Surface materials and surface treatment techniques that must be known to industrial design
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Materials and surface treatment
Chemical plating (autocatalytic plating)
On the surface of the activated substrate, the metal ions in the plating solution are catalyzed to form a metal coating. This is a process engineering that is involved in most of our process, through which we can conduct post-electroplating and other treatment, which is mostly used as the pre-treatment process of plastic parts.
Use electrolysis to form uniform, dense, well-combined metal or alloy sedimentary layer on the surface of the workpiece process, this process is more complex, but it has a lot of advantages, such as more types of metal deposition, can get a variety of colors, compared with the same process is relatively low price.
The process by which metal is deposited on a mold by electrolysis to produce or reproduce a metal product. This approach is that we in the final parts with special surface effect such as clear clear polishing line from the etch or special circumstances, such as acute Angle is used, generally USES copper mass after the shape of a component, through electroplating process means to alloy deposit on the surface, usually sedimentary thickness reaches a few millimeters, then shaped cavity cut set to mold in the shape of cavity respectively, injection molded parts, through such processing parts on the edges and a few boundaries will have special effect, meet the needs of design, In general, we see a lot of plastic parts with clear lines of highlights and etches after electroplating, which have high quality requirements, usually adopt this method for design. Good appearance will be achieved by adopting electroforming technology in the manufacture of angular keypad.
Vacuum plating mainly include vacuum evaporation, sputtering and ion plating several types, they are all used in vacuum condition, by distillation or sputtering methods such as in the deposition of various kinds of metal and nonmetal film on the surface of the plastic, through this way can get very thin surface finishes, fast adhesion good advantage at the same time, but the price is too high, can operate the metal type less, generally used as a high-end product of functional coatings, such as used as internal shielding layer.
Plastic electroplating ------ the characteristics of plastic electroplating
Plastic electroplating products have the characteristics of both plastic and metal. It has small specific gravity, good corrosion resistance, easy to shape, metallic luster and metallic texture, as well as electrical, magnetic and welding properties. It can save complex machining process, save metal materials, and beautiful, decorative strong, at the same time, it also improves the mechanical strength of plastic. Because metal coating has higher stability to the external factor such as light, atmosphere, and so on, after plastic electroplating metal, can prevent plastic aging, prolong the service life of plastic parts.
With the rapid development of industry, the application of plastic electroplating has become one of the important means of surface decoration in plastic products. At present, it has been widely used for electroplating on ABS, polypropylene, polysulfone, polycarbonate, nylon, phenolic glass fiber reinforced plastics, polystyrene and other plastics at home and abroad.
Plastic process -------- the main process of plastic parts electroplating.
Plastic parts - mechanical coarsening - chemical oil removal - chemical coarsening
Sensitization -- -- activation -- -- reduction -- -- chemical nickel -- -- electroplating -- -- finished products
The main technological process of plastic plating
1. Chemical degreasing
To prevent plastic deformation and dissolution, the adaptability of oil removal to plastic should be considered. When using alkaline oil, pay attention to the use of temperature, to prevent deformation; When removing oil with an organic solvent, pay attention to whether it dissolves plastics.
In order to improve the bonding strength, it is necessary to increase the contact area between the coating and the substrate as much as possible. There are two coarsening methods: mechanical coarsening and chemical coarsening. Mechanical coarsening such as sandblasting, rolling grinding, grinding with sandpaper, etc. Chemical coarsening can quickly make the workpiece surface microscopic rough, coarsening layer uniform, meticulous, does not affect the appearance of the workpiece.
The commonly used sensitizing agent in industry is the aqueous solution of stannous chloride or titanium trichloride.
4. Activation treatment
The so-called activation treatment, is adsorbed with reductant parts immersed in a solvent containing oxidants. It is to immerse precious metal salt kind water solution commonly, then precious metal ion is reduced by reductive agent to be precious metal, form precious metal film on the surface of work piece thereby. This layer of noble metal can play an active catalytic role, also known as catalytic film, it can accelerate the reduction reaction of electroless plating. Practice has proved that silver, palladium and other precious metals have this catalytic capacity.
5. Reduction reaction
Electroless plating may be carried out on activated plastic parts after they have been washed with water. Plastic parts before electroless plating, first in a certain concentration of electroless plating used by the reductant solution immersion, not washed out of the activator reduction, this is the reduction process. In electroless copper plating, sodium hypophosphite solution can be used for reduction treatment.
6. Chemical plating
So far, many heavy metals can be deposited from aqueous solution by electroless copper plating. From the economic point of view, the cost of electroless copper plating is the lowest, so it is widely used. The electroless copper plating layer is copper red in appearance and cannot be used as decoration and protection layer. It is usually used as the conductive layer of electroplating thickened coating such as non-metallic coating and metallization of printed circuit board hole. Electroless copper plating can only give plastic parts a layer of conductive power, the coating is very thin. To continue to thicken other coatings, electroplating copper coating with copper plating to thicken. When plating copper, you can use acid copper plating, but also can use alkaline copper plating. After the plastic parts are plated with copper, they can be further plated with other metals as needed.