zinc-aluminum alloy surface treatment

　　A method of special surface chemical treatment or zinc alloy surface treatment on the surface of aluminum alloy or zinc alloy. Surface treatment can improve the appearance, texture, function and other aspects of the product. 1. Surface treatment of zinc-aluminum alloy: Anodizing is mainly anodizing of aluminum alloy die-castings, and zinc-aluminum alloy die-castings cannot be surface treated due to technical reasons. A layer of aluminum oxide film is formed on the surface of aluminum alloy die castings using electrochemical principles. The oxide film has the characteristics of protection, decoration, insulation and wear resistance. Single color, gradient color: polishing/sandblasting/drawing→degreasing→anodic oxidation→neutralization→dyeing→sealing→drying two-color: ① polishing/sandblasting/drawing→degreasing→shielding→anodic oxidation 1→anodic oxidation 2→sealing → Drying ② Polishing/sandblasting/wire drawing → Degreasing → Anodizing 1 → Laser carving → Anodizing 2 → Sealing → Drying technical characteristics: 1. Strengthen the strength 2. Know any color other than white 3. Achieve nickel-free sealing, Technical difficulties and improvement points to meet the requirements of European and American countries: The yield of anodizing is related to the cost of the final product. The key to increasing the anodic oxidation rate is the proper amount of oxidant, proper temperature and current density, which requires continuous exploration and breakthroughs in the production process of aluminum alloy die-casting plants. 2. Electrophoresis can be used for stainless steel, aluminum alloy die-casting, zinc alloy die-casting, etc. It can make products show various colors, maintain metallic luster, improve surface performance, and have good corrosion resistance. Process flow: pretreatment → electrophoresis → drying Advantages: 1. Rich colors; 2. No metal texture, can be used with sandblasting, polishing, wire drawing, etc.; 3. Processing in a liquid environment can achieve surface treatment of complex structures; 4. , Can be used for mass production. Disadvantages: General defect coverage, high requirements for electrophoresis pretreatment of die castings. 3. Micro-arc oxidation In the electrolyte solution (usually a weak alkali solution), the ceramic surface film is formed by the action of high pressure, which is the result of the synergistic effect of physical discharge and electrochemical oxidation. Process flow: pretreatment→hot water washing→hair→drying Advantages: 1. Ceramic texture, dim appearance, no high-gloss products, fine hand feeling, anti-fingerprint; 2. A wide range of substrates: aluminum, titanium, zinc, zirconium, magnesium, Niobium and its alloys; 3. Simple pretreatment, good corrosion resistance, good weather resistance, and good heat dissipation performance. Disadvantages: At present, the colors are limited, only black and gray are mature. At present, bright colors are difficult to achieve; the cost is mainly affected by high consumption, which is a kind of surface treatment cost. 4. PVD vacuum electroplating, the full name of physical vapor deposition, is an industrial production process, mainly using physical process deposition film technology, various zinc alloy die castings, aluminum alloy die castings can use vacuum plating process. Process flow: cleaning before PVD→into the furnace vacuum→cleaning target and ions→coating→finishing, cooling outside the furnace→post-processing (polishing, AFP) Technical features: PVD (physical vapor deposition) can be used for high hardness and high wear resistance Coating on the metal surface 5. Electroplating zinc-aluminum alloy surface treatment technology is a technology that uses electrolysis to attach a metal film to the metal surface to prevent corrosion, improve wear resistance, conductivity, light reflection and improve appearance. Electroplating technology is widely used and can be used for a variety of zinc alloy die castings and aluminum alloy die castings. Process flow: pretreatment → cyanide-free alkaline copper → cyanide-free white copper tin → chromium plating Advantages: 1. The coating has high gloss and high-quality metal appearance; 2. The base material is SUS, Al, Zn, Mg, etc., and the cost is low于PVD. Disadvantages: poor environmental protection and high risk of environmental pollution. 6. Powder spraying. Powder spraying equipment (electrostatic spraying machine) is used to spray powder coating on the surface of zinc alloy die castings and aluminum alloy die castings. Under the action of static electricity, the powder is uniformly adsorbed on the surface of the casting to form a powder coating. The powder coating is dried, baked, leveled and cured at a high temperature, and finally coatings with different effects are obtained (the effects of powder coatings are different). Process flow: loading → electrostatic dust removal → spraying → low temperature leveling → baking Advantages: 1. Rich colors, high brightness, matte optional; 2. Low cost, suitable for building furniture products and radiator shells, etc.; 3. High utilization rate, 100% utilization, environmental protection; 4. Strong ability to shield defects; 5. Can imitate wood grain effect. Disadvantages: At present, it is less used in electronic products. 7. The formation of lines on the surface of zinc alloy die-casting parts by grinding products for metal drawing is a surface treatment method with decorative effect. According to the different patterns after painting, it can be divided into: straight line painting, random painting, wave painting and spiral pattern. Technical features: Wire drawing treatment can make the metal surface obtain a mirror-free metallic luster. At the same time, wire drawing treatment can also eliminate the small defects on the surface of zinc alloy die castings. 8. Sandblasting uses compressed air as power to form a high-speed jet stream, spraying the spraying material on the surface of the zinc alloy die casting at a high speed, thereby changing the appearance or shape of the outer surface of the zinc alloy die casting, so as to obtain a certain degree of cleanliness and different Roughness roughness process. Technical features: 1. Realize different reflection or matt. 2. It can remove microburrs on the surface of zinc alloy die castings, make the surface of zinc alloy die castings smoother, eliminate the hazards of burrs, and improve the grade of zinc alloy die castings. 3. Remove the dirt remaining in the pretreatment process, improve the smoothness of the zinc alloy die castings, make the zinc alloy die castings show a uniform metal color, and make the zinc alloy die castings more beautiful. 9. Polishing. Polishing media such as flexible polishing tools and abrasive particles are used to modify the surface of zinc alloy die castings. According to different polishing processes: rough polishing (basic polishing process), medium polishing (finishing process) and finishing polishing (polishing process) to select the appropriate polishing wheel can achieve the polishing effect and improve the polishing efficiency. Technical features: By improving the dimensional accuracy or geometric accuracy of zinc alloy die-casting parts, a smooth surface or mirror gloss can be obtained, and the gloss can be eliminated at the same time. X. Etching Generally speaking, etching is also called photochemical etching, which refers to removing the protective film of the etched area through exposure after plate making and development, and contacting chemical solutions during the etching process to achieve the effect of dissolving corrosion and forming bumps or voids. Exposure method: According to the drawings, this project provides the size of material preparation→material preparation→cleaning material→drying→coating or coating→drying→exposure→development→dry etching→peeling→OK. Screen printing method: cutting → cleaning plate (metal materials such as stainless steel) → screen printing → etching → peeling → OK Advantages: 1. The surface of zinc alloy die castings can be processed; 2. The special surface effects of zinc alloy die castings are given ; Disadvantages: Most etching solutions (acids, alkalis, etc.) are harmful to the environment.

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