Common methods and characteristics of surface heat treatment of materials
1. Electroless plating
Electroless nickel plating:
Electroless plating does not require an external power supply. It uses a reducing agent to reduce the metal ions in the plating solution and deposits on the surface of the catalytic workpiece to form an electroless plating layer. The thickness is uniform and is not affected by the complexity of the shape of the workpiece, and there is no obvious edge effect. The coating is fine-grained, compact, with few holes, a bright appearance, and good corrosion resistance. Electroless plating has nickel, copper, silver, palladium, gold, platinum, cobalt, and other metals or alloys and composite coatings.
Applicable materials: Metals and non-metals (such as plastics, glass, ceramics, etc.) that have undergone special pre-plating treatments can be directly coated.
Electroless copper plating:
The electroless copper plating layer is generally very thin, with a red copper appearance, and has excellent electrical conductivity and solderability. Mainly used for surface metallization of non-metallic materials, especially hole metallization of printed circuits.
Applicable materials: For example, the production of double-sided or multilayer printed circuit boards with through holes. Metallize plastic waveguides, cavities, or other plastic parts for electroplating, etc.
2. Hot dip plating
Hot-dip plating is a method of immersing a workpiece in molten metal and obtaining a metallurgical combined metal coating by mutual dissolution and diffusion of two metals. The coating metals are low melting point zinc, tin, lead, and aluminum.
Applicable materials: generally only suitable for simple shapes of plates, strips, pipes, wires, etc. Hot-dip galvanizing is mainly used for steel pipes, steel plates, steel strips, and steel wires.
3. Vacuum coating
Vacuum coating refers to a technology of gas-phase coating in a vacuum chamber or a vacuum chamber with inert gas. Mainly include vacuum evaporation, cathode sputtering, and ion plating. The film layer can be further diffused and plated at high temperatures to improve the bonding force with the substrate.
Vacuum evaporation:
The substrate can be metal or non-metal. The coatings are metals such as aluminum, silver, zinc, nickel, and chromium. The film is smooth and bright, with good reflection. The corrosion resistance is better than the electroplated layer, but the covering ability is not as good as the electroplated layer.
Applicable materials: mainly used to make various thin-film electronic components; deposit various optical films, such as car lamp reflectors, etc.; and used as a decorative film on some non-metallic crafts.
Cathodic sputtering:
Compared with vacuum evaporation, it has the advantages of strong bonding force, and the coating material is not affected by melting point and vapor pressure, but the deposition speed is not as good as vacuum evaporation.
Applicable materials: high melting point films such as splashable bond gold and platinum; super hard films such as TiN, TiC, WC, etc.; wear-resistant layers such as MOS2; and decorative films for electronic, optical devices, and plastics.
Ion plating:
It has the comprehensive advantages of vacuum evaporation and cathode sputtering. The substrate can be metal or non-metal, and the material of the film layer can be metal, alloy compound, ceramic, and so on. The film layer and the substrate have a good bonding force.
Applicable materials: aluminum, zinc, cadmium, and other anti-corrosion film layers; aluminum, tungsten, titanium, tantalum heat-resistant film layers; chromium, titanium carbide wear-resistant film layers; gold, silver, and titanium nitride decorative films; plastics Nickel, copper, and chromium are used in automobile and electrical parts, as well as in the production of printed circuit boards, tapes, etc.