Principles, Characteristics And Application Scenarios Of 19 Surface Treatment Methods For Common Materials

1. Electroplating

Principle: Apply an electric field to a solution containing metal salts to be plated, with the plated part as the cathode and the plated metal as the anode. After power is turned on, the metal ions in the solution form a coating at the cathode under the action of the potential difference, and the anode metal enters the solution to maintain the ion concentration.

Features:

① It can improve the appearance, making the product surface bright, beautiful and uniform in metallic color, and has good decorative properties.

② It can enhance corrosion resistance, and the coating can isolate the substrate from contact with external corrosive media and extend the service life.

③ Improve conductivity, and some electroplating layers (such as silver plating and gold plating) have excellent conductivity to meet the needs of electronic components.

④ The coating thickness can be accurately controlled to meet different requirements.

Application scenarios: Commonly used in automotive parts (such as door handles, bumpers), electronic and electrical fields (printed circuit board circuits, connectors) and daily hardware products (faucets, door handles), etc., with both aesthetics and protection.

II. Electrophoretic coating

Principle: Under the action of the DC electric field, cations move to the cathode and deposit, and anions move to the anode. At the same time, there are four effects: electrophoresis, electrodeposition, electrolysis, and electroosmosis. Water-soluble paint is used for coating.

Features:

① Good environmental protection, using water as the medium, reducing the use of organic solvents, reducing pollution and fire hazards.

② High coating efficiency, the coating utilization rate reaches 90%-95%, which can make all parts of the workpiece obtain a uniform paint film, suitable for complex shape workpieces.

③ Excellent coating performance, with the characteristics of full, uniform, flat and smooth coating, and excellent hardness, adhesion, corrosion resistance and other properties.

Application scenario: Widely used in large-scale assembly line operations in the automotive, military, hardware and other industries.

III. Anodic oxidation

Principle: Place the metal material as the anode in the electrolyte solution, and after power is turned on, the cations form an oxide film with micropores on the anode surface, involving two processes: metal dissolution and oxide film formation.

Features:

① Improve hardness and wear resistance, the oxide film has high hardness, and enhances the wear resistance of the substrate.

② It has good corrosion resistance, effectively blocks external corrosion, and adapts to harsh environments.

③ It has both decorative and functional properties, and can be dyed in various colors through process conditions, and the oxide film is firmly bonded to the substrate.

Application scenarios: It is widely used in aerospace (aluminum alloy parts), electronic consumer products (tablets, laptop shells) and architectural decoration (aluminum alloy doors and windows, curtain walls) and other fields, which are both beautiful and durable.

IV. Chemical plating

Principle: Rely on chemical reactions to deposit metal coatings on the surface of the substrate, and the metal ions in the plating solution are reduced to atoms and deposited under the action of a reducing agent, without the need for an external power supply.

Features:

① No power supply equipment is required, the operation is simple, and it is not limited by the shape and size of the substrate. A uniform coating can be obtained on the surface of complex workpieces.

② The coating has good uniformity, and complex structural parts with deep holes and grooves can also be well plated.

③ It can be plated with a variety of metals and alloys to meet different performance requirements, and can also improve the hardness, wear resistance and corrosion resistance of the substrate.

Application scenarios: Applied to the petrochemical industry (pipelines, valves), mold manufacturing field (improving mold demoulding and wear resistance) and the electronics industry (small and complex electronic components), etc., to enhance the relevant performance of components.

V. Thermal spraying

Principle: Use high-temperature flames, arcs and other heat sources to heat the spraying material to a molten or semi-molten state, and then spray it onto the workpiece with a high-speed airflow to form a coating.

Features:

① A variety of spraying materials can be selected, such as metals, ceramics, plastics, etc., and can be selected as needed to achieve different functions (such as metals to improve wear resistance, ceramics to resist high temperatures and heat insulation).

② The coating thickness can be adjusted in a wide range, from tens of microns to several millimeters.

③ It is suitable for a variety of substrate materials and has strong repair performance. It can repair damaged parts at a lower cost than replacing new parts.

Application scenarios: commonly used in the power industry (power station boiler pipelines), metallurgical industry (rollers) and mechanical repair fields (worn shafts, gears), etc., to improve component performance, extend service life and save costs.

VI. Vacuum plating

Principle: Argon is injected under vacuum, argon hits the target material, and the target material molecules are adsorbed by conductive materials to form a metal-like surface layer.

Features:

① Good decorative properties, a uniform and bright metal texture appearance can be obtained.

② Good environmental protection, less environmental pollution.

③ Wide range of applicable materials, covering metals, soft and hard plastics, composite materials, ceramics and glass, etc.

Application scenarios: commonly used in electronic product housings, plastic decorations, automotive interiors, etc., to improve the appearance quality and grade.

VII. Electrolytic polishing

Principle: The workpiece atoms immersed in the electrolyte are converted into ions and removed under the action of current, removing fine burrs and improving brightness.

Features:

① High surface finish, can eliminate burrs and scratches on the workpiece surface, and improve surface quality.

② High degree of automation and low labor costs.

③ The use of milder chemicals can extend the service life of materials such as stainless steel and delay corrosion.

Application scenarios: Mainly used in stainless steel products, precision mechanical parts, medical equipment and other fields with high requirements for finish and corrosion resistance, such as stainless steel tableware and surgical instruments.

VIII. Passivation treatment

Principle: Through chemical or electrochemical methods, a dense and stable oxide film or compound film is formed on the metal surface to prevent further reaction of the metal.

Features:

① Easy operation, just soak the workpiece in the passivation solution to complete the treatment.

② Significantly improve corrosion resistance, effectively isolate corrosive media, and enhance corrosion resistance.

③ Basically does not change the size and appearance of the workpiece, suitable for parts with strict size requirements.

Application scenarios: Widely used in stainless steel products (tableware, kitchenware, medical equipment, architectural decorative components), hardware processing fields (precision small parts) and automotive parts production, etc., to ensure product durability.

IX. Phosphating treatment

Principle: Immerse the metal workpiece in an acidic solution containing dihydrogen phosphate. Under certain conditions, the solution reacts with the metal surface to form a phosphate crystal film, which provides a base for subsequent coating.

Features:

① Enhance the adhesion of the coating. The porous structure of the phosphating film is conducive to the adhesion of the coating, making the coating and the substrate more firmly bonded.

② Improve corrosion resistance. It has a certain corrosion barrier ability and cooperates with the coating to improve the overall performance.

③ Improve lubrication performance and can play a friction-reducing and lubricating role on some friction-matching parts.

Application scenarios: Commonly used in the machinery manufacturing industry (pretreatment of mechanical parts before painting), the automotive industry (body, frame and other parts) and the hardware and furniture manufacturing industry (metal filing cabinets, shelves), etc., to optimize surface quality and improve durability.

X. Blackening treatment (blueing treatment)

Principle: Put the steel products into an alkaline solution containing an oxidant and sodium hydroxide, and a chemical reaction will generate an oxide film whose main component is ferroferric oxide, which appears black or blue-black.

Features:

① Low cost, simple treatment solution composition, low equipment requirements, and good economy.

② It has a certain anti-rust ability, can block air and moisture in a short period of time, and meet the needs of some occasions.

③ It gives a unique appearance, presenting a simple and calm visual effect.

Application scenarios: used for mechanical parts (small parts such as ordinary bolts and nuts), tool manufacturing (fitter tools) and some weapons manufacturing (antique weapons, civilian knives), etc., to achieve rust prevention and appearance decoration purposes.

XI. Micro-arc oxidation

Principle: Under high electric field intensity, plasma micro-arc discharge phenomenon is generated in the micro-area of ​​the metal surface, so that the atoms on the metal surface react with the ions in the electrolyte, and a ceramic oxide film is grown in situ. The film layer is firmly bonded to the substrate and has a porous structure.

Features:

① High hardness and wear resistance, the ceramic oxide film has high hardness, significantly enhances the wear resistance, and adapts to high wear conditions.

② Strong corrosion resistance, dense film layer, can resist harsh corrosion environment, such as marine environment.

③Good insulation, suitable for parts with electrical insulation requirements.

④Functional customization can be achieved, and the film properties can be adjusted by adjusting parameters to expand the scope of application.

Application scenarios: It has important applications in the aerospace field (aluminum alloy structural parts of aircraft, engine parts), the electronics industry (aluminum housings of electronic equipment), and the biomedical field (titanium alloy artificial joints), etc., to improve the performance of components and meet special needs.

XII. Vapor deposition

Principle: It is divided into physical vapor deposition (PVD) and chemical vapor deposition (CVD). PVD converts the source material into a gaseous state by physical methods and then deposits it on the substrate to form a film; CVD uses gaseous precursors to chemically react under activation conditions to generate solid-state deposited films.

Features:

①The coating has high quality, high purity, good density, uniform thickness and good bonding with the substrate, and the parameters can be precisely controlled.

②A variety of functional coatings can be prepared, covering metals, alloys, ceramics, semiconductors, etc., to achieve wear resistance, corrosion resistance, high temperature resistance, optics, electricity and other functions.

③It has little impact on the substrate and is suitable for precision and complex shape workpieces.

Application scenarios: It is widely used in the optical field (manufacturing optical lenses, filters, reflectors), electronic information industry (semiconductor chip manufacturing, electronic display manufacturing) and tool coating field (metal cutting tools), etc., to improve product performance.

Thirteen, ion implantation

Principle: Use an ion source to generate ions, which are accelerated and focused to bombard the surface of solid materials and injected into the lattice to change the surface chemical composition, microstructure and physical properties.

Features:

① It can accurately control the composition and depth, and can accurately select the type of ions, energy and dosage to customize the surface properties.

② It can improve multiple surface properties at the same time without affecting the overall performance and shape of the substrate, which is suitable for precision parts.

③ It is firmly bonded to the substrate, there is no risk of coating shedding, and long-term stability is guaranteed.

Application scenarios: It is used in aerospace parts (engine blades, bearings), medical equipment fields (artificial joints, dental implants) and semiconductor manufacturing (regulating the electrical properties of semiconductor devices), etc., to optimize component performance and ensure the use effect.

Fourteen, Shot Peening

Principle: Use high-speed projectiles to hit the surface of metal workpieces, causing plastic deformation of the surface material, generating residual compressive stress, refining grains, increasing dislocation density, etc.

Features:

① Improve fatigue strength. Residual compressive stress can offset the tensile stress generated by alternating loads and extend the fatigue life of the workpiece.

② Improve surface hardness and wear resistance, increase surface hardness, enhance wear resistance, and extend the life of easily worn parts.

③ The process is simple and the cost is moderate. The equipment is easy to operate. The cost is mainly on the projectile material and the spraying equipment.

Application scenarios: In the aerospace field (aircraft landing gear, wing beams), automobile manufacturing industry (engine crankshafts, connecting rods, transmission gears), and mechanical manufacturing and heavy industry fields (drive shafts, rolling mill rollers), etc., enhance component durability and reduce maintenance frequency.

Fifteen, roller burnishing treatment

Principle: Put the workpiece, abrasive, chemical additives and water into the drum, and rotate the drum to make the workpiece and the abrasive collide and rub against each other, remove surface burrs, scale, rust, etc. and smooth the surface.

Features:

① Good effect of removing surface defects, can effectively deal with impurities on the surface of complex-shaped workpieces, make the surface smooth and flat, and have high efficiency.

② Low cost and easy operation, simple equipment, low material cost, easy to master operation.

③ Batch processing can be achieved, suitable for pretreatment of small and medium-sized workpieces in batch production.

Application scenarios: In the hardware processing industry (metal small accessories), mechanical parts manufacturing (irregular small parts) and jewelry processing field (gold and silver jewelry blanks), etc., improve the appearance and performance of the workpiece and prepare for subsequent processes.

Sixteen, laser surface treatment

Principle: Use a high-energy-density laser beam to irradiate the surface of the material, and generate photothermal, photochemical and other interactions according to different purposes, such as laser cladding, laser quenching, etc.

Features:

① Precisely control the processing area, can accurately modify complex and tiny workpieces locally, and has strong flexibility.

② Fast processing speed and small heat-affected zone, short laser action time, concentrated energy, does not affect the overall shape and most of the performance of the workpiece, suitable for precision parts.

③ Can achieve a variety of functional modifications, including strengthening, surface alloying, cleaning and other functions.

Application scenarios: It plays an important role in the mold manufacturing industry (mold surface quenching and repair), mechanical processing field (high-precision shaft, gear parts strengthening) and cultural relics restoration and cleaning field (removal of dirt on the surface of cultural relics, etc.), and improves the performance and status of parts or cultural relics.

Seventeen, ultrasonic surface treatment

Principle: Place the workpiece in an ultrasonic field containing abrasives and chemical solutions, and remove impurities on the workpiece surface and change the surface roughness through the impact, friction and cavitation generated by high-frequency vibration.

Features:

① Efficient cleaning and surface activation can completely remove surface impurities, enhance the adhesion of subsequent coatings and plating, and improve the processing quality.

② Good adaptability to complex shapes, can penetrate into complex parts of workpieces to ensure uniform treatment effect.

③ Environmentally friendly and safe to operate, the chemical solution is mild, and there is no high temperature and high pressure danger during the treatment process.

Application scenarios: In the electronic and electrical industry (printed circuit boards), precision machining fields (precision gears, small bearings) and medical device production fields (surgical instruments, implantable medical devices), etc., optimize the surface state of the workpiece and ensure the smooth progress of subsequent processes.

XVIII. Carburizing treatment

Principle: Place low-carbon steel or low-carbon alloy steel workpieces in a carbon-rich medium, and allow active carbon atoms to penetrate into the surface of the workpiece at high temperature. After quenching and low-temperature tempering and other heat treatment processes, the surface obtains a high-hardness, high-wear-resistant martensitic structure, and the core maintains a certain toughness and strength.

Features:

① Significantly improve the surface hardness and wear resistance, and the martensitic structure greatly enhances the wear resistance of the workpiece surface.

② The core maintains good performance, which can prevent overall brittle fracture while ensuring surface wear resistance, and the performance is balanced.

③The process is mature and has a wide range of applications. It can be used for related workpieces of various shapes and sizes.

Application scenarios: It is widely used in automobile parts manufacturing (transmission gears, rear axle half shafts), mechanical transmission fields (transmission gears, sprockets, shaft parts), and heavy industrial fields such as mining machinery and engineering machinery (crusher gears, travel gears), etc., to improve the wear resistance and fatigue strength of parts and extend their service life.

XIX. Nitriding treatment

Principle: Put the workpiece into a nitrogen-containing medium, and allow nitrogen atoms to penetrate into the surface of the workpiece at a certain temperature to form a nitrogen-rich hardened layer, which contains a nitride phase and has a variety of excellent properties.

Features:

① High hardness and good wear resistance. The nitride layer can still maintain good hardness at high temperatures and adapt to high temperature, high speed, and high friction conditions.

② Excellent corrosion resistance, effectively blocking corrosive media, and good protection in harsh environments.

③ Small deformation, for precision parts or workpieces with high dimensional accuracy requirements, it can meet the design requirements after treatment.

Application scenarios: It is used in the aerospace industry (aircraft engine turbine blades, combustion chamber components), mold manufacturing (die-casting molds, plastic injection molds) and precision components in mechanical manufacturing (precision screws, high-precision shaft parts) to improve component performance and ensure work requirements.