The purpose of post-plating treatment is to ensure the quality of the coating and improve the protection, decoration and function of the coating. Post-plating treatment is very important, but often easy to be ignored. In the actual production often break down, and even before the failure, so should cause the attention of the concerned personnel.
Electroplating post-treatment process is selected according to the performance of electroplating, use requirements, environmental impact and other factors, usually including polishing, passivation, coloring, coating, sealing, hydrogen removal and other processes.
1. Polishing
Polishing is a process to improve the surface smoothness and reduce the surface roughness of metal workpiece by chemical polishing or mechanical polishing. It can not only be directly used for the surface processing of metal workpiece, but also for the pretreatment and finishing of metal workpiece after plating. Decorative finishing of copper, nickel and other alloys as well as copper, nickel, chromium and other metal coatings after plating.
2. Passivation treatment
The so-called passivation treatment refers to the chemical treatment in a certain solution, forming a layer of solid dense, high stability of the metal surface treatment method on the coating. The passivation greatly improves the corrosion resistance of the coating and increases the surface gloss and anti-pollution ability. This method is very widely used, galvanized, copper, etc., can be passivated.
3. Hydrogen removal
Most metal substrates such as steel, copper in pre-treatment (pickling, cathode electric lift oil) and the process of electrodeposition, produces "hydrogen", some even had time to form a "hydrogen" namely in the form of a "hydrogen" into the substrate and the coating, plating parts produced brittleness, severely reduce the tensile strength of parts, called hydrogen embrittlement. Therefore, parts used in aerospace, automobile manufacturing and other fields must be treated with "hydrogen removal" after plating, and some parts requiring high tensile strength in use should also be treated with "hydrogen removal". The dehydrogenation process is carried out at a temperature of about 200℃, and the processing time is determined according to the tensile strength required by the parts. Dehydrogenation should be carried out within 3 hours after plating.
4. Coloring
Metal surface coloring is to form a layer of different color film or interference film layer on the metal surface by chemical, electrochemical, displacement or heat treatment methods in a specific solution. Due to the different colors of various metal oxides, the colored metal surface presents different colors, changing the appearance of the original metal, to imitate expensive metal, antique, decoration and other purposes.
5. Coating treatment
Coating film is to silver and imitation gold coating parts, coating or dipping a layer of transparent organic film layer, to prevent or continue the process of coating discoloration.
6. Closed treatment
It is in order to improve the corrosion resistance of the workpiece in the atmosphere, using physical, chemical or electrochemical methods, so that its surface (or intermediate coating) evenly covered with a layer of film layer, this process is called closed.
Pre-treatment plays a key role in the effect of electroplating, and post-treatment plays a significant role in promoting the performance of electroplating parts. In order to ensure the performance of electroplating parts, a reasonable post-treatment process is necessary.