and wing beams), automobile manufacturing (such as engine crankshafts, connecting rods, and transmission gears), and heavy machinery (such as drive shafts and rolling mill rollers), significantly enhancing the durability of components, reducing maintenance costs, and prolonging the repair cycles.

 

▲ Shot Peening Process Diagram

 

 

XV. Surface Grinding Process

 

Workpieces, along with grinding media, chemical additives, and water, are placed in a rotating drum. The rotation drives the workpieces and grinding media to collide and rub against each other, eliminating burrs, oxidation layers, and rust stains from the surface, achieving a smoother surface finish.

 

Features:

1. Efficient Removal of Surface Imperfections: The process is especially effective for removing surface impurities from workpieces with complex shapes, significantly improving surface cleanliness and processing efficiency.
2. Cost-Effective and Easy to Operate: The required equipment is simple, material costs are low, and the process is easy to master.
3. Suitable for Batch Preprocessing of Medium-Small Workpieces: Ideal for large-scale production needs.

 

Application Scenarios:

Surface grinding is widely used in hardware products (small metal parts), mechanical manufacturing (special-shaped small parts), and jewelry manufacturing (raw gold and silver jewelry), improving the appearance quality and performance of workpieces and laying the foundation for subsequent processing steps.

 

▲ Surface Grinding Process Illustration

 

 

XVI. Laser Surface Modification Technology

 

This technology involves irradiating the material surface with high-energy laser beams, triggering thermal effects and photochemical reactions according to different requirements, achieving surface modifications such as laser cladding and laser hardening.

 

Features:

1. Precise Control of Treatment Area: The process can precisely modify the surface of complex or small workpieces, offering high flexibility.
2. Fast Processing Speed and Small Heat-Affected Zone: The laser rapidly concentrates energy, minimizing the impact on the overall shape and properties of the workpiece, making it suitable for precision parts.
3. Diverse Functions: Laser surface modification can be used for strengthening, surface alloying, cleaning, and other applications to meet various modification needs.

 

Application Scenarios:

Laser surface modification plays a crucial role in mold manufacturing (such as surface hardening and repair), mechanical processing (such as precision shafts and gear component strengthening), and artifact protection and cleaning (such as removing stains from cultural relics), improving the performance and condition of components or artifacts.

 

▲ Laser Surface Modification Process

 

 

XVII. Ultrasonic Surface Treatment Technology

 

Workpieces are placed in an ultrasonic field containing grinding media and chemical solutions. The high-frequency vibrations generate impacts, friction, and cavitation effects, removing surface impurities and achieving smooth surfaces.

 

Features:

1. Good Surface Cleaning and Polishing Effect: Ultrasonic vibration can remove stubborn dirt and smoothen rough surfaces effectively.
2. Non-Destructive to Workpieces: Ultrasonic treatment has no significant impact on the structural integrity of workpieces, ensuring that sensitive parts are not damaged.
3. Suitable for Precision Parts and Small Workpieces: Due to its non-contact and mild nature, ultrasonic treatment is ideal for handling small and precise workpieces.

 

Application Scenarios:

Ultrasonic surface treatment is widely used in electronics manufacturing (such as semiconductor parts), medical device production (such as small surgical instruments and implants), and jewelry cleaning (such as precious metal ornaments), ensuring that workpieces meet cleanliness and aesthetic standards.

 

▲ Ultrasonic Surface Treatment Process

 

 

XVII. Ultrasonic Surface Treatment Technology (Repetition)

 

The workpieces are placed in an ultrasonic field containing grinding media and chemical solutions. Through the high-frequency vibrations, impact, friction, and cavitation effects are generated to remove surface impurities and adjust surface roughness.

 

Features:

1. High Efficiency in Cleaning: The process is highly efficient in removing surface impurities, enhancing the adhesion of subsequent coatings and improving processing quality.
2. Good Adaptability to Complex-Shaped Workpieces: Ultrasonic treatment can uniformly treat intricate parts, making it suitable for workpieces with complex geometries.
3. Environmentally Friendly and Safe: The process uses gentle chemical solutions and does not involve high temperatures or pressures, making it environmentally safe.

 

Application Scenarios:

This technology is applied in electronics and electrical appliances (such as circuit board manufacturing), precision machining (such as precision gears and small bearings), and medical device manufacturing (such as surgical instruments and implantable medical devices), optimizing the surface condition of workpieces and ensuring the smooth progress of subsequent processing steps.

 

▲ Ultrasonic Cleaning and Surface Treatment

 

 

XVIII. Detailed Explanation of the Carburizing Process

 

This process involves placing steel or alloy materials with low carbon content into an environment rich in carbon elements. Under high-temperature conditions, carbon atoms are activated and penetrate the material's surface. Subsequently, through quenching and low-temperature tempering heat treatment techniques, the material's surface is transformed into a martensitic structure with extremely high hardness and excellent wear resistance, while the internal part maintains appropriate toughness and strength.

 

Features:

1. Improved Surface Hardness and Wear Resistance: The formation of martensitic structure significantly enhances the material's abrasion resistance.
2. Maintains Internal Toughness: While the surface has high wear resistance, the internal part remains tough and strong, avoiding brittleness.
3. Mature and Widely Applicable: The carburizing process is suitable for materials of various shapes and sizes.

 

Application Scenarios:

This process is widely used in automotive manufacturing (such as transmission gears, drive shafts), mechanical transmission systems (such as sprockets, shaft components), and heavy machinery (such as crusher gears, walking mechanisms), effectively improving the wear resistance and fatigue strength of components and extending their service life.

 

▲ Carburizing Process Diagram

 

 

XIX. Detailed Explanation of the Nitriding Treatment Technology

 

This technology involves placing the workpiece in an environment containing ammonia elements. By controlling the temperature, ammonia atoms penetrate the surface of the workpiece, forming a hardened layer rich in ammonia elements. This layer contains nitrides and imparts various excellent properties to the workpiece.

 

Features:

1. High Hardness and Excellent Wear Resistance: Even in high-temperature environments, the nitrided layer can maintain good hardness, making it suitable for high-temperature, high-speed, and high-friction working conditions.
2. Outstanding Corrosion Resistance: The nitrided layer effectively blocks the invasion of corrosive media and provides good protection for the workpiece under harsh environmental conditions.
3. Minimal Deformation: Nitriding treatment ensures that precision parts or workpieces with strict dimensional accuracy requirements retain their design specifications with minimal deformation.

 

Application Scenarios:

Nitriding treatment technology is widely used in aerospace (such as turbine blades, combustion chamber components of aircraft engines), mold manufacturing (such as die-casting molds, injection molds), and precision components in mechanical manufacturing (such as precision lead screws, high-precision shaft parts). This technology significantly enhances the performance of components and ensures the achievement of operational requirements.

 

▲ Nitriding Treatment Process Diagram