Surface treatment is a process to form a surface layer with a certain or various special properties on the surface of materials by physical or chemical methods. Surface treatment can improve the product appearance, texture, function and other performances.
Anodizing: It mainly refers to the aluminium anodized finish, which uses the electrochemical principle to form a layer of Al2O3 (alumina) film on the surface of aluminum and aluminum alloy. The oxide film has special properties of protection, decoration, insulation and wear resistance.
1. Enhance the strength;
2. Realize any color except white;
3. Realize nickel-free sealing to meet the nickel-free requirements of European and American countries.
II. ED-Electrophoresis deposition
ED-Electrophoresis deposition: It is used in stainless steel, aluminum alloy and other materials, which can make the product appear various colors, maintain metal luster, and enhance the surface performance with good corrosion resistance.
1. Rich in color;
2. No metal texture and be suitable for sandblasting, polishing, wire drawing, etc;
3. Process in liquid environment can realize the surface treatment of complex structures;
4. Mature technology and mass production.
Disadvantages: moderate ability to cover up defects, and high pre-treatment requirements for the electrophoresis of die castings
MAO: Micro arc oxidation (MAO) is a process in which a high voltage is applied to an electrolyte solution (usually a weakly alkaline solution) to produce a ceramic surface film. This process is the result of the synergistic effect of physical discharge and electrochemical oxidation.
1. With ceramic texture, dull appearance, no high-gloss products, delicate hand feel, fingerprint proof;
2. A wide range of base materials: Al, Ti, Zn, Zr, Mg, Nb, and their alloys;
2. Simple pretreatment, excellent corrosion resistance, weather resistance and good heat dissipation performance.
Disadvantages: At present, the color is limited. Only colors such as black and gray are quite mature, brighter colors are difficult to realize; the cost is mainly affected by high power consumption, which makes it become one of the surface treatment methods with the highest cost.
IV. PVD vacuum plating
Physical vapor deposition (PVD) : It is a technology of industrial manufacturing that mainly uses Physical process to deposit thin films.
PVD (Physical Vapor Deposition) can be used to coat a cermet decorative coating with high hardness and high abrasion resistance on metal surface.
Electroplating: It is a technology to make a layer of metal film attach to the surface of the metal by electrolysis, so as to prevent corrosion, improve wear resistance, electrical conductivity and reflective property as well as enhance the aesthetic degree.
1. High gloss coating and high quality metal appearance;
2. The base materials are SUS, Al, Zn, Mg, etc; the cost is relatively lower than PVD.
VI. Metal drawing
Wire drawing: It is a surface treatment method with a decorative effect to form lines on the surface of the workpiece by grinding the products. According to the different line patterns after wire drawing, it can be divided into straight wire drawing, random wire drawing, ripple wire drawing and spiral wire drawing.
The wire drawing treatment can make the metal surface obtain non-mirror metallic luster, and at the same time, the wire drawing treatment can also eliminate the slight defects on the metal surface.
Sandblasting: It is a process in which compressed air is used as the power to form a high-speed jet and spray the materials on the surface of the workpiece, so that the appearance or shape of the workpiece surface will be changed, and a certain degree of cleanliness and different roughness can be obtained.
1. Achieve different reflective or matte effects.
2. Clean the tiny burrs on the surface of the workpiece and make the surface more even, which helps to eliminate the harm of burrs and improve the grade of the workpiece.
3. Clean the residual stains left during pretreatment, improve the finish degree of the workpiece, expose uniform and consistent metal color of the workpiece, and make the appearance of the workpiece more beautiful.
Polishing: It is a method to modify the workpiece surface by flexible polishing tools and abrasive particles or other polishing medium.
Technical features: improve the dimensional accuracy or geometric shape accuracy of the workpiece, get smooth surface or mirror gloss, or eliminate the gloss.
Etching: The general etching is usually called photochemical etching, which means to remove the protective film of the etched area after exposure platemaking and development, and contact with chemical solution during etching for dissolution and corrosion to form the concave-convex or hollow molding effect.
1. Fine processing can be carried out on the metal surface ;
2. Give special effect to metal surface
Disadvantage: Most corrosive liquids (acids, bases, etc.) used in etching are harmful to the environment.
X. Powder coating
Powder coating: As a dry spray method, industrial powder coating is used on some metal workpieces by spraying or fluidized bed. The powder can be adsorbed on the surface of the workpieces by static electricity, and there will form a protective film on the surface when the powder is completely dry.
1. Rich in color; both highlight and matte are optional
2. Low cost; be suitable for building furniture products and shell of heat sinks, etc
3. 100% utilization rate; environmental protection
4. Strong ability to cover defects
Disadvantage: less used for electronic products at present