Several surface treatment methods for die-casting parts

Surface treatment is a technical method of artificially forming surface layers with different mechanical, physical, and chemical properties from the surface of the substrate. The purpose of the surface treatment is to meet the corrosion resistance, wear resistance, decorative properties, and other special functional requirements of the product. Below we take you to understand several surface treatment processes of sensor manufacturing, according to the classification method of the common metal surface treatment process, surface treatment is divided into four categories: 1, mechanical surface treatment: sandblasting, shot blasting, polishing, polishing, polishing, polishing, brushing, spraying, painting, wiping oil and so on.2. Chemical surface treatment: blue and black, phosphorization, pickling, chemical plating of various metals and alloys, TD treatment, QPQ treatment, chemical oxidation, etc.3. Electrochemical surface treatment: anodization, electrochemical polishing, electroplating, etc.4. Modern surface treatment: chemical vapor deposition CVD, physical vapor deposition PVD, ion injection, ion plating, laser surface treatment, etc.

Below we will introduce you to several surface treatment processes.

Mechanical surface treatment: sandblasting

Sandblasting is the impact of high-speed sand flow cleaning and the process of coarsening matrix surface, namely the compressed air as power, to form a high-speed jet beam will spray (copper ore, quartz sand, diamond sand, iron sand, Hainan sand) high-speed injection to handle the surface of the workpiece, make the outer surface of the workpiece surface appearance or shape change.

Chemical surface treatment: pickling

Chemical surface treatment technology is an effective method to prevent the corrosion of stainless steel materials, and this treatment method is more cost-effective. In general, the lower the chromium content, the lower the corrosion resistance of stainless steel materials. For optimal corrosion resistance, the damaged metal layer must be removed in time to achieve better integrity of alloy stainless steel surfaces.

For some branded stainless steel materials, a longer pickling time may be required. In this process, there are sometimes some serious color problems, which are usually caused by poor gas purging. The mechanical removal of surface impurities alone may leave the abrasive or other particles (which may affect the corrosion resistance of the material), and this single mechanical method is usually insufficient to fully clean the surface. If mechanical means are used, chemical passivation is also required to achieve optimal corrosion resistance of the material. The pickling process sometimes uses some strong acids, such as a mixture of hydrofluoric acid (HF) and nitric acid (HNO3), to remove the dirt layer and the bottom chromium depletion layer to restore its corrosion resistance. A mixture of HF and HNO3 is the most common and usually the most effective. It is worth mentioning that acids can be used in different forms such as a gel or paste. The commercially available mixture of hydrofluoric acid and nitric acid contains approximately up to 25% HNO3 and 8% HF. Acid washing solutions can also effectively remove embedded contaminants, such as carbon steel, ferrous iron, and iron oxide particles. Besides the HNO3 and HF acid mixtures, many different pickling solutions can be used, some can be used for specialized applications, but their pickling process tends to be slightly slower.

Electrochemical surface treatment: anodization

An electrolytic oxidation process in which the surface of an aluminum and an aluminum alloy is usually converted into an oxide film with protective, decorative, and some other functional properties. From this definition, aluminum anodized oxidation only includes the process of generating anodized film. The parts of metal or alloy are used as an anode to form an oxide film. Metal oxide film changes the surface state and properties, such as surface coloring, improves corrosion resistance, enhances wear resistance and hardness, protects the metal surface, etc. Anodized aluminum or its alloy, improves its hardness and wear resistance, up to 250~500 kg / square mm, good heat resistance, hard anodize film melting point up to 2320K, excellent insulation, wear resistance to voltage up to 2000V, enhances corrosion resistance, in =0.03NaCl salt spray after thousands of hours without corrosion.

Modern surface treatment: physical vapor deposition of PVD

Physical Vapor Deposition (physical vapor deposition), refers to the vacuum condition, using low voltage, high current arc discharge technology, the use of gas discharge to evaporate the target material and the evaporated material and gas are ionized, using the acceleration of the electric field, the evaporated material, and its reaction products deposited on the workpiece. Physical Vapor Deposition (physical vapor deposition), refers to the vacuum condition, using low voltage, high current arc discharge technology, the use of gas discharge to evaporate the target material and the evaporated material and gas are ionized, using the acceleration of the electric field, the evaporated material, and its reaction products deposited on the workpiece.